Operational Performace Comparison: Viper, Beagle, and Stubby

Unread postPosted: 09 Jul 2014, 16:18
by sprstdlyscottsmn
Hello All,

I have received a lot of interest on this comparison, and it is honestly still going. Each aircraft has over 500 data points that must be looked up, cross checked, and calculated. Due to the time this is taking I figured I would go ahead and make the thread and let people know of my progress/limitations I am having.

Just to re-cap, I am comparing certain kinematic parameters for the Viper, the Viper with CFT, the Mudhen/Beagle/Strike Eagle, and "Stubby". All aircraft will have similar payloads (the F-35 will, when clean, have two fewer AAMs) and similar mission sets for both A2A and A2G. These missions are a 500nm CAP/Interdiction, in which loiter time will be measured, and Escort/Deep Strike, in which max range will be measured. Each mission will be calculated once with no external tanks, once with tanks retained, and once with tanks dropped. These again will all be calculated for both an Optimum cruise profile, in which cruise speeds and altitudes will be measured, and for an Operations Limited 20,000ft and 0.8M flight profile. In each case, the Structural G, Lift G, and Thrust (Sustained) G, available at the given cruise speed/altitude is calculated once at the 500nm point. The 0.8-1.2 level acceleration is also recorded to show excess transonic power available.

My calculations for the Stubby's performance is based on all the data that has been publicly released (most helpful of which was the statement of fuel burn at a given speed/alt), all data I have gathered over the last 14 years about dynamic trust, fuel burn, and wave drag, combined with my education as an Aerospace Engineer.

So Far my calculations show a few things to say I am on the right track, under the Op Limit case, Stubby has a radius of just under 600nm (remember, the range estimates are calculated using a "specific flight profile" among other assumptions) and an ability to sustain ~1.25M without Afterburner.

Currently my biggest logjam is decided where to put the Drag Divergence number for the Stubby as it greatly determines the Optimum Cruise speed. The F-16C and F-15E have a difference of ~0.06M when clean in this regard, with the Beagle being the higher of the two. The F-35 has a smaller frontal area than the Beagle, similar Mil Thrust, smaller wetted area, and when I look at all the various "bumps" on the F-35 I notice that as one decreases another grows trending to what is possibly a perfectly smooth (granted not the thinnest) area ruling.

More to come!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 17:56
by hb_pencil
sprstdlyscottsmn wrote:Hello All,

I have received a lot of interest on this comparison, and it is honestly still going. Each aircraft has over 500 data points that must be looked up, cross checked, and calculated. Due to the time this is taking I figured I would go ahead and make the thread and let people know of my progress/limitations I am having.

Just to re-cap, I am comparing certain kinematic parameters for the Viper, the Viper with CFT, the Mudhen/Beagle/Strike Eagle, and "Stubby". All aircraft will have similar payloads (the F-35 will, when clean, have two fewer AAMs) and similar mission sets for both A2A and A2G. These missions are a 500nm CAP/Interdiction, in which loiter time will be measured, and Escort/Deep Strike, in which max range will be measured. Each mission will be calculated once with no external tanks, once with tanks retained, and once with tanks dropped. These again will all be calculated for both an Optimum cruise profile, in which cruise speeds and altitudes will be measured, and for an Operations Limited 20,000ft and 0.8M flight profile. In each case, the Structural G, Lift G, and Thrust (Sustained) G, available at the given cruise speed/altitude is calculated once at the 500nm point. The 0.8-1.2 level acceleration is also recorded to show excess transonic power available.

My calculations for the Stubby's performance is based on all the data that has been publicly released (most helpful of which was the statement of fuel burn at a given speed/alt), all data I have gathered over the last 14 years about dynamic trust, fuel burn, and wave drag, combined with my education as an Aerospace Engineer.

So Far my calculations show a few things to say I am on the right track, under the Op Limit case, Stubby has a radius of just under 600nm (remember, the range estimates are calculated using a "specific flight profile" among other assumptions) and an ability to sustain ~1.25M without Afterburner.


I'm not too sure about your range estimates... depending on your assumptions, 600nm for a full heavy A2A load is incorrect. That's basically the same radius as the A2G load out with 4000lbs of bombs. The Radius with a light A2A load (only two missiles) is around 700~750 NM.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 19:01
by castlebravo
sprstdlyscottsmn wrote:My calculations for the Stubby's performance is based on all the data that has been publicly released (most helpful of which was the statement of fuel burn at a given speed/alt), all data I have gathered over the last 14 years about dynamic trust, fuel burn, and wave drag, combined with my education as an Aerospace Engineer.


Where did you get the fuel burn rate data? The only number I've seen was a comment on a blog post saying ~4600lb/hr at 30k and Mach .75 with a 2500lb weapons load, but it doesn't mention fuel load (or better gross weight), so I don't know how useful that is. A clean ~28klb viper with a full tank will consume something like 1/3rd more fuel/distance at optimum cruise than the same viper at 21klb about to flame out. With a much larger internal fuel fraction, I would imagine that figure varies much more for the F-35 than it does for the F-16C.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 19:45
by sprstdlyscottsmn
Castlebravo, I used the data you listed along with the publicly released figures of the airframe and engine to estimate both the drag, and thus the weight, of the aircraft as there was also the KEY statement of that being the max endurance point.

hb pencil, a mud moving load of ~4700lb or a full 6AAM A2A load of ~2100lb is a difference of ~2600lb on an airframe that is weighing roughly 50,000lb mission starting weight, a mere 5% difference. Since the drag is essentially the same minus the added lift drag the radii for a mud mover and its escort is very small. Also remember that the range figure I gave is for the constrained sub-optimal flight profile (and is in the ball-park of the "official" figure), the optimum profiles are giving numbers in the 700+ range like you state.

Thank you both for you input, I always like to see people thinking critically.

I have Preliminary data for the F-35 (unless I decide through input here to change the drag divergence mach number from the lowest value to a higher value) completed, F-16C completed, F-16C w/CFT and F-15E are about 30-40% done.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 20:49
by castlebravo
sprstdlyscottsmn wrote:Castlebravo, I used the data you listed along with the publicly released figures of the airframe and engine to estimate both the drag, and thus the weight, of the aircraft as there was also the KEY statement of that being the max endurance point.


What was the gross weight you ended up with for 4600lb/hr cruise?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 21:02
by sprstdlyscottsmn
about 39,000lb

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jul 2014, 23:57
by zero-one
Sprts. Can't wait to see this, by the way, what Stubby model are you using? I have a hunch its the A, I'd be happy to see the C model as well, in my oppinion the A and the C models should rival each others Kinematics in different ways.

better T/W ratio vs better W/L,

"A" may have better IST Turn rates and G handling while the C may get better STD Gs esp at higher altitude, similar to the claim that Eagles are more maneuverable than vipers above 30K feet, or something like that

also watching an old JSF documentary, I remember it was the Navy that required more maneuverability which gave Boeing designers a headache with their less maneuverable X-32 design.

The docu didn't say if the AF had any such requirements, I guess they didn't since at the time they thought they would have 300+ insanely maneuverable F-22s anyway.

So i'm guessing they were happy with X-32 class agility, but the docu did say that LM had no problems with the increased performance requirements of the Navy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 00:04
by spazsinbad
'zero-one' not quite sure what you mean by this quote (from an old documentary?):
"...also watching an old JSF documentary, I remember it was the Navy that required more maneuverability which gave Boeing designers a headache with their less maneuverable X-32 design...."

Lots of things give people headaches these days. However it is clear to me that the USN F-35C requires good manueverability at the required minimum/maximum carrier landing approach KIAS and weights. The weight/speed combination is set in stone for the current capacity of arrestor gear. There are no ifs or buts for the maximum required bringback weight and the airspeed combination otherwise the arrestor gear breaks. The KPP is 145 knots for the required F-35C bring back weight KPP (thrown in are the required fuel levels to achieve other criteria accounting for weather etc.).

Is this what you mean?

Classic 'Bowman' quote re USN KPP:
Scorecard: A Case study of the Joint Strike Fighter Program
Geoffrey P. Bowman, LCDR, USN — 2008 April - pages 10-11

"...The Navy has added approach speed as a service specific key performance parameter. The threshold for approach speed is 145 knots with 15 knots of wind over the deck. This must be possible at Required Carrier Landing Weight (RCLW). The RCLW is the sum of the aircraft operating weight, the minimum required bringback, and enough fuel for two instrument approaches and a 100nm BINGO profile to arrive at a divert airfield with 1000 pounds of fuel. The minimum required bringback is two 2000 pound air-to-ground weapons and two AIM-120s. The Navy further requires that the CV JSF be capable of carrier recovery with internal and external stores; the external stations must have 1000 pound capability on the outboard stations and maximum station carriage weight on the inboard."

Source: http://www.f-16.net/f-16_forum_download-id-14791.html (PDF 325Kb)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 00:17
by sprstdlyscottsmn
zero-one, I am doing the A model for this go. I will have to make a few assumptions to create a model for the C to properly account for how the big wing will impact form drag and wave drag. WRT turning, the data I am seeing now is that under most operational scenarios the C will have better instant and sustained turn rates as the F-35A is lift limited under these conditions. What the F-35A will have that I do not expect the C to have is the M1.25 max speed in Mil. But I will do the C comparison against the F/A-18E.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 01:37
by zero-one
spazsinbad wrote:'zero-one' not quite sure what you mean by this quote (from an old documentary?):


I think the title was "Battle of the X planes"

sometime in early development it said that the Navy increased the maneuverability requirement for the JSF

Which was one of the considerations (Im sure there were more) for Boeing changing the design from a heavy Pure delta to tailed delta like the F-22/35, which for a time was being considered to be a Pelikan tail design

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 01:38
by zero-one
sprstdlyscottsmn wrote:zero-one, I am doing the A model for this go. I will have to make a few assumptions to create a model for the C to properly account for how the big wing will impact form drag and wave drag. WRT turning, the data I am seeing now is that under most operational scenarios the C will have better instant and sustained turn rates as the F-35A is lift limited under these conditions. What the F-35A will have that I do not expect the C to have is the M1.25 max speed in Mil. But I will do the C comparison against the F/A-18E.


Wait hold on! the C will have better IST turns than the A?

I thought Smsgtmac said the A will have better ist Turn performance

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 02:04
by spazsinbad
'zero-one' I think my explanation accounts for the doco comment. IT is important that the F-35C lands on a carrier as required in the KPP - otherwise?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 03:09
by zero-one
spazsinbad wrote:'zero-one' I think my explanation accounts for the doco comment. IT is important that the F-35C lands on a carrier as required in the KPP - otherwise?


Possibly, all they said was, "The Navy wanted a more maneuverable fighter"

then Boeing changed their final design, but pushed with the prototype.

Since the F-35 is billed by many to have Hornet like Agility, and the X-32 is less maneuverable than the X-35, then it could be that the X-32 was expected to have less than the F/A-18's performance.

I guess the Navy simply didn't want a step backwards in performance

Again all these are just guesses

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 03:23
by spazsinbad
Just as one speaks of the devil.... youse can hear the chains rattle - or synchronicitical co-incidence? :devil: The long running thread about the MILLStones at where ever will have a test pilot comment about the F-35C Manuver ABilitity. I'm not spellin' well today am I? :doh:

viewtopic.php?f=57&t=15767&p=274976#p274976

Here is the quote there:
"......Another major test programme currently under way at VX-23 is high angle-of-attack (AoA) envelope expansion. Initial envelope expansion and intentional departure testing, which required the use of a spin recovery chute, was conducted with F-35B BF-02 and F-35Cs CF-01 and CF-05. The ITF then conducted initial low-speed departure resistance testing, high AoA loads testing, and high AoA buffet testing with F-35B BF-03 and F-35C CF-02 to prove the recovery characteristics of each variant from uncontrolled flight.

“The ‘B was not expected to be much different from the ‘A because the wings are a similar shape, the tails a similar shape, but the mass properties distribution differs because the propulsion systems are different, and each variant’s fuel load is carried differently. Fundamentally the aerodynamic shape of the ‘B and ‘A is broadly similar, whereas the C has a different wing and a massive tail. While the B is turning out to be very nice, the C is the most remarkable, it’s absolutely awesome at 50 alpha and very controllable,” said Peter Wilson STOVL lead with the Pax F-35 ITF...."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 04:22
by sprstdlyscottsmn
zero-one wrote:
sprstdlyscottsmn wrote:zero-one, I am doing the A model for this go. I will have to make a few assumptions to create a model for the C to properly account for how the big wing will impact form drag and wave drag. WRT turning, the data I am seeing now is that under most operational scenarios the C will have better instant and sustained turn rates as the F-35A is lift limited under these conditions. What the F-35A will have that I do not expect the C to have is the M1.25 max speed in Mil. But I will do the C comparison against the F/A-18E.


Wait hold on! the C will have better IST turns than the A?

I thought Smsgtmac said the A will have better ist Turn performance


Under some circumstances he is correct. Two things limit an planes ITR: Lift and Structure. Generally only one limits at a time and which one is dependent on speed.

Below Corner Velocity a planes turning is limited by how much dynamic pressure it can put on the airframe at Max Lift Coefficient. Dynamic pressure it determined by air density and airspeed. At 30-40kft and subsonic most aircraft are lift limited as the dynamic pressure for corner velocity will be well into the supersonic region.

Above corner velocity a planes turning is limited by the structural loads imposed by the lift limit (in the case of the F-16 we are talking the neighborhood of 234,000lb, or 9G at 26,000lb). At Sea level this occurs between 350 and 500 knt and the speed only goes up as air density goes down.

So, as you can see the 9G F-35A will have the advantage in a super sonic fight or transonic at low altitude, but the F-35C with an extra 50% wing will hold the advantage at lower speeds.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 05:45
by castlebravo
The F-35C also has to contend with higher empty weight. We know that the KPP for the F-35C STR is higher than the F-35A, but for all we know that could be at the same gross weight. It is still entirely possible that the F-35A has greater sustained turn performance than the F-35C when both are carrying a fuel load that gives similar range. I even consider it a likely possibility if the F-35C is carrying a gun pod.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 06:17
by zero-one
spazsinbad wrote: the C is the most remarkable, it’s absolutely awesome at 50 alpha and very controllable,” said Peter Wilson STOVL lead with the Pax F-35 ITF...."
[/quote]

Good find Spaz.

These are the times when I wonder, why didn't they make the A more in common with the C than with the B?

-more wing area
-more fuel
-more range
-more room for weight growth maybe
-and as Spurts is finding out, more maneuverable,

on the other hand
-less acceleration

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 06:21
by zero-one
sprstdlyscottsmn wrote:So, as you can see the 9G F-35A will have the advantage in a super sonic fight or transonic at low altitude, but the F-35C with an extra 50% wing will hold the advantage at lower speeds.


that doesn't seem good as most maneuvering fights occur at high subsonic speeds, So are we saying that the C can hold its own better than the A in a gun fight?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 08:55
by KamenRiderBlade
zero-one wrote:
sprstdlyscottsmn wrote:So, as you can see the 9G F-35A will have the advantage in a super sonic fight or transonic at low altitude, but the F-35C with an extra 50% wing will hold the advantage at lower speeds.


that doesn't seem good as most maneuvering fights occur at high subsonic speeds, So are we saying that the C can hold its own better than the A in a gun fight?

When you say high subsonic, what Mach range are you talking about?

Is it within the Transonic band? of 0.85-1.0?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 15:38
by sprstdlyscottsmn
Update: F-16C with CFTs is done. F-15E is about 50% and will take a while to get right as the data is in a different format. Lastly I will have to get all the findings presented nicely.

castle bravo, the F-35C has between 10 and 17% more weight depending on load carried (as both planes get lighter the difference gets bigger) which gives a first order increase in lift required. It has 50% more wing and larger tails to generate said lift. This is a first order reduction in Cl required to make the 10-17% more lift. Cl is a second order factor in determining drag due to lift, which is dominant in maneuvering flight. So, no matter how much more weight the F-35C carries in the same configuration as an F-35A, it will always have less induced drag at the same G. It will also always have more form drag at any speed/G, but there will come a point when lift-drag overpowers form-drag and the "Sea" will beat out the A in excess power.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 23:42
by zero-one
KamenRiderBlade wrote:When you say high subsonic, what Mach range are you talking about?

Is it within the Transonic band? of 0.85-1.0?


Well, where do most dogfights occur?

AFAIK its Mach 0.75-0.95,

if Navy C models were to practice DACT with AF A models, I think I would put my money on the Topgun pilots.

Same sensors, same avionics, Stealth, (by the way does the A & C have the same RCS?) but with more maneuverability :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Jul 2014, 23:45
by zero-one
By the way Sprts, it looks like the rivalry between A & C's kinematics are getting pretty interesting, can you make a comparison between the 2 also?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Jul 2014, 15:10
by sprstdlyscottsmn
Range and speed are done for the Mudhen. Working on turning and acceleration. The difference in range between a fixed flight profile and an optimum one are astounding.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jul 2014, 19:47
by sprstdlyscottsmn
All data gathered, now just formatting the presentation.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jul 2014, 04:36
by johnwill
This discussion about the relative maneuverability of the "A" vs. "C" sounds very much like comparing F-16 with F/A-18. As a side issue, using mach number to show where each airplane is best could be misleading. Altitude has been mentioned as a factor, but the easiest way to describe the optimum areas of each airplane is Calibrated Airspeed. In the design requirements, corner velocity requirements at several altitudes are shown in velocity vs. g diagrams, where velocity is calibrated airspeed. Just a guess on my part, I would expect the A to have higher turn rates above 350 - 400 kcas, regardless of altitude, and the C to do better under that speed.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jul 2014, 15:22
by sprstdlyscottsmn
KCAS is certainly useful as it really measures the dynamic pressure which handles both the speed and altitude factors.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2014, 23:04
by sprstdlyscottsmn
Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2014, 23:16
by KamenRiderBlade
sprstdlyscottsmn wrote:Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!


Nice job, I'm really looking forward to when you add in the Hornet family.

Are you willing to add in any older US aircraft to that comparison? Maybe like the F-5?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2014, 23:29
by sprstdlyscottsmn
KamenRiderBlade wrote:
Nice job, I'm really looking forward to when you add in the Hornet family.

Are you willing to add in any older US aircraft to that comparison? Maybe like the F-5?


What I add is limited to the resources I have. I do not have a flight manual for the F-5 (with performance section) nor do I have the type of info I would need to generate a model like I did with the F-35. I wish I still had my performance index from the F-4E. Anyway, if you have any public released docs for a plane I can add it in to a later review.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2014, 23:55
by KamenRiderBlade
sprstdlyscottsmn wrote:
KamenRiderBlade wrote:
Nice job, I'm really looking forward to when you add in the Hornet family.

Are you willing to add in any older US aircraft to that comparison? Maybe like the F-5?


What I add is limited to the resources I have. I do not have a flight manual for the F-5 (with performance section) nor do I have the type of info I would need to generate a model like I did with the F-35. I wish I still had my performance index from the F-4E. Anyway, if you have any public released docs for a plane I can add it in to a later review.


If I find anything, I'll definitely post it here for you.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Aug 2014, 03:13
by sirsapo
That's a pretty interesting analysis, but if I may add my 2 cents, if the chart formatting was a little better it would greatly add to the presentation. I'd add some X-axis grid lines, and some minor tick marks between them, along with some units on the axes (you put in the effort to come up with some pretty accurate numbers, might as well present them as such). Personally I think the USAF Test Pilot School format for charts and whatnot looks the most professional, but that may be just because that's what everyone is accustomed to seeing in their pubs.

Nice work

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Aug 2014, 04:17
by cantaz
Watch out for those possessive "its".

Not sure if using a 6 internal AMRAAM F-35 config as the basis for comparison is appropriate at this point. Maybe greater emphasis on it as future growth because right now it reads like a present capability which is not the case (and uncertain if it's still part of block 4).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Aug 2014, 10:18
by zero-one
Reading it now Spurst. This is awsome

I know im probably missing something, but what was the weapons load of the planes when they get to station?

You mentioned that they can carry up to X number of missiles, but Im a bit confused on the exact number of missiles they are carrying when on station, is it the max number or something else?

Also I noticed that there were some F-35(CFT) figures on the altitude page, does the F-35 have CFTs, i thought they only carried EFTs

Im also making assumptions on the bootom of the charts as to what the figures are (minutes for the endurance chart, mach number for the speed chart, etc etc.)
Am I correct.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Aug 2014, 22:59
by gergf-14
Awesome, be nice to see navy strike fighter comparison as well as the marines comparison. :drool:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Aug 2014, 05:35
by sprstdlyscottsmn
I wish I new the official test center format, but you are certainly right that I failed to provide units for my axes. I was importing thecharts from excel. Possessive its always get me. I was using 6 AMRAAM as I was using 2020 as my target year. I didn't list the payloads??? Man, I was so busy gathering data I forgot to make sure you knew what I was doing. A-A was six 120s for Stubby, two 9Xs and four 120s for Vipers, two 9Xs and six 120s for the Beagle. Air to ground was two 120s and two one ton GPS bombs for all, with the Vipers and Beagle adding two 9Xs. Also, the comment about F-35 with CFT was a typo. I will make some clarifications and play with a different format and re post. Thank you so much for the critique!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Aug 2014, 01:47
by zero-one
sprstdlyscottsmn wrote:I wish I new the official test center format, but you are certainly right that I failed to provide units for my axes. I was importing thecharts from excel. Possessive its always get me. I was using 6 AMRAAM as I was using 2020 as my target year. I didn't list the payloads??? Man, I was so busy gathering data I forgot to make sure you knew what I was doing. A-A was six 120s for Stubby, two 9Xs and four 120s for Vipers, two 9Xs and six 120s for the Beagle. Air to ground was two 120s and two one ton GPS bombs for all, with the Vipers and Beagle adding two 9Xs. Also, the comment about F-35 with CFT was a typo. I will make some clarifications and play with a different format and re post. Thank you so much for the critique!


Many thanks Sprst, can you also include the approx. fuel load of the planes when they get to station? just to make it clear what their current T/W ratios and Wing loading is when executing the said speeds, turns, etc...

only if its not too much trouble though :mrgreen:

i also noticed that you placed 29,400 lbs as the F-35A's empty weight, I thought the configuration 240-4 was actually lighter than earlier configs, I think 29,090 was the weight.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Aug 2014, 15:39
by sprstdlyscottsmn
I am making a lot of updates to the presentation aspect. It seems you all want more details so I am adding several pages of text going over the details of the load outs, fuel, drag, etc. I hope to have it up within a day or so.

zero-one, I am adding a page showing effective lifting area based on stability and Clmax. T/W ratio is a dynamic thing so it is a waste to use the uninstalled static sea-level values. Also, Wing Loading would be used to guess turning performance right? I am giving you the turning performance, both what it can sustain and what it can do in a snap pull. I do however concede that showing the fuel used can be of interest so I am showing the fuel burn for each transit phase and the amount remaining for the CAP (fight fuel).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Aug 2014, 00:39
by zero-one
sprstdlyscottsmn wrote:I am making a lot of updates to the presentation aspect. It seems you all want more details so I am adding several pages of text going over the details of the load outs, fuel, drag, etc. I hope to have it up within a day or so.

zero-one, I am adding a page showing effective lifting area based on stability and Clmax. T/W ratio is a dynamic thing so it is a waste to use the uninstalled static sea-level values. Also, Wing Loading would be used to guess turning performance right? I am giving you the turning performance, both what it can sustain and what it can do in a snap pull. I do however concede that showing the fuel used can be of interest so I am showing the fuel burn for each transit phase and the amount remaining for the CAP (fight fuel).


Thanks a lot Sprts, I think I can speak for all when I say, we appreciate your work A LOT I hope you won't mind if I use this for reference on a blog someday.

Also, I always saw T/W ratio as a ball park figure. so when they say T/W ratio is 1.07 I think that could be anywhere from 1.03-1.11 or something like that depending on air density and speed of the air entering the inlet. is this correct?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Aug 2014, 14:44
by sprstdlyscottsmn
This is something best seen. Google the High Fidelity Flight Manual for the sim Falcon 4.0. That taught me a lot about dynamic installed thrust. You see the 29,000lb thrust F100 vary from 32,000 to 5,000.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Aug 2014, 17:37
by archeman
Just reviewing the Conclusion section:

Conclusions
• We see that under actual combat conditions the F-35 can climb, run, and
turn as well as or better than it’s stable mates. It does this while having a
better ECM/EA suite, full IR targeting and spherical tracking, secure LPI
networking, and all aspect X-Band VLO. In short it is more capable than
anything that has ever been used in combat before <<<<<Missing period here
• Optimum Profile was done to show how “Max Range” mission data could
be gathered as these represent leaving a tanker and returning to a tanker
with reserves based on aircraft weight, a true best case scenario.
• Constrained Profile was done to show how mission planners and
battlespace managers may not want aircraft going across so many
altitudes, and max range at 20kft was at much lower speeds than the
0.8M calculated but the mission planners also can’t afford to simply wait
around <<<<<Missing period here
• When looking at the F-35s clean range at altitudes above 30kft it is easy to
see how the last 75nm in and out could be done as 1.25M and still make a <<<<<'as' should be 'at' ?
500nm+ range, which falls in line with the statement “150nm of cruise at
1.25M”. I may do a case study on this in the future.




Also for readability the Drag and Specs sections would work wonderfully as Tables instead of 3 paragraphs split across two pages. This would aid the reader to more easily and directly compare the figures across the types and would also provide the means to expand the aircraft types considered in the future.

Excellent work.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Aug 2014, 21:30
by sprstdlyscottsmn
And to think I had someone else proofread it too! Thanks.

Oh FYI, Drag is being completely redone, but tabulating the specs is a good idea and I am taking that action.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Aug 2014, 21:47
by spazsinbad
Proof reading - done by someone else - is ALWAYS a good strategy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 00:42
by zero-one
I really think this type of info should be placed on a Blog, there are literally dozzens of anti-F-35 blogs out there all calling the F-35 a turkey. and very very few bloggers that counter.

Mangler Muldoon is one of the few that go against the grain.

Hope he makes more F-35 topics in the future, this info may prove useful

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 04:04
by sprstdlyscottsmn
SMSGTMac has a blog, I wonder if he wants to use it?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 06:08
by zero-one
O right, the elements of power is a good source material. But don't you want to use it yourself to?

I mean, surely you didn't spend a good amount of time preparing this just for hardcore F-16.net readers right? :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 14:48
by sprstdlyscottsmn
Actually, I did. I don't have a blog. I did this for the F-16.net readers who are tried of naysayers naive talk about "external drag isn't that high" or "when both loaded to 50% fuel and two AAMs" nonsense and want a practical comparison to use. Well, and I guess I did this because I wanted to just for fun.

Of course while I am doing this I am wishing someone had a Su-27 manual for me to grab info for. I have been a fan of the T-10 series for over 15 years (aerodynamically speaking) and I would love to do a Flanker vs Eagle compro with scramble missions and escorts and CAPs.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 20:40
by mixelflick
sprstdlyscottsmn wrote: I have been a fan of the T-10 series for over 15 years (aerodynamically speaking) and I would love to do a Flanker vs Eagle compro with scramble missions and escorts and CAPs.


Would LOVE to see this myself. I bet the situation changes such that it favors the Flanker, especially the SU-35 vs upgraded F-15C's. REASON: It carries a LOT more gas than the Eagle, requiring less tanking. Add to that it's superior agility, I fear it'll gain quite an edge.

A lot of this hinges upon the unknown. IF the Eagle's AESA is as good as they say it is, IF the AIM-120D has a 50% increase in range and IF the SU-35 really has some measure of signature reduction (doubtful). I dunno man, it's going to be close that's for sure. Have to hand it to Sukhoi, they refined that beast over 3 decades to develop a (speculated) world beater...

Looking forward to it... 8)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Aug 2014, 22:16
by KamenRiderBlade
The one thing I've always like about Russian planes, they know how to pack in as much internal gas into their air frames.

Something America really needs to think about in all future designs.

I'm glad the F-35 is a step in that direction.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 01:00
by zero-one
sprstdlyscottsmn wrote:Actually, I did. I don't have a blog. I did this for the F-16.net readers who are tried of naysayers naive talk about "external drag isn't that high" or "when both loaded to 50% fuel and two AAMs" nonsense and want a practical comparison to use. Well, and I guess I did this because I wanted to just for fun.


Wow, well thank you very much Sprts, we appreciate it, never knew you were having such fun with that.

sprstdlyscottsmn wrote:Of course while I am doing this I am wishing someone had a Su-27 manual for me to grab info for. I have been a fan of the T-10 series for over 15 years (aerodynamically speaking) and I would love to do a Flanker vs Eagle compro with scramble missions and escorts and CAPs.


Yup, the Flanker is the best threat aircraft out there in my opinion, a worthy challange to any NATO air superiority fighter.

The most accurate sim/game I have is "Strike Fighters" and energy management on that game is brutal, (for me :mrgreen: )
F-16s and F-15s turn fastest at around 300+ knots, but bleed energy like mad at that speed,regardless of AB use.

The F-16C at Mach 0.85 has a lower turn rate, but it sustains energy better, still bleeding but a lot less than at 350 knots.

the Su-27S is a monster, turning at Mach 0.85,I have to stop using AB cause the thing keeps accelerating, and at Mach 0.9+ - Mach 1+ the turn rate drops. So I simply tap the AB from time to time.

When it comes to ECM and Target acquisition, the Flanker is behind the Viper and Eagle, the Alamo's Pk is considerably lower than the Sparrow's, and the Pk meter increases a bit slower when locking targets up.

Really teaches you that in A-A, Kinematics isn't everything

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 02:17
by sferrin
Oh boy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 04:12
by KamenRiderBlade
sferrin wrote:Oh boy.


What's that supposed to mean?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 19:09
by sprstdlyscottsmn
Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 19:12
by KamenRiderBlade
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


::Gives you a big hug::

Good job!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 20:49
by sprstdlyscottsmn
So I just saw that the revision was been downloaded (as of the time of this writing) 12 times. I didn't know that many people were interested enough to grab it up so fast! Checking the original file I see 230 downloads! Thanks for the support guys!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Aug 2014, 23:52
by meatshield
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


That is an interesting read! Thanks for posting! Educational. :cheers:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Aug 2014, 01:42
by zerion
Thanks Spurts, it's very informative. My only critique would be on the individual drag pages. Is there room to designate which aircraft at the top of each page?.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Aug 2014, 01:59
by newmanfrigan
Great stuff Sprts. I'm going to find it quite useful.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Aug 2014, 02:02
by KamenRiderBlade
sprstdlyscottsmn

Sent you alot of PM's about flight manuals, you may want to take a look

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Aug 2014, 15:33
by sferrin
sprstdlyscottsmn wrote:So I just saw that the revision was been downloaded (as of the time of this writing) 12 times. I didn't know that many people were interested enough to grab it up so fast! Checking the original file I see 230 downloads! Thanks for the support guys!


I'll bet half of them are from China. :wink:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Aug 2014, 23:44
by mixelflick
Amazing analysis.

How long did that take?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Aug 2014, 04:49
by sprstdlyscottsmn
mixelflick wrote:Amazing analysis.

How long did that take?

Hmm, I would have to guess around a hundred hours or so. The problem is I never had more than about 3 hours to work on it at any one time.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 02:01
by zero-one
This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 02:26
by KamenRiderBlade
zero-one wrote:This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:


http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 05:32
by zero-one
KamenRiderBlade wrote:http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case


I agree, the Wikipedia source was reportedly this one

http://www.jsf.mil/f35/f35_variants.htm

it does say the fuel capacity is 18,498 over there, and I usually just list it down as 18,500 lbs

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 05:59
by KamenRiderBlade
zero-one wrote:
KamenRiderBlade wrote:http://www.lockheedmartin.com/us/produc ... riant.html

Their webpage lists the Fuel Capacity as 18,200 lbs as well.

I'm more willing to believe LockHeedMartin than Wikipedia in this case


I agree, the Wikipedia source was reportedly this one

http://www.jsf.mil/f35/f35_variants.htm

it does say the fuel capacity is 18,498 over there, and I usually just list it down as 18,500 lbs


Maybe that 298 lb difference is the emergency fuel for reserves or APU or something else, something that is not normally used for normal flight calculations

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Aug 2014, 14:12
by sprstdlyscottsmn
zero-one wrote:This is awsome Sprts, just a few questions.

The Empty weight for the F-35A is registered as 29,400 lbs, however Config 240-3 is 29,300 lbs I believe and 240-4 is less than 29,100 if Im not mistaken,

the fuel capacity is also listed as 18,200 lbs, however
Wikipedia has it at 18,498 lbs supported by a credible source

Was just wondering what your source for these figures were :mrgreen:

Given the multitude of sources and their varied values, I went pessimistic and used the higher empty weight and the lower fuel weight.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 12:28
by hornetfinn
Great job, greatly appreciated! :D

I think in real world the range and endurance of F-35A will be even better as you seem to have used rather pessimistic TSFC number of 0.886 lb/lbf/hr. I think it most probably will have significantly lower TSFC as that TSFC number is more consistent with fighter engines produced in 1960s than current times. Modern (but older design) engines (like EJ200, M88) tend to have TSFC numbers of about 0.74 to 0.8 on dry thrust and I doubt F135 will be any worse than those. It might well be that F-35A has maybe even up to 25% better range/endurance than your calculations show. Or am I missing something obvious?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 14:24
by sprstdlyscottsmn
hornetfinn wrote:Great job, greatly appreciated! :D

I think in real world the range and endurance of F-35A will be even better as you seem to have used rather pessimistic TSFC number of 0.886 lb/lbf/hr. I think it most probably will have significantly lower TSFC as that TSFC number is more consistent with fighter engines produced in 1960s than current times. Modern (but older design) engines (like EJ200, M88) tend to have TSFC numbers of about 0.74 to 0.8 on dry thrust and I doubt F135 will be any worse than those. It might well be that F-35A has maybe even up to 25% better range/endurance than your calculations show. Or am I missing something obvious?


No, you are not missing anything obvious. In my research I have found that TSFC is not a static value either so I had to come up with a formula that approximates how it changes with speed and altitude. I am using the publicly available figure of .886 as the base and it only gets worse from there. I always try to go pessimistic if I have incomplete data.

However I don't think it would matter RIGHT NOW as much as you think. I had to use the TSFC to generate the drag model, so if the current TSFC is lower, than the base drag would have been higher, and this would have given worse acceleration and sustained turning performance. So if the data I have is for a pessimistic value, so be it.

I have heard someone, somewhere on the threads, say that a future block will get new avionics hardware and that the new hardware will have reduced cooling needs. Less bypass air cooling the electronics means for the same fuel burn you are getting a higher trust output and thus better TSFC (more range, better acceleration, etc). It might be true, I don't know. So in the effort to "play fair" I use publicly available numbers wherever I can and conservative choices.

I'm glad you all are enjoying this. I have already started gathering Super Hornet data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 16:43
by spazsinbad
"Spurts" I guess you have this Super Hornet Performance Data?

NATOPS FLIGHT MANUAL PERFORMANCE DATA
NAVY MODEL F/A-18E/F
1 AUGUST 2006

http://info.publicintelligence.net/F18-EF-200.pdf (29.6Mb)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Aug 2014, 19:39
by sprstdlyscottsmn
I do. It has the most complex drag matrix of any flight manual I have ever seen.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 03:14
by zero-one
spazsinbad wrote:"Spurts" I guess you have this Super Hornet Performance Data?

NATOPS FLIGHT MANUAL PERFORMANCE DATA
NAVY MODEL F/A-18E/F
1 AUGUST 2006

http://info.publicintelligence.net/F18-EF-200.pdf (29.6Mb)


Downloaded it loads of info, but Im a bit confused about the turn rate graph, it looks so different from the typical buldge looking ones.

30 degrees per second at 7Gs at around ~280 knots?
am I reading this correctly?

What's the altitude and laod for this?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 04:01
by spazsinbad
I had to memorise the A4G NATOPS - hahah - but I'm not going to do that for a Super Hornet I'll never fly. With 408 pages - OK not all are graphs/tables/charts/whatever - it would be pleasant if you give a page number for what is being referenced by your 'turn rate' reference. Thanks. For example: Are you referring to the "TURN CAPABILITIES CHART"?

There is an explanation on the beginning page of that section which explains some stuff I hope: PAGE XI-10-1 OR the beginning of Chapter 10 (bookmark pane is helpful or use search for this string TURN CAPABILITIES CHART

Are we in the same ball park? Beginning of CH.10 is page 367 - chart referenced above is page 372.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:00
by hornetfinn
sprstdlyscottsmn wrote:No, you are not missing anything obvious. In my research I have found that TSFC is not a static value either so I had to come up with a formula that approximates how it changes with speed and altitude. I am using the publicly available figure of .886 as the base and it only gets worse from there. I always try to go pessimistic if I have incomplete data.


Ok, thanks for the explanation. I definitely agree with your approach of going pessimistic with incomplete data. It definitely seems that F-35 is designed to have a very long range/endurance and be very maneuverable especially with A/G loads. Of course this translates to having both very long range and good maneuverability with A/A loads.

Wish you could make similar comparison with F-22... :)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:41
by zero-one
spazsinbad wrote:I had to memorise the A4G NATOPS - hahah - but I'm not going to do that for a Super Hornet I'll never fly. With 408 pages - OK not all are graphs/tables/charts/whatever - it would be pleasant if you give a page number for what is being referenced by your 'turn rate' reference. Thanks. For example: Are you referring to the "TURN CAPABILITIES CHART"?

There is an explanation on the beginning page of that section which explains some stuff I hope: PAGE XI-10-1 OR the beginning of Chapter 10 (bookmark pane is helpful or use search for this string TURN CAPABILITIES CHART

Are we in the same ball park?


Well, its my 1st time to view this type of graph so Im seeing that the load is 2 slammers 2 sidewinders and at 10,000 feet.

but 30 deg\sec at 7Gs around 280 knots,

considering that a block 50 viper at angels 10, with 100% internal fuel and 4 missiles makes only around 18 degrees pulling 8Gs albeit at a higher speed, I think 30 deg\sec on a Rhino seems a little too high, or am I missing something?

can the Rhino pull 7Gs at those slow speeds, I know slow speed maneuvering is one of the Rhino's strong suit, but 280 knots?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 07:52
by spazsinbad
I'll just post what I think is the chart to which you refer. What do you think NATOPS is all about? Misinformation? Probably eh. Bank Angle 81.8°

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 11:08
by bumtish
sprstdlyscottsmn wrote:I have heard someone, somewhere on the threads, say that a future block will get new avionics hardware and that the new hardware will have reduced cooling needs. Less bypass air cooling the electronics means for the same fuel burn you are getting a higher trust output and thus better TSFC (more range, better acceleration, etc). It might be true, I don't know. So in the effort to "play fair" I use publicly available numbers wherever I can and conservative choices.

I'm glad you all are enjoying this. I have already started gathering Super Hornet data.


Thanks for the effort. I agree that it is best to go with with the conservative numbers.

It was probably me who made a comment on the hardware upgrade which would deal with cooling of the electronics. As you mention, thermal management also affect range, drag, thrust, TSFC, et al. all interconnected. This quote should give some of the import.

The F-35's propulsion and avionics are running at higher temperatures than expected. To compensate, more bleed air from the Pratt & Whitney F135 engine is used for cooling, but this reduced propulsion efficiency and shortened range by 19.3km, according to sources familiar with the design issues.

http://www.flightglobal.com/news/articl ... ll-356581/


As I remember it, a hardware fix dealing with avionics thermal issues was notionally scheduled for block 4 (or 5?) or at least 2020-2022.

What are in the works here? Of course there are obvious items such as improvements to GFlops/Watt, increased efficiency of AESA modules and silicon carbide for actuators, and increased engine performance (e.g. ADVENT).

Some of the contracts can be found like this one.

In addition, a $1.5 million award from the Army Research Laboratory will focus on further development of advanced silicon carbide-based power modules for a variety of next-generation power electronics applications, such as motor drives, portable power units, or controlling the charge and discharge of high-voltage storage capacitors.

The F-35 Joint Strike Fighter is one of the first major programs implementing the Air Force’s new “More Electric” and “All Electric” aircraft design philosophy, which mandates the replacement of costly and bulky mechanical hydraulic aircraft flight control systems with lighter, high-reliability, low-maintenance electric motors and drives. The high-power densities and high voltages required to operate mechanical flight systems using electric motors are driving a transition to high-density silicon carbide, power electronic systems that can operate at higher efficiencies, higher voltages, higher power densities, and higher temperatures in comparison with conventional silicon electronics.

The contract will fund the transfer of laboratory -tested silicon carbide power electronics technology developed at APEI to F-35 actuator drive flight systems.

http://www.nwacouncil.org/news/2014/apr ... -northwes/


However, thermal management is far from individual technologies. It is about the system. And there is lots of effort going into F-35 which should be ready for insertion in due course.

Here is an article about INVENT from 2012.

The $150 million program has three phases. Spiral 1 focused on near-term technologies that could be spun off to the F-35 to help tackle thermal-management problems. Goals include doubling ground hold time, and increasing flight time at low altitude fourfold—both times when fuel heats up in the absence of effective cooling.

Spiral 2, now underway, is aimed at midterm requirements for next-generation energy-optimized aircraft. Goals include a 10% increase in range/endurance from integrated systems, a five-fold increase in power and cooling capacity, on demand, with no thermal restrictions.

Invent aims to cut energy demand by reducing combined subsystem weight, now twice that of a single engine, and reducing bleed-air and power-extraction to minimize the fuel-consumption and thrust penalties. The program is demonstrating three key systems for the next generation of more-electric aircraft: adaptive power and thermal management (APTMS), robust electrical power (REPS) and high-performance electromechanical actuation (HPEAS).

http://aviationweek.com/awin/afrl-s-inv ... efficiency


On the system side a lot is explained in this presentation. For F-35 specifics go to slide 31. A lot of this is explained in the rest of the presentation.

http://sdsi.asu.edu/wp-content/uploads/ ... hermal.pdf

In short: lot of opportunity to improve thermal issues on F-35, bot on component and integration level and programs of record underway.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 14:34
by sprstdlyscottsmn
spazsinbad wrote:I'll just post what I think is the chart to which you refer. What do you think NATOPS is all about? Misinformation? Probably eh. Bank Angle 81.8°

That chart is not about aircraft capability, it is about physics. if you pull X-G at Y-speed you would get Z turn rate. Nothing more than that.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Aug 2014, 15:57
by spazsinbad
The chart is about the Super Hornet Performance as indicated over page at the reference pages with salient info repeated here in the two graphics. I still have no idea if these graphics/references are the same that were queried by 'zero-one'. But anyway....

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Aug 2014, 01:22
by zero-one
You got it Spaz!!

I thought to myself, I know that slowspeed maneuvering at low altitude (10,000 feet) is one of the Rhino's strong suit, but man this is way high!!

However at around 420 knots pulling 8Gs (which the Rhino is capable of with the G overide switch), it becomes a more beleivable 20 deg\sec. thats around the block 50's ball park I guess.

question, can the F/A-18 pull 7-8Gs at such slow speeds? (under 300 knots)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Aug 2014, 01:32
by spazsinbad
Do you have F-35B/C NATOPS? These are TRUE AIR SPEEDS in the chart. At 10,000 feet 420KTAS is 350 KIAS approx.

For the Super Hornet then we have to know the weight/drag for any given flight condition.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 00:14
by delvo
I just took my first look at it. I didn't get some of what the graphs were saying, but didn't have much time to spend figuring them out. It seemed like there were labels missing. Maybe more detail on that later after a more on-topic review. For now, though...

You have F-35 carrying pairs of air-to-air missiles. 15 & 16 can't do that? I presumed they all could. I know I've seen an 18 configured that way. If 15 & 16 can't, then that fact should be made explicit instead of just left hanging out there, hopefully also with some reason why if it can be stated in just a sentence or two.

Why give AMRAAM and Sidewinder two separate rows in the table? Listing them separately could be seen as meaning that all of that could be carried at once, instead of just one row or the other, and any fighter on a maxed-out air-to-air mission will carry a combination, not just a whole bunch of the same thing, so the total is the relevant number. And it's mostly the same number for both types anyway, with any little difference between the AMRAAM number and the Sidewinder number just unnecessarily bringing up the question of why they'd be different. Plus, we don't even know the exact number for Sidewinders yet anyway because they haven't officially announced the exact configuration of the future trapeze contraption for internal Sidewinders. Better to just give the total number of air-to-air missiles without messing with how many are which types, so
(1+2+2+2+1) + (1+2+2+2+1) = 16.

"^2" is a poor substitute for a superscript 2, only to be used when a superscript 2 is impossible. If the program you're using to create PDFs somehow doesn't have a superscript option in its font controls or annoyingly increases the space between lines of text when you do use superscripts, use the ASCII character that's designed to look like a superscript 2 even when it isn't superscript: "²". You can copy & paste the one I just put there, or generate it yourself by holding down "Alt" while hitting "253" on the number buttons at the side of the keyboard (not the ones on the top row) and then releasing "Alt".

The abbreviation "ea" for "each" looks weird and only saves one or two characters anyway (1 with a period; 2 without, which is even wronger), and you're not pressed for space here; better to just use the whole word.

What does "aircraft get bounced" mean?

The external tank for F-35 seems to change between 426, 427, and 428 gallons. And that one's been canceled recently anyway, so the only one F-35 might end up with is 600.

Specifying in the conclusions page that its stealth is "X-band" just invites the false reaction that it's only stealthy in one band and not at all in the others. Just calling it "stealthy" or "VLO" is enough for this context and doesn't need additional expansion on how stealth can be slightly better in one band than others but still pretty close for all of them anyway and which bands are most likely to be used by which kinds of enemy sensors blah blah blah... it's a subject best left to some other place, not brought up in a paper on flight characteristics.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 00:47
by delvo
OK, now I see what was getting me about some of the graphs' labels: the labels are there, but aren't necessarily in or adjacent to the graphs. They're (at least sometimes) in the page title above, with paragraphs of text separating them from the graphs. For example, page 25's title says "500nm Interdiction Endurance (min)" and there's nothing in or near the graph to show that the unlabeled numbers on the X-axis are in minutes. It would have been easier to see the graph's meaning if the unit were integrated with the graph near the numbers, either with the phrase "endurance: minutes" or "endurance in minutes" in the middle of the bottom just below the numbers, or the unit behind each number, as in "30 min" instead of just "30". That would also allow the page titles to be more consistent: each page title could be just a mission, instead of sometimes a mission and sometimes a mission plus a "what's being measured for this mission and in what units" combined.

Also, some pages look so much like each other that it's as if they're meant for comparison, but they're separated, not consecutive... or at least they seem to invite comparison whether intentionally or not. For example, pages 17 and 25: they're 8 pages apart but arranged very much like each other, so the difference that F-35's performance looks significantly worse on 17 than on 25 stands out. At first it made me wonder, given a description in the conclusion about F-35 being better in real-world missions, if the point was supposed to be that the early pages presented unrealistic idealized scenarios, such as comparing all planes unarmed so the 15 & 16 would be unnaturally clean, and the later pages were there to correct them, like in the debate method of first stating the opponent's case and then knocking it down. This caused me to keep looking back and forth between them looking for the difference. It's in the titles that one is for a CAP and the other is for an interdiction, but that still leaves me wondering what's so different between those two things that makes such a large difference in F-35's place compared to the others, and why they aren't consecutive and given some explanation of what makes that difference.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 01:09
by sprstdlyscottsmn
CAP is Combat Air Patrol. An air to air mission type where you fly to a location and wait there for something to kill. The Interdiction is an air to ground mission. That is why there are two data sets. All the air to air data and then all the air to ground data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 02:12
by zerion
delvo wrote:What does "aircraft get bounced" mean?


Engaged by enemy aircraft.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 04:24
by sprstdlyscottsmn
delvo wrote:You have F-35 carrying pairs of air-to-air missiles. 15 & 16 can't do that? I presumed they all could. I know I've seen an 18 configured that way. If 15 & 16 can't, then that fact should be made explicit instead of just left hanging out there, hopefully also with some reason why if it can be stated in just a sentence or two.

No, only the F/A-18 can carry double AAMs in the teen series but I have seen loadout charts for both F-22 and F-35 with double AAM loadings on the heavy stations

delvo wrote:Why give AMRAAM and Sidewinder two separate rows in the table? Listing them separately could be seen as meaning that all of that could be carried at once, instead of just one row or the other, and any fighter on a maxed-out air-to-air mission will carry a combination, not just a whole bunch of the same thing, so the total is the relevant number. And it's mostly the same number for both types anyway, with any little difference between the AMRAAM number and the Sidewinder number just unnecessarily bringing up the question of why they'd be different. Plus, we don't even know the exact number for Sidewinders yet anyway because they haven't officially announced the exact configuration of the future trapeze contraption for internal Sidewinders. Better to just give the total number of air-to-air missiles without messing with how many are which types, so
(1+2+2+2+1) + (1+2+2+2+1) = 16.

Only the F-16 is truly interchangeable, all the other aircraft have certain hardpoints that can only carry one type or the other. The CFT stations of the F-15 can only carry radar guided missiles, but the AIM-9 hardpoints on the wing can carry AMRAAMs as well. The F-35 has no plans for internal IR missiles, and two of the wing stations are only for IR missiles and cannot carry an AMRAAM.

delvo wrote:"^2" is a poor substitute for a superscript 2,

You found some in the second posting? I thought I fixed all of those. Which page?

delvo wrote:The external tank for F-35 seems to change between 426, 427, and 428 gallons. And that one's been canceled recently anyway, so the only one F-35 might end up with is 600.

This is due to me forgetting which one it is as I type, sorry. I didn't know it had been cancelled, but my model certainly supports cancelling such a small tank. Here's hoping the Israelis make a good 600 gallon one.

delvo wrote:Specifying in the conclusions page that its stealth is "X-band" just invites the false reaction that it's only stealthy in one band and not at all in the others. Just calling it "stealthy" or "VLO" is enough for this context and doesn't need additional expansion on how stealth can be slightly better in one band than others but still pretty close for all of them anyway and which bands are most likely to be used by which kinds of enemy sensors blah blah blah... it's a subject best left to some other place, not brought up in a paper on flight characteristics.

Your last sentence pretty much sums it up. Thanks for your critique! As for axis labels, I tried a few things and couldn't get it to come out right.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 07:56
by zero-one
Easy there Delvo, remember Spurts isn't being paid to do this, its really just for fun and goodwill for him.

I really appreciate his work on this as I've been using it as a source material against basement dwellers.

Sprts, if you're really having such a good time with this, I wish you can make one with

the F-35's contemporaries on the subject. Multi-role fighters:
-Su-30 SMT
-Rafale
-Gripen NG
-Mig-35

etc.
and another one for Air Dominance fighters
F-22
EF2000
Su-35


And If I can make a suggestion, you recently said that you tend to be pessimistic when you have incomplete data,
I wonder, can you make an optemistic assesment with all the fighters that you have incomplete data on and compare it with your pesimistic calculations, then publish the middle ground of the 2?

For example
Turn rate
20 degrees\sec (optimistic approach)
18 degrees\sec (pesimistic approach)
19 degrees\sec (published data)

What do you think? does this make sense?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 15:24
by KamenRiderBlade
zero-one wrote:Easy there Delvo, remember Spurts isn't being paid to do this, its really just for fun and goodwill for him.

I really appreciate his work on this as I've been using it as a source material against basement dwellers.

Sprts, if you're really having such a good time with this, I wish you can make one with

the F-35's contemporaries on the subject. Multi-role fighters:
-Su-30 SMT
-Rafale
-Gripen NG
-Mig-35

etc.
and another one for Air Dominance fighters
F-22
EF2000
Su-35


And If I can make a suggestion, you recently said that you tend to be pessimistic when you have incomplete data,
I wonder, can you make an optemistic assesment with all the fighters that you have incomplete data on and compare it with your pesimistic calculations, then publish the middle ground of the 2?

For example
Turn rate
20 degrees\sec (optimistic approach)
18 degrees\sec (pesimistic approach)
19 degrees\sec (published data)

What do you think? does this make sense?


I think it'd be easier if you try to find him the manuals for the planes you want him to compare than to toss in numbers without basis?

I don't think it's worth his time to compare using made up numbers.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Aug 2014, 19:24
by archeman
When presenting this graph information to those who are not used to evaluating it they may not understand which direction (Up Down Left Right) is Better.

Also some us are kinda dumb, and need a little help with that stuff.

For example we can see in some charts that the F-35 'clean' line is below the others so that is better or worse (specific graph isn't important for my point here)?

If Up in the graphs is always better then it probably isn't needed, but if Down is sometimes better then the toggling can be harder to follow.

As I understand it, most of the enthusiastic reviewers of this fine work are using it to refute assertions of trolls with facts.
In most cases these trolls are folks who don't want to spend a lot of time researching facts so they will need all the help they can get.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Aug 2014, 00:55
by delvo
sprstdlyscottsmn wrote:You found some {"^2"} in the second posting? I thought I fixed all of those. Which page?
page 6, large font at the ends of the second, third, and fourth bullet sections (two in one case; four total on page)

pages 7, 8, and 9, twice in second line of each page's third bullet section

page 8, first line of final dash section

sprstdlyscottsmn wrote:As for axis labels, I tried a few things and couldn't get it to come out right.
If it's not working built in to the X axis or its labels, how about on top of the graph, as a graph title, instead of as part of the page title?

zero-one wrote:you recently said that you tend to be pessimistic when you have incomplete data,
I wonder, can you make an optemistic assesment with all the fighters that you have incomplete data on and compare it with your pesimistic calculations, then publish the middle ground of the 2?

KamenRiderBlade wrote:I don't think it's worth his time to compare using made up numbers.
It's not clear to me what data is missing or by what methods optimistic or pessimistic estimates for missing data would have been derived.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Aug 2014, 02:58
by zero-one
KamenRiderBlade wrote:
I think it'd be easier if you try to find him the manuals for the planes you want him to compare than to toss in numbers without basis?

I don't think it's worth his time to compare using made up numbers.


You missed my point. i never said those numbers were factual,

You see Sprts said that with incomplete data he tends to be pessimistic, for example with the F-35's empty weight, most sources pin it at 29,300 lbs, however there are some reports that say the latest configuration is less than 29,100 lbs.

The incomplete data and varriation in the sources forced Sprts to become Pesemistic and use 29,400 lbs as the empty weight.

However an optimistic approach would calculate the F-35's empty weight at 29,000 lbs. the middle ground is obviously 29,200 lbs.

I was wondering if there would be changes if that weight was used.

This is just a small example, he also used 18,200 lbs for the max internal fuel of the F35.
Most sources put it at 18,498 lbs.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Aug 2014, 04:47
by rpgrynn
zero-one wrote:
KamenRiderBlade wrote:
I think it'd be easier if you try to find him the manuals for the planes you want him to compare than to toss in numbers without basis?

I don't think it's worth his time to compare using made up numbers.


You missed my point. i never said those numbers were factual,

You see Sprts said that with incomplete data he tends to be pessimistic, for example with the F-35's empty weight, most sources pin it at 29,300 lbs, however there are some reports that say the latest configuration is less than 29,100 lbs.

The incomplete data and varriation in the sources forced Sprts to become Pesemistic and use 29,400 lbs as the empty weight.

However an optimistic approach would calculate the F-35's empty weight at 29,000 lbs. the middle ground is obviously 29,200 lbs.

I was wondering if there would be changes if that weight was used.

This is just a small example, he also used 18,200 lbs for the max internal fuel of the F35.
Most sources put it at 18,498 lbs.


Let the pessimistic numbers stand. Remember, the detractors are going to toss rocks anyway. The worst case numbers
make a very compelling counterpoint to the very strange notion the aircraft can't perform.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Aug 2014, 10:12
by spazsinbad
A bit old yet may be of interest.
DEPARTMENT OF DEFENSE STANDARD PRACTICE
GLOSSARY OF DEFINITIONS, GROUND RULES, AND MISSION PROFILES TO DEFINE AIR VEHICLE PERFORMANCE CAPABILITY
MIL-STD-3013A 9 September 2008

Source: http://www.everyspec.com/MIL-STD/MIL-ST ... 022905.PDF (1Mb)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2014, 13:08
by pron
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


I just saw someone make comments to your comparison at another forum, and I would like to hear your comment on this:

"The analysis goes off the rails on slide 6 where stability is judged by the apparent position of the horizontal stabilizer, leading to a totally bogus "effective lift area". Everything else falls apart from there, not that the fankiddies at f-16.net know or care. The problem is that claimed aerospace engineer "Spurts" is confusing incidence with alpha. The H-stab is in intense downwash from the wing and is in negative alpha even with positive incidence. Find out what company he works for and don't ever fly on their airplanes."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2014, 17:06
by newmanfrigan
[quote="pron"][quote="sprstdlyscottsmn"]Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.[/quote]

I just saw someone make comments to your comparison at another forum, and I would like to hear your comment on this:

"The analysis goes off the rails on slide 6 where stability is judged by the apparent position of the horizontal stabilizer, leading to a totally bogus "effective lift area". Everything else falls apart from there, not that the fankiddies at f-16.net know or care. The problem is that claimed aerospace engineer "Spurts" is confusing incidence with alpha. The H-stab is in intense downwash from the wing and is in negative alpha even with positive incidence. Find out what company he works for and don't ever fly on their airplanes."[/quote]

Lol. You can tell that it's "lowobservable" (ironic name), aka Bill Sweetman, who is nothing more than a Grippen fanboy with a paycheck. He couldn't analyze his way out of a paper bag. He likes to call F16.net the fankiddy forum....on Keypubs. The man has a poor grasp of irony apparently. This is classic psychological projection; F16.net is about 85% former uniform wearers. Keypubs....does it have any veterans (that aren't pro F35) at all? F16.net has an international cast of fighter pilots past, present and future, as well as maintainers, engineers etc. Does Keypubs have any (that aren't pro F35)? I've met Habu pilots on here..I've talked to Raptor pilots. We even have former Iraqi Airforce here.

Does Keypubs have even one single fighter pilot commenting (that's not pro F35)?

Bill Sweetman (lowobservable) has basically destroyed his own already very tenuous credibility over the F35. He's not an engineer, or a veteran of any kind. That's why he stays in his comfort zone in the real "Fankiddy" forum, which is of course the Keypubs. Keypubs is a Euro/Russian fanboy club where the residents comfort each other and make each other feel better about being significantly behind the US in fighter development. They shouldn't worry so much. It's not personal, it's just that the US has made a much larger investment into the critical technologies.

I can't comment on the analysis, as I'm a biologist, not an engineer, but I can say that Mr. Sweetman and the goofballs on Keypubs (Jo Asakura, JSR, MSphere) don't apply the scientific method to their analyses. There's very little of value on that site, unless you want to extrapolate hypothetical wing loadings, and ITRs.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2014, 21:35
by sprstdlyscottsmn
Wow, my analysis jumped forums? I'm honored. Someone decides that my analysis provides enough science to question their viewpoint so they decide to attack my character? That's their problem.

My credentials are getting an Aerospace Engineering degree from Embry-Riddle Aeronautical University (#1 school in the US for an AE degree) where my studies excelled in Aerodynamics and Stability. If whoever this person is doesn't understand trim drag then that is their shortcoming. Oh, and I don't work for any aircraft manufacturer. I work for an avionics company.

I did find a mistake in part of the stability analysis where it applied to the F-15 however. When I calculated the max lift coefficient for the F-15 is was based on stall speed at a given weight. This, in effect, is the modified CLmax. The true CLmax produced by the wing would then have to be INCREASED by the trim drag effects and would put it fairly close to 1.7. The "effective lifting area" for the F-15 was independent from the rest of the analysis and only served to explain why the relatively HUGE wing of the F-15 fails to allow it to generate the kind of turn that the F-16 can generate.

As for the nature of the analysis, the data I had specifically tells the stability margin (CG with respect to the AC of the main wing, which can be geometrically found) so it was not hard to find the geometric CG and estimate the AC of the tailplane to find the moment arm from the center of mass. Incidence, and alpha, angle of the tail is a result of what force is needed by the tailplane to balance the weight of the aircraft with the lift produced by the wing and body surfaces. So while there is a downwash, that only causes the tail to increase it's incidence to reach the required alpha to get the needed lift.

A perfect example of the above was explained to me by either johnwill or Gums (they both taught me so much years ago) that at 25 degrees angle of attack the tailplanes of the F-16 are near max incidence to still provided the upward force needed to stop the plane from flipping up and going into a deep stall.

So, to anyone interested in science, take my analysis and ask doubters to use science to refute it. I have relevant education combined with real world experience of others to back up my assertions. That said, I am always willing to learn new things from people with the right credentials.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2014, 21:57
by newmanfrigan
:
sprstdlyscottsmn wrote:Wow, my analysis jumped forums? I'm honored. Someone decides that my analysis provides enough science to question their viewpoint so they decide to attack my character? That's their problem.



So, to anyone interested in science, take my analysis and ask doubters to use science to refute it. I have relevant education combined with real world experience of others to back up my assertions. That said, I am always willing to learn new things from people with the right credentials.


It was Sweetman. :roll: It's a compliment to be attacked by Sweetman. Those of us who are involved in the sciences are pretty wary of "journalists" and their "analyses". Even though I look at kidney cells all day, and not at EM charts, the flaws in the products of the partially-educated are usually quite glaring.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2014, 23:04
by arrow-nautics
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


I belong to a FB pro-F-35 for Canada (Canadians for the F-35 Lightning II) page & I'd like your permission to post this PDF on that very page.

I await your response - EXCELLENT WORK :applause: :notworthy: :beer:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 01:39
by XanderCrews
sprstdlyscottsmn wrote:So, to anyone interested in science, take my analysis and ask doubters to use science to refute it.


This^

As for Bill, Sweetman gonna Sweetman. I do find it interesting that he involves himself in the "fanboy" accusations that should be beyond a professional such as himself. There are a lot of professional aircraft and military people on forums who actually act professional (or at least their age) and calmly explain things, which is what someone like Sweetman should be acting like, but instead he is bitter jaded and biased.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 01:40
by sprstdlyscottsmn
arrow-nautics wrote:
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


I belong to a FB pro-F-35 for Canada (Canadians for the F-35 Lightning II) page & I'd like your permission to post this PDF on that very page.

I await your response - EXCELLENT WORK :applause: :notworthy: :beer:


I cannot in good conscience allow you to post those PDFs. Only because of my glaring (to me) error in the F-15Es lift coefficient in the "Stability and Lift Area" page. So I fixed it up a bit. You may of course post Revision 2. No additional changes other than clarifying the Lift Area of the F-15E and adjusting the sentence describing my choice for the CLmax value of the F-35.

As an additional note, not that I know if anyone still cares, but my Naval analysis has run into a large snag in that the data presented in the Super Hornet manual is incomplete compared to the F-15/F-16 so I need to build a model for that as well. However because of the data available it is requiring me to make a very specific model (in the wave drag area) to match listed data points.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 02:01
by arrow-nautics
sprstdlyscottsmn wrote:
arrow-nautics wrote:
sprstdlyscottsmn wrote:Okay, here is revision one. I added more detail about the loadout, drag, and fuel burn as well as correcting the typos you all have found.

Oh and guys, please keep the comments civil and relevant to the discussion. People are allowed to have differing opinions and nobody is 100% correct 100% of the time.


I belong to a FB pro-F-35 for Canada (Canadians for the F-35 Lightning II) page & I'd like your permission to post this PDF on that very page.

I await your response - EXCELLENT WORK :applause: :notworthy: :beer:


I cannot in good conscience allow you to post those PDFs. Only because of my glaring (to me) error in the F-15Es lift coefficient in the "Stability and Lift Area" page. So I fixed it up a bit. You may of course post Revision 2. No additional changes other than clarifying the Lift Area of the F-15E and adjusting the sentence describing my choice for the CLmax value of the F-35.

As an additional note, not that I know if anyone still cares, but my Naval analysis has run into a large snag in that the data presented in the Super Hornet manual is incomplete compared to the F-15/F-16 so I need to build a model for that as well. However because of the data available it is requiring me to make a very specific model (in the wave drag area) to match listed data points.
I will respect your wishes :) I will await the revised version & I appreciate it. Tough study there Sprstdlyscottsmn. A big problem in the comparison between the SH & the CTOL is the straight/slanted hybrid wing drag penalty versus the modified delta wing drag penalty . The SH has a wing area of 500 ft² while the CTOL has an area of 460 ft². Also the SH has the (LEX's) forward surface area on each side of the cockpit. Very difficult to draw comparisons between these apples & oranges. I admire your ability to draw the distinctions. You certainly have more clout than even RAND IMO whereas you actually provide data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 03:14
by spazsinbad
'Spurts' probably you have this NATOPS of Performance for the Super Hornet but just in case:

NATOPS FLIGHT MANUAL PERFORMANCE DATA NAVY MODEL F/A-18E/F
165533 AND UP AIRCRAFT 1 AUGUST 2006

http://info.publicintelligence.net/F18-EF-200.pdf (30Mb)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 04:18
by sprstdlyscottsmn
I do have that, thanks. The -1 for the F-15E and for the F-16 are simply FAR more comprehensive. The NATOPS for the SHornet does have the most intricate stores drag matrix I have ever seen, but other than that I find it greatly lacking.

Arrow-Nautics, I guess you missed that I posted revision 2 in that same post. I wanted to fix it up for you before I responded. You should find it at the bottom of my previous post.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 05:13
by arrow-nautics
sprstdlyscottsmn wrote:Arrow-Nautics, I guess you missed that I posted revision 2 in that same post. I wanted to fix it up for you before I responded. You should find it at the bottom of my previous post.
I did notice that but I wasn`t sure if it was the final cut -

Is Spurts your call sign? (I know, likely a dumb question)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 08:18
by hornetfinn
Spurts, what do you think about the Mach 0.94 cruise speed for F-35B/C stated in here in relation to your excellent analysis:
http://www.f-16.net/forum/download/file.php?id=19926&mode=view

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 08:49
by optimist
hornetfinn wrote:Spurts, what do you think about the Mach 0.94 cruise speed for F-35B/C stated in here in relation to your excellent analysis:
http://www.f-16.net/forum/download/file.php?id=19926&mode=view

AFAIK Mach 0.94 is a KPP for the 3 models with 2x2,000 a/c, 2x1,000 b, all with 2x aim-20 and 50-60% fuel . altitude unstated from memory

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 09:54
by sprstdlyscottsmn
That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 11:39
by hornetfinn
It has been stated that F-35 burns about 4,600lb fuel in an hour while cruising with combat load. If it does so by cruising at Mach 0.94, then the range figures seem to be extremely conservative.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 13:18
by optimist
hornetfinn wrote:It has been stated that F-35 burns about 4,600lb fuel in an hour while cruising with combat load. If it does so by cruising at Mach 0.94, then the range figures seem to be extremely conservative.

AFAIK the range figures are for a specific mission and covers various altitudes, speeds and has afterburner as well in a dogfight on the way home

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 14:28
by hornetfinn
Very true optimist. Maybe instead of conservative, I should've said they are realistic. Problem is that many people think that these range figures are comparable to some other aircraft where the max range figures are truly max range figures in perfect conditions without use of AB or any combat maneuvering. I see F-35 having extremely long range compared to aircraft it's replacing and most other fighter aircraft also.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Dec 2014, 16:16
by sprstdlyscottsmn
the 4600pph had a very specific speed, altitude, and payload (.75M, 32,000ft, and 2500lb). This was also listed as being the max endurance speed (induced drag and parasite drag are equal). That was a very critical piece of info as it allowed me to estimate the Cdo.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jan 2015, 07:30
by hornetfinn
Thanks Spurts, that explains it perfectly. Can you tell where those specs (altitude, speed and payload) are from?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jan 2015, 03:07
by sprstdlyscottsmn
hornetfinn wrote:Thanks Spurts, that explains it perfectly. Can you tell where those specs (altitude, speed and payload) are from?


Originally posted here, link in post doesn't really go anywhere anymore however.


bumtish wrote:Post03 Oct 2011 15:03

Hi guys,

Energo wrote this on the Ares Blog. Is it of any help? Or perhaps if Energo tuned in on the thread? :D

"According to Col. Rob Simms at the US embassy in Oslo the F-35s optimal cruise is around 32000 feet and 0.75 mach where it burns about 4600 pph. Simplified this gives about 4 hours of fuel or 1600+ nm effective range (3000+ km) on internal fuel -- still with a 2500 pound internal tactical loadout."

http://www.aviationweek.com/aw/blogs/de ... 234d227276


viewtopic.php?p=205043#205043

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jan 2015, 03:13
by eskodas
Source link isn't working, here's the cached. http://web.archive.org/web/201108120449 ... 234d227276

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jan 2015, 03:25
by sprstdlyscottsmn
arrow-nautics wrote:
Is Spurts your call sign? (I know, likely a dumb question)

Oops, I missed this on the first pass through. I was never fortunately enough to be a military pilot (despite wanting to fly F-16s since I was 6). "Spurts" however was given to me in the same manner as a call-sign.

Back in the day...
viewtopic.php?f=36&t=10031
I hung on every word Gums, johnwill, and Roscoe would share with me. So naturally when johnwill complains about the length of my "name" and Gums decides to shorten it... well then a "callsign" it became.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jan 2015, 05:50
by smsgtmac
sprstdlyscottsmn wrote:That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.


That's not data without a source or altitude. I'd be very surprised if there IS a reliable source for it as AFAIK that KPP data has not been publicly released. No need to factor it into your equations yet. :wink:

Added 3 Jan: I should probably add that the 'Bowman Paper' makes reference (pp 7-8) to a mil power cruise capability of "greater" than .96 Mach 'threshold' and M1.0 'objective' with "internal weapons only" at 30K ft and at an unspecified weight/fuel load. Given that Air Vice Marshall Osley came close to stating the F-35A's trans-sonic acceleration KPP as also described in the Bowman Paper, Bowman data could be seen as increasingly credible, but still incomplete.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2015, 04:31
by dee
sprstdlyscottsmn wrote:Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!

Would you permit me to copy and post this on another blog? I would do so and credit you as the author of course.

Dee

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Jun 2015, 18:49
by sprstdlyscottsmn
dee wrote:
sprstdlyscottsmn wrote:Alright, here it is! I will take some of the initial feedback on this before doing the SHornet, ASHornet, and Sea comparison. There were several times where the performance results surprised me (both high and low) for all the aircraft. I welcome technical/process questions and constructive criticism about the layout and such. Enjoy!

Would you permit me to copy and post this on another blog? I would do so and credit you as the author of course.

Dee

Certainly, but I will let you know that part of my initial analysis has changed (not the main comparison numbers though) as it was pointed out to me that I was misinterpreting the C.G. data for the Strike Eagle. It is not highly stable and is more "neutrally" stable so it's Drag area is not as big as I had initially calculated but it is still around 16-17ft^2 IIRC. I don't have my data in front of me right now. Feel free to comment as such as I do not have a current revision of the data finished.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Jun 2015, 18:51
by sprstdlyscottsmn
smsgtmac wrote:
sprstdlyscottsmn wrote:That's big news to me. It tells me I was rather conservative with transsonic wave drag. I was off by over 7%, which is huge for engineering. I wish I had that data when I was starting.


That's not data without a source or altitude. I'd be very surprised if there IS a reliable source for it as AFAIK that KPP data has not been publicly released. No need to factor it into your equations yet. :wink:

Added 3 Jan: I should probably add that the 'Bowman Paper' makes reference (pp 7-8) to a mil power cruise capability of "greater" than .96 Mach 'threshold' and M1.0 'objective' with "internal weapons only" at 30K ft and at an unspecified weight/fuel load. Given that Air Vice Marshall Osley came close to stating the F-35A's trans-sonic acceleration KPP as also described in the Bowman Paper, Bowman data could be seen as increasingly credible, but still incomplete.


I agree to an extent, but my intial estimation was SO pessimistic that no cruise speed higher than .92M was possible and any weight or altitude. By .9M my initial wave drag was fairly overwhelming.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jun 2015, 11:17
by quicksilver
Use of the term "cruise" is problematic. Be specific, are we talking max endurance or max range?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jun 2015, 13:48
by sprstdlyscottsmn
I will always use Cruise for max range. Loiter speed is max endurance. You want to Cruise to the target using the least fuel to cover the distance and then Loiter around once you get there using your lowest fuel flow possible.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jun 2015, 14:40
by Dragon029
Perhaps, but we also have this document saying that (when you do the maths) that the F-35 at Mach 0.75 and 40,000ft can fly for around 4 hours and over 3000km:

Image

Perhaps the official 2200km range for the F-35 is just rubbish and it can fly more than 3000km at Mach 0.94 (similar to the "over 18,000lb" payload; where the hardpoints are rated for a total of 22,300lb or more and loading ~22,000lb of payload is the only way that you could achieve an F-35A's MTOW of 70,000lb).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jun 2015, 16:25
by sprstdlyscottsmn
fuel burn figures are VERY weight dependent, especially for Max Endurance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Jul 2015, 18:20
by eloise
Spurts someone else in keypub who also study aerodynamic, response to your analysis :D, so what do you think ? is he right? , is he wrong?
Andraxxus wrote: []Well his work seems thorough and accurate in method, I don't share his assumptions, and accuracy of calculations. Let me put a wall of text and some data to point out his mistakes or areas I don't agree.

F-15

F-15 doesn't have fixed 27% MAC stability, its limited between 22-29,9% and typical CG travel during a mission is as follows;

Image
Its reasonable for any maneuvering is required in mid mission, so I assume CG distance is at 24% MAC, and working from wing area and Mean chord length, it translates to 3,632 feet, not 4.

At landing CG detrimental, so that aircraft will not roll back to its rear end, I assume 10 degree AOA at landing, working from wikipedia 3-view drawing and moving backwards from 22% MAC gives CG to be roughly at the 2/3 of the F-15%'s airbrake. (too lazy to draw it and upload it here)

This means distance from the center of the elevators to CG is 7,63 meters or 25,03 feet.

So for X amount of lift, 0,1451X or counter-lift from elevators is required, so roughly 85% of the lift is used.

F-15 Flight manual gives stall speed at 30000 lbs exactly at 110 knots. Calculating Clmax from these gives us Clmax=1,2028 .

Incedentally, F-15's maneuvering Clmax is given by Soviet booklet is 1,0. My calculation gave (1-0,147)*1,2028 = 1,02; not too bad.

F-16

He explains CAT-I limiter well, but its implacions not. We are looking for maneuvering conditions, not stall, so whatever Clmax he found from CFD is irrelevant. AOA@G limitation is there for structural reasons and will change the REAL Clmax of the maneuving aircraft. For example, we know F-16's turn rate, speed and altitude conditions is from its flight manual. F-16 Clmax for M0.4, M0.5 1,3991, 1,5687 respectively. For 9G at 10000 feet, its 1,1.

As for his CFD work; an F-16 blk50 at 36000lbs DI-0 stalls at exactly M0,2 at MIL thrust (according to flight manual). 78kN MIL thrust, 25 degree stall AOA, stall speed, altitude etc are all sufficent to calculate Clmax, which equates to 1,5827.

So F-16's clmax is ballpark around 1.6 for stall and around 1.3 when maneuvering due to CAT-I and 1.1 at 9G ITR turns. Of course that is if we are talking about subsonic only.

F-35

"I estimate clmax of F-35 to be 1.8" No offense to the author, thats utter nonsense, and clearly not good enough.

Typical 64A204 F-16 uses tops out at clmax = ~1,1. F-16 adds to that primarily with LERX vortices and LE flaps to delay the stall and as a result achieves Clmax = ~1,6

What if an aircraft didn't have LERX and LE flaps? Well F-15 uses very similar but thinner 64A203 airfoil. Despite wide body, and 64A006 wing roots, It barely manages to get around Clmax = 1,2

1.8?? Lets see the ONLY competitive aircraft: Su-27 has LERX, le flaps, and achieves Clmax = 1.85 with this THICK airfoil:
Image
And remember, this airfoil more or less makes up the whole Su-27, from lerx to tail, excluding nacelles. Even area from nose to stinger is shaped as a supercritical airfoil, with nose look slightly downwards to improve lift in the "tunnel". As for F-35, such lifting body design is not present on F-35 to any degree (its more like F-15's body lift than Su-27 with lifting body), has no lerx to make airflow stick to wings, and my mk1 eyeball inspection tells it uses MUCH thinner wings than the profile above. (Abominal extensions below wing roots don't count as wings)

So for F-35, Clmax = 1.4 is most reasonable assumption to me, as its right between F-15 and F-16; with # of aerodynamic features is also 0 for F-15, 1 for F-35, and 2 F-16, i just take the middle: (1,6 + 1,2) / 2. This is also ballpark similar to MiG-29 and F-18, and I assume F-35 wont have AOA limitations of F-16, which is unique to that aircraft. So;

And by that, "CL*A" of these aircraft should be as follows (I am also writing in feet so that you can compare with his)
F-15E = 608*1,2*0,85 = 620 ft2 = 57,6m2
F-16C = 302*1,3 = 423 ft2 = 36,41 m2 and 332 ft2 =30,84m2 @9G
F-35A = 460*1,4 = 644 ft2 = 59,83 m2

With these Cl*A's known, we need weight to judge performance. Lets assume dogfight 500nm out take his range graph as accurate (I am also adding Su-27 as potential adversary, and just because I like Su-27)
F-15E = 58% fuel, = 18000kg
F-16C = 83% fuel. = 11735kg
F-35A = 57% fuel. = 18082kg
Su-27 = 40% fuel. = 20060kg (50% should easily reach

While all can pull 9Gs, their ITR will differ by speed;
F-15E = 17,17 deg/s @ 292 m/s,
F-16C = 16,07 deg/s @ 313 m/s,
F-35A = 17,6 deg/s @ 285 m/s,
Su-27 = 20,96 deg/s @ 240 m/s (Su-27's clmax @M0,75 = 1,51)

For STR we simply have insufficent data. Even we assume same Cd, we have to know exact Lift-drag to even make guesstimates about STR.

Lets go on with some other mistakes:

He is right about ANY payload attached to CFT limits F-15E to M1.4 but, again, his interpretion is wrong. To simplify, F-15E's CFT has 6 stations. Two rows are simply groupped as inboard and outboard in flight manual and these do limit to M1.4.
However, F-15 carries AIM-120s on stations 3C, 4C, 6C and 7C EVEN WITH CFT INSTALLED. (those stations extrude from inside CFT, between CT-1, CT-2 and CT-3 like this:
Image

So they are NOT CFT stations, and still subjected to general CFT limit of M2.0:

Image
As for the rest, he is making assumptions. This is his idea, I don't have a clue if they are correct or not.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Jul 2015, 18:56
by basher54321
eloise wrote:Spurts someone else in keypub who also study aerodynamic, response to your analysis :D, so what do you think ? is he right? , is he wrong?



:D

I think Spurts comparison was done after Andraxxus posted a really simplistic comparison based on clmax and turn rate.

viewtopic.php?f=33&t=25718

But there have been some corrections since then - also see
viewtopic.php?f=46&t=27333&start=15

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Jul 2015, 20:49
by borg
Andraax has downloaded and pick his figures from flight manuals.
Both from F-15 and Su-27SK.

If you mean to say he just invent stuff, well just download the fligh tmanuals yourself and go through them.
And then come back and correct any mistakes he made..

About the F-35, ofcourse his figures are not correct, sinse there is no flight manual at this point.
Still i'd say his assumption are not far out eighter.. meaning they look plauseble.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 00:10
by basher54321
borg wrote:If you mean to say he just invent stuff, well just download the fligh tmanuals yourself and go through them.
And then come back and correct any mistakes he made..


No I didn't mean that at all..................perhaps you are better off on a non English forum where you might understand a bit more about what's going on yes!!

Spurts comparison was also done using the same manuals - which I also have.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 01:42
by sprstdlyscottsmn
I appreciate Andraxxus time in going through my data. I certainly have it out there to be reviewed and anyone who can aid in the accuracy only increases the overall knowledge base. I have no way of knowing which version (I have four so far) of my analysis he was judging. My responses to his points are as such, and please go back and share my responses.

Of course the F-15 doesn't have a static MAC. 27% was not the best choice on my part and I have in my most recent version recanted the "Stable" part of that discussion as the Strike Eagle borders on neutral stability per other texts of the Manual.

For Strike Eagle max lift I used 40,000lb at sea level with power off for 125 kt, yielding which gives 1.24. With his 1.2028 I think we are splitting hairs. The reason it is much lower than the others is, in my opinion, due to the lack of full instability, LEF, and any LERX/chines.

For Viper lift, he goes on about how G, speed, and altitude matter. That was not the purpose of this section. I was trying to demonstrate the highest Clmax the F-16 could generate 9G with as that will give the "best" turn, even though the CAT-1 limited gives a best turn rate at ~8G and best radius at ~3G. You cannot use mil thrust as a stall indication as installed dynamic thrust does not equal (is less than at stall speeds) rated thrust.

As for the F-35, it has Chines which perform the same action as the LERX as evidenced by the vortexes they generate so I did not penalize it. The F-35 also has LEF, so again I am not penalizing it. What he is not bringing up is that both of these aircraft are fully unstable. This means the horizontal tails make lift. This added lift "adds" to the "reference" CLmax the same as a LERX does. Relatively speaking, the F-35 has a MUCH larger tail and it is deflected at least as much as the F-16 tail if not moreso when under similar circumstances. This means that that the tail of the F-35 has to make proportionally more lift than the tail of the F-16, so I gave it a higher Clmax. If he wants to disagree on this point he is certainly allowed to, the actual value will not be known to the public for decades to come.

For ITR he seems to take each of them to 9G and calculate ITR for the speed required by his ClMax analysis. I went a different route and showed what their ITR would be at the cruise speed for the mission based on the Manual (F-15E and F-16C) and my CLmax analysis (F-35A). So his is not wrong per say, just different.

STR is given in both Manuals for F-15E and F-16C so there is not a lot of guesswork involved.

For the F-35 I have to generate a model of dynamic thrust and work backwards through the induced drag equation to estimate the extra Cl available. This is, I admit wholly, the least accurate part of my analysis as it requires the most assumptions.

On to the payload. He is using an F-15A-1 not an F-15E-1. The F-15A-D are cleared to 700/2.0M with CFT/Fueselage mounted missiles. The SAME PAGE of the F-15E-1 lists 660/1.4.

Send him my regards, I appreciate the review.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 01:49
by sprstdlyscottsmn
borg wrote:Andraax has downloaded and pick his figures from flight manuals.
Both from F-15 and Su-27SK.

If you mean to say he just invent stuff, well just download the fligh tmanuals yourself and go through them.
And then come back and correct any mistakes he made..

About the F-35, ofcourse his figures are not correct, sinse there is no flight manual at this point.
Still i'd say his assumption are not far out eighter.. meaning they look plauseble.


I don't know if you have read my analysis in the first place, but I also used the F-15E flight manual. I have the Su-27SK manual and the only meaningful performance you can get from it is the V-n diagram (G for speed and weight) and the Cl-alpha to get ClMax. I wish there was more that you could get from it like the F-16 manual gives. Like my last post said, I appreciate his review and "counter analysis" if you will. He has a good technical approach. Peer review is what it is all about.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 03:00
by borg
Yes I agree. I was merly addressing some other members whom seems to cast doubts about andraxx way of work, which b.t.w. I find very helpfull.
Anyway, I meant no disrespect towards you sprst@

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 03:22
by sprstdlyscottsmn
None taken borg. Other than the use of the F-15A-1 for the weapon limitations there was nothing inherently wrong with his analysis. He made assumptions and gave his reasons for doing so. They are different than mine based on my different assumptions.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 05:51
by jessmo111
Hello Guys Long term reader, and frequent visitor.

I would like a laymans explanation on How the super hornet thrives in BFM, and at High AOA.
Since the F-35 seems to look more like a hornet in close, and will exploit peddal turns and probably
Pirouette type manuvers. How can this be exploited? I was never a Big Super hornet fan, so Im very curious.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 06:06
by eloise
sprstdlyscottsmn wrote:I appreciate Andraxxus time in going through my data. I certainly have it out there to be reviewed and anyone who can aid in the accuracy only increases the overall knowledge base. I have no way of knowing which version (I have four so far) of my analysis he was judging. My responses to his points are as such, and please go back and share my responses.

Of course the F-15 doesn't have a static MAC. 27% was not the best choice on my part and I have in my most recent version recanted the "Stable" part of that discussion as the Strike Eagle borders on neutral stability per other texts of the Manual.

For Strike Eagle max lift I used 40,000lb at sea level with power off for 125 kt, yielding which gives 1.24. With his 1.2028 I think we are splitting hairs. The reason it is much lower than the others is, in my opinion, due to the lack of full instability, LEF, and any LERX/chines.

For Viper lift, he goes on about how G, speed, and altitude matter. That was not the purpose of this section. I was trying to demonstrate the highest Clmax the F-16 could generate 9G with as that will give the "best" turn, even though the CAT-1 limited gives a best turn rate at ~8G and best radius at ~3G. You cannot use mil thrust as a stall indication as installed dynamic thrust does not equal (is less than at stall speeds) rated thrust.

As for the F-35, it has Chines which perform the same action as the LERX as evidenced by the vortexes they generate so I did not penalize it. The F-35 also has LEF, so again I am not penalizing it. What he is not bringing up is that both of these aircraft are fully unstable. This means the horizontal tails make lift. This added lift "adds" to the "reference" CLmax the same as a LERX does. Relatively speaking, the F-35 has a MUCH larger tail and it is deflected at least as much as the F-16 tail if not moreso when under similar circumstances. This means that that the tail of the F-35 has to make proportionally more lift than the tail of the F-16, so I gave it a higher Clmax. If he wants to disagree on this point he is certainly allowed to, the actual value will not be known to the public for decades to come.

For ITR he seems to take each of them to 9G and calculate ITR for the speed required by his ClMax analysis. I went a different route and showed what their ITR would be at the cruise speed for the mission based on the Manual (F-15E and F-16C) and my CLmax analysis (F-35A). So his is not wrong per say, just different.

STR is given in both Manuals for F-15E and F-16C so there is not a lot of guesswork involved.

For the F-35 I have to generate a model of dynamic thrust and work backwards through the induced drag equation to estimate the extra Cl available. This is, I admit wholly, the least accurate part of my analysis as it requires the most assumptions.

On to the payload. He is using an F-15A-1 not an F-15E-1. The F-15A-D are cleared to 700/2.0M with CFT/Fueselage mounted missiles. The SAME PAGE of the F-15E-1 lists 660/1.4.

Send him my regards, I appreciate the review.

thanks sprstdlyscottsmn, I found your and Andraxxus analysis very interesting, alot better than the common nonsense " F-35 suck because it look like a pig" or " bla bla... Carlos Kopp said so"

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 08:50
by eloise
BTW here is what he said about the LERX and vortex part :
Andraxxus wrote:If you are referring to the appearant vortex at intakes, its mostly useless, it will help reducing fuselage drag at best.

If you are referring to the canted area at wing roots, yeah it would produce a vortex which would actually be useful (and withness the benefits of CFD, no appearant body part, but airflow is still directed above wings with pressure differences). Still I would question the intensity of such vortex when compared to F-16/18.

F-15's LERX-like structure is a different -symetrical- airfoil (64A006). Its by definition not an extension of the wing's leading edge. It would of course produce a vortex, but again I would question the location and intensity of the vortex.

You have to understand LERX on F-16/18 Su-27 MiG-29 starts very well in front of the wings, even slightly in front of the cockpit canopy. By the time this vortex reach the main wings, it will be so large that entire wing wil be affected. This vortex is so dominant that a) airflows primary velocity is due to rotational action which makes small disturbances in early stall irrelevant, as with increased vortex intensity, air is fast enough reduce pressure further to increase lift. b) such velocity gives air higher inertia which helps delaying flow reversal.

Surely we are not living in 1960s. F-15's wing roots, F-22's chines, F-35's canted wings, Mirage 2000's and Typhoon's vortex generators, F-5E's and MiG-31's tiny root extensions all work in same very basic principle but size does matter here, and none of these can possibly approach 1/4 the intensity F-16/Su-27 achieve with their LERX (size relative to wing size of course). In fact, I would say, only method for improving vortex control even more is close coupled canards like on Rafale, and -if works as advertised- LEVCONs on T-50. For supersonics, Typhoons far positioned canards should work best as it allows distance for vortex intensity to grow

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 12:24
by sferrin
sprstdlyscottsmn wrote: What he is not bringing up is that both of these aircraft are fully unstable. This means the horizontal tails make lift.


Hell, there are pics out there of the F-35 in a turn with the horizontal tails pointed down.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 14:18
by johnwill
Because of AoA and wing wash effects, you have no clue whether tail lift is up or down.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 14:19
by sprstdlyscottsmn
sferrin wrote:
sprstdlyscottsmn wrote: What he is not bringing up is that both of these aircraft are fully unstable. This means the horizontal tails make lift.


Hell, there are pics out there of the F-35 in a turn with the horizontal tails pointed down.

Be careful with a statement like "down". Leading edge down or trailing edge down? Relative to the main wing, the - airflow, or the local airflow? In a stable aircraft the leading edge is always "down" (at negative local AoA) unless the nose is moving down significantly. In an unstable aircraft the leading edge will be "up" ( at positive local AoA) unless the nose is moving up significantly. There are several pictures of the F-16 in a turn with leading edge down relative to the main wing, but if the angle difference is less than the body AoA and any local downwash then it is still LEU at local airflow. Nothing is ever simple.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 14:19
by sprstdlyscottsmn
aw john beat me to it.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 14:20
by sferrin
johnwill wrote:Because of AoA and wing wash effects, you have no clue whether tail lift is up or down.


Just sayin' I don't recall ever seeing an F-15 in a turn with it's tails pointed down. In fact the only reason it jumped out at all is because it seemed so unusual. Like seeing F-22s in formation with F-15s straight and level but the F-22s have flaps partially deployed while the F-15s are flush.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 14:22
by sferrin
sprstdlyscottsmn wrote:
sferrin wrote:
sprstdlyscottsmn wrote: What he is not bringing up is that both of these aircraft are fully unstable. This means the horizontal tails make lift.


Hell, there are pics out there of the F-35 in a turn with the horizontal tails pointed down.

Be careful with a statement like "down". Leading edge down or trailing edge down?


Trailing edge of course. Why would I even mention leading edge down? Nothing notable about that as that's how it is on 99% of the aircraft out there.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 16:14
by sprstdlyscottsmn
Just making sure ;)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 18:08
by sferrin
sprstdlyscottsmn wrote:Just making sure ;)


In short, I was just pointing out that with relaxed stability aircraft things are not as cut and dried as "this much wing area with this weight = result". :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2015, 22:36
by sprstdlyscottsmn
exactly

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Oct 2015, 15:34
by sprstdlyscottsmn
Alright everybody. I will "soon" be coming out with a new comparison that will be much more intensive for me but will also be easier for everyone else. Mission profiles will all include taxi, take-off, climb, opt cruise segment, ingress cruise segment, combat segment, egress cruise segment, opt cruise segment, and descent. All stores will be assumed kept for range calculations as the pilot may get to the combat zone and find no target before RTB.

Combat segment will be equivalent to three sustained 360deg turns at 20K ft, .8M, and full AB. I will record fuel burn and the range of ITR and STR as fuel is burned.

Missions will be as follows.

Scramble - typical AAM load (centerline tank that is dropped when empty for legacy fighters) full AB until egress begins

CAP - Typical AAM load (three tanks for legacy fighters, not dropped) measuring loiter at 200nm from take-off

Escort - Typical AAM load (three tanks for legacy fighters, not dropped) measuring max range

Deep Strike - Two JSOW, 2-4 defense AAM (three tanks for legacy fighters, not dropped) measuring max range

CAS - Load of lighter bombs, TGP, 2-4 defense AAM (tanks as space available for legacy fighters, not dropped) measuring range and travel time with 1hr loiter at 10,000ft

I will do the the above for the following AC

F-15 (E for A-G missions, C for A-A missions) (utilizing F-15E-1)
F-16C (no CFT variants, note that range gets extended but turning decreases) (utilizing F-16C -1)
F/A-18E (utilizing NATOPS)
AV-8B (This will involve less calculation and more interpolation/extrapolation from a NAVAIR doc)
F-35 A/B/C (utilizing my performance model which currently matches all know specs (turn, accel, FF) to between 98.8% and 99.9% accuracy)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Oct 2015, 17:28
by geforcerfx
looking forward to reading it

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Oct 2015, 00:03
by eloise
sprstdlyscottsmn wrote:Alright everybody. I will "soon" be coming out with a new comparison that will be much more intensive for me but will also be easier for everyone else. Mission profiles will all include taxi, take-off, climb, opt cruise segment, ingress cruise segment, combat segment, egress cruise segment, opt cruise segment, and descent. All stores will be assumed kept for range calculations as the pilot may get to the combat zone and find no target before RTB.

Combat segment will be equivalent to three sustained 360deg turns at 20K ft, .8M, and full AB. I will record fuel burn and the range of ITR and STR as fuel is burned.

Missions will be as follows.

Scramble - typical AAM load (centerline tank that is dropped when empty for legacy fighters) full AB until egress begins

CAP - Typical AAM load (three tanks for legacy fighters, not dropped) measuring loiter at 200nm from take-off

Escort - Typical AAM load (three tanks for legacy fighters, not dropped) measuring max range

Deep Strike - Two JSOW, 2-4 defense AAM (three tanks for legacy fighters, not dropped) measuring max range

CAS - Load of lighter bombs, TGP, 2-4 defense AAM (tanks as space available for legacy fighters, not dropped) measuring range and travel time with 1hr loiter at 10,000ft

I will do the the above for the following AC

F-15 (E for A-G missions, C for A-A missions) (utilizing F-15E-1)
F-16C (no CFT variants, note that range gets extended but turning decreases) (utilizing F-16C -1)
F/A-18E (utilizing NATOPS)
AV-8B (This will involve less calculation and more interpolation/extrapolation from a NAVAIR doc)
F-35 A/B/C (utilizing my performance model which currently matches all know specs (turn, accel, FF) to between 98.8% and 99.9% accuracy)

thanks, that is awesome

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Oct 2015, 15:58
by vanshilar
Looking through the analysis, I have a couple of points. Keep in mind that though my background is in engineering (including some aero stuff, like control dynamics of aircraft), it's all really rusty now because I haven't used any of it.

1. I have somewhat of an issue with the Clmax of 1.8 for the F-35. Again, I'm more or less a layman at this (i.e. my understanding is lacking nowadays), but you're basically saying that the effective lift area is about 10% bigger than that of a F-15E due to your estimate. Yes the F-35 has a wider fuselage and larger tail (relative to the F-16), but I think to the average layman it may seem like you're trying to stack the deck in favor of the F-35, seeing as how it's an estimate. If I understand correctly, since the F-35 is unstable then the H-stab actually helps with lift right? I guess some remarks as to why it has such a large effective lift area compared to the other planes would be helpful. Although this would be purely hypothetical, it might also be worth calculating the Clmax for an F-16 if it didn't have the limiter, just to put the F-35's 828 ft^2 in perspective (noting, of course, that it's purely hypothetical and the F-16 in practice only sees the 510 ft^2).

2. I do find this interesting in another way: if the H-stab actually helps with lift for an unstable plane, then is it another reason why wing loading is no longer a good approximation of turning performance for modern military aircraft? Since the H-stab would actually decrease lift for stable planes, so looking purely at wing loading would underestimate the lifting ability of the plane for unstable planes.

3. You chose a mission distance of 500 nm. Is there a reason for this? It's probably arbitrary, but might be nice to have some words to justify it. The best would be to look at past mission data and say this is how far away the action usually was, but I imagine that's a pie-in-the-sky thing to be able to work out (though it's probably what the military planners did when working out the specs). Additionally, can also look at different distances, i.e. 200 nm, 400 nm, 600 nm, etc., to give the reader a sense of how each plane's performance changes; the F-35 has a high amount of internal fuel, so I imagine that a longer distance would actually give it more of an advantage.

Anyway, it looks very interesting. Yes most analysis I see does a "50% fuel load" which basically penalizes the F-35 with an extra 5,500 lb or so of weight compared with an F-16 for example, effectively penalizing the F-35 for having relatively long legs. (Similarly, talking about lifetime costs penalizes the F-35 for having a long designed service life -- I noticed with the Canada thing that people talk about the 30-year lifetime cost of buying a F-35, but never the 30-year lifetime cost of buying a Super Hornet, in which case you're probably talking about needing an expensive Service Life Extension or a replacement.)

My impression of the F-35 is that the planners realized that while aircraft had good performance when "clean", once the aircraft had to do anything their performance fell considerably, so in setting out the specs for the F-35 they went through and thought "what do we almost always stick on as external pods in current planes when they go on a mission? Make them all internal for the JSF" resulting in a bulky airplane because it's carrying fuel, sensors, etc. internally, while for current planes those capabilities need to be strapped on externally. Yet we don't see comparisons being laid out in this way, i.e. what are the operational specs rather than "clean" specs. Looks pretty neat.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 14:03
by sprstdlyscottsmn
vanshilar wrote:Looking through the analysis, I have a couple of points. Keep in mind that though my background is in engineering (including some aero stuff, like control dynamics of aircraft), it's all really rusty now because I haven't used any of it.

1. I have somewhat of an issue with the Clmax of 1.8 for the F-35...


This has been a point of contention by others as well. I don't know which version you read (there are three up here now and I had a fourth ready before I decided to change the analysis to the one mentioned a few posts up). I did analyze the F-16 without limiter and that went beyond 1.8. In one of my versions I did mention the lifting tail aspect and the effects of stability. I also recently did an analysis that was based on wing thickness, aspect ratio, sweep, camber (via flaps and LEF), vortex generation, and lifting tails. Using this I was able to match the values for the F-15 and F-16, and the F-35 still came to 1.8. The F-16 has a better lift curve slope, but the F-35 is allowed to go farther up its slope.

vanshilar wrote:2. I do find this interesting in another way: if the H-stab actually helps with lift for an unstable plane, then is it another reason why wing loading is no longer a good approximation of turning performance for modern military aircraft?


Very much so. Body lift is a red herring (for layman estimations) as wide bodied aircraft often have ~40% of their listed wing area in the body and the body is often listed as generating ~40% of the lift. Tail area on the other hand. That is never included but it contributes greatly. I looked at the CG range of the teen series and was amazed at what I saw. The F-14 has a CG range of 6-17% MAC with wings unswept. A stable design. It only gains stability as the wings go back. The F-15 A-E are around 23-29% MAC and the F/A-18 A-G are all around 16-31. This puts these two on the stable side and unstable side, respectively, of "neutral". They do not lose/gain much lift to the tails. The F-16 seems to sit right at 35% MAC with a range of 30-40%. The F-16 is by far the least stable of the teen series. I had somewhere seen a value of 37% for the F-22 but I don't remember where. There was a research paper done on the F-35 planforms that indicates a value of 44% for the A/B and 34% for the C. These numbers were (in my opinion of reading the paper) aft limits but indicate an +-F-16 level of instability.

vanshilar wrote:3. You chose a mission distance of 500 nm. Is there a reason for this?


It was arbitrary. Ranges needed vary greatly by region. In SW Asia ranges of 500nm are almost never needed. In places like the Pacific the ranges would need to be much larger. The surprise for me from that was seeing how the F-16 is very limited in range once heavily loaded. I see the reason for asking for more ranges but is it was each plane had over 400 points of data I need to look up or calculate and they are often iterative. These analyses are very time consuming. For my current rendition I spent two days freetime (maybe 3 hours or so combined) doing the F-15Cs Scramble mission and only have a 95% solution so far.

Thanks for reading and for thinking critically. I am happy to answer well thought questions.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 16:05
by eloise
Sorry for my ignorance but can someone explain what is CG range and MAC?
and the twin tail will only contribute to lift while plane is bank to turn right?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 16:36
by highflyer9090
eloise wrote:Sorry for my ignorance but can someone explain what is CG range and MAC?
and the twin tail will only contribute to lift while plane is bank to turn right?


Center of gravity (CG) limits are specified longitudinal (forward and aft) and/or lateral (left and right) limits within which the aircraft's center of gravity must be located during flight. The CG limits are indicated in the airplane flight manual. The area between the limits is called the CG range of the aircraft. CG varies due to fuel burn and release of fuel tanks, weapons, etc.

Engineers call the location where the aerodynamic moment remains constant the aerodynamic center (ac) of the airfoil. For rectangular wings, the wing aerodynamic center (ac) is the same as the airfoil ac. But for wings with some other planform (triangular, trapezoidal, compound, etc.) you have to find a mean aerodynamic center (mac) which is the average for the whole wing. The computation of the mac depends on the shape of the planform. The mean aerodynamic chord (MAC) can be seen as the ‘average’ chord of the entire 3D wing.

Horizontal tail will contribute to lift during level flight and during most turn maneuvers for an 'unstable' aircraft. For an ustable aircraft, the 'lift' of the tail (pitch 'down' moment) helps balance the plane which naturally wants to pitch up (definition of unstable).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 20:01
by vanshilar
highflyer9090 wrote:Horizontal tail will contribute to lift during level flight and during most turn maneuvers for an 'unstable' aircraft. For an ustable aircraft, the 'lift' of the tail (pitch 'down' moment) helps balance the plane which naturally wants to pitch up (definition of unstable).


Just to add to this, some diagrams which made it a lot easier to understand for me:

viewtopic.php?f=60&t=9780

Basically, for a stable aircraft, its center of gravity is forward of its center of lift (just like how an arrow has most of its weight in the front to stay stable). This means that the tail in the back actually has to generate downforce-lift to keep the plane flying straight for a stable aircraft, otherwise it would pitch downward toward the ground.

For an unstable aircraft, the center of gravity is actually behind the center of lift, so the horizontal tail in the back actually contributes to lift, rather than detract from it.

The relevance of this (at least for me) comes when the aircraft tries to maneuver, i.e. turn. When turning (assuming sustained turn here) the wings have to generate more lift, so the plane increases its angle of attack to generate that additional lift. But there's a limit to how much lift a wing can generate. So as a proxy to doing all the fancy calculations, it's typical on the 'net to talk about a plane's wing loading. That takes the weight of the aircraft and divides by the area of the wing, so you'll get a value indicating how much lift each square foot of wing has to generate. The lower the value, then the less lift each area of a wing has to produce, meaning that there is more lift capability in reserve for when it wants to do a tight turn and goes into a high angle of attack in the turn. Thus, lower wing loading is better; lower wing loading is associated with greater maneuverability.

Wing loading is an approximate figure. It's fairly good for "tube and wing" designs, but not much so for modern military aircraft, with complex vortices and fuselage shapes and stuff. Even so it's a nice first-order approximation.

But the main thing I noticed, especially going after that linked post and this thread, is that since the F-35 is designed unstable (or maybe relaxed stability? I forget, but I want to say it's actually aerodynamically unstable), the horizontal tail actually contributes to lift, rather than detract from it. In many planes, the wing has to essentially fight the tail to generate lift, which hurts the plane's ability to turn. Thus, the wing loading in actual use is higher than the calculated wing loading, because the wing also has to overcome the downforce of the tail. For an unstable plane, the tail helps the wing to generate lift, decreasing its actual wing loading compared to the calculated value, enhancing the plane's ability to turn. After all, the numerator in the calculated value is just the plane's weight when sitting on the ground, without taking into account aerodynamics forces, especially those coming from the tail.

Why this is relevant is that a lot of Internet armchair generals on the 'net will compare the wing loading of different planes and say "Aha! The F-35 has a really high wing loading. That means it can't maneuver!" But if its tail contributes to lift rather than how the tail detracts from lift for most other planes, this just means wing loading isn't a good comparison between planes, and that unstable aircraft like the F-35 will maneuver better than their wing loading figures would indicate. This is something that isn't taken into account in a lot of the Internet discussions.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 20:27
by vanshilar
sprstdlyscottsmn wrote:This has been a point of contention by others as well. I don't know which version you read (there are three up here now and I had a fourth ready before I decided to change the analysis to the one mentioned a few posts up). I did analyze the F-16 without limiter and that went beyond 1.8.


Yeah I don't dispute the numbers, I'm not qualified to. It's just that since the results point to the F-35 having better performance, which may be unexpected to some people, something like a high Clmax could raise a red flag. Most of the people who read it won't have the technical background to understand what's reasonable and what's not, but will simply take an outlier number as "proof" that the analysis was biased, so having some discussion of it and putting it in context with other planes would be helpful.

I *think* I'm using the most recent version, rev 2.

sprstdlyscottsmn wrote:Body lift is a red herring (for layman estimations) as wide bodied aircraft often have ~40% of their listed wing area in the body and the body is often listed as generating ~40% of the lift. Tail area on the other hand. That is never included but it contributes greatly.


I'm not sure what you mean here -- do you mean body lift is a red herring because people don't account for it, or it's a red herring because people don't need to account for it? Yeah I had never thought of the tail area, especially with respect to stability and lift/downforce, until I made the earlier post.

sprstdlyscottsmn wrote:I see the reason for asking for more ranges but is it was each plane had over 400 points of data I need to look up or calculate and they are often iterative. These analyses are very time consuming. For my current rendition I spent two days freetime (maybe 3 hours or so combined) doing the F-15Cs Scramble mission and only have a 95% solution so far.


Yeah, I know certainly I'm not the one doing the hard work, so it's just as free time allows. However, how are you doing these calculations? When you say iterative, do you mean you're trying out numbers by hand, or are you using some optimization/root finding code via Excel or Matlab or something? Depending on what you're doing and how you're doing it, I might be able to put in some code for it. (One of my professors in grad school was amused that for an assignment to program a Kalman filter from scratch, I elected to do it in Excel. Everyone else did it in Matlab. Nowadays though, depending on the work, I do tend to use Matlab more, though I still find Excel easier as a user interface for plugging in different numbers and seeing their effects right away.)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Oct 2015, 20:52
by sprstdlyscottsmn
By red herring I meant that people like to use it but don't need to. I have seen people say that on the F-35 the wing loading is actually 40% lower because of body lift etc etc, but when I went and measured I found that 40% of the "Wing Area" was in the body anyway so it has zero relevance to the "wing loading" argument. For that, point to the F-4 vs F-16C.

My iterative I am going through the flight manuals calculating for each step. Take off is fine, but for climb I need to know how high to climb to, so I go to long range cruise and estimate how much fuel I will use in climb to get a starting weight. From there I get an optimum altitude. Then I go back to climb and measure the climb for that optimum altitude. That gives me a fuel burn for climb which I then take back to my optimum altitude section. If my guess was good then nothing really changes, if not then "lather, rinse, repeat." Then I have to go backwards from the descent. How much fuel do I need to decend? What range will I cover? Well that depends on my initial descent altitude. So I take a guess at my end of mission weight and get a long range cruise altitude to descend from. Now I have a, initial and final cruise altitude, climb and descent legs, and fuel for each. I then take this data and begin to create the actual mission. How much time/fuel/distance is needed for this segments acceleration? How much fuel would I burn in a 360 degree turn? So I go through and play with the numbers and the charts until I get an inbound leg with greater or equal distance to the out bound leg, fuel burn that leaves a decent reserve, and the total range/combat time are byproducts of making sure the rest of that happens. Well, that is what I am doing currently, my previous versions (all the ones posted) are "tanker to tanker" with no climb or decent calculated. I was unsatisfied with that.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 07:50
by eloise
vanshilar wrote:
Just to add to this, some diagrams which made it a lot easier to understand for me:

viewtopic.php?f=60&t=9780

Basically, for a stable aircraft, its center of gravity is forward of its center of lift (just like how an arrow has most of its weight in the front to stay stable). This means that the tail in the back actually has to generate downforce-lift to keep the plane flying straight for a stable aircraft, otherwise it would pitch downward toward the ground.

For an unstable aircraft, the center of gravity is actually behind the center of lift, so the horizontal tail in the back actually contributes to lift, rather than detract from it.

The relevance of this (at least for me) comes when the aircraft tries to maneuver, i.e. turn. When turning (assuming sustained turn here) the wings have to generate more lift, so the plane increases its angle of attack to generate that additional lift. But there's a limit to how much lift a wing can generate. So as a proxy to doing all the fancy calculations, it's typical on the 'net to talk about a plane's wing loading. That takes the weight of the aircraft and divides by the area of the wing, so you'll get a value indicating how much lift each square foot of wing has to generate. The lower the value, then the less lift each area of a wing has to produce, meaning that there is more lift capability in reserve for when it wants to do a tight turn and goes into a high angle of attack in the turn. Thus, lower wing loading is better; lower wing loading is associated with greater maneuverability.

Wing loading is an approximate figure. It's fairly good for "tube and wing" designs, but not much so for modern military aircraft, with complex vortices and fuselage shapes and stuff. Even so it's a nice first-order approximation.

But the main thing I noticed, especially going after that linked post and this thread, is that since the F-35 is designed unstable (or maybe relaxed stability? I forget, but I want to say it's actually aerodynamically unstable), the horizontal tail actually contributes to lift, rather than detract from it. In many planes, the wing has to essentially fight the tail to generate lift, which hurts the plane's ability to turn. Thus, the wing loading in actual use is higher than the calculated wing loading, because the wing also has to overcome the downforce of the tail. For an unstable plane, the tail helps the wing to generate lift, decreasing its actual wing loading compared to the calculated value, enhancing the plane's ability to turn. After all, the numerator in the calculated value is just the plane's weight when sitting on the ground, without taking into account aerodynamics forces, especially those coming from the tail.

Why this is relevant is that a lot of Internet armchair generals on the 'net will compare the wing loading of different planes and say "Aha! The F-35 has a really high wing loading. That means it can't maneuver!" But if its tail contributes to lift rather than how the tail detracts from lift for most other planes, this just means wing loading isn't a good comparison between planes, and that unstable aircraft like the F-35 will maneuver better than their wing loading figures would indicate. This is something that isn't taken into account in a lot of the Internet discussions.

thanks alot , that very easy to understand
btw , from the picture
Image
i understand that with same amount of wing area
a stable canard result in less wing loading than unstable canard , so why modern fighter like EF-2000 , Typhoon still use unstable canard ?

another question : i heard that , aircraft , missiles ..etc can increased their AOA to improve lift at high altitude , , but how is that possible without TVC ? , i mean the direction of thrust is different from direction of travel so wouldnt the aircraft/missiles will just climb up ward instead of flying horizontally
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 08:12
by eloise
Also i saw this picture floating around for a while :
Image
This graph shows the development of the coefficient of drag versus the Mach number, comparing a straight wing, a 30° swept wing and a 45° swept wing. Below mach 2.1 the bigger the angle of sweep, the less drag , that i can understand ( at least it fit my common sense ,but then suddenly , after a high Mach number (M2.1 on this graph), is the drag more on a 45° swept wing than on a 30°, even a straight wing? why did that happened ? ,
aslo if the graph was accurate then wouldnt it make more sense for aircraft like SR-71 , Mig-31 to have straight wing ? why do they still have sweep back wing ? or why F-111 , F-14 fully sweep their wing at maximum speed ? ( they obviously can fly faster than mach 2.1 wouldnt it make more sense to do the opposite ? )
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 09:40
by vanshilar
sprstdlyscottsmn wrote:By red herring I meant that people like to use it but don't need to. I have seen people say that on the F-35 the wing loading is actually 40% lower because of body lift etc etc, but when I went and measured I found that 40% of the "Wing Area" was in the body anyway so it has zero relevance to the "wing loading" argument. For that, point to the F-4 vs F-16C.


Hmm. I guess maybe different people explain it differently then. I've always thought that the reason why body lift makes a difference is that compared to older "wing plus tube" designs, the wider fuselage of modern planes effectively act like a low-aspect ratio wing, plus modern planes generate vortices with the fuselage (via LEX/chines/etc.) useful for lift at higher angle of attack. So while yes the wing area includes the width of the fuselage, a "flattened" and chined fuselage is going to provide more lift relative to that part of the wing area, compared with a standard old tube of the same length compared to its part of the wing area, especially as the angle of attack increases. (Not sure if this makes sense without diagrams.) If this is the case then the modern wider fuselage *does* still make a difference in improving the plane's performance compared to the wing loading calculations. I've never tried to put a quantitative value to that effect though because I always figured the effect is something you need CFD for due to the vortices and stuff.

I guess the best example of this (that modern fuselages act like a low-aspect ratio wing) is the F-15 whose wing got cut off in an in-flight collision, but was still able to make it back to base (though barely) from the fuselage and the remaining wing.

Yes, I've used the F-4 vs F-16 wing loading example myself, particularly because the 2008 RAND report that is often cited to "prove" that the F-35 sucks at maneuvering also happens to show that the F-4 has lower wing loading than the F-16. I've yet to have anyone on Reddit dispute me on this (that it shows how wing loading is not a good way of comparing maneuverability of modern fighters).

sprstdlyscottsmn wrote:My iterative I am going through the flight manuals calculating for each step. Take off is fine, but for climb I need to know how high to climb to, so I go to long range cruise and estimate how much fuel I will use in climb to get a starting weight. From there I get an optimum altitude. Then I go back to climb and measure the climb for that optimum altitude. That gives me a fuel burn for climb which I then take back to my optimum altitude section. If my guess was good then nothing really changes, if not then "lather, rinse, repeat." Then I have to go backwards from the descent. How much fuel do I need to decend? What range will I cover? Well that depends on my initial descent altitude. So I take a guess at my end of mission weight and get a long range cruise altitude to descend from. Now I have a, initial and final cruise altitude, climb and descent legs, and fuel for each. I then take this data and begin to create the actual mission. How much time/fuel/distance is needed for this segments acceleration? How much fuel would I burn in a 360 degree turn? So I go through and play with the numbers and the charts until I get an inbound leg with greater or equal distance to the out bound leg, fuel burn that leaves a decent reserve, and the total range/combat time are byproducts of making sure the rest of that happens. Well, that is what I am doing currently, my previous versions (all the ones posted) are "tanker to tanker" with no climb or decent calculated. I was unsatisfied with that.


How much of this is automatically calculated, as opposed to you manually looking up values and such? For example, if the data from the flight manuals is in a chart form, they can be put into Excel or Matlab and table lookup formulas could be used. Then you could just plug in different guesses for optimum altitude etc. and it could automatically calculate range and stuff. Both Excel and Matlab have optimization features; for Excel, you can use Excel Solver, and for Matlab, there's the fmincon() function, where you can just have them automatically find the max or min of something for you. In this case it seems like you're trying to calculate the maximum range or endurance, so in Excel for example it's a matter of setting up the model (different portions of the mission, lookup tables, etc.), then telling Excel Solver to maximize range/endurance by adjusting the values that you're currently tweaking (optimum altitude, etc.). *If* it gets coded up properly then the hard part is really just to write the model correctly (as Excel equations, lookups, etc.), and having a good enough initial guess for the tunable parameters, and then it's just a matter of waiting for the program to automatically search different values and figure out what's the best set.

Anyway, just pointing out that (depending on how you're doing it), it may be possible to have the computer automatically try to solve those sorts of problems rather than you doing trial-and-error.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 12:44
by linkomart
eloise wrote:
vanshilar wrote:
Just to add to this, some diagrams which made it a lot easier to understand for me:

viewtopic.php?f=60&t=9780

Basically, for a stable aircraft, its center of gravity is forward of its center of lift (just like how an arrow has most of its weight in the front to stay stable). This means that the tail in the back actually has to generate downforce-lift to keep the plane flying straight for a stable aircraft, otherwise it would pitch downward toward the ground.

For an unstable aircraft, the center of gravity is actually behind the center of lift, so the horizontal tail in the back actually contributes to lift, rather than detract from it.

Image


i understand that with same amount of wing area
a stable canard result in less wing loading than unstable canard , so why modern fighter like EF-2000 , Typhoon still use unstable canard ?




This was discussed in Another thread two years ago:
viewtopic.php?f=33&t=24310&p=260788#p260788

In short, that picture is wrong, you are confusing center of lift whith neutral point. Stable tailed Aircrafts can carry positive load on the tail, and unstable canards do have positive lift on the canard (at least the ones I know about)

Regards

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 17:46
by sprstdlyscottsmn
Body Lift:

I guess I wasn't being too clear. Body lift is real. Now let's say that "body lift" is 40% of total physical lift and each "exposed wing" is 30% of physical lift. This is the typical estimation. If the "exposed wing area" (not part of the wide fuselage planform) is only 60% of the "reference wing area" (the number used to calculate wing loading) and the remaining 40% of the "reference wing area" is within the fuselage then for the purposes of computing wing loading of the "exposed wing" (the only part acting even remotely like the given airfoil shape) you have S*0.6/W and then if you want to add the "body lift" portion by saying it acts equivalent to 40% of the "reference wing area" you are adding S*0.4/W. So something like and F-86 the tube body makes very little lift, but very little of the "reference wing area" is contained within the tube so it balances out. The downside to "body lift" is that it produces more drag per unit lift (worse L/D) because, as you said, it is a very low aspect ratio.

In the case of the Israeli F-15 it lost essentially an entire EXPOSED wing. Now in theory, using the above example, the pilot lost 30% of his lift. He also lost balance. In order to stop flipping over he had to balance the roll moments by (over simplifying here) rolling into the good wing. Doing so reduces the lift of the good wing as a result of the up-aileron but it also adds lift on the opposite side by the trailing edge down Horizontal Stabilator. So now the side with the missing wing is having lift generated by the tail while the side with the wing is having net lift loss through up aileron and trailing edge up Horizontal Stabilator. This generated the needed left-right balance of lift. The big body was able to keep generating it's "40%" because it does not have any control surfaces directly affecting its lift. In this case the lift loss on the good wing was so great and the lift gain from the H-Stab on the opposite side so small that the body was, in this case, likely generating far more than 50% or even 60% of the total physical lift.

Iterative Charts:

I do not think the charts of the -1 can be easily put into a program as they are derived from flight test data. Attached is an example of one of the charts. There are a few dozen of these.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 20:07
by vanshilar
Hmm can you describe how to read those charts? I think simple charts with lines in them are actually relatively easy to digitize, although it does take some human effort initially (unless I want to do optical recognition on it...which I think would be overkill).

I guess what I mean by "read those charts" is what are the input variables you're using for a chart, what is the output variable(s) you're looking for, and how do you use the line(s) in the chart to convert them, etc. The chart doesn't have an X-axis label so I'm guessing it's something like, you know your gross weight and you know your drag index to start, then from your gross weight you move to the right until you hit the altitude line, then you move down until you hit the drag index line, then you move left to find the fuel flow; and the iterative process here is to do this for different altitudes and try to find the one with the lowest fuel flow. Is that correct? If so, something like that wouldn't be difficult to do by code, although to convert between the graph to code I'd likely be linearly interpolating between the lines (such as if there's a drag index of 140, it would be exactly halfway vertically between the lines for drag index 120 and drag index 160) -- I don't know if you do something more accurate for estimating by eyeball.

Additionally, can you set it to 100% of original size? This way the lines are cleaner so it'd be easier to read them (instead of smeared across multiple pixels). Thanks.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Oct 2015, 21:09
by sprstdlyscottsmn
Your guess is correct on how to use the charts. The iterative aspect, using this chart, would be that final endurance fuel flow is determined by final endurance weight, which is determined by how much fuel I need to get home, which is determined by my cruising altitude for the outbound leg, which is determined by the final endurance weight, which is determined by time on station, which is determined by integrating the endurance fuel flows.

I do use Excel to track and run the calculations based on the inputs so that when I replace my initial estimate with the number from the chart I can see how that propagates downpath.

It's much easier from a planning aspect to say "you will use this altitude" so that you can easily backwards plan from the landing with required reserves.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Oct 2015, 10:53
by eloise
:( can someone please answer my question about flying at AoA ? and wing sweep effect at high speed ? :(

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Oct 2015, 15:19
by sprstdlyscottsmn
eloise wrote::( can someone please answer my question about flying at AoA ? and wing sweep effect at high speed ? :(

Sorry was caught up with other stuff.

AoA: Lift is a function on AoA, AoA coefficient of lift, lifting area, and dynamic pressure. Dynamic pressure is 0.5*density*velocity^2. At higher altitudes density is less, so if you have the same speed you have a lower dynamic pressure. To maintain the same lift you need to increase either your AoA, AoA coefficient, or lifting area. By far the easiest one to change is the AoA. This is why AoA increases with altitude, or more accurately as dynamic pressure drops. Remember that under operational conditions planes can generate 4-9 times as much lift as they have in weight. Under the absolute best conditions a fighter plane has ~1.2 times its weight in thrust, and even then only at low altitude and high speed. The amount of thrust that works against gravity is basically Thrust*SIN(AOA). SIN(5)=0.087, so at an AoA of 5 even under these best of circumstances you have a "vertical thrust component" of 10% of weight. Mean while using an AoA coefficent of 0.065, you end up with a total lift coefficient of 0.325, and with a lifting area of 300, a weight of 24000 (using an F-16 at low level as an example) and a dynamic pressure of 1800 (roughly Mach 1.1 at sea level) you get a lift of 7.28 times the weight. 728% of weight due to wing vs 10% of weight due to thrust. As you can see engine thrust will never be as great of a contribution to the total "vertical" force as lift for a plane.

For a HOBS missile first coming off the rail this might change but missile motors do not burn that long.

Sweep: Keep in mind that chart specifically says AR=3 and t/c=0.05. In both the F-11 and the F-14 AR unswept is 7+ and t/c=0.06+. Once swept the AR drops to 2.5- and t/c=0.03-. These are ball park estimations but it shows how variable geometry affects more than just sweep.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Oct 2015, 13:06
by eloise
sprstdlyscottsmn wrote:Sorry was caught up with other stuff.

:D no biggy , thanks alot for the answear
sprstdlyscottsmn wrote:AoA: Lift is a function on AoA, AoA coefficient of lift, lifting area, and dynamic pressure. Dynamic pressure is 0.5*density*velocity^2. At higher altitudes density is less, so if you have the same speed you have a lower dynamic pressure. To maintain the same lift you need to increase either your AoA, AoA coefficient, or lifting area. By far the easiest one to change is the AoA. This is why AoA increases with altitude, or more accurately as dynamic pressure drops. Remember that under operational conditions planes can generate 4-9 times as much lift as they have in weight. Under the absolute best conditions a fighter plane has ~1.2 times its weight in thrust, and even then only at low altitude and high speed. The amount of thrust that works against gravity is basically Thrust*SIN(AOA). SIN(5)=0.087, so at an AoA of 5 even under these best of circumstances you have a "vertical thrust component" of 10% of weight. Mean while using an AoA coefficent of 0.065, you end up with a total lift coefficient of 0.325, and with a lifting area of 300, a weight of 24000 (using an F-16 at low level as an example) and a dynamic pressure of 1800 (roughly Mach 1.1 at sea level) you get a lift of 7.28 times the weight. 728% of weight due to wing vs 10% of weight due to thrust. As you can see engine thrust will never be as great of a contribution to the total "vertical" force as lift for a plane.

For a HOBS missile first coming off the rail this might change but missile motors do not burn that long.

that very interesting
does that mean at same speed , aircraft with higher wing loading have to fly at higher AoA ?
Also i heard from some source that missiles wing are not for generate lift ( because they dont have the curve on either size ) , they only are for stabilize , missiles generate lift by flying at an AoA , is that assessment correct ? can a tube body generate lift at AoA ?
sprstdlyscottsmn wrote:Sweep: Keep in mind that chart specifically says AR=3 and t/c=0.05. In both the F-11 and the F-14 AR unswept is 7+ and t/c=0.06+. Once swept the AR drops to 2.5- and t/c=0.03-. These are ball park estimations but it shows how variable geometry affects more than just sweep.

i understand what is aspect ratio but what actually is t/c ?
btw the lower the aspect ratio the better right ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Oct 2015, 14:10
by sprstdlyscottsmn
eloise wrote:that very interesting
does that mean at same speed , aircraft with higher wing loading have to fly at higher AoA ?

there is still the variable of AoA lift coefficient (ClAlpha) which is the lift coefficient generated per unit of AoA, but if you are simplifying to say they are essentially equal then yes.
eloise wrote:Also i heard from some source that missiles wing are not for generate lift ( because they dont have the curve on either size ) , they only are for stabilize , missiles generate lift by flying at an AoA , is that assessment correct ? can a tube body generate lift at AoA ?

no and yes. A tube can generate lift at AoA, but it is very low lift (poor ClAplha) that generates a high amount of drag. Even a flat plate ("infinitely" thin and uncambered), which missile fins are not, they are thin and symmetrically cambered, generates lift like a wing. So at "cruise" AoA for a missile the fins are doing most of the work. When a turn is initiated it is done by the fins (excluding initial launch of TVC HOBS missiles). Now haw can the fins initiate a turn if they don't make lift? Once at "turn" AoA then what happens is the missile stagnation point (where the pressure is the highest on the nose) shifts down onto the rounded surface of the nose and due to the AoA this point is "above" the CG meaning it will generate a pitch moment due to high local drag.

eloise wrote:i understand what is aspect ratio but what actually is t/c ?
btw the lower the aspect ratio the better right ?

t/c is thickness/chord. A wing that is 4 inches thick and 8 feet in chord (leading edge to trailing edge) has a t/c of 0.0417. Thin wings have less camber so as the air passes around the wing the change in local airspeed/pressure is not as great. As such they typically have lower ClAlpha but they also generate less intense shock waves at supersonic flow.

This is one of the reasons why Delta Wings are used on supersonic aircraft. With such a long root chord (as much as 170% of the exposed half-span) you can have a low t/c and still have a large raw thickness dimension. Take the F-106 planform, at 38ft total span with a body ~6ft wide that leaves 16ft of exposed half span for a total root chord length of 326 inches. At 4% thickness that means the thickest part of the airfoil is 13 inches thick. So that gives a large volume for fuel.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Oct 2015, 18:31
by eloise
sprstdlyscottsmn wrote:no and yes. A tube can generate lift at AoA, but it is very low lift (poor ClAplha) that generates a high amount of drag. Even a flat plate ("infinitely" thin and uncambered), which missile fins are not, they are thin and symmetrically cambered, generates lift like a wing. So at "cruise" AoA for a missile the fins are doing most of the work.
.

a symmetrically cambered wing mean the wing willnot generate lift at zero AoA , is that correct ? :D ( i mean if the wing curve the same on each side then the pressure on each side will be the same hence no lift )

btw if the wing produce most of the lift on missiles at cruise AoA, does that mean missiles like AIM-9L , ASRAAM , Meteor are very tail heavy ( CG at the rear ) while the one like AGM-65 , R-40 , AIM-7 are nose heavy ? :D
i mean for example the ASRAAM , Meteor only have tail fin ,and no fin at the head to hold it's nose up
Image
Image

by contrast , AIM-7 have massive mid body wing
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Oct 2015, 18:39
by eloise
Btw Does it make any different for a missiles ( in term of lift )whether their fin is horizontal or not ? :D
i mean for example an AIM-7 after launched by F-15 will have 2 fin horizontal while 2 fin are vertical with ground , like in this picture
Image

by contrast AIM-7 launch by F-16 will have all of it's fin making an angle with the ground ( like an aircraft banking )
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Nov 2015, 00:13
by sprstdlyscottsmn
front/rear fin size relationship makes no difference is where the CG is. Size does not equal lift. They will have different AoAs and thus different Lift Coefficients. The Front fins are often all moving. And no being straight up and down makes no real difference. Either two sets of fines make lots of lift or four sets of fins make less lift. As to Meteor and ASRAAM, Meteor has a big V-Channel between the intakes so those will act like giant strakes/lifting bodies, while ASRAAM relies on the positive AoA to move the stagnation point I talked about earlier to under the rounded nose. Oh and you are correct that symmetrically curved fins will not make lift at zero AoA.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Nov 2015, 10:05
by KamenRiderBlade
If a missile had normal shaped air foils for it's fins, let's say using a Supercritical Airfoil shape,
https://en.wikipedia.org/wiki/Supercritical_airfoil

could the missile be designed such that it's software to alway keeps the missile in the correct orientation so that the fins generate lift, or is there a technical reason why it would be bad to design a missile to do this?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Nov 2015, 19:11
by sprstdlyscottsmn
A missiles design (Meteor excluded) is axisymetrical. It allows it to turn in any direction at any time with equal efficiency. TO give a missile a "top" means it has to bank/pitch to turn instead of just pitch.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Nov 2015, 23:38
by KamenRiderBlade
sprstdlyscottsmn wrote:A missiles design (Meteor excluded) is axisymetrical. It allows it to turn in any direction at any time with equal efficiency. TO give a missile a "top" means it has to bank/pitch to turn instead of just pitch.


So it's a bad idea in general to design a missile like the Meteor which has a "Top"?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 00:50
by sprstdlyscottsmn
Yes. The Meteor design was likely compromised by conflicting design goals of Ramjet powered (needing intakes) and being able to be carried in semi-recessed locations designed for AMRAAM. I do not know how end game turning ability will be if the motor is still trying to burn. Perhaps it is enough that when it needs to do the final hard "skid turn" (compromising the airflow through the ramjet) that it is still "guaranteed" to be at "top speed".

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 10:57
by eloise
sprstdlyscottsmn wrote:front/rear fin size relationship makes no difference is where the CG is. Size does not equal lift. They will have different AoAs and thus different Lift Coefficients. The Front fins are often all moving. .

i see , so basically a small surface and create more lift than a big surface as long as it have bigger AoA , correct ? :D
Also what is the advantage of unconventional control surface such as grid fin on R-77 and very high aspects ratio fin on R-27 over normal sweep back fin on SM-2, AIM-120, AIM-7.. etc
Image
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 11:36
by eloise
Another question : this may sound really dumb but it really confused the hell out of me, from what i understand, when the fin of aircraft or missiles pitched up or down, the air will hit it and hence turn the body of aircraft/missiles to another heading => changing direction of travel

i was fine with that description untill i saw the space shuttle thruster, and how it maneuver, basically the thruster will do the jobs of the fin ( applied force on the shuttle nose to move it to another direction) , the difference is while the nose point to another heading, the shuttle continue to move in exactly same direction

Image

i was thinking that because aircraft have engine that will propelled it towards wherever it's nose pointed at, but then a missile at burn out can still turn and change direction :shock: very confusing for me

Btw from what i understand, what give aircraft ability to pitch up or down are leading edge flap, slat, canard and stabilator. So why people judge an aircraft turn rate by measuring wing loading of the whole wing? shouldn't we only measures the moving part?, and shouldnt wing shape make different as well?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 12:47
by Dragon029
Because by having low wing loading, you can change your flight vector without increasing your angle of attack as much, which keeps your lift-to-drag ratio high and allows you to maintain your airspeed better.

Having a low wing loading doesn't mean you'll be able to rotate your nose onto a target quicker, but it just means that you can change your direction of flight quicker and more efficiently.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 13:05
by hornetfinn
eloise wrote:
sprstdlyscottsmn wrote:front/rear fin size relationship makes no difference is where the CG is. Size does not equal lift. They will have different AoAs and thus different Lift Coefficients. The Front fins are often all moving. .

i see , so basically a small surface and create more lift than a big surface as long as it have bigger AoA , correct ? :D
Also what is the advantage of unconventional control surface such as grid fin on R-77 and very high aspects ratio fin on R-27 over normal sweep back fin on SM-2, AIM-120, AIM-7.. etc


There are some studies about the matter:
http://goo.gl/hNfw0r

Basically grid fins are very good for many reasons, although they have some drawbacks as well. These are described well in the above thesis in pages 5 and 6.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 13:10
by vanshilar
I think the fundamental confusion is that to change your direction of travel, you're not just pitching the plane up or down, you need to increase the force perpendicular to the direction of travel. Changing your heading (where the nose is pointing) doesn't automatically change your direction of travel. For planes this perpendicular force will usually be lift (although the perpendicular component of thrust will contribute too), often from changing the angle of attack (AOA). Being able to change the pitch of the aircraft quickly, i.e. with nose thrusters or fins, changes the orientation of the object i.e. its AOA but not its lift directly.

Since the ability to change the direction of travel depends on the lift, wing loading is a useful approximation because it tells you how much lift a given area of wing needs to generate. This can be done through a variety of means but commonly, by increasing the wing's AOA. However, there's a maximum to the amount of lift per area of wing that a wing can produce, and increasing its AOA also increases its drag. Thus, having lower wing loading is considered better.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 13:56
by eloise
Dragon029 wrote:Because by having low wing loading, you can change your flight vector without increasing your angle of attack as much, .

i dont quite understand your point
how come lower wing loading give you ability to change flight direction with less AoA?
Dragon029 wrote:Having a low wing loading doesn't mean you'll be able to rotate your nose onto a target quicker, but it just means that you can change your direction of flight quicker and more efficiently.

:| arent these 2 the same thing?
hornetfinn wrote:
There are some studies about the matter:
http://goo.gl/hNfw0r

Basically grid fins are very good for many reasons, although they have some drawbacks as well. These are described well in the above thesis in pages 5 and 6.

thanks hornetfinn, very informative links

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 14:07
by eloise
vanshilar wrote:I think the fundamental confusion is that to change your direction of travel, you're not just pitching the plane up or down, you need to increase the force perpendicular to the direction of travel. Changing your heading (where the nose is pointing) doesn't automatically change your direction of travel. For planes this perpendicular force will usually be lift (although the perpendicular component of thrust will contribute too), often from changing the angle of attack (AOA). Being able to change the pitch of the aircraft quickly, i.e. with nose thrusters or fins, changes the orientation of the object i.e. its AOA but not its lift directly.

:( iam still very confused, wouldn't thruster also create force perpendicular to direction of travel?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 14:26
by vanshilar
eloise wrote: :( iam still very confused, wouldn't thruster also create force perpendicular to direction of travel?


Most of a plane's thrust is in its direction of travel. If the plane is at an angle of attack, however, then some of the thrust will be perpendicular to the direction of travel and effectively giving the plane lift. It's not free, however; there will be less thrust moving the plane forward, so it will slow down.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 15:34
by eloise
vanshilar wrote:
Most of a plane's thrust is in its direction of travel. If the plane is at an angle of attack, however, then some of the thrust will be perpendicular to the direction of travel and effectively giving the plane lift. It's not free, however; there will be less thrust moving the plane forward, so it will slow down.

no no, that not what i mean
because you said " the fundamental confusion is that to change your direction of travel, you're not just pitching the plane up or down, you need to increase the force perpendicular to the direction of travel" that why i am confused, because the thrusters on space shuttle will also able to apply force perpendicular to direction of travel :?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 17:14
by sprstdlyscottsmn
The thrust those put out is insignificant to the velocity vector of the shuttle. Those are for orbital maneuvers, changing the way the nose of the shuttle is pointing while in the vacuum of space. They can afford to have a low impulse burn for a short time (very little delta-V, or change in velocity vector, say on the order of 1 ft/sec while the total magnitude of the vector is 25,667 ft/s) and can take a minute or longer to get the nose where it needs to be.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 17:25
by eloise
sprstdlyscottsmn wrote:The thrust those put out is insignificant to the velocity vector of the shuttle. Those are for orbital maneuvers, changing the way the nose of the shuttle is pointing while in the vacuum of space. They can afford to have a low impulse burn for a short time (very little delta-V, or change in velocity vector, say on the order of 1 ft/sec while the total magnitude of the vector is 25,667 ft/s) and can take a minute or longer to get the nose where it needs to be.

so what you are saying is the thrusters also change the direction of travel of the space shuttle, but it is too negligible compare to the straight line velocity of the shuttle, thus not visible to the naked eye? iam i understand it correctly?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 19:30
by krorvik
That would be correct.

Also remember the space shuttle is long, and *heavy*.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 21:35
by vanshilar
eloise wrote:so what you are saying is the thrusters also change the direction of travel of the space shuttle, but it is too negligible compare to the straight line velocity of the shuttle, thus not visible to the naked eye? iam i understand it correctly?


Yeah, it does change the direction but so small that it's essentially negligible.

Additionally, it depends on the orientation of the thruster relative to the direction of travel. Say the shuttle is traveling forward, i.e. pointing its nose in the direction of travel. If it fires its nose thruster so that the nose pitches upward, then the direction of travel changes slightly upward. If it fires its tail thruster so that the nose pitches upward, the direction of travel actually changes slightly downward. That's because in the former case, the force is pushing upward at the nose, while in the latter case, the force is pushing downward at the nose.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Nov 2015, 23:08
by Dragon029
eloise wrote:
Dragon029 wrote:Because by having low wing loading, you can change your flight vector without increasing your angle of attack as much, .

i dont quite understand your point
how come lower wing loading give you ability to change flight direction with less AoA?
Dragon029 wrote:Having a low wing loading doesn't mean you'll be able to rotate your nose onto a target quicker, but it just means that you can change your direction of flight quicker and more efficiently.

:| arent these 2 the same thing?


If we have a 10 ton aircraft and double it's wing area (without increasing its weight; maybe we swap to new, lighter materials), we halve it's wing loading.

Now, every square meter (every [unit of area]) generates some amount of lift; how much lift it generates varies with angle of attack and airspeed. A wing with no airfoil and no control surfaces, at zero degrees angle of attack generates no lift, but very little drag; a wing at 90 degrees angle of attack generates no lift but a maximum amount of drag.

At 45 degrees (again, for a flat plate wing wit no surfaces) you generate the maximum amount of lift. You also however generate a very large amount of drag. if a Super Hornet, F-35, etc goes to 45 degrees angle of attack, it needs to turn on it's afterburners to sustain flight.

If you graph the coefficient of lift and the coefficient of drag vs angle of attack (for a flat plate; airfoils give you a greater Cl at lower angles of attack), you get this:

Image

Now remember, your lift-to-drag ratio is found based on the ratio of the two (one divided by the other, not one subtract the other) - what this means is that the greatest L:D ratio is down near the 5-10 degrees angle of attack area; after that, the ratio rapidly dwindles as drag catches up and then exceeds lift at (in this example) 45 degrees. Again, this is for a flat plate; when you add an airfoil and/or flaps, your peaks shift to the left.

Anyway, so if you have 2 wings, both are flat plates, but one has twice the surface area as the other, the larger wing will generate twice as many newtons of lift.

Now, remember, when you approach having zero or very little airspeed, you lose control authority; if you're in a fighter with no thrust vectoring, you have very little control authority at (eg) 50 knots, decreasing to no control authority when you get to zero knots. If you have a high thrust-to-weight ratio, this is less of an issue, but at high angles of attack, it's easy for drag to become greater than your thrust on afterburner. For example, if you managed to get an F/A-18C to 40 degrees angle of attack at 200 knots, you would be looking at a minimum of 220kN of drag (that doesn't include parasitic drag or the drag from the tail surfaces, or fuselage not covered under the reference wing area), while both engines on afterburner, combined, provide 158kN of thrust.

So, what does this all mean?

What it simply means is that if you can turn yourself without increasing your angle of attack by much, you can keep turning at that angle; a larger wing area generates more drag, but not necessarily as much as increasing your angle of attack in order to generate the same amount of lift.

And ultimately, in the context of combat, you might be able to whip your nose up 70 degrees, but if you miss with your shot, you've dramatically decreased your airspeed and are now going to be struggling to get back up to an airspeed where you can get enough control authority to keep turning as much as your opponent.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Nov 2015, 11:18
by eloise
vanshilar wrote:Yeah, it does change the direction but so small that it's essentially negligible.

Additionally, it depends on the orientation of the thruster relative to the direction of travel. Say the shuttle is traveling forward, i.e. pointing its nose in the direction of travel. If it fires its nose thruster so that the nose pitches upward, then the direction of travel changes slightly upward. If it fires its tail thruster so that the nose pitches upward, the direction of travel actually changes slightly downward. That's because in the former case, the force is pushing upward at the nose, while in the latter case, the force is pushing downward at the nose.

does that mean for normal aircraft like f-16 initially move slightly down ward when it's horizontal tail pitched down, while canard fighter like Rafale, EF-2000 move slightly upwards when it's canard picthed upwards? ( i understand that the air hitting the main wing will move them upwards eventually, but iam asking about initial momentum of them) :D

Also, do you think the ACM mini thruster on PAC-3, CUDA have effect similar to fin on aircraft or thruster on space shuttle ? ( i mean do you think they powerful enough to change direction of travel or will they only point the missiles nose around? , assuming missiles at burn out of course)
Image
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Nov 2015, 11:31
by vanshilar
eloise wrote:does that mean for normal aircraft like f-16 initially move slightly down ward when it's horizontal tail pitched down, while canard fighter like Rafale, EF-2000 move slightly upwards when it's canard picthed upwards? ( i understand that the air hitting the main wing will move them upwards eventually, but iam asking about initial momentum of them) :D


Yup. The same thing also happens with the rudder, where it initially moves the aircraft in the opposite direction that the aircraft wants to go. Or if (for whatever reason) a car uses its back wheels as the steering wheels rather than its front wheels.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Nov 2015, 16:36
by Dragon029
eloise wrote:Also, do you think the ACM mini thruster on PAC-3, CUDA have effect similar to fin on aircraft or thruster on space shuttle ? ( i mean do you think they powerful enough to change direction of travel or will they only point the missiles nose around? , assuming missiles at burn out of course)
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Due to their position, it's very likely they will primarily point the nose around, only using short little bursts of thrust.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Nov 2015, 16:38
by krorvik
eloise wrote:but it is too negligible compare to the straight line velocity of the shuttle


Straight line is probably not the right words though - it is actually really falling towards the earth. The orbital speed is fortunately keeping it from hitting that same earth while in orbit...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Nov 2015, 17:22
by spazsinbad
DiD does not allow hot linking of images: http://media.defenceindustrydaily.com/i ... led_lg.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 00:08
by eloise
Dragon029 wrote:
Due to their position, it's very likely they will primarily point the nose around, only using short little bursts of thrust.

i dont quite get your point , missile fin also located at one side of the missiles and can still change their direction
krorvik wrote:
Straight line is probably not the right words though - it is actually really falling towards the earth. The orbital speed is fortunately keeping it from hitting that same earth while in orbit...

you are correct , iam just simply it so that my question easier to understand

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 00:52
by Dragon029
The fins (for example) at the rear of an AMRAAM only point it's nose; the body of the missile and the fins near the middle of the missile are the ones that deflect the missile and make it actually change it's direction of travel.

With the CUDA, because those little thrusters are up at the front of the missile, they act like canards; they'll change the direction of travel a bit, but their biggest effect will be changing where the nose points.

Here's an analogy:

Imagine a car with a rocket on the front of it, facing sideways.

Image

When that rocket fires; it will shift the car sideways a little bit, but what it'll do mostly is rotate the car. Lets say that (despite how large I drew it) the rocket isn't super powerful and only fires briefly, so it only kicks the car around 45 degrees. What actually makes the car change it's direction of travel isn't the rocket (although it does have a slight effect), but rather the wheels 'biting' into the ground and the vehicle naturally trying to find the path of least resistance.

In the CUDA's case, those wheels are the fins (and body) of the missile, with the friction between the wheels and the ground being drag / aerodynamic forces; the path of least resistance for the CUDA is having the air stream and fins parallel with each other.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 07:13
by johnwill
Dragon, I appreciate that you are trying to explain complex motion with simple explanations, but I think you know as well as I do that the missile and auto in your last example are not trying to follow the path of least resistance. The path followed is the one in which all forces and moments are balanced, as Newton described many years ago. Remember, sum of forces is mass x linear acceleration, sum of moments is moment of inertia x angular acceleration, along and about a three axis system. Least resistance has nothing to do with it. eloise and others may be struggling with the complexities of six axis motion, but any basic mechanics 101 textbook can explain it.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 11:04
by eloise
johnwill wrote:Dragon, I appreciate that you are trying to explain complex motion with simple explanations, but I think you know as well as I do that the missile and auto in your last example are not trying to follow the path of least resistance. The path followed is the one in which all forces and moments are balanced, as Newton described many years ago. Remember, sum of forces is mass x linear acceleration, sum of moments is moment of inertia x angular acceleration, along and about a three axis system. Least resistance has nothing to do with it. eloise and others may be struggling with the complexities of six axis motion, but any basic mechanics 101 textbook can explain it.

i understood Dragon029 explanation, but now you said it, iam totally confused again :doh: :|
i draw force direction on picture but cant figure out which force propell missiles in new direction :?)(if we assumed missiles at burn out ) , there is gravity downward and lift upward and that it.
wouldn't the "path of less resistance" explanation make more sense? :shock:
i mean like this
Image

P/s : really sorry for my incompetent :roll: , iam just have really hard time to imagine the core of aerodynamic sometime

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 11:15
by eloise
Dragon029 wrote:
If we have a 10 ton aircraft and double it's wing area (without increasing its weight; maybe we swap to new, lighter materials), we halve it's wing loading.

Now, every square meter (every [unit of area]) generates some amount of lift; how much lift it generates varies with angle of attack and airspeed. A wing with no airfoil and no control surfaces, at zero degrees angle of attack generates no lift, but very little drag; a wing at 90 degrees angle of attack generates no lift but a maximum amount of drag.

At 45 degrees (again, for a flat plate wing wit no surfaces) you generate the maximum amount of lift. You also however generate a very large amount of drag. if a Super Hornet, F-35, etc goes to 45 degrees angle of attack, it needs to turn on it's afterburners to sustain flight.

If you graph the coefficient of lift and the coefficient of drag vs angle of attack (for a flat plate; airfoils give you a greater Cl at lower angles of attack), you get this:

Image

Now remember, your lift-to-drag ratio is found based on the ratio of the two (one divided by the other, not one subtract the other) - what this means is that the greatest L:D ratio is down near the 5-10 degrees angle of attack area; after that, the ratio rapidly dwindles as drag catches up and then exceeds lift at (in this example) 45 degrees. Again, this is for a flat plate; when you add an airfoil and/or flaps, your peaks shift to the left.

Anyway, so if you have 2 wings, both are flat plates, but one has twice the surface area as the other, the larger wing will generate twice as many newtons of lift.

Now, remember, when you approach having zero or very little airspeed, you lose control authority; if you're in a fighter with no thrust vectoring, you have very little control authority at (eg) 50 knots, decreasing to no control authority when you get to zero knots. If you have a high thrust-to-weight ratio, this is less of an issue, but at high angles of attack, it's easy for drag to become greater than your thrust on afterburner. For example, if you managed to get an F/A-18C to 40 degrees angle of attack at 200 knots, you would be looking at a minimum of 220kN of drag (that doesn't include parasitic drag or the drag from the tail surfaces, or fuselage not covered under the reference wing area), while both engines on afterburner, combined, provide 158kN of thrust.

So, what does this all mean?

What it simply means is that if you can turn yourself without increasing your angle of attack by much, you can keep turning at that angle; a larger wing area generates more drag, but not necessarily as much as increasing your angle of attack in order to generate the same amount of lift.

And ultimately, in the context of combat, you might be able to whip your nose up 70 degrees, but if you miss with your shot, you've dramatically decreased your airspeed and are now going to be struggling to get back up to an airspeed where you can get enough control authority to keep turning as much as your opponent.

So why do we often considered missiles like AIM-7, R-40, AIM-54 less agile compare to new missiles like Aim-120? ( it is often said that AIM-54, AIM-7, R-40, R-33 were designed to shoot down bomber )
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judging by the wing size and relative weight, these old missiles must have much lower wing loading

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 13:40
by hornetfinn
eloise wrote:So why do we often considered missiles like AIM-7, R-40, AIM-54 less agile compare to new missiles like Aim-120? ( it is often said that AIM-54, AIM-7, R-40, R-33 were designed to shoot down bomber )
...
judging by the wing size and relative weight, these old missiles must have much lower wing loading


There are other things that affect the missile agility than just wing loading. I think modern missiles are much more agile due to having more effective guidance and control systems and control surfaces. They have faster and more powerful (relatively) actuator systems which can turn the control surfaces quicker and with more force. Also the control surfaces are probably more effective at higher angles of attack and turn rates. Modern missiles are also much more aerodynamic and thus capable of keeping speed up for longer time. They likely also lose less speed on maneuvers due to better aerodynamics. This means they can keep turning harder longer.

For example Russian R-33 is claimed to be able to intercept 4G targets. R-27 is claimed able to intercept 8G targets while R-73 and R-77 are capable against 12G targets. Same with SAM systems. Original Crotale R440 missile system was able to maneuver at about 30Gs while fairly modern Crotale NG VT-1 missile is able to achieve 50Gs. At longer ranges the difference becomes much larger as the newer missile loses speed much more slowly.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 16:01
by Dragon029
Not to mention there's also the max-G capability of the missile's avionics & airframe.

eloise; assuming you have the free time and/or money, have you heard of the video game Kerbal Space Program?
I've repeatedly seen people claim that it makes them understand some of the key concepts that we're talking about here; it's not as realistic as something like X-Plane, but it helps provide a visual and (virtual) kinematic learning experience. There's also free addons like Ferram Aerospace Research that simulates additional aerodynamics like mach effects and voxel-based lift/drag simulation.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 17:58
by sprstdlyscottsmn
Not to de-rail the missile physics sub-thread (which has been fun to read BTW) but as an update to Analysis 2.0 I have completed Scramble, CAP, and Escort for the F-15C.

Escort (as an example) includes time/fuel/distance for taxi, take-off, climb to initial cruise, opt cruise segment, mission controlled cruise segment (30k @ 0.9M for 390nm per Norwegian JSF mission profile doc), AB combat time down to 20kft, climb from 20kft to 30kft for mission controlled egress, mission controlled egress, climb to opt cruise, opt cruise segment, and descent to runway with ~1300lb fuel reserves.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Nov 2015, 20:48
by vanshilar
eloise wrote:i understood Dragon029 explanation, but now you said it, iam totally confused again :doh: :|
i draw force direction on picture but cant figure out which force propell missiles in new direction :?)(if we assumed missiles at burn out ) , there is gravity downward and lift upward and that it.
wouldn't the "path of less resistance" explanation make more sense? :shock:
i mean like this
Image

P/s : really sorry for my incompetent :roll: , iam just have really hard time to imagine the core of aerodynamic sometime


I think it might be easier if you stop thinking about it as a missile for a moment. Instead, just think about some object moving forward from a physics point of view, say a spacecraft in space. Without any force acting on it, it just keeps going forward. If a force pushes on it from behind or from the front, it will accelerate forward or backward, respectively, but its direction of travel won't change.

If a force pushes on it from the side, however, then its direction of travel changes. If the force were perpendicular to the direction of travel, then the object's speed doesn't change, just its direction of travel. An example of this is the Earth's orbit around the Sun. The Sun's gravity is pulling on the Earth (roughly) perpendicular to the Earth's direction of travel. Thus, the Earth travels in a (roughly) circular orbit around the Sun, maintaining (roughly) the same speed but constantly changing its direction of travel. I say "(roughly)" because the Earth's orbit is actually slightly elliptical, but it's easier to think about it as a circular orbit for this.

Note that this force doesn't really depend on what direction the Earth itself is facing -- it is constantly rotating much faster than its orbit around the Sun, it doesn't need to be facing its direction of travel or anything. The point that I'm bringing up here is that the direction of travel is different from the orientation of an object.

Now, onto an aircraft (or missile). It's harder to analyze because gravity is constantly pulling the aircraft down, aerodynamic drag is constantly pulling the aircraft back, the aircraft's engine(s) is constantly pushing it forward, and its aerodynamic surfaces are contributing to these forces as well (primarily generating lift to counteract the downward pull of gravity). In "steady flight", then all these forces cancel out and the aircraft travels in the same direction. To change its direction of travel, something needs to "give", that is, some force doesn't cancel out resulting in a net acceleration on the aircraft perpendicular to its direction of travel. For example if the aircraft tilts upward, then the increased angle of attack of its wings relative to the airflow generates additional lift, overpowering gravity, causing it to climb, changing its direction of travel.

For a missile like the CUDA, if it's pointing toward its direction of travel, the mini-thrusters in the front do change its direction of travel slightly. However, their main effect is that they change the missile's orientation relative to its direction of travel. The missile's fins then provides additional lift (due to their new angle of attack relative to direction of travel) to change the missile's direction of travel.

So why not just use the mini-thrusters as the missile's main means of changing its direction of travel? It's because the fins are much more efficient; as you can see from Dragon029's plot, for lower angles of attack the lift generated compared to their drag is pretty good.

In essence, I think if you're looking to understand principles of flight (at a high level rather than at a fluids level), it might be more helpful to familiarize yourself with physics (i.e. classical or Newtonian mechanics) before trying to dive into aerodynamics or principles of flight directly -- it'll make understanding the concepts a lot easier.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Nov 2015, 21:17
by eloise
Dragon029 wrote:Not to mention there's also the max-G capability of the missile's avionics & airframe.

eloise; assuming you have the free time and/or money, have you heard of the video game Kerbal Space Program?
I've repeatedly seen people claim that it makes them understand some of the key concepts that we're talking about here; it's not as realistic as something like X-Plane, but it helps provide a visual and (virtual) kinematic learning experience. There's also free addons like Ferram Aerospace Research that simulates additional aerodynamics like mach effects and voxel-based lift/drag simulation.

i saw some video on Youtube , it seem great :mrgreen:
even explained aircraft stability

vanshilar wrote:

I think it might be easier if you stop thinking about it as a missile for a moment. Instead, just think about some object moving forward from a physics point of view, say a spacecraft in space. Without any force acting on it, it just keeps going forward. If a force pushes on it from behind or from the front, it will accelerate forward or backward, respectively, but its direction of travel won't change.

If a force pushes on it from the side, however, then its direction of travel changes. If the force were perpendicular to the direction of travel, then the object's speed doesn't change, just its direction of travel. An example of this is the Earth's orbit around the Sun. The Sun's gravity is pulling on the Earth (roughly) perpendicular to the Earth's direction of travel. Thus, the Earth travels in a (roughly) circular orbit around the Sun, maintaining (roughly) the same speed but constantly changing its direction of travel. I say "(roughly)" because the Earth's orbit is actually slightly elliptical, but it's easier to think about it as a circular orbit for this.

Note that this force doesn't really depend on what direction the Earth itself is facing -- it is constantly rotating much faster than its orbit around the Sun, it doesn't need to be facing its direction of travel or anything. The point that I'm bringing up here is that the direction of travel is different from the orientation of an object.

Now, onto an aircraft (or missile). It's harder to analyze because gravity is constantly pulling the aircraft down, aerodynamic drag is constantly pulling the aircraft back, the aircraft's engine(s) is constantly pushing it forward, and its aerodynamic surfaces are contributing to these forces as well (primarily generating lift to counteract the downward pull of gravity). In "steady flight", then all these forces cancel out and the aircraft travels in the same direction. To change its direction of travel, something needs to "give", that is, some force doesn't cancel out resulting in a net acceleration on the aircraft perpendicular to its direction of travel. For example if the aircraft tilts upward, then the increased angle of attack of its wings relative to the airflow generates additional lift, overpowering gravity, causing it to climb, changing its direction of travel.

For a missile like the CUDA, if it's pointing toward its direction of travel, the mini-thrusters in the front do change its direction of travel slightly. However, their main effect is that they change the missile's orientation relative to its direction of travel. The missile's fins then provides additional lift (due to their new angle of attack relative to direction of travel) to change the missile's direction of travel.

So why not just use the mini-thrusters as the missile's main means of changing its direction of travel? It's because the fins are much more efficient; as you can see from Dragon029's plot, for lower angles of attack the lift generated compared to their drag is pretty good.

In essence, I think if you're looking to understand principles of flight (at a high level rather than at a fluids level), it might be more helpful to familiarize yourself with physics (i.e. classical or Newtonian mechanics) before trying to dive into aerodynamics or principles of flight directly -- it'll make understanding the concepts a lot easier.

thanks you , very easy to understand
one think i realised is that technically a missiles even burn out can do a 180 degree turn ( at the cost of speed obviously )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Nov 2015, 21:38
by eloise
[quote="hornetfinn"]

There are other things that affect the missile agility than just wing loading. I think modern missiles are much more agile due to having more effective guidance and control systems and control surfaces. They have faster and more powerful (relatively) actuator systems which can turn the control surfaces quicker and with more force. Also the control surfaces are probably more effective at higher angles of attack and turn rates. Modern missiles are also much more aerodynamic and thus capable of keeping speed up for longer time. They likely also lose less speed on maneuvers due to better aerodynamics. This means they can keep turning harder longer.[/code]
I do agree that modern missiles can have more effective guide but i cant see how can they have more powerful control surface ( since they are much smaller ) , i do agree that they are more aerodynamic though ( since they tend to be long and thin ) but then massive old missiles have such big motor that can keep them on power for really long so so their relative cruise speed probably be similar :? , and even if Aim-120 can have better actuator , more effective guidance than AIM-54 , R-33 , i dont think it can still enjoy the same advantage again RVV-BD :? or even R-27ER

Also come to think of it , Meteor probably doesnt need to care about high wing loading since it's motor is practically on all the way to target , so as long it can point it's nose to target , the motor will propel missiles to that direction


Strange enough , modern BVR missiles doesnt have really small wing compared to their predecessor :|
for example RVV-BD have smaller wing than R-33 , KS-172 fin is practically non existence
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Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Nov 2015, 21:55
by eloise
sprstdlyscottsmn wrote:Not to de-rail the missile physics sub-thread (which has been fun to read BTW) but as an update to Analysis 2.0 I have completed Scramble, CAP, and Escort for the F-15C.

Escort (as an example) includes time/fuel/distance for taxi, take-off, climb to initial cruise, opt cruise segment, mission controlled cruise segment (30k @ 0.9M for 390nm per Norwegian JSF mission profile doc), AB combat time down to 20kft, climb from 20kft to 30kft for mission controlled egress, mission controlled egress, climb to opt cruise, opt cruise segment, and descent to runway with ~1300lb fuel reserves.

:D did you re up the 2.0 file or will you upload a new version ? :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Nov 2015, 15:06
by sprstdlyscottsmn
I will upload the new version starting with when I complete the A-A analysis. F-15C is complete and F-16C is nearly so.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Nov 2015, 02:29
by sprstdlyscottsmn
F-16C complete.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Nov 2015, 02:42
by eloise
sprstdlyscottsmn wrote:F-16C complete.

awesome , seem like very detail analysis

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 04:15
by sprstdlyscottsmn
Does anybody have anything, written or verbal, that can help me figure out the SHornets Sustained Turn capabilities? The NATOPs Performance Manual is no help in this. I tried making a model but the Sustained turns are coming out way too high, like clean F-16 with half fuel too high. I don't want to kill the engine power because it is almost too low already.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 11:16
by eloise
sprstdlyscottsmn wrote:Does anybody have anything, written or verbal, that can help me figure out the SHornets Sustained Turn capabilities? The NATOPs Performance Manual is no help in this. I tried making a model but the Sustained turns are coming out way too high, like clean F-16 with half fuel too high. I don't want to kill the engine power because it is almost too low already.

may be it really does got good sustain turn performance :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 14:32
by zero-one
well at what speed and altitude are you trying it on? I mean we do know that at slow speeds the Bug pretty much turns inside of anything short of a Raptor.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 14:38
by sprstdlyscottsmn
20K .8M with 8 AAMs. I will try looking at the climb charts to see if I can get a Ps snapshot so that I can see which direction my issue lies in.

Edit: well, my Ps model is conservative by 5.3% so that part is looking pretty good. My calculation for Sustained G involved making a Thrust Coefficient, subtracting the zero lift drag coefficient to get an excess drag available coefficient and running that through the CDi equation to get CL available. I felt that would be simple yet elegant. Obviously my problem is not in basic thrust or drag because my Ps comes out pretty well, so perhaps it lies in a breakdown of the CDi equation under higher loads, vortex lift/drag and whatnot.

Edit #2: I was able to find installed dynamic thrust ratings for the F414 as well as a few Sust G specs. Now I have much better data to work for my model.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 17:24
by blindpilot
sprstdlyscottsmn wrote:20K .8M with 8 AAMs. I will try looking at the climb charts to see if I can get a Ps snapshot so that I can see which direction my issue lies in.

Edit: well, my Ps model is conservative by 5.3% so that part is looking pretty good. My calculation for Sustained G involved making a Thrust Coefficient, subtracting the zero lift drag coefficient to get an excess drag available coefficient and running that through the CDi equation to get CL available. I felt that would be simple yet elegant. Obviously my problem is not in basic thrust or drag because my Ps comes out pretty well, so perhaps it lies in a breakdown of the CDi equation under higher loads, vortex lift/drag and whatnot.

Edit #2: I was able to find installed dynamic thrust ratings for the F414 as well as a few Sust G specs. Now I have much better data to work for my model.


I would think you are looking in the right area (CDi, LEX-Vortex effects) and there are some F-18 unique considerations. You might get some insight here .. http://www.nasa.gov/centers/dryden/pdf/ ... H-2149.pdf

BTW thanks for your efforts. We do appreciate them.
BP

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Nov 2015, 18:22
by sprstdlyscottsmn
Thanks BP! That looks like "just what the doctor ordered" to get a feel for the Hornets vortex characteristics!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Nov 2015, 03:13
by sprstdlyscottsmn
wow, so based on that experimental data (BPs listed doc) when under that particular condition the oswalds efficiency factor (for modeling purposes) ranges from .224 at 40 degrees (CLmax) to .497 at ~17 degrees. That tells me that using 0.8 in my model could very well be why my STRs were coming in as much as 2.5 deg/sec too high from another source I found. I will tweak that value until I get the STRs for the three data points I have to match within 5% while keeping everything else I have within parameters.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Nov 2015, 05:08
by eloise
sprstdlyscottsmn wrote:wow, so based on that experimental data (BPs listed doc) when under that particular condition the oswalds efficiency factor (for modeling purposes) ranges from .224 at 40 degrees (CLmax) to .497 at ~17 degrees. That tells me that using 0.8 in my model could very well be why my STRs were coming in as much as 2.5 deg/sec too high from another source I found. I will tweak that value until I get the STRs for the three data points I have to match within 5% while keeping everything else I have within parameters.

what that ? :shock:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Nov 2015, 09:42
by Dragon029
The Oswald's efficiency factor is essential a number between 0 and 1 which tells you how closely the lift-to-drag efficiency of a real wing matches that of a hypothetical ideal wing (a wing with the same aspect ratio, but with elliptical lift distribution).

It changes based on angle of attack (because one wing design can generate less drag and/or more lift at higher angles of attack than another design), so you need to see what the Oswald's factor is across a number of situations, but it allows you to more easily calculate the lift and drag under different conditions, because you can run the numbers on the theoretical ideal wing and then just multiply the results by the Oswald's factor to get the approximate result for the real wing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Nov 2015, 14:55
by sprstdlyscottsmn
Yeah sorry, I forget to not use Engineer Speak sometimes. By using the "standard default" value of 0.8 in my model I was making the SHornet lift more efficient (in terms of induced drag generated) that it really is under higher AoA.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Nov 2015, 23:15
by sprstdlyscottsmn
A-A missions for Super Hornet complete, A-A missions (estimations) for Harrier complete. Now I need to make a simulation for take-off for my Stubby/Bee/Sea model and we should be in business for the A-A mission sets.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Dec 2015, 01:26
by eloise
sprstdlyscottsmn wrote:A-A missions for Super Hornet complete, A-A missions (estimations) for Harrier complete. Now I need to make a simulation for take-off for my Stubby/Bee/Sea model and we should be in business for the A-A mission sets.

iam so excited for the release date :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Dec 2015, 17:25
by sprstdlyscottsmn
I know that I am posting more on updates than the actual document, but I just wanted to give another status update.

Stubby is complete.

My take-off model looks pretty good but I had to change my climb model as the numbers I was getting were looking too good. I was averaging ROC at initial and final altitudes and that was giving ROC that was seemingly too fast. I looked at a few parameters (mil thrust, drag area, weight) and all those indicated that the F-35 SHOULD be the best climber but I was still unsatisfied with how good it was. So I made a model that takes the climb in 1,000ft increments and calculates the time, fuel, and distance for each increment which is then summed. This resulted in an total ROC that was 70% of the "Average of min and max" ROC. This model also allowed me to improve my cruise fuel burn models.

Now time to take these lessons and move on to the Bee and Sea, compile the data into text format, and present an analysis of A-A performance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 15:06
by sprstdlyscottsmn
Okay. Raw data is complete and the results are... surprising. Now I just need to put it all into format and I will load it up.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 15:25
by eloise
**** yessssss :mrgreen: finally :D :D :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 15:27
by sferrin
sprstdlyscottsmn wrote:Okay. Raw data is complete and the results are... surprising. Now I just need to put it all into format and I will load it up.


Don't be a tease. Give us a thumbnail picture. :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 18:21
by sprstdlyscottsmn
sferrin wrote:Don't be a tease. Give us a thumbnail picture. :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 19:56
by eloise
sprstdlyscottsmn wrote: :D

is there any particular reason why aircraft fly at 30K ft ingress instead of 40 or 45K ft ? wouldnt fly higher give more range to weapon and also using less fuel due to thin air ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Dec 2015, 20:13
by sprstdlyscottsmn
eloise wrote:is there any particular reason why aircraft fly at 30K ft ingress instead of 40 or 45K ft ? wouldnt fly higher give more range to weapon and also using less fuel due to thin air ?


That profile is not an "optimum" profile. I took it from a JSF document where that profile was described for an attack profile so I kept the same profile for their "escort". Subsonic handling up above 40k becomes a fairly "straight line" affair. In the case of the F-16 even supersonic handling is greatly degraded at 40k.

In the end any profile I chose allows for questions of "what about a profile that looks like this?" Where as last time I did two profiles only (optimum and 20k @0.8M) and there was only cruise profile sections for four aircraft, this time I am doing three profiles with sections from taxi through descent to landing including fuel reserves for max thrust combat for seven aircraft.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Dec 2015, 12:11
by eloise
sprstdlyscottsmn wrote:
That profile is not an "optimum" profile. I took it from a JSF document where that profile was described for an attack profile so I kept the same profile for their "escort". Subsonic handling up above 40k becomes a fairly "straight line" affair. In the case of the F-16 even supersonic handling is greatly degraded at 40k.

that interesting , does that mean in case of F-15 supersonic handling still great above 40K ft ? ( does that have to do with wing loading ? )
Also does that mean supercruise aircraft will fly at much higher altitude ? ( since they cruise at supersonic )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Dec 2015, 15:36
by SnakeHandler
sprstdlyscottsmn wrote:
eloise wrote:is there any particular reason why aircraft fly at 30K ft ingress instead of 40 or 45K ft ? wouldnt fly higher give more range to weapon and also using less fuel due to thin air ?


That profile is not an "optimum" profile. I took it from a JSF document where that profile was described for an attack profile so I kept the same profile for their "escort". Subsonic handling up above 40k becomes a fairly "straight line" affair. In the case of the F-16 even supersonic handling is greatly degraded at 40k.

In the end any profile I chose allows for questions of "what about a profile that looks like this?" Where as last time I did two profiles only (optimum and 20k @0.8M) and there was only cruise profile sections for four aircraft, this time I am doing three profiles with sections from taxi through descent to landing including fuel reserves for max thrust combat for seven aircraft.


How are you defining subsonic and supersonic handling above 30K?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Dec 2015, 17:08
by deadseal
eloise wrote:
sprstdlyscottsmn wrote: :D

is there any particular reason why aircraft fly at 30K ft ingress instead of 40 or 45K ft ? wouldnt fly higher give more range to weapon and also using less fuel due to thin air ?

the viper cant maneuver for sh*t above 30K......20Kagl also gets you above most IR sams and med AAA so all you really do is sacrifice the ability to maneuver against threats that can reach you no matter what your altitude is....so really the sweet spot IMHO is the 20-29 block. To shoot AAM you bump up/speed up for those shots you are talking about, and also to get a longer stick on your JDAM. the viper wing just wasnt designed for high altitude ops.

try having a high war above 30K :? its sucks

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Dec 2015, 23:04
by eloise
deadseal wrote:the viper cant maneuver for sh*t above 30K......20Kagl also gets you above most IR sams and med AAA so all you really do is sacrifice the ability to maneuver against threats that can reach you no matter what your altitude is....so really the sweet spot IMHO is the 20-29 block. To shoot AAM you bump up/speed up for those shots you are talking about, and also to get a longer stick on your JDAM. the viper wing just wasnt designed for high altitude ops.

try having a high war above 30K :? its sucks

that make me wonder, if an F-15 ( or similar aircraft like Su-27) meet an f-16 in WVR at 30K ft, their best option is to climb up? correct?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Dec 2015, 23:16
by deadseal
eloise wrote:
deadseal wrote:the viper cant maneuver for sh*t above 30K......20Kagl also gets you above most IR sams and med AAA so all you really do is sacrifice the ability to maneuver against threats that can reach you no matter what your altitude is....so really the sweet spot IMHO is the 20-29 block. To shoot AAM you bump up/speed up for those shots you are talking about, and also to get a longer stick on your JDAM. the viper wing just wasnt designed for high altitude ops.

try having a high war above 30K :? its sucks

that make me wonder, if an F-15 ( or similar aircraft like Su-27) meet an f-16 in WVR at 30K ft, their best option is to climb up? correct?


as my weapons officers have always said....it depends
what is the energy state of either fighter?
what is the missile state?

as a dutch guy i knew who was an exchange pilot said...."irregardlessly" i would want to take my own fighter down across the bottom, use the earths G to help me point at him first and come up missiles a'blazin, because chances are they got stuck somewhere up in the bozosphere trying to flip over at 50 thousand feet, and they just allowed me to point first with enough weapons seperation to shoot across the circle (its a 2 circle fight, just sideways).
now if the dude has archers with HMCS? well at that point...it depends

BFM is like surfing, everyone has their own style

ive been on a posting rampage recently, and am going to stop for awhile...cheers

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 00:18
by borg
eloise wrote:
deadseal wrote:the viper cant maneuver for sh*t above 30K......20Kagl also gets you above most IR sams and med AAA so all you really do is sacrifice the ability to maneuver against threats that can reach you no matter what your altitude is....so really the sweet spot IMHO is the 20-29 block. To shoot AAM you bump up/speed up for those shots you are talking about, and also to get a longer stick on your JDAM. the viper wing just wasnt designed for high altitude ops.

try having a high war above 30K :? its sucks

that make me wonder, if an F-15 ( or similar aircraft like Su-27) meet an f-16 in WVR at 30K ft, their best option is to climb up? correct?


It depends on situation ofcourse.
But Afaik, as a general rule F-15 and F-16 should not engage in a climb/turn vs Flankers..
Well if the Flanker is heavy with fuel it does not matter.. it would lose against an F-4E.
But 90% of the times you would face a Flanker with 40-60% fuel, and with the lifting areal of Flanker and good thrust you would not last long in a climb.
I guess the same goes for scissors type of maneuvering.

Perhaps Gums could elaborate on this?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 03:00
by eloise
borg wrote:
It depends on situation ofcourse.
But Afaik, as a general rule F-15 and F-16 should not engage in a climb/turn vs Flankers..
Well if the Flanker is heavy with fuel it does not matter.. it would lose against an F-4E.
But 90% of the times you would face a Flanker with 40-60% fuel, and with the lifting areal of Flanker and good thrust you would not last long in a climb.
?

if i remember correctly , su-27 turn very good but F-15 , F-16 accelerate better
anyway according to Andraxxus rough estimation
To fly 500 nm and back
F-15E need 58% fuel, total weight = 18000kg
F-16C need 83% fuel. total weight = 11735kg
F-35A need 57% fuel. total weight = 18082kg
Su-27 need 40% fuel. total weight = 20060kg
with that fuel state , their estimated max turn rate are
F-15E = 17,17 deg/s at 292 m/s,
F-16C = 16,07 deg/s at 313 m/s,
F-35A = 17,6 deg/s at 285 m/s,
Su-27 = 20,96 deg/s at 240 m/s
so it seem that su-27 turn better , but at slower speed

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 14:49
by borg
eloise wrote:
borg wrote:
It depends on situation ofcourse.
But Afaik, as a general rule F-15 and F-16 should not engage in a climb/turn vs Flankers..
Well if the Flanker is heavy with fuel it does not matter.. it would lose against an F-4E.
But 90% of the times you would face a Flanker with 40-60% fuel, and with the lifting areal of Flanker and good thrust you would not last long in a climb.
?

if i remember correctly , su-27 turn very good but F-15 , F-16 accelerate better
anyway according to Andraxxus rough estimation
To fly 500 nm and back
F-15E need 58% fuel, total weight = 18000kg
F-16C need 83% fuel. total weight = 11735kg
F-35A need 57% fuel. total weight = 18082kg
Su-27 need 40% fuel. total weight = 20060kg
with that fuel state , their estimated max turn rate are
F-15E = 17,17 deg/s at 292 m/s,
F-16C = 16,07 deg/s at 313 m/s,
F-35A = 17,6 deg/s at 285 m/s,
Su-27 = 20,96 deg/s at 240 m/s
so it seem that su-27 turn better , but at slower speed



Which is exactly what I tried to say.
Once the speed drops the Flanker exelles.
And doing both climb and turning kills energy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 15:27
by popcorn

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 19:10
by borg


Oh no.. not that guy again..

What about the latest exercises in UK?
The MKI pilots were better pilots, obviously..
That USAF Colonel did take a crap at the Indian pilots at RF08 in his speech , did he not?

Anyway.. He also did say -their jets is a tad better than our?
Meaning F-15/16.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 19:53
by XanderCrews
borg wrote:


Oh no.. not that guy again..

What about the latest exercises in UK?
The MKI pilots were better pilots, obviously..
That USAF Colonel did take a crap at the Indian pilots at RF08 in his speech , did he not?

Anyway.. He also did say -their jets is a tad better than our?
Meaning F-15/16.


Whenever some russian export customer gets smoked by the US/west/Israelis , fanbois blame the customer, whenever a customer wins the fanbois give the equipment the credit.

The double standard of peace. Russian gear has suffered intensely the last 30 years and every time it loses the excuses flow like water, but luckily the idea that a Russian aircraft will be better in certain areas clearly means it's superior now. I don't think it's news that russian aircraft will have advantages in certain aspects, what's new is people trying to parlay that into superiority

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Dec 2015, 21:31
by borg
XanderCrews wrote:
borg wrote:


Oh no.. not that guy again..

What about the latest exercises in UK?
The MKI pilots were better pilots, obviously..
That USAF Colonel did take a crap at the Indian pilots at RF08 in his speech , did he not?

Anyway.. He also did say -their jets is a tad better than our?
Meaning F-15/16.



Whenever some russian export customer gets smoked by the US/west/Israelis , fanbois blame the customer, whenever a customer wins the fanbois give the equipment the credit.

The double standard of peace. Russian gear has suffered intensely the last 30 years and every time it loses the excuses flow like water, but luckily the idea that a Russian aircraft will be better in certain areas clearly means it's superior now. I don't think it's news that russian aircraft will have advantages in certain aspects, what's new is people trying to parlay that into superiority


For once I agree with you.
But why are we even mention/bringing up that Colonel from RF08 again?
He add nothing to this debate.

Its well known that a Flanker gets the upper hand as speed drops.
It has both F-15c and SH Stronk side Inherent in its design.
The downer is when it toppen up on fuel.

Which was what I said a few post above.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 02:13
by popcorn
Why bring him up again?
1. because he is an actual, former F-15C and test pilot who was in the loop of events, sharing his perspective on how tactics and training that leverage a platform's strengths really, really matter and not just aircraft brochure performance.
2. because his insights outweigh those of internet fanbois and media wannabes.
3. lastly, because I knew it would solicit a predictable defensive knee-jerk reaction which Is amusing :devil:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 03:45
by sprstdlyscottsmn
popcorn wrote:3. lastly, because I knew it would solicit a predictable defensive knee-jerk reaction which Is amusing :devil:

And that is the type of behavior that I would prefer to avoid on my thread.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 03:50
by popcorn
sprstdlyscottsmn wrote:
popcorn wrote:3. lastly, because I knew it would solicit a predictable defensive knee-jerk reaction which Is amusing :devil:

And that is the type of behavior that I would prefer to avoid on my thread.

Noted Spurts...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 04:10
by eloise
popcorn wrote:This.
oo
https://youtu.be/WKEa-R37PeU

in this video at 8:21 the colonel did mentioned that F-22 can sustained 28 degree/second at 20K feet , i think that sound a bit too much , an aerodynamic engineer i talked to said that feat is impossible :? so what is your opinion ? Spurts

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 07:47
by geforcerfx
eloise wrote:in this video at 8:21 the colonel did mentioned that F-22 can sustained 28 degree/second at 20K feet , i think that sound a bit too much , an aerodynamic engineer i talked to said that feat is impossible :? so what is your opinion ? Spurts


Nothing is impossible, I remember reading about a British engineer (in the early 70's) said that a VTOL/STOVL aircraft would never go supersonic, there have been 2 demonstration aircraft and one in in service that prove him wrong.

I am not a engineer but if the aircraft can create enough lift and has enough power to overcome the drag it can sustain any turn rate, whether the pilot can is a different matter.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 15:59
by borg
Do we not know the E M charts for the EF?
The Luftwaffe EF fared pretty well against the F-22 in Red Flag.

The MKI fared pretty well against RAF EF earlier this year..

Something is evidently wrong here.. the EF does NOT have a sustaned 28 deg at 20K. The MKI does NOT have sustained 28 deg at 20K.
And for the record, neighter has F-22!

End of story.

I'm not entierly sure the Colonel meant sustained at 20K.
Must have been instant 28deg if anything.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Dec 2015, 19:17
by sferrin
geforcerfx wrote:
eloise wrote:in this video at 8:21 the colonel did mentioned that F-22 can sustained 28 degree/second at 20K feet , i think that sound a bit too much , an aerodynamic engineer i talked to said that feat is impossible :? so what is your opinion ? Spurts


Nothing is impossible, I remember reading about a British engineer (in the early 70's) said that a VTOL/STOVL aircraft would never go supersonic, there have been 2 demonstration aircraft and one in in service that prove him wrong.


Which is particularly uninformed as by then the Mirage IIIV had done so.


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Dec 2015, 05:33
by eloise
geforcerfx wrote:
Nothing is impossible, I remember reading about a British engineer (in the early 70's) said that a VTOL/STOVL aircraft would never go supersonic, there have been 2 demonstration aircraft and one in in service that prove him wrong.

I am not a engineer but if the aircraft can create enough lift and has enough power to overcome the drag it can sustain any turn rate, whether the pilot can is a different matter.

well according to him , the problem is at 30K the air is much thinner , thus there will be less lift ,and even an empty F-22 wont be able to sustain 28degrees/sec at 20K feet :? ( he made some calculation as well , i will try to find the post )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Dec 2015, 03:45
by geforcerfx
eloise wrote:well according to him , the problem is at 30K the air is much thinner , thus there will be less lift ,and even an empty F-22 wont be able to sustain 28degrees/sec at 20K feet :? ( he made some calculation as well , i will try to find the post )

How does he know how much lift the f-22 can produce at 30k or 20k? If hes only going off the wingarea that's leaving a lot of lifting surface out of the equation.
sferrin wrote:
Which is particularly uninformed as by then the Mirage IIIV had done so.



Even I always forget about the Mirage IIIV, which is a shame was a unique aircraft. He may have been doing the"it has to Vertical takeoff, then go supersonic", but even the f-35b can't do that soo. Been trying to find the book with the quote, something tells me it was a library book when I was in school.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Dec 2015, 05:55
by eloise
geforcerfx wrote:How does he know how much lift the f-22 can produce at 30k or 20k? If hes only going off the wingarea that's leaving a lot of lifting surface out of the equation.

here is his exact word
"Yes, that is very old and inaccurate evaluation from DERA, you should take it with a grain of salt.
Anyway, I don`t use youtube videos for serious, numerical evaluation. The video example I presented is there to express the level of performance EF2000 has even with 3 EFT and missiles, nothing more nothing less.
In real simulated fights against the F-22 German pilots feel very comfortable WVR and I take that much more seriously than DERA evaluation.

But the point was not about who is better in WVR fight, F-22 or EF2000. The point was that the planes are very close to each other and for a fact EF2000 or Rafale don`t have even close ITR to 28°/s at 20,000 ft! Their ITR at that height is in the range of 22°/s (according to scarce data) and STR is in the range of 13-14°/s.
Now, the difference between ITR and STR is growing with height.
For example:
At sea level F-15 has 23,9°/s ITR and 20,5°/s STR
At 30,000 ft F-15 has 16,4°/s ITR and 8,4°/s STR
At sea level the difference is very small, but at height the difference between ITR and STR rate is huge, almost double!
At higher altitude the air is very thin and because of that the engines produce far less thrust and the wings produce far less lift for the same speed (regarding subsonic WVR conditions).
The thing is, at sea level the best ITR is done at lower speed than STR, but at high altitude (30,000 ft for example) the best ITR is done at similar or somewhat higher speed than STR.
At low altitude, where the air is much more dense, the plane is able to produce enough lift to generate the max G load at lower speed for max ITR, but because the drag (caused by higher AoA) at that flight condition is very high, the plane is having negative SEP (the engines don`t have enough thrust to fight the drag so the plane is losing speed). In order to sustain its max G load the plane must fly at higher speed to generate the same amount of lift but at lower AOA. At the speed where the plane is pulling its max G load with 0 SEP we have the best sustained turn rate.
At high altitude where the air is much thinner, the plane simply doesn`t have enough thrust to sustain its max G load (At 20,000 ft F-15 can sustain only little more than 6G). But since instantaneous turn performance describes the capability of an airplane at a particular flight condition, at an instant in time, there is no consideration of the airplane’s ability to sustain the performance for any length of time, nor is there any consideration of the energy rate at these conditions. Because of that the plane can go faster at high altitude to generate enough lift to pull the (instant) max G load for max ITR.
That`s the reason we have such a big difference between the ITR and STR at high altitude.
Also, wing loading has greater effect at high altitude, but it would take to much time for me to explain that. Just consider that at sea level F-16 block30 has much superior STR performance than F-15C, but at 30,000 ft F-15 would dominate the F-16 regarding STR. Similar case is with Su-27 (it has better wing loading than F-16 but worse than F-15). At low altitude Su-27 will dominate the F-15, but at 30,000 ft the difference is very small (in Su-27`s favour) regarding max ITR and STR.
"During more or less a decade of service with the Italian Air Force, the F-16 has been extensively used to train Typhoon pilots in WVR engagements. According to the Italian pilots, the F-16 matches the EF2000 under 10,000 feet. But above that height the Typhoon becomes quite difficult to beat."

Now consider this!
The planes with the best STR at sea level (considering available data) are F-16 block30, Ef2000, Rafale, Su-27. All are in the (plus - minus) 23°/s range (I,m taking fuel fraction in to consideration).
At 20,000 ft almost all are in the range of 12 to 14°/s.
At 30,000 ft difference between F-15, F-16, Su-27 and Mig-29 in max STR is in the range less than 1°/s.

And now we have the F-22 that is having not 2 or 3°/s advantage (which would be somehow reasonable), it is having two times better STR at high altitude (some of the planes mentioned here even have better WL and T/W ratio than F-22 and very advanced aerodynamic solutions)!
If we even consider that F-22 has 28°/s STR at sea level (which would be huge advantage over any know fighter plane in existence!), how in the world will F-22 have 28°/s STR at 20,000 ft?
It means that its engines will have no drop of thrust at that altitude and its wings would need to produce the same amount of lift. How`s that even possible?
If the EF2000 has better ITR at some flight condition than F-22 (according to some sources), it means that the performance of the two planes are very close. At 20,000 ft EF2000 deosn`t have even close to to 28°/s ITR, let alone STR because the difference between ITR and STR at that height is huge."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Dec 2015, 08:29
by geforcerfx
eloise wrote:here is his exact word
"Yes, that is very old and inaccurate evaluation from DERA, you should take it with a grain of salt.
Anyway, I don`t use youtube videos for serious, numerical evaluation. The video example I presented is there to express the level of performance ....


I still see the F-22 being very dominate up high over those other platforms, none of them we designed with combat at 50,000ft in mind, the F-22 (and YF-23) were. I'm not saying they were thinking about dog fighting up there, but the whole aircraft was designed to fight and fight well at 10,000-20,000ft higher than the F-15.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Dec 2015, 14:42
by charlielima223
*in response to the infamous 28 degree per second turn rate of the F-22*

This all my own opinion based SWAG from gathered reading other sources that have for more experience and knowledge than me.

I know that we all despise APA here but unfortunately this is the only place I could find it; an interview with retired test pilot Paul Metz

http://www.ausairpower.net/API-Metz-Interview.html

To generate the same maneuver supersonically as subsonically, the controls must be deflected further. This, in turn, results in a big increase in supersonic trim drag and a subsequent loss in acceleration and turn performance. The F-22 offsets this trim drag, not with the horizontal tails, which is the classic approach, but with the thrust vectoring. With a negligible change in forward thrust, the F-22 continues to have relatively low drag at supersonic maneuvering speed. . But drag is only part of the advantage gained from thrust vectoring. By using the thrust vector for pitch control during maneuvers the horizontal tails are free to be used to roll the airplane during the slow speed fight. This significantly increases roll performance and, in turn, point-and-shoot capability. This is one of the areas that really jumps out to us when we fly with the F-16 and F-15. The turn capability of the F-22 at high altitudes and high speeds is markedly superior to these older generation aircraft. I would hate to face a Raptor in a dogfight under these conditions.


Then I remembered this by SMSgt Mac

http://elementsofpower.blogspot.com/201 ... -spec.html

Even though he was discussing the sustained G spec change for the F-35 something always stuck out to me...

Depending on airspeed, the bank angle could translate into a ‘small’ or a ‘large’ difference in turn rate and turn radius. Without knowing for certain what the weight, speed, and altitude


So here we have the USAF Colonel stating that

When he's in a turn and he's coming around the corner and you have an inexperienced guy because the experienced guy knows not to get there. But the inexperienced guy has and this is no sh*t; a 28 degrees per second turn radius at 20000 feet. The F-15 has an instantaneous of 21 and a sustained of about 15 to 16 degrees. The Raptor can sustain 28 degrees.


of course it is helpful to note that the USAF Colonel was talking about post stall maneuvering before this and that he was mentioning this as a condition the Raptor can do BEFORE post stall maneuvering...

Some of these young guys, that's not enough that want more than that... and he pulls to the point where he goes post stall maneuvering


So some things come to my mind. First we "know" that according to that Colonel the F-22 can do 28 degree per second turn at 20000 feet. What we don't know is speed, weight, bank angle, ect of the aircraft. Is this 20000 AGL or 20000 above sea level? It should be noted and this occurred over the Nellis Air Force Range. Simply put we just don't know all the factors. Also it would seem that beyond that, that is the absolute limit of what the F-22 can (or can't) do. Beyond that the F-22 goes into post stall.

Every F-22 pilot will tell you the F-22 can maneuver with the best of them and still able to do more than the best of them.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 03:12
by XanderCrews
eloise wrote:
geforcerfx wrote:How does he know how much lift the f-22 can produce at 30k or 20k? If hes only going off the wingarea that's leaving a lot of lifting surface out of the equation.

here is his exact word
"Yes, that is very old and inaccurate evaluation from DERA, you should take it with a grain of salt.
Anyway, I don`t use youtube videos for serious, numerical evaluation. The video example I presented is there to express the level of performance EF2000 has even with 3 EFT and missiles, nothing more nothing less.
In real simulated fights against the F-22 German pilots feel very comfortable WVR and I take that much more seriously than DERA evaluation.

But the point was not about who is better in WVR fight, F-22 or EF2000. The point was that the planes are very close to each other and for a fact EF2000 or Rafale don`t have even close ITR to 28°/s at 20,000 ft! Their ITR at that height is in the range of 22°/s (according to scarce data) and STR is in the range of 13-14°/s.
Now, the difference between ITR and STR is growing with height.
For example:
At sea level F-15 has 23,9°/s ITR and 20,5°/s STR
At 30,000 ft F-15 has 16,4°/s ITR and 8,4°/s STR
At sea level the difference is very small, but at height the difference between ITR and STR rate is huge, almost double!
At higher altitude the air is very thin and because of that the engines produce far less thrust and the wings produce far less lift for the same speed (regarding subsonic WVR conditions).
The thing is, at sea level the best ITR is done at lower speed than STR, but at high altitude (30,000 ft for example) the best ITR is done at similar or somewhat higher speed than STR.
At low altitude, where the air is much more dense, the plane is able to produce enough lift to generate the max G load at lower speed for max ITR, but because the drag (caused by higher AoA) at that flight condition is very high, the plane is having negative SEP (the engines don`t have enough thrust to fight the drag so the plane is losing speed). In order to sustain its max G load the plane must fly at higher speed to generate the same amount of lift but at lower AOA. At the speed where the plane is pulling its max G load with 0 SEP we have the best sustained turn rate.
At high altitude where the air is much thinner, the plane simply doesn`t have enough thrust to sustain its max G load (At 20,000 ft F-15 can sustain only little more than 6G). But since instantaneous turn performance describes the capability of an airplane at a particular flight condition, at an instant in time, there is no consideration of the airplane’s ability to sustain the performance for any length of time, nor is there any consideration of the energy rate at these conditions. Because of that the plane can go faster at high altitude to generate enough lift to pull the (instant) max G load for max ITR.
That`s the reason we have such a big difference between the ITR and STR at high altitude.
Also, wing loading has greater effect at high altitude, but it would take to much time for me to explain that. Just consider that at sea level F-16 block30 has much superior STR performance than F-15C, but at 30,000 ft F-15 would dominate the F-16 regarding STR. Similar case is with Su-27 (it has better wing loading than F-16 but worse than F-15). At low altitude Su-27 will dominate the F-15, but at 30,000 ft the difference is very small (in Su-27`s favour) regarding max ITR and STR.
"During more or less a decade of service with the Italian Air Force, the F-16 has been extensively used to train Typhoon pilots in WVR engagements. According to the Italian pilots, the F-16 matches the EF2000 under 10,000 feet. But above that height the Typhoon becomes quite difficult to beat."

Now consider this!
The planes with the best STR at sea level (considering available data) are F-16 block30, Ef2000, Rafale, Su-27. All are in the (plus - minus) 23°/s range (I,m taking fuel fraction in to consideration).
At 20,000 ft almost all are in the range of 12 to 14°/s.
At 30,000 ft difference between F-15, F-16, Su-27 and Mig-29 in max STR is in the range less than 1°/s.

And now we have the F-22 that is having not 2 or 3°/s advantage (which would be somehow reasonable), it is having two times better STR at high altitude (some of the planes mentioned here even have better WL and T/W ratio than F-22 and very advanced aerodynamic solutions)!
If we even consider that F-22 has 28°/s STR at sea level (which would be huge advantage over any know fighter plane in existence!), how in the world will F-22 have 28°/s STR at 20,000 ft?
It means that its engines will have no drop of thrust at that altitude and its wings would need to produce the same amount of lift. How`s that even possible?
If the EF2000 has better ITR at some flight condition than F-22 (according to some sources), it means that the performance of the two planes are very close. At 20,000 ft EF2000 deosn`t have even close to to 28°/s ITR, let alone STR because the difference between ITR and STR at that height is huge."


The F-22 has thrust vectoring. It's not just for airshows it's for operating at high altitudes as was envisioned

the tailfins have as much area as an F-16 wing just to try and keep some perspective, and the ef typhoon has no thrust vectoring.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 07:53
by eloise
XanderCrews wrote:
The F-22 has thrust vectoring. It's not just for airshows it's for operating at high altitudes as was envisioned

the tailfins have as much area as an F-16 wing just to try and keep some perspective, and the ef typhoon has no thrust vectoring.

thrust vectoring on aircraft is for post stall maneuver
Sustained turns are not made at high AOAs
Performing greatest sustain turn , TVC nozzles will be locked at 0deg position to achieve the greatest thrust to overcome the drag

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 08:12
by eloise
charlielima223 wrote:
So some things come to my mind. First we "know" that according to that Colonel the F-22 can do 28 degree per second turn at 20000 feet. What we don't know is speed, weight, bank angle, ect of the aircraft.

IMHO at high altitude , air is relative thin hence fighter dont have enough lift , if the aircraft bank too much it will have less lift which make the problem even worse
Andraxxus wrote:Its basically due to the fact air gets thinner at the altitude. In order to stay in level -let alone make a turn- an aircraft a) higher lift coefficient -OR- b) needs to go faster.

a) Higher lift coeefficient, always require higher AOA. As to WHY wing loading affects high altitude performance;

Lift = 1/2 * density * Wing Area * Lift Coefficient * airspeed ^2 and Lift = aircraft weight * amount of G aircraft pulls;

Wing loading = Aircraft Weight / Wing area; or we can say: aircraft weight = wing loading * wing area;

For a level flight condition; if we are to put this into lift formula it becomes;

Wing loading * aircraft G load = 1/2 * air density * Lift coefficent * airspeed^2

In other words; Wing loading is directly proportional to Lift coefficient aircraft requires to pull a G load. Lower wing loading means less Cl, or in other words less AOA is required. This generally leads to less drag coeffient so aircraft flies -or turns- more efficiently.

At sea level aircraft fly proportionally too fast to make this relevant, as Cl increase is linear, but Cd increase is more exponential: I couldn't find 64A204 but lets take 64A215 airfoil, its similar to the F-16's airfoil, but thicker and does not have LE flaps:
Image
(Though this graph made by to CFD modelling there are inaccuracies; there should be minimal CD increase between 0-5 deg AOA following the parabolic behaviour of the graph)

Lets take this airfoil as the F-16's airfoil;

For an F-16 blk50 (27,87m2 wing area) flying with 50% fuel + 4 missiles (12690 kg) at sea level (air density = 1,2)

Level flight at M0,5 reqiures 0,23 CL. this (coindicentally) happens at 0 AOA, and with minimal drag coefficient. As drag is also multipled with wing area, having smaller wings is beneficial and will create less drag. This will help in level flight accelerations.
Turning at 9G at M0,85 requires: 0,72 CL. This happens at 5 deg AOA; still at very low Cd. Low Cd multipled with low wing Area results in low drag, which explains the impressive sustained turn performance of the F-16. If F-16 had bigger wings, it would only increase its drag, and lower its sustained turn performance.

However when same aircraft reaches 30k feet (air density = 0,35)

Level flight at M0,5 requires 0,98 Cl at 10 deg angle of attack; this corresponds to 0,02 Cd; Now the Wing Area becomes important: IF F-16 aircraft had 33% larger wings; it would have required ~0,75 cl and had 0,01 Cd: This 33% increase in wing area and 50% decrease in Cd would actually resulted in 33% LESS draggy aircraft (despite being physically larger), directly improving acceleration.

Turning at 4Gs at 30k feet would require 1,27 Cl at 15 deg AOA resulting in 0,06 Cd (note that this is not entirely accurate for the Real Life F-16 has LE flaps which would decrease the Cd). If F-16 had twice the wing area; it would have had only 0,01 Cd; and be 300% less draggy;

Wing Loading also tells about how much available lift aircraft can produce; At M0,85 Clmax= 1,5; F-16 can pull 5Gs at best, resulting in 10,3 deg/s instantenious turn rate at 30k feet. Greater the wing area, greater the instantenious turn rates.

This all comes to optimization and engineering choices: Current small wings of F-16, are optimal at Sea level, but inferior at 30k feet. Slightly enlarging wings would improve both maneuvering and acceleration performance at high altitude, at the cost of low altitude performance. Enlarging wings too much would horribly worsen the low altitude turn, acceleration and climb performance; worsen high altitude acceleration, but improve high altitude turn performance. And I am talking purely about aerodynamics; an increase in deadweight would also decreased payload and further increased the drag etc etc.

With ever increasing payloads; smaller winged and lighter aircraft have more drastic increases in wing loading;

When we fuel an F-16 and Su-27 at 50% fuel load; they will have 383 and 338 kg/m2 wing loading respectively. However if we are to add 3 tons of fuel/payload; they will become; 490 and 387 kg/m2 respecively. Remembering the formula above; this means, F-16 will require 28% greater lift coefficient to achieve same turn rate; Su-27 will only require 14%; Considering Cd increases exponentially, that means there will be huge performance drop for F-16 while both accelerating and turning; but -aerodynamically speaking- Su-27 wont be affected at all while accelerating; and only a slight performance drop while turning. That is if we are speaking about high altitude.

In simpler terms smaller the aircraft gets, greater the Cl requirement will become with equal payload. Wings stay same; so there will be greater AOA requirement; and lower L/D as in this graph.
Image
As to add to the discussion; let me try to explain how wing loading, T/W, and other factors can be used to *roughly* estimate and compere maneuverability: look at F-15; F-15 uses NACA 64A203 airfoil, very similar to the F-16's 64A204.

At 50% fuel clean, F-16 has wing loading of 383 kg/m2, whereas F-15 has 285 kg/m2. Wing's Low AOA behaviour is the same, but F-16 has Clmax of ~1.6 at M0,5 maneuvering conditions F-15 has 1,1; due to lack of LE flaps it stalls earlier.

Remembering this formula: Wing loading * aircraft G load = 1/2 * air density * Lift coefficent * airspeed^2

45% less Clmax + 26% less wing loading means F-15 will have less available G and less instantenious turn rate by 8% at sea level. Obviously this is no coincidence that FM data shows at M0,5 F-16 can pull 24,2 deg/s and F-15 22 deg/s, 9% difference.

As wing behaviour is similar due to similar airfoils; 26% less wing loading = 26% less necessary Cl at 9G; We can assume (albeit a little inaccurrately) that means 26% decrease in Cd. F-15 has 202% greater wing area (read = drag) of F-16, it has 63% greater static thrust. All relations are linear; so multiplying all relations will tell us; F-15 will have 91% Sustained turn performance of F-16; Real numbers are 20,5 vs 21,5 respectively; 5% drop in performance.

As Su-27 uses different airfoil such estimate about STR is not possible because we simply dont know how Cd changes; We can however estimate Instantenious turn rate:

Compared to F-16; it has 15% better Clmax; and 11% less wing loading. Knowing this; means we can estimate 24,2*1.11*1.15 = 30,8 deg/s ITR at M0,5. But that would result in greater than 9Gs; Truth is Su-27 achieves its highest ITR at M0,48 (30,2 deg/s); That is still an accurate estimate.

Here is the STR graphs of 4th gen fighters compared to F-4E at 30k feet when clean 50% fuelled:
Image
-F-22 or any aircraft with present days tech cannot sustain 28 deg/s at 30k feet, not to mention carry 6 AAMs. A clean F-16 cannot even sustain 8 deg/s. With much superior wing loading, less drag and better T/W, PW220 engined F-15C can only sustain 8.4. I won't go into it futher.

-MKI may or may not sustain 22/23 but that is again at sea level. Su-27 can do 8.55 deg/s at 30k, MKI wont be much different than that.



charlielima223 wrote: Is this 20000 AGL or 20000 above sea level? . .

i think here probably where problem lie ,may be the ground level of the area is alot lower than average sea level

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 08:39
by geforcerfx
eloise wrote:
XanderCrews wrote:
The F-22 has thrust vectoring. It's not just for airshows it's for operating at high altitudes as was envisioned

the tailfins have as much area as an F-16 wing just to try and keep some perspective, and the ef typhoon has no thrust vectoring.

thrust vectoring on aircraft is for post stall maneuver
Sustained turns are not made at high AOAs
Performing greatest sustain turn , TVC nozzles will be locked at 0deg position to achieve the greatest thrust to overcome the drag


Umm no, the main reason the F-22 has TVC to enable more control at the higher altitudes, the nozzles can deflect to certain degrees without effecting thrust levels. This has been said before by both pilots and engineers multiple times throughout the last 20 years. The post stall maneuvering was another benefit of having them, but that's not the way they mainly designed the aircraft to fight. High, Fast, stealthy and rain missiles down on enemies from BVR, if they launch missiles back the F-22 has the engine power, lifting surface, and control surfaces (TVC) to remain relatively mobile up high.

Again wingloading doesn't take into account the several other major lifting surfaces on modern day fighter aircraft. As Crews just pointed out the tail surfaces have the same wing area as a F-16's, the F-22 has a lot of lifting surfaces that the Wing area doesn't show.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 08:55
by eloise
geforcerfx wrote:

Umm no, the main reason the F-22 has TVC to enable more control at the higher altitudes, the nozzles can deflect to certain degrees without effecting thrust levels. This has been said before by both pilots and engineers multiple times throughout the last 20 years. The post stall maneuvering was another benefit of having them, but that's not the way they mainly designed the aircraft to fight. High, Fast, stealthy and rain missiles down on enemies from BVR, if they launch missiles back the F-22 has the engine power, lifting surface, and control surfaces (TVC) to remain relatively mobile up high.

yes TVC help point the nose of aircraft when the tail fin doesnt provide enough pitch to turn the aircraft , which happened at either post stall speed ( speed to low, not enough lift ) or high altitude ( air too thin , not enough lift ) , however it doesnt help your sustain turn rate

geforcerfx wrote:Again wingloading doesn't take into account the several other major lifting surfaces on modern day fighter aircraft. As Crews just pointed out the tail surfaces have the same wing area as a F-16's, the F-22 has a lot of lifting surfaces that the Wing area doesn't show.

both F-16 and su-27 have body lift ( especially su-27 with it's whole body is an airfoil ), so i dont think f-22 is the exception here

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 12:19
by borg
eloise wrote:
geforcerfx wrote:

Umm no, the main reason the F-22 has TVC to enable more control at the higher altitudes, the nozzles can deflect to certain degrees without effecting thrust levels. This has been said before by both pilots and engineers multiple times throughout the last 20 years. The post stall maneuvering was another benefit of having them, but that's not the way they mainly designed the aircraft to fight. High, Fast, stealthy and rain missiles down on enemies from BVR, if they launch missiles back the F-22 has the engine power, lifting surface, and control surfaces (TVC) to remain relatively mobile up high.

yes TVC help point the nose of aircraft when the tail fin doesnt provide enough pitch to turn the aircraft , which happened at either post stall speed ( speed to low, not enough lift ) or high altitude ( air too thin , not enough lift ) , however it doesnt help your sustain turn rate

geforcerfx wrote:Again wingloading doesn't take into account the several other major lifting surfaces on modern day fighter aircraft. As Crews just pointed out the tail surfaces have the same wing area as a F-16's, the F-22 has a lot of lifting surfaces that the Wing area doesn't show.

both F-16 and su-27 have body lift ( especially su-27 with it's whole body is an airfoil ), so i dont think f-22 is the exception here



Wing loading does take into account all lifting surfaces.

Wing loading:
-Lift(overall total lifting surfaces)
-Weight(this is not a constant, but it has a very imprtant impact)

-Lift/Drag(different airfoils, Smaller wings vs larger wings, blended body/wing, etc)

TVC is beside this point.

As andraxx state:

Su-27 airfoil is ticker vs F-15, but thinner vs F-22.
Su-27 has much higher lift due to blended wing/body design, larger wings, over F-15 and F-16.
F-22 also have large lifting surface(large wings), but also is conciderable heavier over Su-27.

pretty easy to see how the MKI did well against EF and other jets.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 14:15
by basher54321
borg wrote:

Wing loading does take into account all lifting surfaces.


Basically no - wingloading typically only uses a Wing ref area - there should be quite a few old threads on here you can search for that can help you with this.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 14:59
by sprstdlyscottsmn
basher54321 wrote:Basically no - wingloading typically only uses a Wing ref area - there should be quite a few old threads on here you can search for that can help you with this.


And if everyone would please stop using the "body lift" argument, that is nothing but a red herring.

"But Spurts, on plane X the body can make up to 40% of the lift!"

Yes, and on plane X the body also covers 40% of the Reference Wing Area... so guess what? It is a null point!

Stability is the factor that will add to or even take away from usable lifting area, not body lift.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Dec 2015, 18:47
by geforcerfx
borg wrote:F-22 also have large lifting surface(large wings), but also is conciderable heavier over Su-27.


Yeah, not at loaded weights(full fuel) theres around 3,000lbs of difference and the f-22 has a significant (11,000 + lbs) thrust advantage to make up the difference.

Also as has been said now cointless times on the forum and just above the vast majority of the lifting body is in the wing area so is part of the wing loading.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Dec 2015, 02:54
by eloise
I just come across this
http://thebetacoefficient.blogspot.co.u ... i.html?m=1
how accurate is it? Sprut?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Dec 2015, 16:11
by sprstdlyscottsmn
Well, the F-16A never had an F110 motor, so his assumptions are incorrect. His results are rather incomplete, showing only STR at sea level in Mil power at a zero fuel state.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 12:34
by eloise
sprstdlyscottsmn wrote:Well, the F-16A never had an F110 motor, so his assumptions are incorrect. His results are rather incomplete, showing only STR at sea level in Mil power at a zero fuel state.

I see, still it quite interesting to see that LCA over perform F-16 in Mil thrust

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 12:47
by popcorn
eloise wrote:
sprstdlyscottsmn wrote:Well, the F-16A never had an F110 motor, so his assumptions are incorrect. His results are rather incomplete, showing only STR at sea level in Mil power at a zero fuel state.

I see, still it quite interesting to see that LCA over perform F-16 in Mil thrust

Comparing LCA to an aircraft from 40 years back?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 12:51
by eloise
popcorn wrote:Comparing LCA to an aircraft from 40 years back?

That aircraft from 40 year back still able to dogfight with anything bellow 10K feet

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 14:04
by popcorn
eloise wrote:
popcorn wrote:Comparing LCA to an aircraft from 40 years back?

That aircraft from 40 year back still able to dogfight with anything bellow 10K feet

So why are you surprised that an aircraft built 40 years later would outperform it?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 14:06
by popcorn
eloise wrote:
popcorn wrote:Comparing LCA to an aircraft from 40 years back?

That aircraft from 40 year back still able to dogfight with anything bellow 10K feet
o
So why the surprise that an aircraft built 40 years later may ohtperform it? Wouldn't the surprise be if it couldn't?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 14:25
by eloise
popcorn wrote:So why the surprise that an aircraft built 40 years later may ohtperform it? Wouldn't the surprise be if it couldn't?

I surprise because LCA have weak engine and does not look like it have many lift oriented features that would allow it to surpass F-16 significantly

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2015, 14:43
by basher54321
Talk about take some random numbers and make them up - all I would say is that I hope the Tejas is not as poor as his SL chart shows 8)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Dec 2015, 02:45
by popcorn
eloise wrote:
popcorn wrote:So why the surprise that an aircraft built 40 years later may ohtperform it? Wouldn't the surprise be if it couldn't?

I surprise because LCA have weak engine and does not look like it have many lift oriented features that would allow it to surpass F-16 significantly

Weaker engine but a subsrtantially lighter jet. AFAIK the way any aircraft handles would be primarily dependent on the sophistication of the FBW system which optimizes the control surfaces. Problematic to assess unless you have insight into the software/hardware interaction.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Dec 2015, 21:13
by sprstdlyscottsmn
Hello all. The write-up is more time consuming than I anticipated. I have far more text this time around and less "pretty pictures". I have attached the Interception mission profile results, which does NOT include the previous 11 pages of general supporting documentation and discussion. I figured you all deserved more than just "it's not done yet." Enjoy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Dec 2015, 21:17
by eloise
sprstdlyscottsmn wrote:Hello all. The write-up is more time consuming than I anticipated. I have far more text this time around and less "pretty pictures". I have attached the Interception mission profile results, which does NOT include the previous 11 pages of general supporting documentation and discussion. I figured you all deserved more than just "it's not done yet." Enjoy.

:mrgreen: :drool: thanks alot sprut

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Dec 2015, 21:59
by spazsinbad
Thanks for the doc. I'm a committed non-user of Microsoft Office products however I do use the viewer and the PDF attached is a result of that use. Please let me know if errors are apparent - opened the .doc with the viewer and printed to PDF via Adobe Acrobat Reader DC (I'm using a new laptop computer at moment without all my usual bells & whistles).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Dec 2015, 23:22
by neurotech
sprstdlyscottsmn wrote:Hello all. The write-up is more time consuming than I anticipated. I have far more text this time around and less "pretty pictures". I have attached the Interception mission profile results, which does NOT include the previous 11 pages of general supporting documentation and discussion. I figured you all deserved more than just "it's not done yet." Enjoy.

There is some interesting info in there, but I think the profile for the Rhino could do with some clarification. They wouldn't fly with that many missiles on pylons as it would be way more efficient to fly with 2xAIM-120 on the conformal stations, and two AIM-9s on the wingtips. Without wing pylons, The jet can dash about ~M1.45, even with the center tank. I also think that you overestimated the climb fuel, by going faster than optimal for the drag index, and then leaving less fuel to accelerate on top.

One inaccuracy in a lot of interpretation of the acceleration charts is that an F/A-18 would "zoom climb", then accelerate to supersonic dash speed. The F-35 would probably do the same.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2015, 00:00
by sprstdlyscottsmn
neurotech wrote:There is some interesting info in there, but I think the profile for the Rhino could do with some clarification. They wouldn't fly with that many missiles on pylons as it would be way more efficient to fly with 2xAIM-120 on the conformal stations, and two AIM-9s on the wingtips. Without wing pylons, The jet can dash about ~M1.45, even with the center tank. I also think that you overestimated the climb fuel, by going faster than optimal for the drag index, and then leaving less fuel to accelerate on top.

One inaccuracy in a lot of interpretation of the acceleration charts is that an F/A-18 would "zoom climb", then accelerate to supersonic dash speed. The F-35 would probably do the same.

Hey neurotech.

I went with a single midboard pylon with dual racked AIM-120s as it looks like that is lower drag than any other method of four pylon loaded missiles. You are correct that I could neuter the loadout to improve dash performance, but then I would need to do the same to everything else. Just fuselage AMRAAMS for the Eagle, just Tip-RAMs for the Viper, etc. I went with what I thought represented an operational loadout and F/A-18Es have even done airshow demos configured as I have them in my comparison. Obviously if I am told by someone in the know that an intercept loadout really does consist of low drag munitions only I would be more than happy to go back and correct my work.

As for climb, I'm pretty sure I went with the optimum AB climb profile for the weight and DI but I am willing to double check.

Not sure what you meant by "One inaccuracy in a lot of interpretation of the acceleration charts is that an F/A-18 would "zoom climb", then accelerate to supersonic dash speed". Are you saying people inaccurately assume that is what happens or people inaccurately use the charts as listed but operationally they actually do a zoom climb? I could probably make a zoom climb model but I would need parameters for it, initial speed, climb angle, is the angle held constant, is the angle decreased to maintain a certain min speed? etc. I certainly want these to be as operationally representative as possible.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2015, 00:58
by neurotech
sprstdlyscottsmn wrote:
neurotech wrote:There is some interesting info in there, but I think the profile for the Rhino could do with some clarification. They wouldn't fly with that many missiles on pylons as it would be way more efficient to fly with 2xAIM-120 on the conformal stations, and two AIM-9s on the wingtips. Without wing pylons, The jet can dash about ~M1.45, even with the center tank. I also think that you overestimated the climb fuel, by going faster than optimal for the drag index, and then leaving less fuel to accelerate on top.

One inaccuracy in a lot of interpretation of the acceleration charts is that an F/A-18 would "zoom climb", then accelerate to supersonic dash speed. The F-35 would probably do the same.

Hey neurotech.

I went with a single midboard pylon with dual racked AIM-120s as it looks like that is lower drag than any other method of four pylon loaded missiles. You are correct that I could neuter the loadout to improve dash performance, but then I would need to do the same to everything else. Just fuselage AMRAAMS for the Eagle, just Tip-RAMs for the Viper, etc. I went with what I thought represented an operational loadout and F/A-18Es have even done airshow demos configured as I have them in my comparison. Obviously if I am told by someone in the know that an intercept loadout really does consist of low drag munitions only I would be more than happy to go back and correct my work.

US Navy F/A-18E/Fs rarely (if ever) fly Air Sovereignty Alert, although they have flown airborne CAP (e.g Noble Eagle) with wing tanks etc. The NATOPS does cover the 2+2 configuration for performance charts. The Navy doesn't have the need to fly operationally with on alert with that configuration. The point is that alert profile as specified, was not "favorable" to the F/A-18E/F platform.
sprstdlyscottsmn wrote:As for climb, I'm pretty sure I went with the optimum AB climb profile for the weight and DI but I am willing to double check.

I'd have to double check to be certain of the optimal profile for the weight and DI, but the climb figures as specified seems high.
sprstdlyscottsmn wrote:Not sure what you meant by "One inaccuracy in a lot of interpretation of the acceleration charts is that an F/A-18 would "zoom climb", then accelerate to supersonic dash speed". Are you saying people inaccurately assume that is what happens or people inaccurately use the charts as listed but operationally they actually do a zoom climb? I could probably make a zoom climb model but I would need parameters for it, initial speed, climb angle, is the angle held constant, is the angle decreased to maintain a certain min speed? etc. I certainly want these to be as operationally representative as possible.

The acceleration time in level flight is what the performance charts specify, although trading altitude for airspeed while passing through M1.0 is done operationally, due to the high transonic drag. My comment about "zoom climb" is based on the premise that the F/A-18 would likely climb above the cruise altitude (eg. 35,000) before accelerating. It sure ain't going to go supersonic on climb with a full (high DI) loadout. It would really depend on the exact profile flown.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2015, 14:33
by eloise
Sprut how about the problem of thrust reduced at higher altitude , speed ?
Thrust[1].JPG

what if engine of one fighter reduced thrust at faster rate than the others ? ( I mean higher bypass engine often suffer more performance plenty at high altitude , speed than the low bypass one )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2015, 16:28
by sprstdlyscottsmn
eloise wrote:what if engine of one fighter reduced thrust at faster rate than the others ? ( I mean higher bypass engine often suffer more performance plenty at high altitude , speed than the low bypass one )

That is why I find data points to match when I have to make even a partial model. For the Harrier, Rhino, Stubb-A, Stubb-B, and Stubb-C I had acceleration and STR specs to match. That is why I will not add the F-22 into the analysis. There are NO data points to match. Most of my data comes directly from the flight manuals from the F-15, F-16, and F/A-18E. I was able to build a good Harrier model from one document that held a lot of mission data in it. My F-35 model is based on the few public data points (accel and Sust G for all variants with one fuel flow point for the A as well). I tweak my basic engine model until I get my theoretical data to match measured data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Dec 2015, 17:24
by eloise
sprstdlyscottsmn wrote:
eloise wrote:what if engine of one fighter reduced thrust at faster rate than the others ? ( I mean higher bypass engine often suffer more performance plenty at high altitude , speed than the low bypass one )

That is why I find data points to match when I have to make even a partial model. For the Harrier, Rhino, Stubb-A, Stubb-B, and Stubb-C I had acceleration and STR specs to match. That is why I will not add the F-22 into the analysis. There are NO data points to match. Most of my data comes directly from the flight manuals from the F-15, F-16, and F/A-18E. I was able to build a good Harrier model from one document that held a lot of mission data in it. My F-35 model is based on the few public data points (accel and Sust G for all variants with one fuel flow point for the A as well). I tweak my basic engine model until I get my theoretical data to match measured data.

I see , that very interesting

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Jan 2016, 21:00
by sprstdlyscottsmn
I have good news and bad news.

Bad news, my analysis will be delayed.

Good news, I obtained an F/A-18C NATOPS and will be adding it into the analysis. I also obtained an A-10A -1 and will be adding that into the A-G portion.

Edit: and FYI I added two pages of analysis to the Interception mission. I will also try and tweak my high alt engine model.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jan 2016, 02:56
by sferrin
Just thought I'd put this here (seems relevant). They seem to have cut loose a bit more than I've seen in other videos.


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jan 2016, 06:39
by hornetfinn
Very nice video sferrin, thanks for it! I really like the Transformers style looks and wing sweep operation of F-14. Nice maneuvers too!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jan 2016, 13:32
by eloise
Spurt , I heard you want F-14 flight manual the other day , so here it is https://publicintelligence.net/u-s-navy ... t-manuals/
:mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jan 2016, 15:07
by sprstdlyscottsmn
Eloise,

I appreciate the notice, but I already have the 1037 page version of the F14AAD-1. It is completely missing the Performance Data which is in F14AAP-1.1. F14AAD-1 has given me some great information about the C.G. balancing of the aircraft and overall handling but little else. I have a single page of the F14AAD-1.1 I picked up from another thread as well as the F14AAP-1B which I was able to use to get a lot of data including Drag Index info and descent data which I can use to get both drag coefficient and stability estimates but it may be enough for me to try and build a model from. Other than re-hashing my old Bombcat vs Beagle thread I see little value in what my analysis would bring to the boards. This threads analysis focuses on current aircraft and the Cat has been retired for 11 terrible years.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Jan 2016, 22:57
by quicksilver
sferrin wrote:Just thought I'd put this here (seems relevant). They seem to have cut loose a bit more than I've seen in other videos.



Vertigo-inducing video of a beautiful, classic aircraft.

GE motors...almost an entirely different jet, performance-wise.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 Jan 2016, 01:03
by sprstdlyscottsmn
That is the most Sierra Hotel demo I have ever seen done with a Cat.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2016, 14:40
by sprstdlyscottsmn
I think it may be time to abandon this thread and move the analysis to Modern Military Aircraft. What started as a pretty simple F-35 vs other Air Force mud movers has become the following due to an expansion of available data and enhanced modeling tools.

Aircraft – This study will investigate the classic “Teen-Series” of fighters as well as the aircraft that have or will replace them. The following aircraft will be investigated in depth with additional aircraft being used for reference. Air aircrafts performance data will come from the source listed below.

F-15C Eagle – data taken directly from F-15C -1 using F100-PW-220 data, A-A only
F-15E “Mudhen” – data taken directly from F-15E -1 using F100-PW-229 data, A-G only
F-22A Raptor – data estimated from stated performance and engineering analysis

F-16C “Viper”– data taken directly from HAF -1 using F110-GE-129 data
A-10C “Hog”– Data taken directly from A-10A -1, A-G only
F-35A “Stubby” – data estimated from stated performance and engineering analysis

AV-8B Harrier– data derived from partial NATOPS and engineering analysis
F-35B “Bee” – data estimated from stated performance and engineering analysis

F-14D Tomcat – data derived from partial NATOPS and engineering analysis.
F/A-18E “Rhino” – data taken directly/derived from NATOPS and engineering analysis

F/A-18C Hornet – data taken directly/derived from NATOPS and engineering analysis
F-35C “Sea” – data estimated from stated performance and engineering analysis

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Mar 2016, 03:05
by sprstdlyscottsmn
Since eloise asked for an update.

Progress is going well, but slowly. I keep making a pass through a section, say intercept, and then realize I screwed up something in the mission parameters and redo the whole thing, then I get to CAP and realize my fuel flow and wave drag models are need work so I go back and fix them and re-do Intercept and CAP. I have to put the CAP data in the report and also generate the Escort data for the report, but I think the way I did the CAP data it can double as escort if I change the mission parameters.

And as a side note, the Eagle is a beast. From what I can see it can do a 228 min CAP at 200nm, can do a 60 minute CAP over 1,000nm from base, and has an optimum cruise radius of 1337nm with three gas bags. It seriously makes me question if I read the data from the -1 correctly.

The Tomcat does not have enough fuel.

Stubby does indeed have poor sustained turns but great transient turns.

On to Escort, then adding data to the report, then I can release the Air to Air section.

Oh, and from what I can see the Rutowski profile has a downside too. Using a given starting altitude and speed with a target end speed at the same altitude, you end up either wasting time/fuel/distance in an initial subsonic climb or in a supersonic climb afterwards. I did not use any Rutowski profiles in my analysis but I did want to analyze them.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Mar 2016, 05:40
by rheonomic
Got a question for you. I've been wanting to review aircraft performance, but my undergrad didn't cover much on performance, and for my grad work (both in aero) I'm pretty heavy into the controls side. Any recommended resources for brushing up?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Mar 2016, 06:15
by sprstdlyscottsmn
rheonomic wrote:Got a question for you. I've been wanting to review aircraft performance, but my undergrad didn't cover much on performance, and for my grad work (both in aero) I'm pretty heavy into the controls side. Any recommended resources for brushing up?

I have sent you a PM.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Apr 2016, 03:15
by Scorpion82
sprstdlyscottsmn wrote:Hello all. The write-up is more time consuming than I anticipated. I have far more text this time around and less "pretty pictures". I have attached the Interception mission profile results, which does NOT include the previous 11 pages of general supporting documentation and discussion. I figured you all deserved more than just "it's not done yet." Enjoy.


Thank you for your effort!

One question though, despite a slightly inferior T/W ratio your calculation puts the B slightly faster at the target height than the A. When it comes to accelerating, however the A trumps the B hands down. How does this match up?

I suppose the acceleration performance is based on the public claims which put the A ahead of the B. However the difference in climb performance seems counter intuitive.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Apr 2016, 03:23
by eloise
sprstdlyscottsmn wrote:Since eloise asked for an update.

Progress is going well, but slowly. I keep making a pass through a section, say intercept, and then realize I screwed up something in the mission parameters and redo the whole thing, then I get to CAP and realize my fuel flow and wave drag models are need work so I go back and fix them and re-do Intercept and CAP. I have to put the CAP data in the report and also generate the Escort data for the report, but I think the way I did the CAP data it can double as escort if I change the mission parameters.

.

Thanks so much for your efforts. This is probably the most anticipated thread here along with Dragon youtube video

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Apr 2016, 05:25
by sprstdlyscottsmn
This is a perfect example of why I keep re-doing and re-editing.

Scorpion82 wrote:One question though, despite a slightly inferior T/W ratio your calculation puts the B slightly faster at the target height than the A. When it comes to accelerating, however the A trumps the B hands down. How does this match up?

I suppose the acceleration performance is based on the public claims which put the A ahead of the B. However the difference in climb performance seems counter intuitive.


I actually had to go back and look at what I had uploaded as I have changed things since then. The difference may have been in the take-off profiles as that was measuring time from alert to 35,000ft. I have re-done the drag profiles on the F-35s since then, twice, and currently the A and B both seem to take 7.4 minutes to climb to 36,000ft. I added a significant figure to my view of the data and see the A coming in at 7.36 (1.73 for climb) and the B coming in at 7.43 (1.78 for climb). Rounding makes them appear to be equals, and in truth we are talking about .07min difference, ~4sec. In my models the F-35B always has more form drag but less induced drag initially as the difference in empty weights is less than the difference in fuel capacity.

As a general measure of progress I have raw data for Intercept, CAP, and Escort complete for all ten aircraft being compared for air to air. I have my current work out for format review based on the difference between my Phase by Phase analysis of the now ten aircraft with a final summary for the legacy compared to it's replacement and the CAP analysis where it is strictly legacy replacement pairs with three graphs giving fuel, speed, and altitude information for the pair followed by an analysis of how each pair compares. I added a lot of turning information that may need to be it's own small section.

I have begun CAS and Deep Strike profiles for three of the eleven aircraft for air to ground. The A-10 may out loiter the F-16 and even the F-15E under the current profile, but it is SLOW. Takes almost 20 minutes to cover 100nm while the other guys can do it in just over 11min. From the data I was able to gather a quad rack of SDB is not exactly low drag, but the Mudhen can drag around a mind boggling amount of ordnance or fuel.

I am very excited to get this finished but my reviewer has been slow in getting back to me. Thanks for the feedback!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Apr 2016, 14:15
by mikemag
Fantastic work Spurts. Can't wait to see the finished product!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 02:42
by sprstdlyscottsmn
Alright, take three... or is it fifteen? I lost count. Here is the report with air to air data. Now that this is done I can go back to work on the air to ground missions. As always I am open to questions about why I chose the profiles I did, format concerns, spelling/grammar issues, etc. I wanted to look at different metrics for each mission as each has important data to present.

This thing takes forever, but it is a labor of love.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 08:46
by Dragon029
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 10:32
by Dragon029
A few points:

When looking at hardpoints, it might be worth noting that the F-35 does have 2 H-W hardpoints. The F-35-optimised tanks they've designed as well are meant to carry 426 gallons / 2897lb each; I wouldn't recommend considering them in analysis, but it could be worth a footnote.

On page 8 you accidentally wrote EASA instead of AESA.

Page 10 "The Phoenix missile was only carried by the F-14 and was retired before the Tomcat was iteself."

Page 14, do you mean CFT analysis or CFD analysis?

Page 33, the first table has a broken border on the right.

Otherwise, it was good info and I'm looking forward to the air-to-ground report; any chance of you releasing your notes, etc for working for custom mission analysis?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 11:04
by eloise
Awesome, finally, iam so hyped for this hahah :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 11:10
by garrya
Great job

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 12:24
by gideonic
Very nice read!

I have one question though, why are you comparing F-35 to F/A-18C not E?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 12:33
by Dragon029
gideonic wrote:Very nice read!

I have one question though, why are you comparing F-35 to F/A-18C not E?

The F-35C replaces the F/A-18C, not the E. The E/F variants are being replaced in some 15 or so years by the F/A-XX.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 13:30
by sprstdlyscottsmn
Dragon029 wrote:A few points:

When looking at hardpoints, it might be worth noting that the F-35 does have 2 H-W hardpoints. The F-35-optimised tanks they've designed as well are meant to carry 426 gallons / 2897lb each; I wouldn't recommend considering them in analysis, but it could be worth a footnote.

On page 8 you accidentally wrote EASA instead of AESA.

Page 10 "The Phoenix missile was only carried by the F-14 and was retired before the Tomcat was iteself."

Page 14, do you mean CFT analysis or CFD analysis?

Page 33, the first table has a broken border on the right.

Otherwise, it was good info and I'm looking forward to the air-to-ground report; any chance of you releasing your notes / working for custom mission analysis?

Thanks! I don't see the broken border on page 33 in the .doc, it must be a formatting thing. When I release the full write up I will go back through and check for those in the .pdf. As for the 426gal externals, they were in my first comparison and I found they added almost no range unless they were dropped and it was then pointed out that development of them was cancelled. Israel is making some, but without specifications I have no way of knowing how to include them. I am running into a similar issue on the air to ground mission set with the F-35 gun pod. I have a weight, but it would be a shot in the dark WAG to estimate the drag.

And you are right in your answer to gideonic. I would no more compare the F-35C to the F/A-18E than I would the F-35A to the F-22. Besides, all one has to do is flip back a few pages from the F-35C and see what the F/A-18E did if they want. Likewise this can be done for more classic "F-15 vs F-14" and "F-16 vs F/A-18" debates.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 18:46
by garrya
i have a small suggestions, since many of the information were interpreted from flight manual as you said, may be you could add the photo of the base manual graph that you used? something like this for example :
Image
apart from that, excellent work

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 19:00
by sprstdlyscottsmn
garrya wrote:i have a small suggestions, since many of the information were interpreted from flight manual as you said, may be you could add the photo of the base manual graph that you used? something like this for example :
Image
apart from that, excellent work


That would more than double the size of the document. Just for the F-16 turning I can think of four charts I had to use and I only have two pages where the F-16s turning is mentioned.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 19:17
by sferrin
APG-63 (even older mods) in the F-15C has LPI. MSIP 2 introduced it IIRC. (Read an article back in the day that they singled those Cs out specifically to send over for Desert Storm. Anecdotal evidence suggested they had LPI incorporated.)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 20:14
by sprstdlyscottsmn
sferrin wrote:APG-63 (even older mods) in the F-15C has LPI. MSIP 2 introduced it IIRC. (Read an article back in the day that they singled those Cs out specifically to send over for Desert Storm. Anecdotal evidence suggested they had LPI incorporated.)

Thanks, I'll update that then.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Apr 2016, 23:55
by bigjku
My suggestion for a chart since you basically did a radius of action would be to actually illustrate it on a map. Makes it more approachable for masses. Demonstrate difference with a realistic basing option of what the two comparison points could do.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 00:58
by quicksilver
Did I miss it or is there no discussion of propulsion system performance?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 01:14
by cantaz
sprstdlyscottsmn wrote:That would more than double the size of the document. Just for the F-16 turning I can think of four charts I had to use and I only have two pages where the F-16s turning is mentioned.


Necessary evil. You can always do 2 versions, one with the manual pages and one without.

Demonstrating the sources makes a big difference from a legitimacy standpoint.

Could you include in the future comparisons between the F-35A and both Hornets? I think us Canadians would really appreciate it.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 02:11
by quicksilver
Also...

Is the mission configuration normalized (to the degree possible)? There is no mention of a resulting drag index and impact on fuel burn rates.

This is a really laudable effort but representative of the dissonance in some of this is the relative performance of F-18 and F-35C.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 02:50
by count_to_10
Something about the Tomcat vs. Super Hornet seems horribly wrong. Everything I've heard indicates that the TC vastly out ranges the SH. Is it the fact that it is basically carrying an extra 2000 lbs of missile, or is there something about optimal cruise speed?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 08:35
by garrya
sprstdlyscottsmn wrote:
That would more than double the size of the document. Just for the F-16 turning I can think of four charts I had to use and I only have two pages where the F-16s turning is mentioned.

I dont think people mind even if the size of the documents increase 3 times, but add graph will increase the credibility of your analysis significantly, especially to people who not in F-16.net

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 09:01
by spazsinbad
Attachment file size for F-16.net is 11 Mb. I can crunch PDFs down if need be and still retain quality with Acrobat 11.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 09:06
by hornetfinn
count_to_10 wrote:Something about the Tomcat vs. Super Hornet seems horribly wrong. Everything I've heard indicates that the TC vastly out ranges the SH. Is it the fact that it is basically carrying an extra 2000 lbs of missile, or is there something about optimal cruise speed?


I don't get how Tomcat would have much better range than Super Hornet. SH is smaller aircraft carrying significantly more fuel (with EFTs). Of course Tomcat has its own advantages for range, but I doubt it's that much more efficient flyer than SH to counter the larger size and smaller amount of fuel.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 09:14
by spazsinbad
PUBLICintelligence has both the F-14A and FnA18E/F NATOPS PDFs for free download - facts and figures are available:

https://publicintelligence.net/u-s-navy ... t-manuals/
&
https://publicintelligence.net/u-s-navy ... t-manuals/

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 13:47
by garrya
Oh and since you talk about missiles range in your files it probably worth it to talk about their agility too
you can get the information from here

https://www.scribd.com/doc/12515933/Tactical-Missile-Design-Presentation-Fleeman

digital copy of "Tactical Missile Design : 2nd Edition"

http://www.mediafire.com/view/jeofkq9csiu7fss/%28AIAA_Education%29_E._Fleeman-Tactical_Missile_Design%2C_Second_Edition-AIAA_%282006%29.pdf

missiles agility can also be estimate by this spreadsheet :
http://www.mediafire.com/view/2uz1qmg2q ... ility.xlsx

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 13:52
by eloise
cantaz wrote:Necessary evil. You can always do 2 versions, one with the manual pages and one without.

Demonstrating the sources makes a big difference from a legitimacy standpoint.

Could you include in the future comparisons between the F-35A and both Hornets? I think us Canadians would really appreciate it.

I second this
and you did a great job

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 15:18
by sprstdlyscottsmn
bigjku - While there are great tools out there for mapping radii of action there would inevitably be some one who wants to see it from a different location than anything I put up. People can feel free to take my numbers to mapping tools and plug it in for whatever base they choose.

quicksilver - You did not miss anything. Thus far there is no discussion of propulsion system performance beyond the correlated mission capability performance. Configurations are normalized in the sense that each aircraft has a required load to carry and the load details are given in specifics for each mission. Drag Index doesn't tell you anything until you apply it to the base drag coefficient and wing area to get Drag Area, which I provide. To show the difference DI has on fuel burn rates I would have to do multiple run of each aircraft on each profile for each variation of DI. The F/A-18C performed better than I expected but I won't omit data because it doesn't line up with my preconceived notions.

cantaz - I listed my sources in the beginning of the document. A little "google-fu" and anyone can get the entire documents themselves. The F-35A and both Hornets are already in this comparison, all the info is already there.

count_to_10 - I agree, I had heard all the same things and without doubt there are configurations and profiles where that would be true. The Phoenix makes a lot of drag, both the Phoenix and the Sparrow are heavy, the Tomcat is heavy, and yes I found that the optimal cruise speed for the Tomcat is very low. Had the Tomcat been upgraded with AMRAAM it would have done much better. Perhaps the air to ground section will shed more light on this issue.

garraya - I mind if the document gets bloated. As I said to cantaz every source I used can be found via Google. With regards to missile agility, that is not my current concern, but I appreciate the links. I will review them sometime.

hornetfinn - it wasn't until the Escort mission where I compared total weight and not just fuel weight that the full impact of their fuel fractions hit me, much the same as with the F-22A and F-15C. Being efficient is one thing, having a massive fuel load is another.

spazsinbad - that is where I got those two documents. avialogs.com is where I got most of the rest.

The file has been downloaded over 400 times in roughly 36 hours. My original has 550 downloads after 20 months. I thank you all for the support and feedback. I know I can't please everyone so I ask that you be understanding if I can't make large scale changes so satisfy a curiosity. It is mentally exhausting to decide what data to tease out of the manuals and how to display it. Running the actual calculations is the easy and fun part, presenting it is the hard part.

How do you all feel about flight envelope comparisons or perhaps replacing the current turn comparison with overlayed doghouse plots? I feel there could be much to be gained by doing those and they SHOULD be straightforward to do.

I found the Luftwaffe MiG-29 manual, I am tempted to do a "1980s" comparison with the F-15 and F-16, but that will have to wait. And as always I am still missing the Performance Index for the F-14 so the most complex aircraft of the bunch takes an excel model.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 15:40
by les_paul59
sprstdlyscottsmn that was awesome work bro, keep it up if you have the time!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 16:23
by jetblast16
sprstdlyscottsmn I greatly appreciate your efforts in compiling this important information. Thank you!

So, the F-22A has "speed and angels". Big wing, high thrust allow cruising at higher altitudes--thinner air--for more range at a given fuel load.

From the comparisons, there is something to be said about carrying a sizable fuel load internally, along with air-to-air and/or strike munitions; e.g., F-35/F-22 over 'legacy' platforms :wink:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 17:59
by sprstdlyscottsmn
Range differences become a lot more interesting in the air to ground world.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 18:58
by spazsinbad
'sprstdlyscottsmn' said above: "...spazsinbad - that is where I got those two documents. avialogs.com is where I got most of the rest...." The publicintelligence NATOPS URLs were for those interested & thanks for http://www.avialogs.com site.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 19:58
by zero-one
Great work as always Sprts. Nicely done. A few questions though.

1. Were the comparisons in speed, turning and range all done in 1 hypothetical mission or were they separate test for each parameter.

2. What is "Ps ft/s" on the turning performance comparison?

3. In the past, you did the turn performance comparison after the 2 planes reached 500nm, is it the same for this one?

4. For the deceleration G, is that their maximum deceleration G for that altitude and air speed or is it how much they decelerate when performing that type of turn.

Im sorry I can't understand everything in the graph right off the bat, but I am trying to figure them out as much.

Great work once again

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 20:28
by sprstdlyscottsmn
zero-one wrote:Great work as always Sprts. Nicely done. A few questions though.

1. Were the comparisons in speed, turning and range all done in 1 hypothetical mission or were they separate test for each parameter.

2. What is "Ps ft/s" on the turning performance comparison?

3. In the past, you did the turn performance comparison after the 2 planes reached 500nm, is it the same for this one?

4. For the deceleration G, is that their maximum deceleration G for that altitude and air speed or is it how much they decelerate when performing that type of turn.

Im sorry I can't understand everything in the graph right off the bat, but I am trying to figure them out as much.

Great work once again


1. Everything in Intercept was for the one mission, speed, altitude, missile, turning, all of it. CAP was it's own mission as was Escort.

2. Specific Excess Power given by the equation ((Thrust - Drag) Velocity/Weight). It is indicating what the energy loss rate is for a max ITR turn at full power at corner velocity.

3. This one is the turn performance at the maximum range acheived in the Intercept Mission.

4. Deceleration G is the Ps normalized for the aircraft velocity.

Hope that helps

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 20:57
by basher54321
Very good read - thanks for your time.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 21:44
by gideonic
sprstdlyscottsmn wrote:How do you all feel about flight envelope comparisons or perhaps replacing the current turn comparison with overlayed doghouse plots? I feel there could be much to be gained by doing those and they SHOULD be straightforward to do.

Yes yes, please do! :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 23:14
by sprstdlyscottsmn
I'll see what I can do.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 23:29
by quicksilver
"quicksilver - You did not miss anything. Thus far there is no discussion of propulsion system performance beyond the correlated mission capability performance. Configurations are normalized in the sense that each aircraft has a required load to carry and the load details are given in specifics for each mission. Drag Index doesn't tell you anything until you apply it to the base drag coefficient and wing area to get Drag Area, which I provide. To show the difference DI has on fuel burn rates I would have to do multiple run of each aircraft on each profile for each variation of DI. The F/A-18C performed better than I expected but I won't omit data because it doesn't line up with my preconceived notions."

So, do I understand correctly you added fuel, weapons, pylons and pods but none of the drag index associated with such additions?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Apr 2016, 23:40
by sprstdlyscottsmn
quicksilver wrote:So, do I understand correctly you added fuel, weapons, pylons and pods but none of the drag index associated with such additions?

Not at all. I took the Drag Index, divided by 10,000, multiplied by the reference Wing Area, and added to the base Drag Area. I frequently list Drag Areas as a contrast. Drag Index is only used to get the right information out of the charts but in of itself is a useless number without context. An F-15 with a DI of 50 has the same amount of added drag as an F-16 with a DI of 100, but the F-16 still has a smaller Drag Area.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 00:33
by quicksilver
sprstdlyscottsmn wrote:
quicksilver wrote:So, do I understand correctly you added fuel, weapons, pylons and pods but none of the drag index associated with such additions?

Not at all. I took the Drag Index, divided by 10,000, multiplied by the reference Wing Area, and added to the base Drag Area. I frequently list Drag Areas as a contrast. Drag Index is only used to get the right information out of the charts but in of itself is a useless number without context. An F-15 with a DI of 50 has the same amount of added drag as an F-16 with a DI of 100, but the F-16 still has a smaller Drag Area.


I understand all that. The point is that the relative similarities between some of these aircraft should be a red flag to you about some of the assumptions you've made or the end-to-end methodologies you've used to come to many of these conclusions. They certainly are to some of us who have flown these things or been around them for significant periods of our operational lives.

The relatively small differences in listed drag between aircraft, in spite of a clear need by the non-F35 players to carry lotsa external fuel, weapons, and pods (and the associated drag), doesn't pass the sniff test. Did you calculate the specific configured DI for each aircraft for the specified mission up front? It is also unclear what fuel loads are assumed for each aircraft at the beginning of each mission. The F18C total (17530) doesn't sum from the individual totals listed (15290). The lack of a propulsion system discussion as well as fuel flow data may be worthy of a re-attack as you scrutinize the current iteration.

I laud the time and effort that has gone into creating this. :notworthy: :salute:

The results just don't add up (yet).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 03:38
by sprstdlyscottsmn
quicksilver wrote:I understand all that. The point is that the relative similarities between some of these aircraft should be a red flag to you about some of the assumptions you've made or the end-to-end methodologies you've used to come to many of these conclusions. They certainly are to some of us who have flown these things or been around them for significant periods of our operational lives.

The relatively small differences in listed drag between aircraft, in spite of a clear need by the non-F35 players to carry lotsa external fuel, weapons, and pods (and the associated drag), doesn't pass the sniff test. Did you calculate the specific configured DI for each aircraft for the specified mission up front? It is also unclear what fuel loads are assumed for each aircraft at the beginning of each mission. The F18C total (17530) doesn't sum from the individual totals listed (15290). The lack of a propulsion system discussion as well as fuel flow data may be worthy of a re-attack as you scrutinize the current iteration.

I laud the time and effort that has gone into creating this. :notworthy: :salute:

The results just don't add up (yet).


I see what you mean about fuel flow, I only give specific ranges a few times and it is a useful comparison metric as aircraft with identical drag and different engines will have different fuel flow.

I did calculate each DI for each aircraft for each mission and in the case of Intercept I did multiple DIs for before and after tanks are dropped. F-16C missile only at 53, plus single belly tank to 68, plus wing tanks to 125. If you have a challenge to some of my loadout assumptions based on personal experience then by all means let me know what a better set would be, but don't insult me by telling me I didn't bother using DI to calculate anything.

You kind of have me lost on the F/A-18C fuel comment. The 17,530 comes from 10,810 internal plus three 330-gal fuel tanks at 2,240 each (Figure 2-6, I-2-19, JP-5 @ 6.8lb/gal). I don't list 15,290 anywhere. Even using the lighter JP-5 and the smaller 314 gallon tanks I still get 16,450lb.

Now, I do struggle with "what data do people really want to see?" and you obviously are very interested in fuel use and Drag Index. I have all the raw data for those so I would be willing to expand a table to include it. And again, if you know of any factual inaccuracies, i.e. "Service Hornets never fly with three 330gal tanks ever for any reason, always two 314gal tanks" please let me know. I tried to normalize my assumptions as much as possible.

Hornet..........DI......Drag Area (ft^2)
clean............0.......9.76
missile only.....39......11.32 (tip winders, body amraams, one amraam on the outboard pylon for each wing)
one tank........52.5....11.86 (as above plus centerline tank)
two tank........96.5....13.62 (as above plus two wing tanks inboard)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 08:07
by zero-one
Question about sustained and instantaneous turn rates.
The way I understand it, the measurement is done with a pilot banking to his desired direction
then he pulls back on the stick as hard as he can.

The aircraft then executes an instantaneous turn but continues to loose speed or turn rate (or both) until it levels out at a certain speed, G and turn rate.
Where it levels out is called the sustained turn rate and the aircraft will maintain this rate until it runs out of fuel.

Is this correct. Or does the pilot perform a sustained turn rate differently from an instantaneous turn rate.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 09:29
by hornetfinn
Thank you a lot for your work, it definitely gives the most interesting insight to modern fighter performance! :D I want to thank a lot those people who read it and made some very good comments!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 13:54
by quicksilver
"You kind of have me lost on the F/A-18C fuel comment. The 17,530 comes from 10,810 internal plus three 330-gal fuel tanks at 2,240 each (Figure 2-6, I-2-19, JP-5 @ 6.8lb/gal). I don't list 15,290 anywhere. Even using the lighter JP-5 and the smaller 314 gallon tanks I still get 16,450lb."

On page 7 of your document you list internal and external fuel numbers in the first two columns, and then total them in the third. For F18C you list 17530 in the third column, but the total of columns one and two is 15290.

In addition to the relative range performance of F18C and F35C, as well as the relative range performance of F22 and the entire F35 series, the loiter at range charts flagged my interest (they seem dramatically 'optimistic'). There just seems to be something going on in the methodology with drag and fuel flows in all of the comparisons.

Also, something else to consider -- operationally, for almost all types, unless one is on a ferry mission it is highly unusual to max load a jet for fuel. The reason being that the increase in range is offset by a disproportionate increase in drag. (As one of my elders pointed out back in the day, "...those are external fuel tanks son...dont drop them unless you need to save yourself and/or your jet"). While there have been occasions where such a thing has occurred, the dropping of 'drop tanks' is unusual.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 14:52
by sprstdlyscottsmn
quicksilver wrote:On page 7 of your document you list internal and external fuel numbers in the first two columns, and then total them in the third. For F18C you list 17530 in the third column, but the total of columns one and two is 15290.


:doh: :doh: :doh: I only put external fuel for two tanks!! :doh: :doh: :doh: talk about a huge oversight! FIXED! Thanks!

quicksilver wrote:In addition to the relative range performance of F18C and F35C, as well as the relative range performance of F22 and the entire F35 series, the loiter at range charts flagged my interest (they seem dramatically 'optimistic'). There just seems to be something going on in the methodology with drag and fuel flows in all of the comparisons.


I don't know what to tell you here. I would like to understand your concern to see if I made an error.
Fuel Flow during loiter.
F/A-18C 4650-3400 pph for DI of 96.5 at weights of 42,100 to 31,500 (Figure 11-155)
F-35A 4474-3295 pph for DI 0 at weights 46,100 to 34,800
recall the statement of 4600pph FL320 0.75M 2,500lb load and having 4 hrs of fuel, my model hits this at ~47,500lb, minus stated 2500lb load and empty weight for 15,900lb fuel load. Subtracting the 2500lb reserve (one of my assumptions) that leaves 13,400lb for flying. Averaging that out over 4 hours gives 3,350pph. My model shows a min value of 3,199pph. Compared to the given statement my numbers seem conservative, but there is more than enough error in my reserve assumption to account for that.
F-35B 4324-3609 pph for weights from 44,200 to 37,400 (same general profile at F-35A but with a tad more drag, numbers look okay here)
F-35C 4616-3487 pph for weights from 52,800-40,800 (heavier weights and more frame drag, but the bigger wing lets it loiter at a lower speed)
So we are seeing here that my F-35 models show same ballpark drag when clean as an F/A-18C with six missiles and three tanks.
F-22A is burning 5651-4079pph, much higher.


quicksilver wrote:Also, something else to consider -- operationally, for almost all types, unless one is on a ferry mission it is highly unusual to max load a jet for fuel. The reason being that the increase in range is offset by a disproportionate increase in drag. (As one of my elders pointed out back in the day, "...those are external fuel tanks son...dont drop them unless you need to save yourself and/or your jet"). While there have been occasions where such a thing has occurred, the dropping of 'drop tanks' is unusual.

Okay, I was making an assumption that when max time on station or max penetration range was desired that max fuel tanks would be carried. What is more typical? I see that the two wing tanks on an F-15 make less drag than one belly tank so if the Eagle is not carrying full tanks it stands to reason that is the one to get rid of. This is different from the Hornet where each wing tank individually carries more drag than the centerline. With the expection of the Intercept supersonic dash mission I never assumed tanks are dropped, and I pessimistically assume no ordnance is ever dropped and has to be drug back home.

Sorry this discussion got off to such a rocky start. I appreciate the constructive criticism. I want this comparison as contextually accurate as possible. The excel aircraft models are challenging as I only have publicly released data and a handful of performance metrics to match up with. I did find it interesting that while it was not even a real metric (due to lack of actual data) that the statement of the F-35B and F-35C being bingo fuel once at 1.6M played out in my Intercept scenario.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 14:56
by sprstdlyscottsmn
zero-one wrote:Question about sustained and instantaneous turn rates.
The way I understand it, the measurement is done with a pilot banking to his desired direction
then he pulls back on the stick as hard as he can.

The aircraft then executes an instantaneous turn but continues to loose speed or turn rate (or both) until it levels out at a certain speed, G and turn rate.
Where it levels out is called the sustained turn rate and the aircraft will maintain this rate until it runs out of fuel.

Is this correct. Or does the pilot perform a sustained turn rate differently from an instantaneous turn rate.


At full power there will always be an amount of G available to the pilot without losing speed. It may be 1G (level flight only) or it may be full aft stick (the situation you described). What I listed is the amount of G at the listed speed that the pilot can sustain at full power without losing speed/altitude.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 15:37
by zero-one
sprstdlyscottsmn wrote:
At full power there will always be an amount of G available to the pilot without losing speed. It may be 1G (level flight only) or it may be full aft stick (the situation you described). What I listed is the amount of G at the listed speed that the pilot can sustain at full power without losing speed/altitude.


Okay, so the way I understand it, to achieve the rates you published, the pilot of each plane had to conduct 4 turns.

1. To get the IT turn rate, the pilot performs a full aft stick pull at 20,000 feet Mach 0.8, then repeat the process at Corner velocity to get the IT turn rate at Corner velocity.

2. To get the sustained turn rate, the pilot performs a carefully calculated pull to maintain energy and altitude at mach 0.8, 20,000 feet, then repeat the process at Corner velocity to get the sustained turn rate at Corner velocity.

Is this right?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 16:30
by mikemag
Really phenomenal work Spurts. I can't applaud you enough!

I have one question if you don't mind clarifying. I'm particularly interested in the F-16C vs. F-35A comparison on pages 20-22. On page 20, it looks like the figures are at take-off weight (full fuel). But I assume the figures on page 22 (figure 5) are for the max distance from the airfield, before RTB, correct? If that's the case, then would it be correct that Stubby's turn performance is penalized a little in comparison since the Viper has a shorter RTB distance, and therefore relatively less onboard fuel, than the F-35?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 16:37
by sprstdlyscottsmn
zero-one wrote:Okay, so the way I understand it, to achieve the rates you published, the pilot of each plane had to conduct 4 turns.

1. To get the IT turn rate, the pilot performs a full aft stick pull at 20,000 feet Mach 0.8, then repeat the process at Corner velocity to get the IT turn rate at Corner velocity.

2. To get the sustained turn rate, the pilot performs a carefully calculated pull to maintain energy and altitude at mach 0.8, 20,000 feet, then repeat the process at Corner velocity to get the sustained turn rate at Corner velocity.

Is this right?


I think you may be overthinking it. They are just four points of data that could be represented on a single graph.

IF you really wanted to hit every point I list then the best bet would be for the pilot to begin with his Sustained Turn at 0.8M and wait for the opportune moment to give a hard pull. At this point the pilot pulls the stick "to his lap" as he decelerates to corner velocity (assuming corner velocity is actually lower) and once he has hit the corner velocity instant turn he eases off the pull to that speeds sustained rate.

viewtopic.php?t=26829

The Ps=0 line is the sustained turn line

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 16:50
by sprstdlyscottsmn
mikemag wrote:Really phenomenal work Spurts. I can't applaud you enough!

I have one question if you don't mind clarifying. I'm particularly interested in the F-16C vs. F-35A comparison on pages 20-22. On page 20, it looks like the figures are at take-off weight (full fuel). But I assume the figures on page 22 (figure 5) are for the max distance from the airfield, before RTB, correct? If that's the case, then would it be correct that Stubby's turn performance is penalized a little in comparison since the Viper has a shorter RTB distance, and therefore relatively less onboard fuel, than the F-35?

Figure 5 on page 20 is before take-off, yes. Figure 6 on page 22 is right before RTB, yes. Is Stubby's turn "penalized"? not really. The biggest reason I do this comparison is that it ISN'T "0.8M at FL150 with 60%fuel and two AAMs". It is mission based. In this case the Stubby has under 4,000lbs of fuel, or less than 21% fuel. The Viper has about 1,500 lbs on board, or (huh, interesting) 21%. Well, I didn't see that coming.

The turn performance is what it is. If the Stubby was turning at the same distance as the Viper it would be lugging around a LOT more fuel than it is here. This mission is what the Viper was built for, rapid dash and a trans-sonic knife fight. What I found interesting is that in the escort mission the Stubby actually out turns the Viper.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 22 Apr 2016, 18:24
by zero-one
sprstdlyscottsmn wrote:
I think you may be overthinking it.


I think so to,

so basically the scenario for the turn rates is, both aircraft take off with full fuel (and the mandatory EFT if needed) to get to a location, then just before RTB, with enough fuel to make 3 full 360 turns at full AB, they execute 2 turns. The first turn is done at Mach 0.8, 20,000 feet and the second one is done at their aircraft's corner speed.

On both occasions they do a full aft stick.

Question though, most pilots always say that the Viper holds a decisive edge over the Eagle below 30,000 feet. But on these test done at 20K, the Eagle seems to be dominant over the Viper, the only edge the F-16 has is on Sustained turn rates at corner velocity, and not by a whole lot.

Is it because the F-15 is extremely lightweight at this point or is it something else?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 May 2016, 18:21
by sprstdlyscottsmn
it never ends... I messed up part of the F-35B Escort fuel and I was able to get ahold of an F-14A performance NATOPS that tells me I made a wrong assumption about tomcat drag somewhere as my fuel flows are about 50% higher. I am well aware that the F110 was rated with a higher TSFC than the TF30 but 50% is too big of a change. All this when I was 7/11 done with the air to ground data.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 May 2016, 19:49
by vanshilar
Heh recently Gilmore (DOT&E) said for CAS at a 250 NM distance, the A-10 has a 60-minute loiter time and a 90-minute loiter time with external fuel tanks. He also said the F-35B has a 25-40 minute loiter time. How does your model square with this (although I know you're not doing the A-10), and what kind of assumptions are needed to generate the results (25-40 minute loiter time for the F-35B) that Gilmore stated? Keep in mind of course that Gilmore was using the F-35B rather than the F-35A even though it's the F-35A that would be competing with the A-10. I *believe* Gilmore was also assuming that the A-10 had 4 500-lb bombs while the F-35B had 2 1000-lb bombs internally, but I'm not sure on that (he said that in addition to the longer loiter time, the A-10 could drop 4 air-to-surface weapons, while the F-35 could only drop 2).

Based on Gilmore's own numbers for the F-35B, and taking the F-35A as having 5,000 lb more fuel for loiter, as a back-of-the-envelope calculation, it looks like the F-35A would have around 44-71 minutes of loiter time, and more once you start including things like reserve fuel and stuff (for a more realistic mission profile). I know your models resulted in the F-35A having a 90-minute loiter time at a 500 NM distance, so I'm curious if, say, Gilmore assumed the F-35B was loitering at 10,000 ft or something ("because you need to stay low for CAS!" And that's probably the optimum loiter altitude for the A-10...), and seeing how the F-35A would perform under those conditions, as well as under optimal conditions.

(Is CAS at 250 NM or 500 NM a better assumption? I don't know how far away CAS missions typically are from home base or the refueling point. I should note it looks like the A-10 apparently only has a range of 700 NM though -- and that's range not radius, so 500 NM distance away would be out. Also, considering the loiter time ignores that the A-10 spends a lot of time just going to and from the home base/refueling point, so you'd need more A-10's in your stack to maintain continuous CAS coverage compared with a jet that can get there faster.)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 May 2016, 21:01
by sprstdlyscottsmn
vanshilar wrote:How does your model square with this (although I know you're not doing the A-10), and what kind of assumptions are needed to generate the results (25-40 minute loiter time for the F-35B) that Gilmore stated?


I actually am gathering data for the A-10 for the A-G missions. I gained access to an A-10A -1.

My "CAS Mission profile" involves larger volumes of weapons as long as performance is not compromised. For the A-10 this is ECM/AIM-9, LITENING/LAU-68, 2 SDB racks, and GAU-8. I am counting 3 rockets as an attack and a two second cannon burst as an attack. This gives the A-10C a total of about 23 attacks; 8 mid altitude, 15 low altitude.

The flight profile is a military power climb to optimum cruise altitude, opt cruise to a "station" 200nm from base, descent from opt cruise (to the nearest 5k altitude block) and full mil run in response to the CAS call, 60 minute loiter at 15,000ft (higher than trash fire can reach, close enough that targeting pod can see a clear picture), optimum cruise RTB.

I see the A-10 having a total range of 281nm from base in this case. Lower altitude will increase fuel flow for loiter.

I have the F-35B (two SDB rack, gun pod, clean wings for STO performance, 8 mid-alt attacks, 2 low-alt attacks) ranging 270nm from the LHA.

I have the F-35A (two SDB rack, internal gun, two twin-mounted GBU-12 on inboard wing station, two GBU-12 on midboard wing station, 14 mid-alt attacks, 1(1.5) low-alt attacks) ranging 355nm from a base.

Now the thing about these types of comparisons is that data can always be twisted one way or another just by changing a parameter. Constrain the whole flight profile (no optimum sections) and things will certainly swing one way or another.

The F-35s are moving almost twice as fast as the A-10 during the inbound phase. Troops will like that.
The A-10 can put one "attack" on target every 55 seconds for almost 22 minutes thanks to it's payload and turning ability at loiter speed. Troops will like that.
F-35A can put one "attack" on target every 53 seconds for almost 14 minutes with nearly every one of them being explosive and 1-5m CEP accurate. Troops will like that.
F-35s can gather tremendous battlefield intel to share with the guys on the ground. Troops will like that.

As for the EFT, according to out local A-10 pilot here there are no combat rated EFTs for the A-10, and I can tell you that the weight and drag they generate kill climb and cruise performance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 01:14
by quicksilver
"So we are seeing here that my F-35 models show same ballpark drag when clean as an F/A-18C with six missiles and three tanks." -- spurts

Recommend you re-look your F18C drag numbers in that (three tank) configuration. That jet is a pig, and the numbers should not be comparable in terms of drag to any F35 in a clean configuration.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 01:46
by quicksilver
"Okay, I was making an assumption that when max time on station or max penetration range was desired that max fuel tanks would be carried. What is more typical?" -- spurts

I would offer that it depends on the mission, the threat and an assessment of allowable risk. Configuration choices (SCLs) have an enormous impact on aircraft aerodynamic performance -- far more than the general public understands. When one is getting shot at, it sucks to be flying the dump truck when you need the Ferrari, but the usual choice is a balance of things since we want to be able to fight but we also have to get home, particularly if it's a ways to go to get to the tanker track. Speaking of tankers, tanker availability is a limfac for just about everything these days but the answer to the limiting factor isnt always to configure for max fuel for the reasons suggested above.

Hornet can barely get over mach with three tanks and ordnance. In practical terms, it really doesn't since it takes too much time/fuel in AB to do so. If you dont see huge differences in drag/fuel flow between a one tank and a three tank Hornet you should re-look your drag assumptions; similar dramatic kind of differences should be apparent in Viper as well, particularly when you clean off A-G ordnance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 02:26
by quicksilver
"I did find it interesting that while it was not even a real metric (due to lack of actual data) that the statement of the F-35B and F-35C being bingo fuel once at 1.6M played out in my Intercept scenario."

I'd be careful with that idea. Range size can have a big impact on what the test guys have to do to get a good test point.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 02:28
by quicksilver
One last thought -- how did you accommodate interference drag in your model?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 04:08
by sprstdlyscottsmn
quicksilver wrote:"So we are seeing here that my F-35 models show same ballpark drag when clean as an F/A-18C with six missiles and three tanks." -- spurts

Recommend you re-look your F18C drag numbers in that (three tank) configuration. That jet is a pig, and the numbers should not be comparable in terms of drag to any F35 in a clean configuration.

F/A-18C: Drag index 96.5, Drag Area 13.62ft^2, Trust Loading 0.79 lbf/ft^2(rated military thrust in tons over drag area)
F-35C: Drag Index 0, Drag Area 12.40 ft^2, Thrust Loading 1.13 lbf/ft^2

Drag Area is similar, but performance is not.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 04:30
by sprstdlyscottsmn
quicksilver wrote:"Okay, I was making an assumption that when max time on station or max penetration range was desired that max fuel tanks would be carried. What is more typical?" -- spurts

I would offer that it depends on the mission, the threat and an assessment of allowable risk. Configuration choices (SCLs) have an enormous impact on aircraft aerodynamic performance -- far more than the general public understands. When one is getting shot at, it sucks to be flying the dump truck when you need the Ferrari, but the usual choice is a balance of things since we want to be able to fight but we also have to get home, particularly if it's a ways to go to get to the tanker track. Speaking of tankers, tanker availability is a limfac for just about everything these days but the answer to the limiting factor isnt always to configure for max fuel for the reasons suggested above.

Hornet can barely get over mach with three tanks and ordnance. In practical terms, it really doesn't since it takes too much time/fuel in AB to do so. If you dont see huge differences in drag/fuel flow between a one tank and a three tank Hornet you should re-look your drag assumptions; similar dramatic kind of differences should be apparent in Viper as well, particularly when you clean off A-G ordnance.


Since one tank with ord is a DI of ~50 and three tanks with ord is a DI of ~100 there would be a very significant difference in fuel flow. Let's see.

At the beginning of an optimum cruise segment the tanked out Hornet has a specific range of 0.093 and when it is just about to begin final descent it has a specific range of 0.129. A Centerline-only Hornet begins cruise with a DI almost 50 lower and ~6000lb lighter (weight of two tanks and their fuel) and has a starting specific range of 0.118. Right before descent the DI is still lower but the weight difference is only 1200lb (the weight of the tanks as by this point all external tanks are empty) so the specific range is 0.145. On average an 18.5% better fuel flow for one tank, but three tanks carries 34.3% more fuel.

I chose "Max Fuel" for the CAP and Escort missions because if I didn't and the F-35s creamed the 4th gens then the anti-JSF crowd would cry fowl saying "You handicapped the F-1x, it can carry more fuel than you showed!". Like you said configuration has a HUGE impact on performance. When it comes to planes with EFTs you generally have to choose between range or agility. For the Agility comparison (Intercept) I allowed them to have an Agility configuration (dropped centerline EFTs) and for the Range/Stamina comparisons (CAP/Escort) I maxed the fuel loads. I will never satisfy everyone with my choices.

Thanks for the chat quicksilver!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 04:31
by sprstdlyscottsmn
quicksilver wrote:One last thought -- how did you accommodate interference drag in your model?


The NATOPS takes care of that

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 05:46
by charlielima223
sprstdlyscottsmn wrote:
Now the thing about these types of comparisons is that data can always be twisted one way or another just by changing a parameter. Constrain the whole flight profile (no optimum sections) and things will certainly swing one way or another.

The F-35s are moving almost twice as fast as the A-10 during the inbound phase. Troops will like that.
The A-10 can put one "attack" on target every 55 seconds for almost 22 minutes thanks to it's payload and turning ability at loiter speed. Troops will like that.
F-35A can put one "attack" on target every 53 seconds for almost 14 minutes with nearly every one of them being explosive and 1-5m CEP accurate. Troops will like that.
F-35s can gather tremendous battlefield intel to share with the guys on the ground. Troops will like that.



my $0.02

yes, troops like all of that good sh*t! Unless you're already on station or close to my AO, I don't want to wait around taking fire with my thumb up my rectum. Get here most quick ricky-f-ing-tick. If you have to make more than one attack; run one of a few things has happened or is happening. You missed. There are more targets out there giving me grief. The worse case SHTF scenario. EVAC or MedEVAC need top cover... and so on...

The very true term "situation dictates" always comes up.

What is the situation? What do I have available to me? How can I use it?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 05:51
by quicksilver
"Since one tank with ord is a DI of ~50 and three tanks with ord is a DI of ~100..."

I think this is the essence of the problem. Generally speaking, a one (centerline) tank jet should have the lowest DI; two tank jet should be more than 2x the DI of a one tank jet, and a triple-bubble should have more than 3x the DI of a one tank jet. As a consequence (and perhaps for additional reasons) your fuel flows are dramatically optimistic.

Additionally, your concern about nut case basement dwellers allows them to have it both ways; a jet with lotsa range (but no aero performance) when they wanna argue range, or jets with operationally unrealistic aero performance (air show configurations) that fairy dust the matter of meaningful sensors, range or TOS.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 06:01
by charlielima223
sprstdlyscottsmn wrote:
I chose "Max Fuel" for the CAP and Escort missions because if I didn't and the F-35s creamed the 4th gens then the anti-JSF crowd would cry fowl saying "You handicapped the F-1x, it can carry more fuel than you showed!". Like you said configuration has a HUGE impact on performance. When it comes to planes with EFTs you generally have to choose between range or agility. For the Agility comparison (Intercept) I allowed them to have an Agility configuration (dropped centerline EFTs) and for the Range/Stamina comparisons (CAP/Escort) I maxed the fuel loads. I will never satisfy everyone with my choices.

Thanks for the chat quicksilver!


No you can't please them all and none of us here at F-16.net expect you too. One thing I've always seen is..

Oh well the other aircraft can lighten its load to be more agile by jettisoning its fuel tanks... the F-35 can't


that is very true but one thing I've learned is to take their comment and make them question it.

Okay the F-1X just jettisoned its 2 or 1 EFT to make it lighter and maneuverable for that dogfight. That aircraft now has 7000lbs of fuel to play with. If that pilot and aircraft is either victorious or comes it to a draw and decides to break away and disengage how much fuel does that aircraft have an does it have left? Does it have enough to get to the closest tanker or get home?

I know I'm preaching to the choir here...

Former Test pilot Jon Beesley described the abstract concept of fuel+weapons = weight, range, and performance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 May 2016, 15:22
by sprstdlyscottsmn
quicksilver wrote:"Since one tank with ord is a DI of ~50 and three tanks with ord is a DI of ~100..."

I think this is the essence of the problem. Generally speaking, a one (centerline) tank jet should have the lowest DI; two tank jet should be more than 2x the DI of a one tank jet, and a triple-bubble should have more than 3x the DI of a one tank jet. As a consequence (and perhaps for additional reasons) your fuel flows are dramatically optimistic.

Additionally, your concern about nut case basement dwellers allows them to have it both ways; a jet with lotsa range (but no aero performance) when they wanna argue range, or jets with operationally unrealistic aero performance (air show configurations) that fairy dust the matter of meaningful sensors, range or TOS.

Allow me to clarify, of the ~50 and ~100 DI for the single and tripple bubble Hornets 39 of the DI is two wingtip winders, two body mounted AMRAAM, and two outboard pylons with AMRAAM. All my data is coming straight out of the NATOPS, if the NATOPS is too optimistic, nothing I can do there. If my mission profiles are different that what is really done, I would like that info.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 00:21
by quicksilver
A triple bubble Hornet will be around 6K#/hr.

NATOPS? The right page of the manual, the right GW, the right altitude, the right configuration, the right DI...? Dunno, but there is lotsa stuff to 'oops' on easily. 3-4K#/hr vs 6K#/hr is a big difference...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 00:36
by sprstdlyscottsmn
quicksilver wrote:A triple bubble Hornet will be around 6K#/hr.

NATOPS? The right page of the manual, the right GW, the right altitude, the right configuration, the right DI...? Dunno, but there is lotsa stuff to 'oops' on easily. 3-4K#/hr vs 6K#/hr is a big difference...

Cruise? Optimum or not?
Loiter? Optimum or not?
While 6k is good to know there are a lot of conditions that need to be known. I 'll have a look at the NATOPS later.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 00:46
by quicksilver
Here's a bar napkin Hornet mission...

Start, Checks, Taxi, T/O -- 1K#
Climb (to 30K' for ~50nm) -- 1K#
Enroute Out ~(200nm@ 7nm/min and 6K#/hr) -- ~2.5K#
Enroute In -- (assume a lighter jet) -- 2K#
Descent, Approach, Land -- 1K#
Reserve -- 2.5K#

That's 10K just to go there and get home with the specified reserve. That's about 7.5K to play w/ on-station.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 01:25
by sprstdlyscottsmn
quicksilver wrote:Here's a bar napkin Hornet mission...

Start, Checks, Taxi, T/O -- 1K#
Climb (to 30K' for ~50nm) -- 1K#
Enroute Out ~(200nm@ 7nm/min and 6K#/hr) -- ~2.5K#
Enroute In -- (assume a lighter jet) -- 2K#
Descent, Approach, Land -- 1K#
Reserve -- 2.5K#

That's 10K just to go there and get home with the specified reserve. That's about 7.5K to play w/ on-station.


With a weight of 43,500 and a DI of 96.5 I think it is pretty easy to see where I get my fuel flows from. While this is the heaviest the Hornet is cruising at it is also an optimum cruise. 0.094nm/lb at .83M and FL355 comes out to just over 5000pph.

Cruise 1.jpg


You napkin approach indicates a speed of 0.71-0.73 depending on altitude (30k-36k and up) and since you don't have an altitude listed for enroute I have to make assumptions. Going to the Specific range charts I get the following fuel flows for 7nm/min
FL300@46klb - 5250pph (essentially Max E for altitude)
FL350@46klb - 5500pph- (0.06M BELOW Max E) no point in looking at higher altitudes
FL250@46klb - 5500pph- (0.698M, between Max E and Max R)
FL200@46klb - 6000pph (0.684M, right over Max R)

So the difference in what you know and what I calculate seems to boil down 100% to profile

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 01:27
by sprstdlyscottsmn
quicksilver wrote:Reserve -- 2.5K#

Just saw this, is this really what the reserve is? I was using 1500#

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 02:55
by quicksilver
sprstdlyscottsmn wrote:
quicksilver wrote:Reserve -- 2.5K#

Just saw this, is this really what the reserve is? I was using 1500#


No, I took your assumption of 2500 from one of your earlier posts -- "Subtracting the 2500lb reserve (one of my assumptions) that leaves 13,400lb for flying..."

There are SOPs for min fuel in various circumstances in peacetime training, and they are generally followed even when the shooting starts. I think 2.5 is a little fat.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 03:06
by quicksilver
sprstdlyscottsmn wrote:
quicksilver wrote:Here's a bar napkin Hornet mission...

Start, Checks, Taxi, T/O -- 1K#
Climb (to 30K' for ~50nm) -- 1K#
Enroute Out ~(200nm@ 7nm/min and 6K#/hr) -- ~2.5K#
Enroute In -- (assume a lighter jet) -- 2K#
Descent, Approach, Land -- 1K#
Reserve -- 2.5K#

That's 10K just to go there and get home with the specified reserve. That's about 7.5K to play w/ on-station.


With a weight of 43,500 and a DI of 96.5 I think it is pretty easy to see where I get my fuel flows from. While this is the heaviest the Hornet is cruising at it is also an optimum cruise. 0.094nm/lb at .83M and FL355 comes out to just over 5000pph.

Cruise 1.jpg


You napkin approach indicates a speed of 0.71-0.73 depending on altitude (30k-36k and up) and since you don't have an altitude listed for enroute I have to make assumptions. Going to the Specific range charts I get the following fuel flows for 7nm/min
FL300@46klb - 5250pph (essentially Max E for altitude)
FL350@46klb - 5500pph- (0.06M BELOW Max E) no point in looking at higher altitudes
FL250@46klb - 5500pph- (0.698M, between Max E and Max R)
FL200@46klb - 6000pph (0.684M, right over Max R)

So the difference in what you know and what I calculate seems to boil down 100% to profile


That would seem to be the case. I offer the observation that a triple bubble Hornet doesnt spend too much time above FL300 until it gets light.

We now also agree that the FF is not between 3.x and 4.x.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 03:45
by quicksilver
Another observation I would offer is that just because there's a chart in NATOPS for something, that doesn't mean you're ever going to see that condition in real life.

For example, istr a page in SH performance NATOPS for a 34K# gross weight condition. Anyone checked the OWE empty for a SH lately? :wink:

Obtw, the engine charts you provided are for the -400 engine. -402 has been the standard for quite some time. Thrust and FF are slightly higher.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 04:38
by sprstdlyscottsmn
quicksilver wrote:Another observation I would offer is that just because there's a chart in NATOPS for something, that doesn't mean you're ever going to see that condition in real life.

For example, istr a page in SH performance NATOPS for a 34K# gross weight condition. Anyone checked the OWE empty for a SH lately? :wink:

Obtw, the engine charts you provided are for the -400 engine. -402 has been the standard for quite some time. Thrust and FF are slightly higher.

I have commented in the paper itself that I only have -400 data and that the -402 is more potent. I did not realize they also burned more fuel. And as for looking at things in a NATOPS that can't happen, I look in the NATOPS for the configuration I come up with, so no 22,000# Hornets here. The 2500# reserve was for the F-35 not for the Hornet. With so much data flying around I can see why things get confusing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 10:40
by zero-one
Hi Sprts, if you don't mind, why does the Eagle seem to have better turn rate numbers than the F-16. Everyone seemed to point out that the Viper was the best turner of all American 4th gens except above 30,000 feet where LERX looses it's effects.

Is this incorrect?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 13:08
by sprstdlyscottsmn
zero-one wrote:Hi Sprts, if you don't mind, why does the Eagle seem to have better turn rate numbers than the F-16. Everyone seemed to point out that the Viper was the best turner of all American 4th gens except above 30,000 feet where LERX looses it's effects.

Is this incorrect?

My understanding of the "common knowledge" there was that the Eagle had the transient turn while the Viper had the sustained turn. Of course, these block 50 birds are heavy so that takes a toll on turning. Suffice to say the results surprised me there.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 14:05
by zero-one
sprstdlyscottsmn wrote:My understanding of the "common knowledge" there was that the Eagle had the transient turn while the Viper had the sustained turn. Of course, these block 50 birds are heavy so that takes a toll on turning. Suffice to say the results surprised me there.


Well the Block 50s also have significantly more thrust than the early Block 15s. Here are the words of Lt. Col. Fred "Spanky" Clifton that has flown Eagles and Migs.

I've flown all the C/D versions – Blocks 25, 30, 32, 40, 42, 50, 52. The Pratt-powered Blocks 25, 32 and 42 are good performers, but not great. The GE-powered Blocks 30, 40 and 50, plus the Pratt-powered Block 52 are absolute beasts.

WVR (within visual range) scenario: An F-15C and GE-powered F-16C merge head-on, no missiles, guns only. This is truly where the F-16 excels. The F-15 is absolutely no slouch in this arena and the margin for error is small, but he F-16 enjoys a sustained turn rate advantage and a thrust-to-weight advantage. My game plan would be not to slow down too much in the F-16. Where the F-16 starts to fall off in comparison is when it gets slow and butts up against its hard-wired angle-of-attack limiter. Slow is not a place to be in the F-16 unless absolutely necessary. I wanted to keep my airspeed up relative to the Eagle and beat him down to where his nose track starts to slow and use the vertical as required and the F-16's turn rate advantage to bring my nose to bear.


http://foxtrotalpha.jalopnik.com/how-to ... 1682723379

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 14:20
by deadseal
zero-one wrote:
sprstdlyscottsmn wrote:My understanding of the "common knowledge" there was that the Eagle had the transient turn while the Viper had the sustained turn. Of course, these block 50 birds are heavy so that takes a toll on turning. Suffice to say the results surprised me there.


Well the Block 50s also have significantly more thrust than the early Block 15s. Here are the words of Lt. Col. Fred "Spanky" Clifton that has flown Eagles and Migs.

I've flown all the C/D versions – Blocks 25, 30, 32, 40, 42, 50, 52. The Pratt-powered Blocks 25, 32 and 42 are good performers, but not great. The GE-powered Blocks 30, 40 and 50, plus the Pratt-powered Block 52 are absolute beasts.

WVR (within visual range) scenario: An F-15C and GE-powered F-16C merge head-on, no missiles, guns only. This is truly where the F-16 excels. The F-15 is absolutely no slouch in this arena and the margin for error is small, but he F-16 enjoys a sustained turn rate advantage and a thrust-to-weight advantage. My game plan would be not to slow down too much in the F-16. Where the F-16 starts to fall off in comparison is when it gets slow and butts up against its hard-wired angle-of-attack limiter. Slow is not a place to be in the F-16 unless absolutely necessary. I wanted to keep my airspeed up relative to the Eagle and beat him down to where his nose track starts to slow and use the vertical as required and the F-16's turn rate advantage to bring my nose to bear.


http://foxtrotalpha.jalopnik.com/how-to ... 1682723379


this is not very realistic.....fighters rarely merge with no missiles........thus the HOBS defense was born. it truly is a matter of who can point first. Imagine this... you are in a blk50 and you merge with a flanker, intel says they are russian made with archers and a hmcs, last person to turn decides the fight so you wait and take him 2 circle, as you plant your skull against the headrest and start your break, you finally see him and he is crushing the HCA, i mean it is obvious that he is making serious angles on you, do you just say "screw it, he would have shot me on the way to the merge and thus cant have any missiles left?"....personally i wouldn't. If he starts to point at you, you have to point at him to min range the possibility of an aa-11. technique only. Im sure that an f-18 guy could pipe in here, but i would rather be in a hornet with a 9x in a 1v1. I understand that that is not what was said above, and that this is gun only, but not everything is in a vacuum, and the reality is that in 7 years flying the viper i never once merged gun only in an LFE. just sayin

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 14:53
by zero-one
deadseal wrote:this is not very realistic.....fighters rarely merge with no missiles........thus the HOBS defense was born. it truly is a matter of who can point first. Imagine this... you are in a blk50 and you merge with a flanker, intel says they are russian made with archers and a hmcs, last person to turn decides the fight so you wait and take him 2 circle, as you plant your skull against the headrest and start your break, you finally see him and he is crushing the HCA, i mean it is obvious that he is making serious angles on you, do you just say "screw it, he would have shot me on the way to the merge and thus cant have any missiles left?"....personally i wouldn't. If he starts to point at you, you have to point at him to min range the possibility of an aa-11. technique only. Im sure that an f-18 guy could pipe in here, but i would rather be in a hornet with a 9x in a 1v1. I understand that that is not what was said above, and that this is gun only, but not everything is in a vacuum, and the reality is that in 7 years flying the viper i never once merged gun only in an LFE. just sayin


Thanks deadseal. Question, what is HCA? I'm also curious at this statement
If he starts to point at you, you have to point at him to min range the possibility of an aa-11. technique only.


Are you saying that in a HOBS fight with an archer equiped flanker, your strategy would be to go to R-min? (minimum range right?)

Also my earlier question was about the F-15 compared to the F-16. Most Viper drivers have said that the Viper was the tighter turner of the 2 birds, however in the outstanding work done by Sprts, The Eagle seemed to have better turn rates

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 15:18
by sprstdlyscottsmn
zero-one wrote:
Also my earlier question was about the F-15 compared to the F-16. Most Viper drivers have said that the Viper was the tighter turner of the 2 birds, however in the outstanding work done by Sprts, The Eagle seemed to have better turn rates

Re-read what you quoted.

"zero missiles". These planes have missiles and thus have the drag of the missiles. F-15 has much lower drag carriage for his missiles.

"Viper needs to keep his speed above the Eagle and use superior sustained turn". I show the Eagle with a corner of ~.8M with a Sustained turn rate of 11.0 while the Viper is best at .9 with a Sustained turn rate of 11.3.

Nothing in my report actually contradicts the statement you gave. The weight of the block 50 hinders the instantaneous turn regardless of thrust level.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 18:58
by zero-one
sprstdlyscottsmn wrote:
"zero missiles". These planes have missiles and thus have the drag of the missiles. F-15 has much lower drag carriage for his missiles.

"Viper needs to keep his speed above the Eagle and use superior sustained turn". I show the Eagle with a corner of ~.8M with a Sustained turn rate of 11.0 while the Viper is best at .9 with a Sustained turn rate of 11.3.

Nothing in my report actually contradicts the statement you gave. The weight of the block 50 hinders the instantaneous turn regardless of thrust level.


Oh okay, thank you, I was never questioning your work Mr. Sprts, if anything, I was actually confused and was willing to think that these viper pilots may have been over emphasizing their advantage over The F-15. In other words they're wrong because you are right.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 20:16
by sprstdlyscottsmn
zero-one wrote: In other words they're wrong because you are right.

I would never, ever, say that. You just need to learn how to read between the lines about what is actually being said and what isn't being said.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 22:39
by johnwill
sprstdlyscottsmn wrote:
"zero missiles". These planes have missiles and thus have the drag of the missiles. F-15 has much lower drag carriage for his missiles.



Well, maybe. Depends on where the missiles are mounted. F-15 AMRAAM on the fuselage or F-16 AMRAAM or AIM-9 on the wing tip are all very low drag. Either airplane with underwing missiles will have higher drag than the above.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 23:07
by basher54321
johnwill wrote:
Well, maybe. Depends on where the missiles are mounted. F-15 AMRAAM on the fuselage or F-16 AMRAAM or AIM-9 on the wing tip are all very low drag. Either airplane with underwing missiles will have higher drag than the above.


I noticed the F-16XL had 4 x AIM-120 under the fuselage ( realise it was extended) - but was there any consideration to adding one each side under the F-16 in a similar place? e.g:

GF-16.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 23:15
by sprstdlyscottsmn
basher54321 wrote:
johnwill wrote:
Well, maybe. Depends on where the missiles are mounted. F-15 AMRAAM on the fuselage or F-16 AMRAAM or AIM-9 on the wing tip are all very low drag. Either airplane with underwing missiles will have higher drag than the above.


I noticed the F-16XL had 4 x AIM-120 under the fuselage ( realise it was extended) - but was there any consideration to adding one each side under the F-16 in a similar place? e.g:

GF-16.jpg

My configuration was four under-wing mounted missiles for the Eagle (plus four on the body) and Viper (plus two on the tips). Eagle has a lower drag carriage (DI is lower and DI*wing area is still lower)

And yes there was consideration of mounting an AIM-7 on the gear doors many many years ago.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 May 2016, 23:22
by basher54321
sprstdlyscottsmn wrote:
And yes there was consideration of mounting an AIM-7 on the gear doors many many years ago.


John stated some time back that probably wasn't viable for the AIM-7, don't know about the AMRAAM .

The XL mounted them differently to that on the bottom of the Blended fuselage.

Capture1.JPG

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 00:59
by sprstdlyscottsmn
basher54321 wrote:
sprstdlyscottsmn wrote:
And yes there was consideration of mounting an AIM-7 on the gear doors many many years ago.


John stated some time back that probably wasn't viable for the AIM-7, don't know about the AMRAAM .

The XL mounted them differently to that on the bottom of the Blended fuselage.

Capture1.JPG

I know, but trying to mount a single missile in such a manner on a regular Viper wing would interfere with the inboard pylon.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 01:07
by johnwill
Spurts, I would still disagree with your comment that the F-15 had "much lower" missile drag than F-16, even with the explanation you gave. "Lower", possibly. "Much lower", doubtful.

Another thing many don't understand about Drag Index, is that is in only applicable to one mach number, 0.80. DI is intended to help pilots estimate external store drag effects on cruise range, that's all. It was chosen because it is below transonic effects, where drag starts to increase at very different rates for different airplanes and store loadings. It's all you have, but it is not a very good indicator of drag at most conditions.

Basher, the AMRAAMs on XL were strictly fake, being made of wooden bodies with sheet metal fins screwed on. The bodies were carved out to match the standard lower OML of the airplane and there were no upper fins. Remembering the political situation with relation to F-15, USAF would not allow the early block F-16 to have BVR missiles, so there was no real plan to include them. The AIM-7/Sky Flash installation on the YF-16 main gear door permitted the launch of test missiles, but was not practical, since the F-16 external 370 fuel tanks were moved 10 inches inboard from the YF-16 and would not clear the missiles. The YF-16 airplanes had only two underwing hard points (BL 135, 80) while the F-16 has three (Bl 70, 120, 157). BL means buttock (?) line, or distance from the airplane centerline.

EDIT Sorry, Spurts, did not see your intermediate post.

Please indulge me while I tell another old story about the XL airplane in the nice photo you posted. You can see the aft AMRAAM is mounted directly in front of the speedbrake, which has upper and lower panels opening equally. The structural design of the speedbrake mount is such that the load on the panels must be roughly balanced. No one took into account the AMRAAM directly in front of the lower panel would shield it from most of the air flow. When the brake was tested at 1.6/30k, a rather loud noise accompanied the extension, so the pilot retracted the brake. Chase came alongside, said everything looked OK, so they repeated the test. In addition to the noise, there was a hydraulic system failure on whichever system drives the brake. The very brief RTB allowed the pilot to explore single system hydraulic handling qualities and landing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 04:30
by sprstdlyscottsmn
johnwill wrote:Spurts, I would still disagree with your comment that the F-15 had "much lower" missile drag than F-16, even with the explanation you gave. "Lower", possibly. "Much lower", doubtful.


"Much" lower was both vague and probably an overstatement.

Eagle: DI of 24.2 for a 1.47ft^2 drag area increase
Viper: DI of 46 for a 1.38ft^2 drag area increase

Well, I made a mistake. I don't know what it was I was thinking about when I said it was lower when combined with wing area. I obviously didn't check my data before posting that.

As to DI being useless supersonic, yeah it's a pain. I can only assume the manuals adjust the increase for an average of that DI. I know when I have to make full models I have to ensure my wave drag increase changes with DI.

Thanks for the anecdote about the speed brake on the XL!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 05:40
by johnwill
Sorry to drag this out even more, but you are more correct than I gave you credit. The drag force from missiles is essentially the same for both airplanes, but when considered as percentage impact on performance, it is much less for the F-15 due to its greater mass and thrust.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 11:43
by eloise
summary :mrgreen:
Image
btw how come F-35A have better instantaneous turn rate than F-35C ? does it have higher wing loading ? , and why do some of them turn slower at their corner velocity ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 13:42
by sprstdlyscottsmn
eloise wrote:summary :mrgreen:
Image
btw how come F-35A have better instantaneous turn rate than F-35C ? does it have higher wing loading ? , and why do some of them turn slower at their corner velocity ?

Huh, originally I had that information joined up like you see there but with the axis switched and it was too bloated and took up two charts. That looks much cleaner.

Anyway, on to your question. The Stubb-A is pulling 1.5G more than Stubb-C, albeit at a higher airspeed, putting more stress on the pilot. The Stubb-A is out rating the Stubb-C by less than 2%, Stubb-C is turning inside the Stubb-A by over 13%. Stubb-A is decelerating at 2.4G while Stubb-C is only decelerating at 1.5G. Who is really performing better at corner velocity? On the Sustained side Stubb-C is pulling lower G with faster rate and tighter radius.

As for "why do some of them turn slower at corner velocity?" I am not sure what you mean. Every one of them improves the instant turns at Corner (by definition) so you must mean sustained turn. Sustained turn rates tend to peak at .8-.9M for afterburning fighters at altitude as the dynamic thrust is increasing and the wave drag has not kicked in yet (or is greatly reduced compared to 1.0M+ anyway). So when you have a corner velocity down below 0.7M your engines are making less thrust than at 0.8M and you need a higher Cl, and thus higher AoA, for any given level of lift. So you are making less thrust and you have more drag for any given G, it becomes perfectly reasonable why sustained rates are going down at corner V relative to 0.8M. You will see though that while the rate go down a little the Radii drop a lot. You are flying a smaller circle, you are just doing it a tad slower.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 18:06
by basher54321
johnwill wrote:
Basher, the AMRAAMs on XL were strictly fake, being made of wooden bodies with sheet metal fins screwed on. The bodies were carved out to match the standard lower OML of the airplane and there were no..........


:notworthy:

Great stuff thank you.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 22:48
by eloise
sprstdlyscottsmn wrote:Huh, originally I had that information joined up like you see there but with the axis switched and it was too bloated and took up two charts. That looks much cleaner.

Anyway, on to your question. The Stubb-A is pulling 1.5G more than Stubb-C, albeit at a higher airspeed, putting more stress on the pilot. The Stubb-A is out rating the Stubb-C by less than 2%, Stubb-C is turning inside the Stubb-A by over 13%. Stubb-A is decelerating at 2.4G while Stubb-C is only decelerating at 1.5G. Who is really performing better at corner velocity? On the Sustained side Stubb-C is pulling lower G with faster rate and tighter radius.

As for "why do some of them turn slower at corner velocity?" I am not sure what you mean. Every one of them improves the instant turns at Corner (by definition) so you must mean sustained turn. Sustained turn rates tend to peak at .8-.9M for afterburning fighters at altitude as the dynamic thrust is increasing and the wave drag has not kicked in yet (or is greatly reduced compared to 1.0M+ anyway). So when you have a corner velocity down below 0.7M your engines are making less thrust than at 0.8M and you need a higher Cl, and thus higher AoA, for any given level of lift. So you are making less thrust and you have more drag for any given G, it becomes perfectly reasonable why sustained rates are going down at corner V relative to 0.8M. You will see though that while the rate go down a little the Radii drop a lot. You are flying a smaller circle, you are just doing it a tad slower.

thanks spurt

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 May 2016, 23:13
by sferrin

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 May 2016, 15:42
by basher54321
Great find that video thanks - shame that they got Benny Hill to provide the music!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 May 2016, 00:19
by mixelflick
basher54321 wrote:Great find that video thanks - shame that they got Benny Hill to provide the music!


Indeed :)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2016, 20:40
by sprstdlyscottsmn
count_to_10 wrote:Something about the Tomcat vs. Super Hornet seems horribly wrong. Everything I've heard indicates that the TC vastly out ranges the SH. Is it the fact that it is basically carrying an extra 2000 lbs of missile, or is there something about optimal cruise speed?


So I don't know if I had said this yet, but I found a snippit of F-14A data for cruise. My drag model was way off for the Tomcat. I initially had no cruise data to compare against so I went back and found the initial assumption that was proven false (idle thrust during descent). This changed base drag area, trim drag, and turning efficiency. End result? Cruise fuel burn will get better, Sustained turn got a little worse, PS during max G turn got much worse (but I feel more accurate when I run it against the one turning chart out there). Also, I am re-doing the Tomcat loadout for Sparrows and Sidewinders only. This represents the capability available when the program was closed as the Phoenix was already retired. Comparing a 2005 Tomcat with a 2020 SHornet seems wrong though. I even up the Harrier to a "2020" spec with AIM-120D since it currently can carry AMRAAM. So what do I do here? Keep it 2005 spec or upgrade to 2020 spec with a missile it was never operationally cleared for (since the funds were diverted to LANTIRN integration)?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2016, 20:54
by sprstdlyscottsmn
garrya wrote:Oh and since you talk about missiles range in your files it probably worth it to talk about their agility too
you can get the information from here

https://www.scribd.com/doc/12515933/Tactical-Missile-Design-Presentation-Fleeman

digital copy of "Tactical Missile Design : 2nd Edition"

http://www.mediafire.com/view/jeofkq9csiu7fss/%28AIAA_Education%29_E._Fleeman-Tactical_Missile_Design%2C_Second_Edition-AIAA_%282006%29.pdf

missiles agility can also be estimate by this spreadsheet :
http://www.mediafire.com/view/2uz1qmg2q ... ility.xlsx


So looking at the missile spreadsheet I started taking into account turn rates and radii of the missiles. with the assumptions I have made about best missile AoA (I perused the other docs looking for this but they are quite large and I found nothing) I assumed 2 deg for body and I think 5 deg for the steering fin I found that the corner velocity for an AIM-120C is at something nuts like 1.64M at FL360. I noted the G and the Turn Rate. I then thought I would see how the heavier Sparrow compared. The much bigger wings drop the corner V to ~1.05M for an even better rate and radius. Matching the Turn rates between the AIM-7M and the AIM-120C gives a lower speed for the AIM-7 still, 0.67M. So this got me thinking that in a head on intercept the AIM-7 can be allowed to slow down much much more than the AIM-120 to have the same turn rate to counter last ditch maneuvers by the target. The AIM-7 has a tighter turn radius as well. This means I could in theory extend the minimum speed for the AIM-7 to give it more flight range, but this also means the F-14 humming along at 1.88M would pass it's own missiles. And of course with the lower speed it has less energy to burn on these turns than the AMRAAM.

What would be the best parameter to use as the "end of missile flight"? Arbitrary speed? Speed of launching aircraft? Corner Velocity? Min velocity to achieve a given turn rate? Do I somehow take warhead size into account? I am rapidly wanting to expand the scope to include the lethality of the weapons the aircraft use.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2016, 21:24
by count_to_10
sprstdlyscottsmn wrote:
count_to_10 wrote:Something about the Tomcat vs. Super Hornet seems horribly wrong. Everything I've heard indicates that the TC vastly out ranges the SH. Is it the fact that it is basically carrying an extra 2000 lbs of missile, or is there something about optimal cruise speed?


So I don't know if I had said this yet, but I found a snippit of F-14A data for cruise. My drag model was way off for the Tomcat. I initially had no cruise data to compare against so I went back and found the initial assumption that was proven false (idle thrust during descent). This changed base drag area, trim drag, and turning efficiency. End result? Cruise fuel burn will get better, Sustained turn got a little worse, PS during max G turn got much worse (but I feel more accurate when I run it against the one turning chart out there). Also, I am re-doing the Tomcat loadout for Sparrows and Sidewinders only. This represents the capability available when the program was closed as the Phoenix was already retired. Comparing a 2005 Tomcat with a 2020 SHornet seems wrong though. I even up the Harrier to a "2020" spec with AIM-120D since it currently can carry AMRAAM. So what do I do here? Keep it 2005 spec or upgrade to 2020 spec with a missile it was never operationally cleared for (since the funds were diverted to LANTIRN integration)?

:thumb:
On the missile load out: it depends on what we are trying to compare. If it is the effectiveness of the underlying airframe, then the missiles should be the same. If we are looking at historical effectiveness, then the missile loadout should be "as was".
I think I'd rather see the former.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2016, 21:44
by sprstdlyscottsmn
count_to_10 wrote: :thumb:
On the missile load out: it depends on what we are trying to compare. If it is the effectiveness of the underlying airframe, then the missiles should be the same. If we are looking at historical effectiveness, then the missile loadout should be "as was".
I think I'd rather see the former.


I think you are right. Otherwise I should compare a 2005 Tomcat with a 2005 SHornet. The rest of them simply ARE being replaced in the 2020 timeline. 2020 planes for all it is.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jun 2016, 13:53
by hornetfinn
I have to bump this thread as I found this: Transonic Free-To-Roll Analysis of the F/A-18E and F-35 Configurations

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040110952.pdf

I know it's rather old but wondered if it would be useful for this performance comparison or otherwise interesting. I could not find this posted here, so this might be interesting to those who understand aerodynamics better than me. I find it interesting that this analysis seemed to be pretty spot on that F-35C has had some wing drop tendencies and F-35A doesn't.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jun 2016, 16:14
by spazsinbad

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jun 2016, 13:15
by hornetfinn
LOL, thanks Spaz, should've known that it has already been posted. Tried to find if it was, but obviously failed to spell the magic words to do so.... :oops:

Anyway, I'm still interested if that document contains anything interesting for the performance comparisons as I don't have enough aerodynamics knowledge to do so and because the models and methods were obviously very accurate.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jun 2016, 14:36
by garrya
sprstdlyscottsmn wrote:
So looking at the missile spreadsheet I started taking into account turn rates and radii of the missiles. with the assumptions I have made about best missile AoA (I perused the other docs looking for this but they are quite large and I found nothing) I assumed 2 deg for body and I think 5 deg for the steering fin I found that the corner velocity for an AIM-120C is at something nuts like 1.64M at FL360. I noted the G and the Turn Rate. I then thought I would see how the heavier Sparrow compared. The much bigger wings drop the corner V to ~1.05M for an even better rate and radius. Matching the Turn rates between the AIM-7M and the AIM-120C gives a lower speed for the AIM-7 still, 0.67M. So this got me thinking that in a head on intercept the AIM-7 can be allowed to slow down much much more than the AIM-120 to have the same turn rate to counter last ditch maneuvers by the target. The AIM-7 has a tighter turn radius as well. This means I could in theory extend the minimum speed for the AIM-7 to give it more flight range, but this also means the F-14 humming along at 1.88M would pass it's own missiles. And of course with the lower speed it has less energy to burn on these turns than the AMRAAM.

What would be the best parameter to use as the "end of missile flight"? Arbitrary speed? Speed of launching aircraft? Corner Velocity? Min velocity to achieve a given turn rate? Do I somehow take warhead size into account? I am rapidly wanting to expand the scope to include the lethality of the weapons the aircraft use.

This is very interesting, can you do similar analysis with Meteor?
btw, based on your model what is the maximum speed that each aircraft can reach using military thrust and fly at optimum altitude? ( iam wondering because not long ago i read an article about F-35 it's ability to maintain speed of mach 1.2 for 150 miles without afterburner, what is the reason for the distance limitations? is it that it run out of fuel? or it can only pass Mach barrier by afterburner and slowly decelerating?
and do you know or can you estimate the roll rate of each aircraft?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jun 2016, 15:32
by sprstdlyscottsmn
garrya wrote:This is very interesting, can you do similar analysis with Meteor?
btw, based on your model what is the maximum speed that each aircraft can reach using military thrust and fly at optimum altitude? ( iam wondering because not long ago i read an article about F-35 it's ability to maintain speed of mach 1.2 for 150 miles without afterburner, what is the reason for the distance limitations? is it that it run out of fuel? or it can only pass Mach barrier by afterburner and slowly decelerating?
and do you know or can you estimate the roll rate of each aircraft?

I have not yet done the Meteor, Sidewinder, or Phoenix. They are on my list to analyze.

As to Military Thrust Envelope issues my model would only be used for the Harrier, Stubby family, Tomcat, and Raptor. The rest I would take from the manuals. As to the Stubby cruise, my model currently supports (for example, this is not the only condition) 1.197M sustained at 36,000f and at a weight of 40,447lb (50% fuel 6 AIM-120D) with a specific range of .04782nm/lb. So With that fuel flow traveling 150nm would consume 3,137lb of fuel. It is not an issue of "It can't go any farther in Mil power" so much as "that is how far you can go with still having a more optimum cruise segment and a reasonable range". However, it is still very much a case of needing to use AB or a Rutowski profile to get there as the acceleration in Mil at M1.1 is only 0.02G (most flight manuals consider practical acceleration to end at 0.03G) or 0.66ft/s^2 or 0.39kt/s.

According to my model anyway. I have gone through great lengths and many iterations to ensure that my model supports all known verified performance claims.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jun 2016, 18:27
by castlebravo
Would you be able to create an estimated plot of drag coefficient vs mach for the F-35A?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jun 2016, 20:16
by sprstdlyscottsmn
castlebravo wrote:Would you be able to create an estimated plot of drag coefficient vs mach for the F-35A?

Of course, I need to have that in order to get the right performance anyway. You would just need to be aware that my Wave Drag models are a byproduct of matching my model performance to known performance so a lot of it also depends on my Thrust curves. So while my output data may match to within 99+% accuracy the individual components may be off by much much more. Thrust especially does a lot of weird things in the dynamic environment that I simply cannot guesstimate.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2016, 17:40
by garrya
I just had a look at this http://su-27.com/info/records/, basically these are the list of record that Su-27 airframe hold
turn out, the Su-27 (with 1000 kg payload ) is a able to maintain speed of 1718 km/h for 1000 km, at altitude around 40k feet, that is equal to mach 1.6, nearly as fast as F-22 and it fly for much longer distance.
Anyway my question is, based on your fuel consumption model, assuming the same speed as the su-27 ,and same optimum altitude , how far can F-22, F-14, F-15, F-16, F-35, F-18 fly?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2016, 23:23
by sprstdlyscottsmn
The record did not say how much fuel was consumed in the attempt. The 540nm distance covered in 0.58hr means that if 19000lb of fuel were used than the Su-27 would have had a fuel flow of just under 33000pph or a specific range of 0.028nm/lb. I don't have my model handy so I can't compare to the other planes.

Edit 1: 19,000lb of fuel is unlikely as the aircraft has to take off, climb, and accelerate while still having fuel to land. 15,000 is more likely giving just under 26,000pph or 0.036nm/lb.

Edit 2:
An F-22 starting with 14,000 pounds of fuel and going until 1,000 remains ( Accounting for take-off, climb, acceleration, and having a base/tanker nearby for the attempt) flying at the same speed and alittude averages 19,000pph and 0.0483nm/lb meaning that for the 13,000 pounds of fuel used it could travel for 0.684 hrs (41 minutes) and 627.9nm (1,162.8km).

An F-35A starting with 13,260 pounds and going until 1,000 remains flying at the same speed and altitude averages 38,044pph and 0.0241nm/lb meaning that for the 12,260 pounds of fuel used it could travel for 0.322 hrs (19 minutes) and 295nm (546km)

An F-15C starting with 10,233 pounds and going until 1,000 remains flying at the same speed and altitude averages 45,000pph and 0.0204nm/lb meaning that for the 9,233 pounds of fuel used it could travel for 0.205 hrs (12 minutes) and 188nm (348km)

Looking at the afterburning fuel flows of the Eagle and the Stubby-A I am really questioning the fuel burn on these Su-27 runs. The record does not list any altitude information so stating it was all done at a given altitude is fairly meaningless. The Raptor would far outrange the Flanker, and while I can still imagine the Flanker outraging the Eagle due to the difference in fuel load alone I would also not be too surprised by it outranging the F-35A due to more excess thrust at said speed to be able to climb to higher altitudes.

If we assume that the speed is the key factor than an acceleration at FL360 would have the F-35A starting the speed run with 13,621 pounds of fuel and would use 7,672 more to climb to FL510 over 162 miles at which point it is burning 24,000pph or 0.0382nm/lb meaning that with the remaining 4,949 pounds of fuel (to get to 1,000 pounds remaining) it would go 189nm further in addition to the 162nm done in climb for a total of 351nm (650km).

Given that 1.6M is the design point for the F-35 (fixed inlets) while the Su-27 is rated for 2.35M (variable inlets) it comes as no surprise that the Su-27 would be able to climb more quickly at 1.6M to quite possibly an even higher altitude (reducing drag and thus fuel burn required to maintain the speed). Keep in mind that a 2,200 pound payload for an Su-27 is little more than two Alamo's with Pylons and tip Archers while for the F-35A it is six AIM-120s.

I am being reminded of why I was such a "fanboi" over the Flankers kinematics 18 years ago. "Oh my gosh, this plane beat all the Streak Eagles records!"

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 03:47
by smsgtmac
AFAIK the Sukhoi Su-27 'Speed' and 'Climb' records were claimed by the P-42 configuration variant. That configuration hardly resembled an Su-27 except it had about 90% of the outer mold line shape of the production/operational aircraft. Internally, 40%+ of the systems/structure in weight was removed, with the engines tweaked to produce about 2K more lbs of thrust each at some unstated penalty in operational life to give near T/W = 2. It was a tremendous aeronautical if not military fighter product, and the mods involved made the Streak Eagle mods look trivial.

But as the theme of the thread is 'Operational Performance Comparison' the configuration of the planes being discussed/compared should be kept in mind. The P-42 could be said to be the unvarnished, unleashed essence of the Su-27, but the operational Su-27 (and derivatives), while still impressive could never have come close to the P-42's claimed performance. I say 'claimed' because as far as I can tell the speed runs were not certified by the FAI like the climbs were (There was the Cold War goin' on y'know). I see no reason to not believe the speed records given the described configuration, I'm just filling in the blanks.

Gorgeous lines. Some good views of it here.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 03:54
by garrya
sprstdlyscottsmn wrote:
An F-35A starting with 13,260 pounds and going until 1,000 remains flying at the same speed and altitude averages 38,044pph and 0.0241nm/lb meaning that for the 12,260 pounds of fuel used it could travel for 0.322 hrs (19 minutes) and 295nm (546km)

An F-15C starting with 10,233 pounds and going until 1,000 remains flying at the same speed and altitude averages 45,000pph and 0.0204nm/lb meaning that for the 9,233 pounds of fuel used it could travel for 0.205 hrs (12 minutes) and 188nm (348km)


If we assume that the speed is the key factor than an acceleration at FL360 would have the F-35A starting the speed run with 13,621 pounds of fuel and would use 7,672 more to climb to FL510 over 162 miles at which point it is burning 24,000pph or 0.0382nm/lb meaning that with the remaining 4,949 pounds of fuel (to get to 1,000 pounds remaining) it would go 189nm further in addition to the 162nm done in climb for a total of 351nm (650km).

!"

what if they used external fuel tank and discard the external fuel tank when they reached the required altitude ? how would an F-15E with CFT do in similar situation? How about F-16 with CFT?
Btw iam quite surprised at how long (162nm) does it take for the F-35 to climb from 36k feet to 51k feet, is it a fuel savings profile? how long would an F-15 take to climb to similar altitude

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 04:00
by garrya
smsgtmac wrote:AFAIK the Sukhoi Su-27 'Speed' and 'Climb' records were claimed by the P-42 configuration variant. That configuration hardly resembled an Su-27 except it had about 90% of the outer mold line shape of the production/operational aircraft. Internally, 40%+ of the systems/structure in weight was removed, with the engines tweaked to produce about 2K more lbs of thrust each at some unstated penalty in operational life to give near T/W = 2. It was a tremendous aeronautical if not military fighter product, and the mods involved made the Streak Eagle mods look trivial.

But as the theme of the thread is 'Operational Performance Comparison' the configuration of the planes being discussed/compared should be kept in mind. The P-42 could be said to be the unvarnished, unleashed essence of the Su-27, but the operational Su-27 (and derivatives), while still impressive could never have come close to the P-42's claimed performance. I say 'claimed' because as far as I can tell the speed runs were not certified by the FAI like the climbs were (There was the Cold War goin' on y'know). I see no reason to not believe the speed records given the described configuration, I'm just filling in the blanks.

Gorgeous lines. Some good views of it here.

According to the website, the climb record was done by P-42, however the speed record was done by Su-27 (595)
which is this aircraft below, it dont have a radar and IRST or wingtip ECM pod but the rest is similar to a normal Su-27, it even have a TVC nozzle
Image
http://estrellaroja-fotos.blogspot.com/ ... p.html?m=1

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 04:17
by madrat
Probably because brute force will only overcome wave drag so much, whereas climb records are all about brute thrust to weight and lift. In your attempt for climb records, you are not going to climb near as fast pointing the nose to the sky like a rocket although it's probably not an obvious revelation for enthusiasts.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 04:41
by sprstdlyscottsmn
garrya wrote:what if they used external fuel tank and discard the external fuel tank when they reached the required altitude ? how would an F-15E with CFT do in similar situation? How about F-16 with CFT?
Btw iam quite surprised at how long (162nm) does it take for the F-35 to climb from 36k feet to 51k feet, is it a fuel savings profile? how long would an F-15 take to climb to similar altitude


They would have to discard the tank before starting the speed run at all. It would help a bit with the range to be sure.

A "clean" Mudhen (do the CFTs count as "payload", or the pylons on them?) would probably crush it as it is still more than capable of Mach 2.0 (I see 1.6M above FL550 at a fuel state of empty CFT but full internal with a fuel flow of 33,000pph at FL500 with would give 361nm on that remaining fuel alone). There is no data in the -1 for the Supersonic Climb time/fuel/distance so I have no idea how much fuel would be spent getting up there without spending an hour trying to tease out a guesstimate.

F-16C+ with a DI of 50 (fairly representative of the 1000kg load) shows 1.6M only up to about FL470 with non-CFT fuel and a Max AB of ~2500pph yielding a further 382nm beyond what it took to get there.

And you seem to have missed that it took Stubby that far to climb while at 1.6M. Not a lot of excess thrust left in my model (1.74M is max aero speed at FL360 and this drops to 1.6M at FL500).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 04:42
by sprstdlyscottsmn
madrat wrote:Probably because brute force will only overcome wave drag so much, whereas climb records are all about brute thrust to weight and lift. In your attempt for climb records, you are not going to climb near as fast pointing the nose to the sky like a rocket although it's probably not an obvious revelation for enthusiasts.

Only for the 10,000ft record.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 08:21
by smsgtmac
garrya wrote: According to the website, the climb record was done by P-42, however the speed record was done by Su-27 (595) which is this aircraft below, it dont have a radar and IRST or wingtip ECM pod but the rest is similar to a normal Su-27...

OK thanks! The tail number helped me find the FAI records as well. Looking at this one-off (no production version) demonstrator configuration with no radar or hardpoints, I'd say this plane had about the same level of customization compared to other models as the Streak Eagle had to the Eagle. Wonder what engines it had at what empty weight for the record runs.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 15:01
by garrya
sprstdlyscottsmn wrote:
They would have to discard the tank before starting the speed run at all. It would help a bit with the range to be sure.

A "clean" Mudhen (do the CFTs count as "payload", or the pylons on them?) would probably crush it as it is still more than capable of Mach 2.0 (I see 1.6M above FL550 at a fuel state of empty CFT but full internal with a fuel flow of 33,000pph at FL500 with would give 361nm on that remaining fuel alone). There is no data in the -1 for the Supersonic Climb time/fuel/distance so I have no idea how much fuel would be spent getting up there without spending an hour trying to tease out a guesstimate.

F-16C+ with a DI of 50 (fairly representative of the 1000kg load) shows 1.6M only up to about FL470 with non-CFT fuel and a Max AB of ~2500pph yielding a further 382nm beyond what it took to get there.

And you seem to have missed that it took Stubby that far to climb while at 1.6M. Not a lot of excess thrust left in my model (1.74M is max aero speed at FL360 and this drops to 1.6M at FL500).

So as a quick recap, if we don't count take off, climb and accelerate distance, the range that fighter can fly at mach 1.6 are as follows :
F-22 can fly for 627.9nm (1,162.8km)
F-15C can fly for 188nm (348km)
F-35 can fly for 295nm (546km)
F-15E with CFT can fly for 361nm ( 668 km)
F-16 with CFT can fly for 382nm (707 km)
did i make any mistakes ?

IMHO, F-16 seem to be even better supersonic cruiser than F-15E, quite a big surprise for me, and Btw if F-22 can fly for over 1000 km at mach 1.6, how come the recommended combat radius only included 100 nm of supercruising? ( if i remember correctly the recommended combat radius is 360 nm with 260 nm subsonic and 100 nm supercruise)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 16:36
by sprstdlyscottsmn
The numbers you have for the Raptor, Eagle, and Lighting there all assume staying at 40,000 ft. The numbers for the Mudhen and Viper+ does not include the supersonic climb portion and also assumes they had full internal fuel at altitude. Essentially none of those numbers are accurate. As to the super cruise, the Raptor can fly twice as far subsonic. And you are remembering the radius wrong I think. IIRC it is 360 sub plus 100 super.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 17:04
by sferrin
sprstdlyscottsmn wrote:I am being reminded of why I was such a "fanboi" over the Flankers kinematics 18 years ago. "Oh my gosh, this plane beat all the Streak Eagles records!"


It doesn't hurt that the P-42 was a completely stripped aircraft, with engines who's lifetime was probably in the double-digits. The thing was flying with engines "tweaked" to produced almost 30k thrust. Imagine the Streak Eagle with a pair of F100-PW-229s. Even so, it didn't beat the Streak Eagle by much.

Capture2.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 18:14
by sferrin
garrya wrote:I just had a look at this http://su-27.com/info/records/, basically these are the list of record that Su-27 airframe hold
turn out, the Su-27 (with 1000 kg payload ) is a able to maintain speed of 1718 km/h for 1000 km, at altitude around 40k feet, that is equal to mach 1.6, nearly as fast as F-22 and it fly for much longer distance.
Anyway my question is, based on your fuel consumption model, assuming the same speed as the su-27 ,and same optimum altitude , how far can F-22, F-14, F-15, F-16, F-35, F-18 fly?





Yes, yes, it's a bigger aircraft. Just amazing what it was able to do on roughly the same power as an F-15 or Su-27. It beat the Su-27s record and it was carrying a 2000kg payload. (1200.19 mph, 2000kg, 1000km)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2016, 19:52
by sprstdlyscottsmn
Sferrin, thanks! The P-42 mods are crazy! And no surprise about the B-58. Shy of J58s, never bet against J79s for speed. Even the F-4 topped out at 2.64M while setting the "absolute speed record"

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Jul 2016, 02:59
by garrya
sprstdlyscottsmn wrote:The numbers you have for the Raptor, Eagle, and Lighting there all assume staying at 40,000 ft. The numbers for the Mudhen and Viper+ does not include the supersonic climb portion and also assumes they had full internal fuel at altitude. Essentially none of those numbers are accurate.

Ah ,i see it now , in Mudhen and Viper+ case , you assumed they used the fuel in external fuel tank to climb , then drop them ,am i correct ?

btw i asked an engineer about the record ,and here are his thought
Well, other than the fact that Su-27 still hold the record it doesn't say many things. Like I've said many times, I don't have fuel consumption data for Su-27, but I do for its smaller sibling, MiG-29. Flying at M1.4, fuel consumption can vary from ~16 kg/sec @ 2000 meters, to <2kg/sec for 18000 meters, so without altitude info its not logical to speculate about fuel consumption.

If record procedure allow it, record may not even be at constant speed or altitude; Su-27 could take off with full fuel, spend some of it to climb to an high altitude at mil thrust, then accelerate quickly by diving at full AB during first 200-300 km of the record attempt, sustain speed for some 500 km while re-gaining altitude (as reduced fuel means optimal cruise altitude constantly increases during the flight) then reduce throttle and complete the remaining 200-300 km while decelerating and losing altitude. In terms of numbers, for example, Su-27 can climb to 16000m@M0,8, then dive to 10000m@M2.0, start record timer somewhere along that dive. Cruise at M2.0, run short on fuel at 14000m@M2.0, switch to min AB (or even MIL thrust) and end up finishing the record flight at 1000m@M1.3. Since end point of the closed circuit can be pre-planned, record aircraft can end up just at the start of the glidepath, and Su-27 could then land with a 200-250 kg of fuel. (speaking of ability, pilot can even land it unpowered at that point).

Or the procedures can be way different, and none of just I've written may be true. The real question is, Su-27 and F-15 made their record flights in very early introduction into service, their airframe modifications predate their introduction. SR-71 had much more secrecy, so did MiG-25 back then, but those aircraft had their share of record flight as well. F-22 has 8 prototypes unfit for military service, and aircraft is in service for 11 years. If it is so impressive of an aircraft, why anyone even attempted a record flight?

Technically, had "supercruise" brought half the advantages people bragging about, F-22 should have broken Su-27's record a dozen times without one single modification to its airframe. Even production aircraft could have done that. Its not necessary to look far to see the obvious, the simplest explaination is it can't.
-Supercruise on one side, 20% smaller wing area (linearly contribute to drag), 15% more fuel capacity, variable inlets, an aerodynamically optimized airframe without internal bay or stealth considerations on the other side. How on earth supercruise brings a definite advantage is beyond me.
-F-22's combat radius is 852 km, if 182 km of the flight spend on supercruise. So it can fly 1704 km in total 1340 subsonic and 364 km supersonic. Su-27's combat radius is 1760km, it can fly 3520km subsonic. Subtract the subsonic parts, and Su-27 will still have more than 60% fuel after travelling 1340 km. Su-27 can fly @~M1.4-1.5 for way more than 12-13 minutes if it has 5000+kg fuel to spend, perhaps 20-25 minutes. You may say F-22 can supercruise at higher speeds, but there is an acceleration/deceleration parts to that, so average of M1.4-1.5 seems logical to me.

There is another aspect of it though, F-22 can still do that with 8 missiles, Su-27 probably can't. As for F-35, its unfair to compare it with Su-27.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Jul 2016, 05:40
by johnwill
The B-58 pilot, Maj. Dutchendorf, and airplane were based at Carswell AFB in Fort Worth. His son John was in a Scout troop led by my boss at General Dynamics. He later changed his name to John Denver.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 02:23
by sferrin
Apparently the F-35 can climb:


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 03:40
by sprstdlyscottsmn
sferrin wrote:Apparently the F-35 can climb:

Oh the things you have to do to stay under 500 some-odd knots.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 06:58
by wrightwing
Here's a pro-tip: there's no way an operational Flanker is going to be flying at M1.5 with weapons, for anywhere near 20 to 30 min. As for the F-22, as far back as 2006, it was stated that it can supercruise for 41 minutes (at more than M1.5).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 14:53
by sferrin
wrightwing wrote:Here's a pro-tip: there's no way an operational Flanker is going to be flying at M1.5 with weapons, for anywhere near 20 to 30 min. As for the F-22, as far back as 2006, it was stated that it can supercruise for 41 minutes (at more than M1.5).


There are all kinds of odd one-off statements out there. One pilot mentioned supercruising at Mach 1.9 and 60,000 feet. Another mentioned supercruising at Mach 1.7 on 55% power. :shrug:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 16:27
by wrightwing
sferrin wrote:
wrightwing wrote:Here's a pro-tip: there's no way an operational Flanker is going to be flying at M1.5 with weapons, for anywhere near 20 to 30 min. As for the F-22, as far back as 2006, it was stated that it can supercruise for 41 minutes (at more than M1.5).


There are all kinds of odd one-off statements out there. One pilot mentioned supercruising at Mach 1.9 and 60,000 feet. Another mentioned supercruising at Mach 1.7 on 55% power. :shrug:

I can't find the links at the moment, but I recall 2 other articles, suggesting that the supercruise range is considerably more, than some of the conservative estimates. You've probably seen them, too. One was where a pilot was flying to an airshow, and mentioned that were it not for speed restrictions over CONUS, he could've supercruised the entire way. The other article was in reference to scrambling from Langley AFB, and flying to defend D.C. airspace at greater than supercruise speeds (it mentioned a very short flight time, which would've required M2+ dash), and then still loitering at high speeds, for ~45 minutes, before RTB.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jul 2016, 16:54
by sferrin
wrightwing wrote: One was where a pilot was flying to an airshow, and mentioned that were it not for speed restrictions over CONUS, he could've supercruised the entire way.


If it's the same one I recall they said they could have made the trip (800 miles) "in about a half hour".

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 03:52
by garrya
@Spurt , @johnwill What do you guys think about this comment here :
LEG wrote: Whoot!

Now let's look at close combat as the wings. Instead of the clipped/modified deltas of the F-15/16/22 which have superb stall resistance, they are basically F-5/F-18 tapered trapezoids, shoved as far back as possible to keep transonic drag rise under control and reliant upon forebody lift off the weapons bay area to compensate. The problem with this is that you have a staggerwing effect. Even without opening the weapons bays to completely destroy the high-pressure aeros while prepping quickdraw missiles, as the forebody rises, it's effective AOA goes up faster than the trailing primary airfoil's does. Added to which is the close coupling between the F-35 tails and the wings which denies the option of (2` up LEF) 'trimming in the tails' to set the turn and (on the F-16) gain rather than lose 100sqft or so of effective lift as a genuine 9G capability.

Which is why the F-16, 40 years old, can do this-

https://www.youtube.com/watch?v=HBlP4cCRVmk

Despite having the lowest (27.5, without chin pods) alpha regime of any in-service fighter. May not mean much in a HOBS environment you say, but then again F-35 doesn't have a HOBS missile or the ability to add one without directly effecting it's already incredibly limited internal strike mission payload. And its a long, long, ways from your 6nm NEZ last-AMRAAM to the 4,000ft of 25mm gunzo followup.

On the F-35, the effective lift differential and lack of vectoring to trim the jet in results in a split lift curve as the reason why the jet is running at 'transitional' alpha limits around 20-23 units, when most jets are only entering this regime at 27 and it has a direct effect upon FLCS authority to continue pitch rates as the jet nears TRO territory and the flight controls have to start limitering thrown to keep the 'carefree' handling.

It is the reason why, despite having a nominal 60-70 absolute Alpha regime, the F-35 is in fact functionally on a monorail above 30` with ZERO ability to bring the nose across as the threat reverses and tucks under in the most basic of BFM snakes and rolling scissors. Because both the verticals and the stabs are having to _fight_ to keep the nose up and the jet is bleeding down, unable to generate lift to sustain even a 6G turn as the F-16 did against the F-4E shown here-

http://forum.keypublishing.com/showthread.php?2902-F-32
I kinda feel like he just threw a bunch of acronym together but i still wanna hear opinions from you experts

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 04:31
by wrightwing
The AMRAAM has HOBS capabilities, and is effective as close as 2000m. The guy is misinformed.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 05:17
by vanshilar
garrya wrote:Now let's look at close combat as the wings. Instead of the clipped/modified deltas of the F-15/16/22 which have superb stall resistance, they are basically F-5/F-18 tapered trapezoids, shoved as far back as possible to keep transonic drag rise under control and reliant upon forebody lift off the weapons bay area to compensate.


I'll admit he lost me here. Maybe I'm not an aero expert but both the F-22 and F-35 seem to have similar wing planforms to my untrained eyes. Granted the F-22's wings are a bit clipped near the wingtips, but I don't see how one can arbitrarily be called "tapered trapezoids" and bad while the other is "clipped/modified delta" and good. Does nature have some magical aspect ratio limit at which point one is good at dogfighting and the other is bad?

Furthermore, I thought both the F-22 and F-35 get quite a bit of lift from the fuselage, and use similar design methods, i.e. chined nose, shaping of air intakes, etc. And as for close-coupling of the tail and wing, the F-22's tails extend into its wings for crying out loud! Yet apparently it's bad for the F-35.

Basically it seems like you could replace "F-35" with "F-22" in his criticisms of the F-35 and they'd all still make sense.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 05:36
by garrya
vanshilar wrote:
Basically it seems like you could replace "F-35" with "F-22" in his criticisms of the F-35 and they'd all still make sense.

kinda how i feel too , i didnt quoted all of his post , but the rest was ridden with mistakes that rather easily to see. But i want to give him some benefit of the doubt for this part

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 05:52
by spazsinbad
I don't know the meanings of the word salad quoted however overall it reminds me of an 'S&M'? or 'M&S' post from other forums - mix a bunch of made up military terms to sound like 'someone in the know' and mix it up with facts and factoids both real and imagined - sounds like me eh. :mrgreen: HERE WE GO - I spy...:

viewtopic.php?f=61&t=26629&p=282919&hilit=Plummer#p282919 'M&S' is Kurt Plummer whois/wuz 'GALOOT'? viewtopic.php?t=24103 Read the posts in this here thread y'all.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 08:06
by mk82
garrya wrote:@Spurt , @johnwill What do you guys think about this comment here :
LEG wrote: Whoot!

Now let's look at close combat as the wings. Instead of the clipped/modified deltas of the F-15/16/22 which have superb stall resistance, they are basically F-5/F-18 tapered trapezoids, shoved as far back as possible to keep transonic drag rise under control and reliant upon forebody lift off the weapons bay area to compensate. The problem with this is that you have a staggerwing effect. Even without opening the weapons bays to completely destroy the high-pressure aeros while prepping quickdraw missiles, as the forebody rises, it's effective AOA goes up faster than the trailing primary airfoil's does. Added to which is the close coupling between the F-35 tails and the wings which denies the option of (2` up LEF) 'trimming in the tails' to set the turn and (on the F-16) gain rather than lose 100sqft or so of effective lift as a genuine 9G capability.

Which is why the F-16, 40 years old, can do this-

https://www.youtube.com/watch?v=HBlP4cCRVmk

Despite having the lowest (27.5, without chin pods) alpha regime of any in-service fighter. May not mean much in a HOBS environment you say, but then again F-35 doesn't have a HOBS missile or the ability to add one without directly effecting it's already incredibly limited internal strike mission payload. And its a long, long, ways from your 6nm NEZ last-AMRAAM to the 4,000ft of 25mm gunzo followup.

On the F-35, the effective lift differential and lack of vectoring to trim the jet in results in a split lift curve as the reason why the jet is running at 'transitional' alpha limits around 20-23 units, when most jets are only entering this regime at 27 and it has a direct effect upon FLCS authority to continue pitch rates as the jet nears TRO territory and the flight controls have to start limitering thrown to keep the 'carefree' handling.

It is the reason why, despite having a nominal 60-70 absolute Alpha regime, the F-35 is in fact functionally on a monorail above 30` with ZERO ability to bring the nose across as the threat reverses and tucks under in the most basic of BFM snakes and rolling scissors. Because both the verticals and the stabs are having to _fight_ to keep the nose up and the jet is bleeding down, unable to generate lift to sustain even a 6G turn as the F-16 did against the F-4E shown here-

http://forum.keypublishing.com/showthread.php?2902-F-32
I kinda feel like he just threw a bunch of acronym together but i still wanna hear opinions from you experts


What the f*ck did I just read? This is either some really stupid sh*t or this guy is off his anti-psychotic meds? Or may be both :mrgreen: . Seriously Garrya, tell this LEG dude to f*ck off. My IQ dropped by 10 points reading that word salad.

Look at this classic example.....An F16 was able to pull 6Gs against a F4E....sure.....but that was not at high AOA (i.e. > 30 degrees AOA)....no sirree! And that has no relationship to the high AOA capabilities of the F35. And Norwegian fighter pilots have proven that the F35 ain't no monorail at high AOA (even at its flight computer control limit)...it still retains excellent nose pointing ability. The only monorail here is this LEG dude's one tracked mind...oh Kurt....you done it again!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 14:48
by count_to_10
wrightwing wrote:The AMRAAM has HOBS capabilities, and is effective as close as 2000m. The guy is misinformed.

Not only that, but he states a 6 nm NEZ as if NEZ means "minimum weapons range" instead of "no escape zone".
I'm no expert on the subject of aerodynamics, but that whole diatribe seems to me like confident-sounding but ignorant bluster.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 20:31
by vanshilar
As an aside, if you're bringing in comments from other forums, especially Keypubs, 1) typically, don't; people who want to read the content in those forums can go to those forums themselves, and 2) start its own thread, or better yet, stick it in the basement dwellers thread where it belongs rather than cluttering up other threads.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Sep 2016, 21:03
by neurotech
sferrin wrote:
wrightwing wrote:Here's a pro-tip: there's no way an operational Flanker is going to be flying at M1.5 with weapons, for anywhere near 20 to 30 min. As for the F-22, as far back as 2006, it was stated that it can supercruise for 41 minutes (at more than M1.5).


There are all kinds of odd one-off statements out there. One pilot mentioned supercruising at Mach 1.9 and 60,000 feet. Another mentioned supercruising at Mach 1.7 on 55% power. :shrug:

Its possible the supercruise performance might vary due to FADEC settings, to extend turbine life. Also, Some engine/intake configurations are actually more efficient above a certain Mach, at high altitude. The F-22 max. speed in burner is limited by the canopy and skin temperature, not the engines.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Sep 2016, 11:18
by hornetfinn
garrya wrote:@Spurt , @johnwill What do you guys think about this comment here :
LEG wrote: Now let's look at close combat as the wings. Instead of the clipped/modified deltas of the F-15/16/22 which have superb stall resistance, they are basically F-5/F-18 tapered trapezoids,


I'm no aerodynamics expert, but I think this statement is "somewhat" wrong... :roll:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Sep 2016, 18:42
by eloise
LEG got tore apart over there

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Sep 2016, 19:06
by quicksilver
I'm kinda with mk82...or maybe I watched too much football this weekend.

ALL aircraft designs...ALL aircraft designs are compromises between competing design 'requirements.'

The 'it's all about the STOVL penalty' meme is tired. The Air Force did not want a large, heavy, twin engine, whatever because it had to be a force structure replacement for its F-16s -- i.e. affordable. The rule of thumb at the time was that a new jet would be about $1500/lb. Get 'bigger and/or heavier' and you get less 'affordable.' Get bigger and/or heavier and you also get less STOVL capability. F-35 did not get bigger and heavier because of STOVL; it got bigger and heavier because the USAF and the USN wanted more range, signature control and internal payload. Get bigger and heavier and you have to scale the propulsion system performance up to meet the STOVL requirement and the up and away performance requirements for the others. Thus, the vicious design cycle begins. JW or others who have been closer to it can explain that cycle in detail.

The tanker/AAR profile... Anyone who has ever done a trans-oceanic flight with AAR knows that the fuel planning is exceptionally conservative (as someone above has noted). At any point in the flight, the jet has to have enough JP onboard to transit (without further AAR) to the nearest suitable divert, make an approach, a second approach, and if missed again, remain airborne for another specified period of time (without AAR) at a specified max endurance altitude and speed; none of which necessarily utilize the optimum parameters for the jet. Most of the time you cruise at the optimum speed for the tanker.

Also of note, there is plenty of stuff that is demonstrably false (e.g. hi alpha and subsonic accel, as commented upon by the international guys at Luke) as well as other stuff that is plain trolling since it has either been discussed at length in other years and other forums ad nauseum, or will not ever be discussed because it isn't public information.

So, we have some people who show up on some website with all kinds of numbers or rationale that suit their strawman on some particular topic. Really, again? Why? Because there are fighter competitions going on at various places in the world where the outcome is not yet decided. :roll:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Sep 2016, 21:56
by spazsinbad

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Nov 2016, 11:05
by garrya
This may be of interest to spurt and the aerodynamic jock here, there are some strong claim regarding F-35 boxy shape and AoA, so what you guys think?
https://forums.eagle.ru/showthread.php?t=35070&page=334

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Nov 2016, 13:55
by sprstdlyscottsmn
garrya wrote:This may be of interest to spurt and the aerodynamic jock here, there are some strong claim regarding F-35 boxy shape and AoA, so what you guys think?
https://forums.eagle.ru/showthread.php?t=35070&page=334

Most of that argument seems to center around 10k ft altitude charts when the data from me was for 20kft. Not shown in the chart of my data was also the acknowledgement of the bogus F-14 G limits with additional turning data for a 9.5G Tomcat, as that is what Grumman tested to. Seems like Hummingbird has just enough information available to not realize he is looking at it wrong.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Nov 2016, 14:51
by garrya
sprstdlyscottsmn wrote:Most of that argument seems to center around 10k ft altitude charts when the data from me was for 20kft.

Actually, i did mentioned that in last page , but he still think the number is too far from F-14 20K feet graph and closer to 25k feet graph

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Nov 2016, 22:31
by basher54321
sprstdlyscottsmn wrote:Most of that argument seems to center around 10k ft altitude charts when the data from me was for 20kft. Not shown in the chart of my data was also the acknowledgement of the bogus F-14 G limits with additional turning data for a 9.5G Tomcat, as that is what Grumman tested to. Seems like Hummingbird has just enough information available to not realize he is looking at it wrong.


Can I just confirm because I had assumed those figures are calculated at the weight the aircraft is at around 120 whatever miles out in the turning phase of the profile?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Nov 2016, 13:31
by sprstdlyscottsmn
There was not a fixed range with that one. Each plane was at the maximum intercept range based on a max speed profile. Each plane had enough fuel for "three sustained turns at .8M at 20,000ft and then had to perform an optimum cruise profile RTB.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Nov 2016, 22:44
by garrya
Is it possible to estimate F-35 CLmax from this chart ?
Image
http://www.heritage.org/research/report ... nt-process
We speculate that F-16 in comparison is in wild weasel config with all 3 pods on ( because a clean F-16 would normally has better STR than F-15 in dogfight).So after jettison this would still leave around 3300 lbs in added weight and a Drag Index of 114. Such F-16 will be limited to 8 G
We know that F-35 is limited to 7 G at the moment. So, if an F-35 at 7G has the same ITR as F-16 at 8G, is it possible to draw any conclusion regarding its CLmax ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 05:22
by smsgtmac
garrya wrote:Is it possible to estimate F-35 CLmax from this chart?
...
We speculate that F-16 in comparison is in wild weasel config with all 3 pods on ( because a clean F-16 would normally has better STR than F-15 in dogfight).So after jettison this would still leave around 3300 lbs in added weight and a Drag Index of 114. Such F-16 will be limited to 8 G
We know that F-35 is limited to 7 G at the moment. So, if an F-35 at 7G has the same ITR as F-16 at 8G, is it possible to draw any conclusion regarding its CLmax ?

1. No.
2. W(ho)TF is this "we" doing all of the unsupported 'speculation'?
3. Still no.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 10:14
by mk82
On a tangent, that Heritage Foundation graph reminded me that former A10 pilots rated the slow speed responsiveness of the F35 to be better than that of the A10! It's total hogwash from armchair pilots/A10 fanboys that the F35 can't fly well in the low and slow part of it's flight envelope. In fact, I am not surprised that the F35 ironically flies better "low and slow" than an A10 (not that "low and slow" tactics would be used often...too tactically risky in most situations)!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 11:06
by garrya
smsgtmac wrote:1. No.
3. Still no.

why not ?
shouldnt it be possible to estimate CL from ITR ?
smsgtmac wrote:W(ho)TF is this "we" doing all of the unsupported 'speculation'? .

Just someone on another forum

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 13:46
by count_to_10

So, reading through that paper, this is the passage that I find most notable:
The requirement for the Joint Strike Fighter (JSF) came about when technology was growing so rapidly that it would be hard to field a jet that was not already approaching obsolescence. DoD agreed on an approach that would combat that challenge by moving to acquire a system while many components of the aircraft were still undergoing some level of research and development. That concurrent development brought with it a level of risk that by its very nature will be present throughout the course of the F-35’s initial fielding.

Component, sensor, and airframe development were (and still are) all happening at the same time, and even small changes in the weight, size, performance, and schedule of any component could affect the weight, size, performance, and schedule of the entire system. While some believe the risk associated with portions of the F-35 concurrent development program equate to acquisition malpractice,[29] the benefits are potentially enormous. The risks of developmental delays and cost overruns were accepted to mitigate an even bigger risk: that the United States would field its own version of the Tornado F-3. The costly risk of delays was known, and only extraordinary leadership could mitigate it. That should have been factored into the whole of the acquisition process, but it wasn’t.


Also interesting: only two of the interviewed pilots were F-15C pilots, but 75% of the 31 pilots preferred the F-15C to the F-35A in the offensive/defensive tail-chase?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 15:25
by steve2267
count_to_10 wrote:Also interesting: only two of the interviewed pilots were F-15C pilots, but 75% of the 31 pilots preferred the F-15C to the F-35A in the offensive/defensive tail-chase?


Nice observation. The only thing that really comes to mind is that perhaps many more than two pilots had F-15C experience, but only two came directly from F-15C units?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 16:14
by count_to_10
steve2267 wrote:
count_to_10 wrote:Also interesting: only two of the interviewed pilots were F-15C pilots, but 75% of the 31 pilots preferred the F-15C to the F-35A in the offensive/defensive tail-chase?


Nice observation. The only thing that really comes to mind is that perhaps many more than two pilots had F-15C experience, but only two came directly from F-15C units?



On further reflection, the fact that it was exactly 75% instead of 23/31 suggests that maybe the question was only asked of those who had F-15C experience, and a multiple of four.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 17:13
by basher54321
garrya wrote:We speculate that F-16 in comparison is in wild weasel config with all 3 pods on ( because a clean F-16 would normally has better STR than F-15 in dogfight).So after jettison this would still leave around 3300 lbs in added weight and a Drag Index of 114.



You don't need to speculate GarryA because the configuration is given in the report:

A Direct Comparison.

Thirty-one experienced pilots currently flying the F-35A were asked to rate the energy and maneuvering characteristics of their previous fourth-generation fighters in a combat configuration throughout the dogfighting maneuver envelope in a combat configuration [23 ] after jettisoning their external stores. They were then asked to rate the performance of the F-35A using the same scale, with fuel and internal munition loads associated associated with a combat loadout. [24] under their current G and CLAW restrictions.[25]

23. “Combat configuration” refers to an aircraft with stores that remain after pilots drop or jettison everything they can drop or jettison before going to a merge. For the F-16, this would leave the Harm Targeting Pod (HTS), IR Targeting Pod, ECM pod, MAUs, rails, and air-to-air missiles; for the F-15C, the fuel tank racks; for the F-15E, the Targeting Pod, MAUs, rails, and air-to-air missiles; for the A-10, the IR Targeting Pod, ECM pod, and enough racks and rails from which to hang a city’s worth of meat.

24. Combat configuration for the F-35A: 13,000 pounds of fuel to replicate retaining internal munitions and roughly half internal fuel. The F-35A will have no external stores during any anti-access, high-threat environment.


F-16 G limit in that config likely under 8G tbh

btw wasting your time arguing over max CL and EM charts that only show level turn performance you wont be proving much at all in the end apart from more speculation.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 17:39
by garrya
basher54321 wrote:

You don't need to speculate GarryA because the configuration is given in the report:

A Direct Comparison.

Thirty-one experienced pilots currently flying the F-35A were asked to rate the energy and maneuvering characteristics of their previous fourth-generation fighters in a combat configuration throughout the dogfighting maneuver envelope in a combat configuration [23 ] after jettisoning their external stores. They were then asked to rate the performance of the F-35A using the same scale, with fuel and internal munition loads associated associated with a combat loadout. [24] under their current G and CLAW restrictions.[25]

23. “Combat configuration” refers to an aircraft with stores that remain after pilots drop or jettison everything they can drop or jettison before going to a merge. For the F-16, this would leave the Harm Targeting Pod (HTS), IR Targeting Pod, ECM pod, MAUs, rails, and air-to-air missiles; for the F-15C, the fuel tank racks; for the F-15E, the Targeting Pod, MAUs, rails, and air-to-air missiles; for the A-10, the IR Targeting Pod, ECM pod, and enough racks and rails from which to hang a city’s worth of meat.

24. Combat configuration for the F-35A: 13,000 pounds of fuel to replicate retaining internal munitions and roughly half internal fuel. The F-35A will have no external stores during any anti-access, high-threat environment.


F-16 G limit in that config likely under 8G tbh

.

That interesting , i didnt paid attention to that part TBH

basher54321 wrote:btw wasting your time arguing over max CL and EM charts that only show level turn performance you wont be proving much at all in the end apart from more speculation

Well , i would think that we can speculate F-35 ITR from CLmax , could be useful
And since EM chart give SEP too , should it be useful for vertical fight as well ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Nov 2016, 23:50
by basher54321
Well shows potential energy to climb - not much else in that regards.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 12 Jan 2017, 15:49
by sprstdlyscottsmn
So in the last released version I added weaponry to the "Intercept" profile and measure the time it took each fighter to lob a missile 150nm away from the base. While an interesting stand alone data point it was not particularly useful without context, so I added a target.

Early warning radars paint a pair of incoming Su-24s, which spy photography has shown are being loaded with Kh-59M2 missiles. These missiles have a range of 150nm. The last radar contact showed the planes descending and accelerating, clearly an attack profile. Fighters are launched. Once the interceptors begin climbing their EW gear (if they have it) starts detecting signals from an IRBIS-E, the Fencers have escorts.

The scenario includes two Su-24s at 1.08M using NOE flying, one Su-35S also doing NOE flying with radar on passive, one Su-35S doing a high-speed high-altitude dash with radar active. The Su-35s will be armed as we saw in Syria: R-74, R-27(E)T, R-77.

This situation will include radar performance against a variety of target types: low alt high RCS (Su-24 50m^2 used), low alt med RCS (Su-35 3m^2 used), low alt low RCS (Kh-59 .1m^2 used), high alt med RCS (Su-35). The Su-35s will have the latest operational wingtip jamming pods. The onboard ECM of the interceptors will come into play against the IRBIS-E. The interceptors will have to try and destroy the Su-24s before they can launch or else they will have to engage the missiles directly.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Jan 2017, 03:57
by garrya
sprstdlyscottsmn wrote:So in the last released version I added weaponry to the "Intercept" profile and measure the time it took each fighter to lob a missile 150nm away from the base. While an interesting stand alone data point it was not particularly useful without context, so I added a target

Did you uploaded it already in the place of the old file or you will upload it ?


sprstdlyscottsmn wrote:This situation will include radar performance against a variety of target types: low alt high RCS (Su-24 50m^2 used), low alt med RCS (Su-35 3m^2 used), low alt low RCS (Kh-59 .1m^2 used), high alt med RCS (Su-35). The Su-35s will have the latest operational wingtip jamming pods. The onboard ECM of the interceptors will come into play against the IRBIS-E. The interceptors will have to try and destroy the Su-24s before they can launch or else they will have to engage the missiles directly.

That very cool but also quite complex because RCS change alot with aspect angle, side aspect of Su-35 probly reach a thounsand M2
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Jan 2017, 13:36
by sprstdlyscottsmn
It is not uploaded yet. There is so much complexity that I have not finished a single planes review. I also have spent over one hundred hours on making a new performance model to properly simulate supersonic climbs, descents, deceleration, and the Rutowski push, as well as improving the wave drag effects of weapons.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Jan 2017, 14:21
by garrya
sprstdlyscottsmn wrote:It is not uploaded yet. There is so much complexity that I have not finished a single planes review. I also have spent over one hundred hours on making a new performance model to properly simulate supersonic climbs, descents, deceleration, and the Rutowski push, as well as improving the wave drag effects of weapons.

needless to say , we really appreciate your effort :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Jan 2017, 14:24
by hornetfinn
garrya wrote:needless to say , we really appreciate your effort :D


Yes we definitely do! :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 01:38
by sprstdlyscottsmn
So part of the complexity of my current model set is missile tracks and evasion. I had been using MiniZap but found glaring errors in that it does not actively track a target when fired from a specified range, it only gives you the maximum range possible in which the minimum speed remains satisfied. It also doesn't help with missile turn performance to compare evasion maneuvers. So I wrote my own missile simulator. I have the vertical tracking working well enough. From any starting position I can change the target altitude, speed, and range and see how it impacts the flight profile and the ending speed of the missile at "impact". Next is to add the horizontal component to hit a target that is turning. So far doctrine is becoming an issue. Does a solo plane with two missile available fire one missile each at two targets, or two missiles at a single target? But either way, even the F-15C is being challenged by this scenario.

I also think I will grade on points.

+10 for a target desroyed
-1 for a missile fired (either side)
-10 per subject plane destroyed
-1 per ton of fuel used each plane

I think this will fairly subjectively rate the planes.

Say the F-22 pair kills all four planes (+80, four planes and four cruise missiles) before they can launch any missiles and uses eight of their own missiles (-8) and burns 6 tons of fuel each on the mission (-6), it scores a 66.

Say the F-15C pair kills three planes (+30) using eight missiles (-8) but the bombers launch the missiles (-4) and the Eagles destroy them too (+40) using four more missiles (-4) but had a combined 4 missiles fire back at them (-4) and burns 5 tons each (-5), it scores a 45.

Say a Stubby pair kills only the two bombers (+20) and their missiles (+40 -4) and uses eight missiles to do so (-8) and burns 4 tons of fuel each (-4), it scores a 44. It left more planes alive to fight another day but it was never seen or shot at.

Thoughts?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 02:02
by count_to_10
sprstdlyscottsmn wrote:Thoughts?

Sounds overly simplistic and deterministic. There is a lot of uncertainty in this kind of thing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 02:08
by steve2267
sprstdlyscottsmn wrote:
Say the F-22 ... scores a 66.

Say the F-15C ... scores a 45.

Say a Stubby pair ... scores a 44.

Thoughts? Canada should definitely buy the F-15. :devil:

Makes sense. You could argue about relative merits / weights (e.g. ton of fuel vs missiles fired), but your weights seem reasonable. Do you distinguish between IR missiles and BVR radar missiles? One might argue that AIM-120s should be a cost of 2, and AIM-9 be a cost of 1. Don't know that that is a huge deal, though.

Of course, if someone guns a missile, that should be +100, and gunning an enema aircraft should be +25. :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 02:18
by steve2267
Here's a thought... since you are including F-15C in your comparison, perhaps you can run two simulations for the F-35: stealthy and max weps load (e.g. external stores). In the 12 x AIM-120 + 2 x AIM-9X, the F-35 will be able to double up missiles on targets. I do not know current doctrine, but being able to put two missiles on each target from the outset would seem to be the way to go. You will have to up the fuel burn on the F-35 to account for the increased drag, of course...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 13:29
by sprstdlyscottsmn
The intercept mission is effectively a six missile mission for drag reasons. Only the F-15 and F-22 will have eight as they don't have any drag penalty. I looked at that in a previous rundown and it was the hornets that made me cap it at six. Any more and they were nearly subsonic. Even the Su-35S threat aircraft can only carry six missiles and fly its part of the mission. BTW Russian missiles have lots of drag.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 14:45
by garrya
sprstdlyscottsmn wrote:The intercept mission is effectively a six missile mission for drag reasons. Only the F-15 and F-22 will have eight as they don't have any drag penalty. I looked at that in a previous rundown and it was the hornets that made me cap it at six. Any more and they were nearly subsonic. Even the Su-35S threat aircraft can only carry six missiles and fly its part of the mission. BTW Russian missiles have lots of drag.

If F-35 were to carry AIM-9X or AIM-132 at wing tip, would that affect its drag significantly ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2017, 16:10
by sprstdlyscottsmn
garrya wrote:If F-35 were to carry AIM-9X or AIM-132 at wing tip, would that affect its drag significantly ?

No, but moreso than on the F-15C and the top end thrust margin is so small for the C model and B model that it may impact top speed. Also, while I suspect that the -9X pylon has that weird double cant for VLO reasons, I have no proof.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jan 2017, 03:15
by sprstdlyscottsmn
Okay, I finally finished my new (version 4 I think) Intecept Mission for the F-15C. Hopefully now that all the tools I needed to get all these data points have been made the next planes will go faster.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jan 2017, 06:44
by garrya
sprstdlyscottsmn wrote:Okay, I finally finished my new (version 4 I think) Intecept Mission for the F-15C. Hopefully now that all the tools I needed to get all these data points have been made the next planes will go faster.

Thank you Spurt
Excuse my ignorance but i don't quite understand this chart
Image

Would you mind elaborate? ( does the missiles hit or those Su-24simply running away ? )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jan 2017, 13:26
by sprstdlyscottsmn
Heh, you want to know the funny thing? That is the decluttered version of that chart. That chart is part of what I used to build the narrative and really doesn't make sense without it. I only included it as a visual reference to show how much can happen after a missile is launched. The narrative details that the Su-24s make it home.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jan 2017, 17:55
by garrya
sprstdlyscottsmn wrote:Heh, you want to know the funny thing? That is the decluttered version of that chart. That chart is part of what I used to build the narrative and really doesn't make sense without it. I only included it as a visual reference to show how much can happen after a missile is launched. The narrative details that the Su-24s make it home.

Fair enough.
btw , i found chart like this very useful to compare aircraft.Moreover, it also shows the dramatic impact of air density on aircraft performer
Image
When you finished ,would you mind making an overlap version similar to this :mrgreen:
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jan 2017, 18:46
by sprstdlyscottsmn
garrya wrote:btw , i found chart like this very useful to compare aircraft...
When you finished ,would you mind making an overlap version...

I realized that those charts would be more useful on seeing the reactions of my text-based, two data-point, turn tables. I will make an overlap chart in the end but it will not have that many aircraft to avoid clutter. Each Legacy plane, its replacement, and an Su-35S, all at 20k and with the total loadout (fuel and weapons) seen in either the Intercept mission or the Escort mission (I haven't decided yet).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 13:03
by spiteful
Have you considered using $ costs instead of points for scoring? Fuel, missiles and aircraft costs all added up should give a decent opportunity cost, as opposed to points which are somewhat arbitrary and haven't been calibrated.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 15:45
by sprstdlyscottsmn
spiteful wrote:Have you considered using $ costs instead of points for scoring? Fuel, missiles and aircraft costs all added up should give a decent opportunity cost, as opposed to points which are somewhat arbitrary and haven't been calibrated.

I have considered it, but time makes that a hard figure. What cost do I use? Acquisition cost at the time? Adjusted cost for inflation? An F-14D costed about $30 million in 1991 when production stopped, an current planned upgrades to F-15Cs cost nearly that much.

A new F-16C Block 50+ costs $30 million. A Strike Eagle costs north of $100 million. So you can lose a quarter of a squadron of F-16s and have the same penalty as losing a single Mudhen?

Fuel then costs ~$2,000/ton while an AIM-120D costs $1,000,000. Fire off eight to twelve of those and it costs almost as much as the bomber you are trying to shoot down, but shoot howdy you can burn fuel all day long and not impact your score.

People get so hung up on the "CPFH" which is often nothing more than fuel and scheduled maintenance that they forget that a single drop tank costs more than fuel for an entire mission, to say nothing of actual munitions. My scoring is more about physical logistics. At any given time there are a limited number of munitions and fuel on a post. If one fighter does the job using half the fuel and the other one does it using half the munitions then you are looking at a pretty even break for how long ops tempos can keep up before the next re-supply.

Also, I am trying to get the weighting right so that the minimum missiles required to bring down all targets balances out to 100points.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 18:01
by eloise
Spurt, what do you think about this:
Our take-off mass was 16.1t (10.8t basic and 5.3t fuel) carrying one supersonic fuel tank centreline.

Climbing to 15,000ft into the test area was flown at 350kt, full afterburner and 35° nose-up. In air-to-ground DFCS Stores Position 1 (ST1) at 350kt, mild buffet was encountered at +4.5g with 4t of fuel. In full dry power, a wind-up turn showed that the aircraft could maintain 350kt at +5.0g with just 10° of nose-down pitch.

https://www.flightglobal.com/news/artic ... le-334383/

Rafale is so much better than i imagined, sustain 5G in Military power at 15.000 feet, and the speed is only 350kt , That is with 1 supersonic fuel tank.
The value look a lot better than anything else

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 19:52
by steve2267
eloise wrote:Spurt, what do you think about this:
Our take-off mass was 16.1t (10.8t basic and 5.3t fuel) carrying one supersonic fuel tank centreline.

Climbing to 15,000ft into the test area was flown at 350kt, full afterburner and 35° nose-up. In air-to-ground DFCS Stores Position 1 (ST1) at 350kt, mild buffet was encountered at +4.5g with 4t of fuel. In full dry power, a wind-up turn showed that the aircraft could maintain 350kt at +5.0g with just 10° of nose-down pitch.

https://www.flightglobal.com/news/artic ... le-334383/

Rafale is so much better than i imagined, sustain 5G in Military power at 15.000 feet, and the speed is only 350kt , That is with 1 supersonic fuel tank.
The value look a lot better than anything else

Not to be too terribly rude, but perhaps you could take that inquiry over to the

F-35 Lightning II vs Dassault Rafale thread?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 21:35
by eloise
steve2267 wrote:Not to be too terribly rude, but perhaps you could take that inquiry over to the

F-35 Lightning II vs Dassault Rafale thread?

My bad, just wanna hear Spurt expert opinion, and i want to know how it fares with F-22, F-15 too

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 21:52
by sprstdlyscottsmn
eloise wrote:Spurt, what do you think about this:
Our take-off mass was 16.1t (10.8t basic and 5.3t fuel) carrying one supersonic fuel tank centreline.

Climbing to 15,000ft into the test area was flown at 350kt, full afterburner and 35° nose-up. In air-to-ground DFCS Stores Position 1 (ST1) at 350kt, mild buffet was encountered at +4.5g with 4t of fuel. In full dry power, a wind-up turn showed that the aircraft could maintain 350kt at +5.0g with just 10° of nose-down pitch.

https://www.flightglobal.com/news/artic ... le-334383/

Rafale is so much better than i imagined, sustain 5G in Military power at 15.000 feet, and the speed is only 350kt , That is with 1 supersonic fuel tank.
The value look a lot better than anything else

First, it is not sustained, it is nose down. I'm going to have to go with the speed value being given as indicated airspeed. At 15000ft 350kt indicated is roughly 431kt true (.69M), and 728ft/sec. A 10 deg nose down attitude means the plane had a steady Ps of -126ft/sec. Taking the listed weight, fuel weights, and some rough order of magnitude estimations I guess that the Rafale in question was a C model carrying six MICA missiles and a small centerline fuel tank.

A similarly configured F-16 weighs in at 14.5t at take off, with 4.2 t of fuel and 3.1 t remaining at maneuver (75% of takeoff fuel) and at the same speed and nose angle can maintain 3.2G. Of note is that the Rated Mil T/W ratios are .69 for the Rafale and .64 for the F-16.

So yeah, that is a great value it seems. So much so that I wonder what information is missing. It is heavier but it has a lot of wing but the viper has a lifting tail but the Viper has a bigger fuel tank for more drag but this but that. Not sure what to make of it in of itself. Possible? I guess. Plausible? Sure.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Jan 2017, 23:51
by vanshilar
I'm a little bit confused...what does the nose-down pitch thing mean?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 00:44
by basher54321
In the turn the nose is pitched down ten degrees so it is losing altitude and likely pulling more G than it would if it was in a level turn. (So not a sustained turn by definition which needs a constant altitude).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 02:25
by sprstdlyscottsmn
So scoring is going to have to be scrapped based on having missile reactions. The F-15 scored a whopping 9 points due to the sheer number of missiles fired on each side and the Kh-59s being the only kills. The F-22 pair would have a negative score as they fire three missiles each only to have all targets turn around and head for home after dodging max range shots from a plane they never saw (although I am dubious of the effectiveness of the RWR in a Su-24 after what happened with Turkey). That or I need to not do max range shots? But if not max range what criteria do I use in an intercept?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 02:53
by eloise
sprstdlyscottsmn wrote:First, it is not sustained, it is nose down.

How can the Rafale turn 5G with a nose down ? is it like negative G ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 03:59
by blindpilot
eloise wrote:
sprstdlyscottsmn wrote:First, it is not sustained, it is nose down.

How can the Rafale turn 5G with a nose down ? is it like negative G ?


It`s speaking of nose down relative to the horizon banking in a turn. Think of spiraling down in altitude.

Sustained turn rate is by definition holding altitude.

BP

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 14:26
by count_to_10
sprstdlyscottsmn wrote:So scoring is going to have to be scrapped based on having missile reactions. The F-15 scored a whopping 9 points due to the sheer number of missiles fired on each side and the Kh-59s being the only kills. The F-22 pair would have a negative score as they fire three missiles each only to have all targets turn around and head for home after dodging max range shots from a plane they never saw (although I am dubious of the effectiveness of the RWR in a Su-24 after what happened with Turkey). That or I need to not do max range shots? But if not max range what criteria do I use in an intercept?

To some extent, you need to go through an array of strategies for each. An F-22 should be able to get much closer than max range without being detected.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 16:11
by sprstdlyscottsmn
count_to_10 wrote:To some extent, you need to go through an array of strategies for each. An F-22 should be able to get much closer than max range without being detected.


So I just checked out what would happen if the F-22 pilot waited until he was 30nm closer than he was before, essentially looking at the "Shoot" cue for 60 seconds while he does it, and the end result is the same. The issue is that by the time the the radar goes active the AMRAAM is 42 degrees nose down at a bit over Mach 3 while aiming almost three miles in front of the tagret and seven miles in front of itself. The target pulling a 180 right after the RWR goes off means that aimpoint shifts 2 miles to the side in five seconds, causing the missile to lose an entire Mach of speed. Five more seconds and the aimpoint moves three miles further to the side and a mile further down range. All this last second adjusting has now cost the missile greatly. It is now only 34 degrees nose down and is having to pull up as the aimpoint moves further downrange but it only has a speed of 1.3M and dropping fast.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 16:33
by steve2267
sprstdlyscottsmn wrote:
count_to_10 wrote:To some extent, you need to go through an array of strategies for each. An F-22 should be able to get much closer than max range without being detected.


So I just checked out what would happen if the F-22 pilot waited until he was 30nm closer than he was before, essentially looking at the "Shoot" cue for 60 seconds while he does it, and the end result is the same. The issue is that by the time the the radar goes active the AMRAAM is 42 degrees nose down at a bit over Mach 3 while aiming almost three miles in front of the tagret and seven miles in front of itself. The target pulling a 180 right after the RWR goes off means that aimpoint shifts 2 miles to the side in five seconds, causing the missile to lose an entire Mach of speed. Five more seconds and the aimpoint moves three miles further to the side and a mile further down range. All this last second adjusting has now cost the missile greatly. It is now only 34 degrees nose down and is having to pull up as the aimpoint moves further downrange but it only has a speed of 1.3M and dropping fast.

Can you model a Meteor to see if it also suffers the same ill effects of the target performing an immediate 180° turn? Also, could you model a theoretical dual-pulse AIM-120E whereby it has a dual-pulse motor and the missile ignites the second pulse at the first sign of major target evasion?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 16:40
by botsing
steve2267 wrote:Can you model a Meteor to see if it also suffers the same ill effects of the target performing an immediate 180° turn? Also, could you model a theoretical dual-pulse AIM-120E whereby it has a dual-pulse motor and the missile ignites the second pulse at the first sign of major target evasion?

I second this request. It might give another clue as to why so much money is put into Meteor.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 17:15
by steve2267
As an aside, how difficult would it be to develop a LPI dar for an AIM-120? If the enema never hears the slammer go active...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 17:59
by wrightwing
sprstdlyscottsmn wrote:So scoring is going to have to be scrapped based on having missile reactions. The F-15 scored a whopping 9 points due to the sheer number of missiles fired on each side and the Kh-59s being the only kills. The F-22 pair would have a negative score as they fire three missiles each only to have all targets turn around and head for home after dodging max range shots from a plane they never saw (although I am dubious of the effectiveness of the RWR in a Su-24 after what happened with Turkey). That or I need to not do max range shots? But if not max range what criteria do I use in an intercept?

What were the assumptions used in the model, in terms of an enemy target being aware of an incoming AMRAAM?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 18:04
by sprstdlyscottsmn
That is why both the Russians and the French have IR NVR missiles. An LPI AMRAAM is only a factor of cost I'm sure.

I fully intend to model a Meteor but with my comparison being U.S. based I can't put it into the comparison. I will however be putting in the ability to target for SM-6 missiles for the Marines and Navy, as both LHAs and CVNs have DDGs in their battle groups. In this, the F-35B may out perform the F-35A.

I assume that once the slant range from the target to the missile is 12 NM the seeker goes active and within a second the targeted planes are beginning to evade.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jan 2017, 18:32
by wrightwing
sprstdlyscottsmn wrote:That is why both the Russians and the French have IR NVR missiles. An LPI AMRAAM is only a factor of cost I'm sure.

I fully intend to model a Meteor but with my comparison being U.S. based I can't put it into the comparison. I will however be putting in the ability to target for SM-6 missiles for the Marines and Navy, as both LHAs and CVNs have DDGs in their battle groups. In this, the F-35B may out perform the F-35A.

I assume that once the slant range from the target to the missile is 12 NM the seeker goes active and within a second the targeted planes are beginning to evade.

I've seen slightly different numbers (i.e. 12km to 15km), for when AMRAAM goes active. Of course there are also modes, where it never goes active. Using those numbers, how does that change the outcome, in the simulation?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 00:03
by popcorn
What if the AMRAAM is triggered to go active via data link when it;s much closer , say at 5kM or even closer?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 04:35
by sprstdlyscottsmn
So I checked a 12 km trigger and the turn still evades, a 5 km trigger and the turn still evades. I'm wondering if once the trigger goes active it needs to aim at the target itself instead of the aimpoint. My Google-Fu also failed me when looking for seeker range, can any one shoot me a link to a source?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 05:05
by count_to_10
sprstdlyscottsmn wrote:
count_to_10 wrote:To some extent, you need to go through an array of strategies for each. An F-22 should be able to get much closer than max range without being detected.


So I just checked out what would happen if the F-22 pilot waited until he was 30nm closer than he was before, essentially looking at the "Shoot" cue for 60 seconds while he does it, and the end result is the same. The issue is that by the time the the radar goes active the AMRAAM is 42 degrees nose down at a bit over Mach 3 while aiming almost three miles in front of the tagret and seven miles in front of itself. The target pulling a 180 right after the RWR goes off means that aimpoint shifts 2 miles to the side in five seconds, causing the missile to lose an entire Mach of speed. Five more seconds and the aimpoint moves three miles further to the side and a mile further down range. All this last second adjusting has now cost the missile greatly. It is now only 34 degrees nose down and is having to pull up as the aimpoint moves further downrange but it only has a speed of 1.3M and dropping fast.

Wouldn't that mean that the AMRAAAM is useless in BVR for any aircraft? That doesn't seem right.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 06:10
by sprstdlyscottsmn
I agree, I'm looking into my terminal homing logic to see if I can make it make more sense. By the current logic a hard turn instantly defeats any missile shot.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 07:20
by garrya
sprstdlyscottsmn wrote:My Google-Fu also failed me when looking for seeker range, can any one shoot me a link to a source?

I cant find any source regarding AIM-120 seeker range, but there are some info regarding R-77 seeker range, they should be quite similar i would say
Image

sprstdlyscottsmn wrote:I fully intend to model a Meteor but with my comparison being U.S. based I can't put it into the comparison

I dont think people would mind if you have Meteor in the comparison, I would be ver interested in the No escape zone of F-35 equipped with Meteor vs F-22 equipped with AIM-120D, or F-22 with future T-3 (which i guess have similar performer as Meteor )
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 Jan 2017, 08:13
by garrya
sprstdlyscottsmn wrote:I agree, I'm looking into my terminal homing logic to see if I can make it make more sense. By the current logic a hard turn instantly defeats any missile shot.

This may help a little bit?
Image
Apart from improving detection, the Japanese aim to guide the missile on a shorter, and thus faster, trajectory.

The first air-to-air and surface-to-air missiles, in the 1940s and 1950s, simply pointed at their targets. Because the targets moved, the missiles followed a curved path. With the introduction of proportional navigation, later weapons headed toward where targets maintaining course and velocity would be, although changes in target direction and speed would still force the missile to change course, wasting energy, losing range and extending engagement time.

TRDI’s diagrams show that its system goes a step further by predicting where a turning target will be. Ideally, the missile should adjust for changes in target velocity too, but TRDI does not mention such a feature.

With a target directly ahead of the firing aircraft and both flying at 12,000 meters (40,000 ft.) altitude, application of target-motion prediction reduces the flight time of the missile to intercept by 12%, to 13.2 sec. from 15.0 sec., TRDI says.

Missile-seeker and guidance technology is closely guarded. Other countries may be working on the same idea or even have it in service. But it is at least new to Japan. In 2013 European missile-maker MBDA was working on a system intended to increase the effectiveness of air-to-air missiles by predicting the target’s maneuvers. Details are scanty, but the algorithms were supposed to make the missile more effective and give the pilot a better idea of the likelihood of a kill and suitable timing for disengagement.

It is not clear what role the firing aircraft or ground-launch apparatus plays in TRDI’s new guidance system.

The planned weapons intended to benefit from Japan’s work are the NSAM, a medium-long-range surface-to-air missile, and the NAAM, the successor to the current Mitsubishi Electric AAM-4 medium-range air-to-air missile. The latest version of the latter, the AAM-4B, has a seeker with an active, electronically scanning array (AESA). That technology alone improves performance against stealthy targets, because it can transmit greater radio power for a given antenna size. Moreover, Japan, like other countries, is working on radars using gallium-nitride transistors, which further increase transmission power.

For target-location prediction, an AESA radar, capable of instantaneous adjustment of beam and scanning field, would offer the advantage of agile switching to a newly estimated location. Conceivably, it might also instantaneously tighten or widen the scanning field according to the confidence of a location prediction.

TRDI intends that the NSAM surface-to-air firing apparatus will draw information not only from radars specifically assigned to it, as would be the case in an older system, but also from a single integrated air picture built up by many radars on a network. In diagrams explaining the concept, TRDI shows a traditional system with two radars that fail to see the target, while on an integrated network, the target is detected and tracked, thanks to the availability of different types of radars looking from different directions. Some are remote from the launcher.

Sensor data would be compressed before being sent on to the network, TRDI says.

Apart from the plan to incorporate target movement prediction, no information about NAAM appears to have been made available.

http://www.w54.biz/showthread.php?1157- ... #post55744

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Jan 2017, 00:19
by sprstdlyscottsmn
So I tried a variety of activation ranges and tracking methods. Nothing dramatically improved the odds of that first shot. Then I remembered my scenario description.

"It will be assumed that radar missiles fired against the Su-24s and Su-35S will be fired two per target to account for maneuvers and countermeasures..."

So I looked at what would happen if a second shot happened 5 seconds later my dropping the launch range but having the evasive maneuver begin five seconds sooner. End result? Second missile hits, at least in the scenario I looked at. I will now need to go back to the Eagle and look at his missile shots to see if this impacts anything and then re-do the Raptor as well.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Jan 2017, 00:39
by count_to_10
sprstdlyscottsmn wrote:So I tried a variety of activation ranges and tracking methods. Nothing dramatically improved the odds of that first shot. Then I remembered my scenario description.

"It will be assumed that radar missiles fired against the Su-24s and Su-35S will be fired two per target to account for maneuvers and countermeasures..."

So I looked at what would happen if a second shot happened 5 seconds later my dropping the launch range but having the evasive maneuver begin five seconds sooner. End result? Second missile hits, at least in the scenario I looked at. I will now need to go back to the Eagle and look at his missile shots to see if this impacts anything and then re-do the Raptor as well.

That sounds a bit like bracketing the target. If you analysis is here is qualitatively accurate, I would almost have to assume (if I were the enemy) that AMRAAMs come with (at least) two firing options: one that assumes the target keeps going as it was, and one that assumes that the target turns around and runs away.
On that thought, have you worked if a missile that assumed that the target would turn around and run would be able to hit if the target kept flying forward?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Jan 2017, 09:34
by eloise
sprstdlyscottsmn wrote:So I tried a variety of activation ranges and tracking methods. Nothing dramatically improved the odds of that first shot. Then I remembered my scenario description.

"It will be assumed that radar missiles fired against the Su-24s and Su-35S will be fired two per target to account for maneuvers and countermeasures..."

So I looked at what would happen if a second shot happened 5 seconds later my dropping the launch range but having the evasive maneuver begin five seconds sooner. End result? Second missile hits, at least in the scenario I looked at. I will now need to go back to the Eagle and look at his missile shots to see if this impacts anything and then re-do the Raptor as well.

So in theory they are more likely to hit if there is no course prediction ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Jan 2017, 15:06
by hornetfinn
sprstdlyscottsmn wrote:So I just checked out what would happen if the F-22 pilot waited until he was 30nm closer than he was before, essentially looking at the "Shoot" cue for 60 seconds while he does it, and the end result is the same. The issue is that by the time the the radar goes active the AMRAAM is 42 degrees nose down at a bit over Mach 3 while aiming almost three miles in front of the tagret and seven miles in front of itself. The target pulling a 180 right after the RWR goes off means that aimpoint shifts 2 miles to the side in five seconds, causing the missile to lose an entire Mach of speed. Five more seconds and the aimpoint moves three miles further to the side and a mile further down range. All this last second adjusting has now cost the missile greatly. It is now only 34 degrees nose down and is having to pull up as the aimpoint moves further downrange but it only has a speed of 1.3M and dropping fast.


I think that AMRAAM goes for some aimpoint only during the inertial navigation part of the flight. When the missile goes active, it searches for the target and then locks on to it (single-target-track). This means the AMRAAM gets almost instant updates about the target flight path or speed changes and can react almost instantly. Then the targeting follows some variation of proportional navigation logic (usually). This means the missile is guided by the angular measurements where the target is going and not by aimpoint. Basically when the target maneuvers and its direction changes rapidly, the missile changes direction proportional to the how quickly the target changes direction. Not sure how this affects your calculations.

About missile guidance:
http://www.google.com/patents/US6064332 (Interesting patent and dates coincide well with AMRAAM development)
http://techdigest.jhuapl.edu/TD/td2901/ ... ciples.pdf

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 30 Jan 2017, 16:41
by sprstdlyscottsmn
I use the term aimpoint for lack of any other term. My intention is that the missile was always aiming at some point in front of the target, never at the target.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 14:41
by hornetfinn
Ok, that should roughly approximate the proportional navigation logic in this case.

I'm not sure if I got this correctly. I got that Su-24 are flying at low altitude at Mach 1.08 and are reacting instantly when the AMRAAM goes active? Then they do 180 degree reversal within 10 seconds. That doesn't sound possible for combat loaded Su-24 or even for the Su-35s. Am I getting the missile avoidance maneuver wrong? Do the target aircraft retain speed during the turns.

I'm also not sure if I understand the AMRAAM trajectory correctly. Is the missile going directly towards the aimpoint before going active? How much higher the missile is compared to say Su-24 before it goes active? Does your missile simulator take into account the higher potential energy (from higher altitude) of the missile while it maneuvers to catch the target?

I wonder if this simulation study would be helpful for your missile simulation:
http://www.dtic.mil/dtic/tr/fulltext/u2/a243123.pdf

I do think that AMRAAM (or any missile) hit probability will lower significantly if the target gets accurate warning early and can maneuver freely to avoid it. I think this is why firing two or more missiles simultaneusly (not necessarily by the same aircraft) is good tactic against some targets. I think that it's likely that AMRAAM seeker goes active depending on situation and if it receives target updates it will go active at shorter range than maximum. Any RWR system needs time to detect and identify the threat radar. Pilot definitely need time to analyze the situation before taking evasive actions. I bet it likely takes at least couple of seconds before any pilot can make that decision and act to it. So if AMRAAM goes active say 5 km away from the target, there might well be insufficient time for the pilot to do much to it. If it goes active 15 km away, there might well be enough time for the pilot to counter it provided that the RWR system very quickly detects it and gives pilot accurate warning. I also think that AMRAAM has pretty good LPI/LPD capabilities which makes it more difficult for the RWR system to do that giving the missile valuable time to get closer before target knows it's under attack.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 15:47
by sprstdlyscottsmn
hornetfinn wrote:I'm not sure if I got this correctly. I got that Su-24 are flying at low altitude at Mach 1.08 and are reacting instantly when the AMRAAM goes active? Then they do 180 degree reversal within 10 seconds. That doesn't sound possible for combat loaded Su-24 or even for the Su-35s. Am I getting the missile avoidance maneuver wrong? Do the target aircraft retain speed during the turns.


The Su-24 is listed as a 6+G aircraft. I am assuming that it it limited to 5G due to the cruise missiles. The thrust required to get to 1.08M at low level means that a 5G turn becomes sustainable at Mach 0.92. The high dynamic pressure means a low Cl is required and thus induced drag is not that great. It is bleeding speed from 1.08 to 0.92. And I am assuming a 1 second reaction time from <M> showing up on the RWR to the pilot banking and yanking to "get out of Dodge".

hornetfinn wrote:I'm also not sure if I understand the AMRAAM trajectory correctly. Is the missile going directly towards the aimpoint before going active? How much higher the missile is compared to say Su-24 before it goes active? Does your missile simulator take into account the higher potential energy (from higher altitude) of the missile while it maneuvers to catch the target?


At the point of a 12km activation (I was using 12nm before) the missile is now 52 degrees nose down passing 30,000ft at 2.49M. Gravity is producing 150lb of "thrust" but the missile is experiencing 950lb of drag. As the missile enters denser air it slows down more which changes the time to intercept which makes it maneuver to reach the new point of aim which adds drag. Vicious cycle. In short, yes potential energy is being converted to kinetic energy but it is ultimately being lost to drag.

hornetfinn wrote:
I wonder if this simulation study would be helpful for your missile simulation:
http://www.dtic.mil/dtic/tr/fulltext/u2/a243123.pdf


Wow, just looking at the table of contents I can see this will be good. I'll read through this before I go any further and see where I can use it to improve my missile simulator.

hornetfinn wrote:
I do think that AMRAAM (or any missile) hit probability will lower significantly if the target gets accurate warning early and can maneuver freely to avoid it. I think this is why firing two or more missiles simultaneusly (not necessarily by the same aircraft) is good tactic against some targets. I think that it's likely that AMRAAM seeker goes active depending on situation and if it receives target updates it will go active at shorter range than maximum. Any RWR system needs time to detect and identify the threat radar. Pilot definitely need time to analyze the situation before taking evasive actions. I bet it likely takes at least couple of seconds before any pilot can make that decision and act to it. So if AMRAAM goes active say 5 km away from the target, there might well be insufficient time for the pilot to do much to it. If it goes active 15 km away, there might well be enough time for the pilot to counter it provided that the RWR system very quickly detects it and gives pilot accurate warning. I also think that AMRAAM has pretty good LPI/LPD capabilities which makes it more difficult for the RWR system to do that giving the missile valuable time to get closer before target knows it's under attack.


Unfortunately variable activation time is pretty speculative. There are so many questions where the answer is classified. Does Home On Jam work against a DRFM jammer? The Khibiny was designed to defeat AMRAAM but the D was designed with improved ECCM, so which is going to defeat which? If a Khibiny can defeat a D, how many can it defeat at once? Can datalinked target coordinates in the terminal phase counter a Gate Pull Off jam? Can HOJ counter a Gate Pull Off jam? Absolutely no one who has the answers will say anything, and nor should they.

So I am going on the following assumptions:
Activations will be 12km for all terminal active phase missiles.
TEWS cannot defeat R-77-1. (Barracuda can, EPAAWS would if I were doing a 2020 Eagle instead of a 2016 Eagle)
Khibiny can only jam one AIM-120D effectively.
Once terminal, a missile no longer listens to the datalink.
HOJ does not work against DRFM.

Is any of that correct? I have no idea (except that Barracuda can defeat the seeker of an R-77-1, pretty sure it can). I am not an expert in RF, ECM, ECCM. I just need an approximation to show how different aircraft function. It would be an absolute fallacy to have an F-35 in my comparison and ignore the next level ECM and ECCM it has, otherwise I would be treating it just like a 4th gen. I realize that by using the same mission profiles I, in a way, am still using 4th gen measuring sticks but I am trying to show relative merit of each measure.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 17:27
by garrya
sprstdlyscottsmn wrote:Unfortunately variable activation time is pretty speculative. There are so many questions where the answer is classified. Does Home On Jam work against a DRFM jammer? The Khibiny was designed to defeat AMRAAM but the D was designed with improved ECCM, so which is going to defeat which? If a Khibiny can defeat a D, how many can it defeat at once? Can datalinked target coordinates in the terminal phase counter a Gate Pull Off jam? Can HOJ counter a Gate Pull Off jam? Absolutely no one who has the answers will say anything, and nor should they.

So I am going on the following assumptions:
Activations will be 12km for all terminal active phase missiles.
TEWS cannot defeat R-77-1. (Barracuda can, EPAAWS would if I were doing a 2020 Eagle instead of a 2016 Eagle)
Khibiny can only jam one AIM-120D effectively.
Once terminal, a missile no longer listens to the datalink.
HOJ does not work against DRFM.

Is any of that correct? I have no idea (except that Barracuda can defeat the seeker of an R-77-1, pretty sure it can). I am not an expert in RF, ECM, ECCM. I just need an approximation to show how different aircraft function. It would be an absolute fallacy to have an F-35 in my comparison and ignore the next level ECM and ECCM it has, otherwise I would be treating it just like a 4th gen. I realize that by using the same mission profiles I, in a way, am still using 4th gen measuring sticks but I am trying to show relative merit of each measure.

Iam not saying that i have the answer for everything but i think my summary of ECM could help some what?
https://basicsaboutaerodynamicsandavion ... asure-ecm/

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 17:50
by SpudmanWP
Once terminal, a missile no longer listens to the datalink.


That does not happen. Actually, the D added a two way datalink so that it can communicate with a friendly right up to the moment of impact and give it's own BDA. The D also added a GPS enhancement to the mix so that it can constantly receive the coordinates of it's target and use it as a "checksum" of what it's seeker is telling it. Using the GPS enhancement, it should be able to get close enough to "burn through" most jamming.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 18:03
by sprstdlyscottsmn
SpudmanWP wrote:
Once terminal, a missile no longer listens to the datalink.


That does not happen. Actually, the D added a two way datalink so that it can communicate with a friendly right up to the moment of impact and give it's own BDA. The D also added a GPS enhancement to the mix so that it can constantly receive the coordinates of it's target and use it as a "checksum" of what it's seeker is telling it. Using the GPS enhancement, it should be able to get close enough to "burn through" most jamming.

Hmm, I suppose that makes sense for a mechanism of the improved ECCM. Thanks.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 31 Jan 2017, 18:17
by sprstdlyscottsmn
garrya wrote:Iam not saying that i have the answer for everything but i think my summary of ECM could help some what?
https://basicsaboutaerodynamicsandavion ... asure-ecm/

This is great too! I can definitely use this to improve my understanding and thus my assumptions. Thank you!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 01:00
by count_to_10
eloise wrote:So in theory they are more likely to hit if there is no course prediction ?

I've been thinking about this a bit. At any point in it's trajectory, there should be a volume of space that the missile can maneuver to, and that should be approximately calculable. Were I programing the missile logic, and knowing that aircraft can turn and loose speed rapidly but can't really increase their speed much in 15 seconds, I would have the missile keep the "target maintains course and speed" predicted intercept point just inside boundary of the hittable volume, with the rest of the volume directed toward the "target turns around" possible intercept points.

Another thing to note is that these missiles fly at around 1 km/s. So, if you get a warning at 15 km, you probably have just enough time to recognize the danger, pull your 180, and then get another km or two before intercept (assuming that the missile doesn't suddenly slow down). At 10 km, I doubt you will even finish the U-turn. At 5 km, do you have enough time to deploy any kind of countermeasures?

If you can get a missile withing 1 or 2 km of the target before it trips a warning, I can't see any downside to turning on active homing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 10:22
by nathan77
I recall reading an in-depth article on the evolution of BVR missiles and hit-probability, originally linked from Quora. But I haven't been keeping a close eye on this thread, so I might be posting on something irrelevant to the discussion.

From what I recall, modern AMRAAMs in a BVR engagement once launched immediately rapidly gain altitude using their fast burn engine (so they can use altitude to maximize range). Once at peak altitude, it sets a predicted course, which is corrected regularly, and switches to a longer-lasting slow-burn engine, trading altitude for distance to keep air-speed high. When in terminal phase the missile will flatten out to slow down, and decrease the speed differential between it and the target. In previous iterations of missiles, despite the missile being able to pull up to 40G's, a well time evasive maneuver from the target could cause the missile to overshoot. I can't remember what the speed differential is anymore, but essentially even the most maneuverable aircraft are highly unlikely to evade a modern AMRAAM. This is one of the reasons why trying to build ever increasingly agile planes is a dead-end - planes (while piloted by man) will never have the maneuverability to escape a missile with enough energy left in its terminal phase.

Unfortunately though, I can't find the article - so I can't back-up what I've just written. :bang:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 10:26
by spazsinbad
Interesting. The RAAF have long claimed that aircraft cannot evade modern BVR missiles - there are several instances of these claims on this forum. Do I need to find these claims?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 12:58
by hornetfinn
sprstdlyscottsmn wrote:
hornetfinn wrote:I'm also not sure if I understand the AMRAAM trajectory correctly. Is the missile going directly towards the aimpoint before going active? How much higher the missile is compared to say Su-24 before it goes active? Does your missile simulator take into account the higher potential energy (from higher altitude) of the missile while it maneuvers to catch the target?


At the point of a 12km activation (I was using 12nm before) the missile is now 52 degrees nose down passing 30,000ft at 2.49M. Gravity is producing 150lb of "thrust" but the missile is experiencing 950lb of drag. As the missile enters denser air it slows down more which changes the time to intercept which makes it maneuver to reach the new point of aim which adds drag. Vicious cycle. In short, yes potential energy is being converted to kinetic energy but it is ultimately being lost to drag.


I see you got the thing covered pretty thoroughly. :D

Wow, I never realized how much drag missile experiences during high speed flight. Maybe this is one area where your model is too pessimistic for the missile? What's the drag coefficient you are using for AMRAAM?

sprstdlyscottsmn wrote:
hornetfinn wrote:
I wonder if this simulation study would be helpful for your missile simulation:
http://www.dtic.mil/dtic/tr/fulltext/u2/a243123.pdf


Wow, just looking at the table of contents I can see this will be good. I'll read through this before I go any further and see where I can use it to improve my missile simulator.


You are welcome, I find your performance comparison absolutely fascinating. I found another one which is very close to what you are doing with more focus on the aerodynamics and kinematic performance of the missile than the previous one. Maybe it might also help find problem areas or confirm your model and assumptions:

http://www.dtic.mil/dtic/tr/fulltext/u2/a384590.pdf

Interesting is the claim that AMRAAM seeker is activated 5-7 seconds prior to impact on page 38. Also interesting is the missile acceleration and velocity profiles. Do they match your profiles or is there large difference between them.

sprstdlyscottsmn wrote:
hornetfinn wrote:
I do think that AMRAAM (or any missile) hit probability will lower significantly if the target gets accurate warning early and can maneuver freely to avoid it. I think this is why firing two or more missiles simultaneusly (not necessarily by the same aircraft) is good tactic against some targets. I think that it's likely that AMRAAM seeker goes active depending on situation and if it receives target updates it will go active at shorter range than maximum. Any RWR system needs time to detect and identify the threat radar. Pilot definitely need time to analyze the situation before taking evasive actions. I bet it likely takes at least couple of seconds before any pilot can make that decision and act to it. So if AMRAAM goes active say 5 km away from the target, there might well be insufficient time for the pilot to do much to it. If it goes active 15 km away, there might well be enough time for the pilot to counter it provided that the RWR system very quickly detects it and gives pilot accurate warning. I also think that AMRAAM has pretty good LPI/LPD capabilities which makes it more difficult for the RWR system to do that giving the missile valuable time to get closer before target knows it's under attack.


Unfortunately variable activation time is pretty speculative. There are so many questions where the answer is classified. Does Home On Jam work against a DRFM jammer? The Khibiny was designed to defeat AMRAAM but the D was designed with improved ECCM, so which is going to defeat which? If a Khibiny can defeat a D, how many can it defeat at once? Can datalinked target coordinates in the terminal phase counter a Gate Pull Off jam? Can HOJ counter a Gate Pull Off jam? Absolutely no one who has the answers will say anything, and nor should they.

So I am going on the following assumptions:
Activations will be 12km for all terminal active phase missiles.
TEWS cannot defeat R-77-1. (Barracuda can, EPAAWS would if I were doing a 2020 Eagle instead of a 2016 Eagle)
Khibiny can only jam one AIM-120D effectively.
Once terminal, a missile no longer listens to the datalink.
HOJ does not work against DRFM.

Is any of that correct? I have no idea (except that Barracuda can defeat the seeker of an R-77-1, pretty sure it can). I am not an expert in RF, ECM, ECCM. I just need an approximation to show how different aircraft function. It would be an absolute fallacy to have an F-35 in my comparison and ignore the next level ECM and ECCM it has, otherwise I would be treating it just like a 4th gen. I realize that by using the same mission profiles I, in a way, am still using 4th gen measuring sticks but I am trying to show relative merit of each measure.


I agree a lot of how the missile seeker and guidance works is speculative but I think we can find some answers without knowing the specifics.

1. I don't think HOJ will work on DRFM jamming. DRFM is a form of deception jamming which sends back the stored radar signals with or without chaning signal parameters. I doubt there is a reliable way to home on to such jamming as it's very difficult for missile to distinguish it as jamming as DRFM jammer sends back same or very similar signals as the radar itself uses using very similar power levels. Noise jammers generally overwhelm radars by brute force and is clearly seen as a very large increase in noise level from jammer direction. Another problem is that missile seeker has to stop transmitting if it wants to use HOJ and DRFM jammer would likely stop transmitting then. Acquiring the target again would be difficult for the missile seeker as range has now decreased.

2. Aircraft installed DRFM jammer might not be very effective against missile seeker as it goes active pretty close to target and there is very little time to counter it using stored radar signals and transmitting them back. I think system like BriteCloud or modern towed decoy is much better where the expendable decoy uses DRFM methods to lure missiles. DRFM jammer or any other deception jamming system is likely more effective in disrupting the operation of the fighter radar than missile radar.

3. I would bet that all ARH missiles with one-way datalinks stop listening to fighter radar once the missile goes active. Those with two-way datalinks (AIM-120D and Meteor) and accurate GPS/INS guidance might well use both missile seeker and fighter radar together to guide the missile to target. The missile and fighter radar might be able to "talk" to each other to counter ECM. No idea how this might affect the hit probability in real situation.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 15:01
by sprstdlyscottsmn
spazsinbad wrote:Interesting. The RAAF have long claimed that aircraft cannot evade modern BVR missiles - there are several instances of these claims on this forum. Do I need to find these claims?

That is exactly why I am re-looking over my guidance logic. So far the changes I have made are resulting in more hits.

nathan77 wrote:From what I recall, modern AMRAAMs in a BVR engagement once launched immediately rapidly gain altitude using their fast burn engine (so they can use altitude to maximize range). Once at peak altitude, it sets a predicted course, which is corrected regularly, and switches to a longer-lasting slow-burn engine, trading altitude for distance to keep air-speed high.

This is true, but it all happens faster than you are thinking. The high impulse motor lasts less than a second and the slower sustainment motor last another 16 or so seconds after that.

hornetfinn wrote:I agree a lot of how the missile seeker and guidance works is speculative but I think we can find some answers without knowing the specifics.

After looking through the link garraya sent it seems there is no jamming that can defeat the combination of LPI AESA radar using a 2-way datalink to guide a HOJ capable missile. The Deceptive jamming that works against HOJ is nullified by the frequency agile radar on the shooter still seeing the true target and communicating that through datalink, thus telling the missile it is being jammed, causing it to reset the terminal acquisition.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 15:18
by zero-one
sprstdlyscottsmn wrote:After looking through the link garraya sent it seems there is no jamming that can defeat the combination of LPI AESA radar using a 2-way datalink to guide a HOJ capable missile. The Deceptive jamming that works against HOJ is nullified by the frequency agile radar on the shooter still seeing the true target and communicating that through datalink, thus telling the missile it is being jammed, causing it to reset the terminal acquisition.


Question, if the missile entered an electronically contested area, would it still receive the datalink signals? I believe this is one of the requirements for the LRASM, it should be able to autonomously find its target even after being cut off from any sort of datalink, even in GPS contested areas.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 15:32
by sprstdlyscottsmn
zero-one wrote:
Question, if the missile entered an electronically contested area, would it still receive the datalink signals? I believe this is one of the requirements for the LRASM, it should be able to autonomously find its target even after being cut off from any sort of datalink, even in GPS contested areas.

That kind of question is beyond my scope, sorry.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Feb 2017, 15:46
by sprstdlyscottsmn
hornetfinn wrote:Interesting is the claim that AMRAAM seeker is activated 5-7 seconds prior to impact on page 38. Also interesting is the missile acceleration and velocity profiles. Do they match your profiles or is there large difference between them.

Changing the seeker activation from x dist to y time has been profound. Seeker goes active five seconds out, one second after that the targeted pilot begins a bank and yank, four seconds later it goes splat having only been able to make a 30 degree heading change and a 1200ft lateral movement.

Also, yes my acceleration and velocity profiles do approximate what was shown there with obvious differences for launch parameters.

Hmmm, this will change things for the F-15 avoiding the R-77-1s as well.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Feb 2017, 00:22
by popcorn
Is the assumption that the AMRAAM is a head-on shot? If the AMRAAM was engaging from a different aspect how would this impact the chances of success?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Feb 2017, 08:55
by hornetfinn
zero-one wrote:
sprstdlyscottsmn wrote:After looking through the link garraya sent it seems there is no jamming that can defeat the combination of LPI AESA radar using a 2-way datalink to guide a HOJ capable missile. The Deceptive jamming that works against HOJ is nullified by the frequency agile radar on the shooter still seeing the true target and communicating that through datalink, thus telling the missile it is being jammed, causing it to reset the terminal acquisition.


Question, if the missile entered an electronically contested area, would it still receive the datalink signals? I believe this is one of the requirements for the LRASM, it should be able to autonomously find its target even after being cut off from any sort of datalink, even in GPS contested areas.


Jamming a air-to-air missile datalink would be very difficult. They use very low power levels as they are basically one-way systems (from fighter to missile and possibly vice versa), they are frequency hopping and transmit sporadically. The missile is also closer to transmitter than the jammer would be in most cases. This means they are very difficult to detect and also very difficult (almost impossible) to deceive with deception jamming. Very high power noise jamming might work but that creates serious problem when missile has HOJ capability.

It's somewhat different with LRASM which might well fly long distances over enemy held waters or territory. Enemy might be able to put jammers between LRASM and other participants of the data link. Say ships, barges, aircraft or ground based systems that carry suitable jammers to jam the data link. Being physically in the data link LOS or close to it would make jamming much more effective. Such jammer would also be relatively safe and also expendable, so it could well use simple high power noise jamming to cut off the data link.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Feb 2017, 10:20
by hornetfinn
count_to_10 wrote:
eloise wrote:So in theory they are more likely to hit if there is no course prediction ?

I've been thinking about this a bit. At any point in it's trajectory, there should be a volume of space that the missile can maneuver to, and that should be approximately calculable. Were I programing the missile logic, and knowing that aircraft can turn and loose speed rapidly but can't really increase their speed much in 15 seconds, I would have the missile keep the "target maintains course and speed" predicted intercept point just inside boundary of the hittable volume, with the rest of the volume directed toward the "target turns around" possible intercept points.

Another thing to note is that these missiles fly at around 1 km/s. So, if you get a warning at 15 km, you probably have just enough time to recognize the danger, pull your 180, and then get another km or two before intercept (assuming that the missile doesn't suddenly slow down). At 10 km, I doubt you will even finish the U-turn. At 5 km, do you have enough time to deploy any kind of countermeasures?

If you can get a missile withing 1 or 2 km of the target before it trips a warning, I can't see any downside to turning on active homing.


That sounds like pretty smart method and probably close to the way missile mid-course guidance works. Since aircraft performance figures are well known, the guidance system most likely takes that into account. When missile goes active, it will usually follow some variation of proportional navigation (PN) logic which keeps the missile and target on collision course. This means the missile tries to keep the LOS rate between it and target zero. So it automatically takes into account target and missile speed changes as these will change the LOS rate from zero. As far as I can see, what you propose would mean that the maneuvering would be close to minimal, no matter what the target does to avoid the missile at any point of the engagement. Of course the target can still avoid the missile by running the missile out of energy or by overcoming the seeker capabilities with maneuvers and/or countermeasures.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Feb 2017, 10:48
by hornetfinn
sprstdlyscottsmn wrote:
hornetfinn wrote:Interesting is the claim that AMRAAM seeker is activated 5-7 seconds prior to impact on page 38. Also interesting is the missile acceleration and velocity profiles. Do they match your profiles or is there large difference between them.

Changing the seeker activation from x dist to y time has been profound. Seeker goes active five seconds out, one second after that the targeted pilot begins a bank and yank, four seconds later it goes splat having only been able to make a 30 degree heading change and a 1200ft lateral movement.

Also, yes my acceleration and velocity profiles do approximate what was shown there with obvious differences for launch parameters.

Hmmm, this will change things for the F-15 avoiding the R-77-1s as well.


I think the y time activation sounds good as the missile speed can vary a lot during engagements. A fixed distance could mean very different time to go for the missile and give target a very long warning time. A tail-chase scenario might well mean it would take 15 seconds to reach the target whereas in head-on scenario the missile would have only 6 seconds to go.

I would bet all credible air forces in the world have studied how quickly a human pilot can react to different situations and reaction time to missile warning is well known. This is probably affecting how long before impact missiles go active. Of course it varies between individuals and situation a lot, but there is probably some usual range where it falls. I think 1 second is extremely short time for intelligent reaction, but fighter pilots have some incredible qualities to become fighter pilots. Of course there are other unknowns like how quickly RWR can warn the pilot.

Yes, I think even F-15 (or any other fighter in the world) would be in bad spot if R-77-1 goes active. It probably uses pretty similar system to AMRAAM in guidance overall, although I'd bet AIM-120D is clearly better overall with GPS/INS and two-way data link.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Feb 2017, 15:36
by sprstdlyscottsmn
UGH! Nothing like going through the model for the Su-24 to discover that even in Mil climbs I was using AB TSFC. The TSFC for AB climbs was fine, just Mil that was messed up. I knew it didn't pass the "sniff test" that it was burning 1/3 of it's fuel load in climb. Sorry for the every present delays everyone. I am making the Red force less arbitrary in their attack profile and figuring out how aggressive they can be with flight planning and still have gas to get home. My previous M1.08 on the deck with two big missiles for 150nm in and then back out the same way? Yeah, not even close.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Mar 2017, 14:52
by sprstdlyscottsmn
Red Air flight profiles finished. I had to swap the Fencer for a Fullback and I changed the escort Flanker flight profile to provide better protection for the Fullbacks and as a result they have ~3,000lb of extra fuel to play around with for potential maneuvers. Now, back to the F-15.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Mar 2017, 18:33
by garrya
sprstdlyscottsmn wrote:Red Air flight profiles finished. I had to swap the Fencer for a Fullback and I changed the escort Flanker flight profile to provide better protection for the Fullbacks and as a result they have ~3,000lb of extra fuel to play around with for potential maneuvers. Now, back to the F-15.

Darn. You really put considerable effort in the analysis

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Mar 2017, 19:40
by sprstdlyscottsmn
garrya wrote:Darn. You really put considerable effort in the analysis

To me this is what makes the difference between trying to perform a comprehensive mission performance based analysis and a "comparing wing loading, T/W, and the range listed on Wikipedia" analysis.

This current iteration looks at missile performance, radar performance, ballpark RCS (i.e. the Eagle sits at 25m^2 while the Fullback/Flanker-E with "roughly an order of magnitude lower RCS than legacy" get a 3m^2), ECM (Khibiny on the Sukhoi jets is a DRFM setup), ECCM (LPI AESA radars don't care that Khibiny is DRFM), actual range between two opposing airbases, and supporting systems inherent to the target (when the target is a CVN or LHA, there are going to be DDGs nearby so F-35s can sling SM-6s).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Mar 2017, 07:39
by hornetfinn
Your analysis is always awesome and well worth waiting for. :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Mar 2017, 09:20
by garrya
sprstdlyscottsmn wrote:To me this is what makes the difference between trying to perform a comprehensive mission performance based analysis and a "comparing wing loading, T/W, and the range listed on Wikipedia" analysis.

Indeed, in my opinion the later one can hardly be called an analysis. It is more like : opinion based on questionable understanding

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 05:13
by sprstdlyscottsmn
Alright you remaining fans, here is the current format. Of particular note is the timeline based narrative for the mission and following it with performance charts from the models used. I'll wait a few days to gather format feedback before I do the rest of the interceptors. It takes about 100 hours to make a base model, 5-10 hours to make a specific aircraft model, and 3-5 hours to run numbers I need for the mission. As such I will not be changing much as far as how the mission pans out, but if there is data you generally want to see and I have it available I will throw it in.

Yet another format.pdf
(887.75 KiB) Downloaded 667 times

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 08:36
by eloise
sprstdlyscottsmn wrote:Alright you remaining fans, here is the current format. Of particular note is the timeline based narrative for the mission and following it with performance charts from the models used. I'll wait a few days to gather format feedback before I do the rest of the interceptors. It takes about 100 hours to make a base model, 5-10 hours to make a specific aircraft model, and 3-5 hours to run numbers I need for the mission. As such I will not be changing much as far as how the mission pans out, but if there is data you generally want to see and I have it available I will throw it in.

Yet another format.pdf

Why dont you let Su-35 carry 4 R-77 instead of R-27?
is the new analysis include Meteor for F-35 ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 08:43
by garrya
sprstdlyscottsmn wrote:Alright you remaining fans, here is the current format. Of particular note is the timeline based narrative for the mission and following it with performance charts from the models used. I'll wait a few days to gather format feedback before I do the rest of the interceptors. It takes about 100 hours to make a base model, 5-10 hours to make a specific aircraft model, and 3-5 hours to run numbers I need for the mission. As such I will not be changing much as far as how the mission pans out, but if there is data you generally want to see and I have it available I will throw it in.

Yet another format.pdf

I know you have spend a significant amount of time doing the analysis and typing it down.I really appreciate that. But i think the narrative could be easier to imagine if you use picture
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 14:08
by sprstdlyscottsmn
eloise wrote:Why dont you let Su-35 carry 4 R-77 instead of R-27?
is the new analysis include Meteor for F-35 ?

For the sole reason that when they actually deployed to Syria this was the loading they used.

I have not done the F-35 analysis as of yet. Use of the Meteor would be limited to Brit Bees wouldn't it? I wish the US was getting them sometimes but even as is the -120D has great range. I do want to put in the Meteor but I'm not sure how just yet as I'm comparing the Bee to the AV-8B+ which was USMC only.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 14:11
by sprstdlyscottsmn
garrya wrote:I know you have spend a significant amount of time doing the analysis and typing it down.I really appreciate that. But i think the narrative could be easier to imagine if you use picture
Image

I'll need to get scaled side views (I'll want to represent altitude if I do that) for everything but that should be doable. Thanks for the input.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 14:16
by shania
sprstdlyscottsmn wrote:but if there is data you generally want to see and I have it available I will throw it in.


Nice! Thank you, I cant wait for rest. If you can include time/distance graph like last time, it wold be perfect (and i would like to have info about current speed and alt too)

https://s28.postimg.org/gcvwye8zx/wut.png



Q1: F-15 cant accomplish this mission with only 4 AIM-120, so It would be better to wait a little or fire 1 missile at Rmax to force target to defensive and then fire 2 closer to target.

Q2: Last time your missile simulator dont have much luck in killing targets, what changed?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 14:25
by shania
Q3: since you have models for Su-34, Su-35, coul you please provide more data about them?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Mar 2017, 16:07
by eloise
sprstdlyscottsmn wrote:I have not done the F-35 analysis as of yet. Use of the Meteor would be limited to Brit Bees wouldn't it? I wish the US was getting them sometimes but even as is the -120D has great range. I do want to put in the Meteor but I'm not sure how just yet as I'm comparing the Bee to the AV-8B+ which was USMC only.

From i gathered, Japan also cooparate with MBDA to make an AESA version of Meteor, undoubtedly to equip their F-35A. Others EU nations will likely purchase Meteor for their F-35 fleet too.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Mar 2017, 00:52
by sprstdlyscottsmn
And I just realized I forgot to include an important ability of the Su-35S, combine mechanical and electronic beam steering. Ugh, back to running the first mission again. Sorry everyone. I should have this re-done in a day or two, then I will add diagrams better illustrating range, altitude, and position for key time points.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Apr 2017, 09:41
by spiteful
I noticed that you decelerate your aircraft during the intercept- wouldn't maintaining energy be better?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Apr 2017, 15:46
by sprstdlyscottsmn
spiteful wrote:I noticed that you decelerate your aircraft during the intercept- wouldn't maintaining energy be better?

It's a two part advantage. You slung your long range missile at the target. You don't want to get closer to his missiles if you can avoid it. It also saves a ton of fuel.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Apr 2017, 18:31
by spiteful
If it's about relative speed (closing speed) as opposed to kinetic energy couldn't you turn?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 23 Apr 2017, 23:28
by sprstdlyscottsmn
That takes care of closure, sure, but not the fuel burn.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 01:04
by luke_sandoz
To say nothing of exposing the big,hot aft end to the enemy sensors & missiles

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 02:13
by f-16adf
Spurts, what a superb examination!

I thoroughly enjoyed reading this. I understand that this involves considerable time involvement on your part; very much appreciated.


For the F-22, the lift area is derived from the canted vertical tails, unstable horizontal tail, tail booms, nose chines, and intake chines? So it nearly doubles the reference area? Hence, all added together = 1680.


CFT= Captive Flight Test?



Thanks again-



If my estimation is wrong, ahh..., university was 20 years ago for me. So I'm getting kinda old. LOL

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 12:51
by sprstdlyscottsmn
CFT = conformal fuel tank. Thanks for the kind words, it helps to get me through the tough ones. I have had less than an hour a week lately to work on this and the F-16 is taking a long time. So much 'move counter-move'.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 15:40
by sferrin
sprstdlyscottsmn wrote:CFT = conformal fuel tank. Thanks for the kind words, it helps to get me through the tough ones. I have had less than an hour a week lately to work on this and the F-16 is taking a long time. So much 'move counter-move'.


In your doc you show the F-22 capable of carrying 4 external tanks. It's only ever flown with two. They originally wanted to carry four, a test rig was built to test the fuel system and such, but the plane has never been flown with four even in flight testing.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 15:48
by f-16adf
In the Lift Area section, CFT appears 3 lines down: "...and otherwise are found using either a CFT analysis, ..."

I thought it meant captive flight test in this prose.





A few questions about different designed air-frames:

1. So generally if you compare the Su-27/35, F-15C, F-14D (all clean) They all have boxy draggy VG intakes, yet shouldn't a clean Flanker technically have a higher CL and lower CD since the tail is not adding a weight component against total lift (less trim drag while subsonic/smaller amounts supersonic)? And the Flanker has a smoothly blended top fuselage (wing-body/LERX similar to F-16)? While the F-14 and F-15 do not exhibit such fine wing/fuselage amalgamation.

2. What is really hurting the Flanker is its higher DI AAMs R-27, R-73, R-77? I do not have their respective DI numbers; but I know that the Aim-7 on the Eagle is only 1.8, and on the F-14 it's 2 if loaded under the fuselage and 6 on the stub wing pylon. Aim-9 on the Tomcat's stub wing pylon is an 8, while on the Eagle it's only 2.1?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 16:43
by sprstdlyscottsmn
sferrin wrote:
sprstdlyscottsmn wrote:CFT = conformal fuel tank. Thanks for the kind words, it helps to get me through the tough ones. I have had less than an hour a week lately to work on this and the F-16 is taking a long time. So much 'move counter-move'.


In your doc you show the F-22 capable of carrying 4 external tanks. It's only ever flown with two. They originally wanted to carry four, a test rig was built to test the fuel system and such, but the plane has never been flown with four even in flight testing.

Oh yes, I looked into the EFT number only to find that 2 is all that have ever been used. I just haven't re-edited the beginning of the document. Thanks for bringing that to my attention.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 17:13
by sprstdlyscottsmn
f-16adf wrote:In the Lift Area section, CFT appears 3 lines down: "...and otherwise are found using either a CFT analysis, ..."

I thought it meant captive flight test in this prose.





A few questions about different designed air-frames:

1. So generally if you compare the Su-27/35, F-15C, F-14D (all clean) They all have boxy draggy VG intakes, yet shouldn't a clean Flanker technically have a higher CL and lower CD since the tail is not adding a weight component against total lift (less trim drag while subsonic/smaller amounts supersonic)? And the Flanker has a smoothly blended top fuselage (wing-body/LERX similar to F-16)? While the F-14 and F-15 do not exhibit such fine wing/fuselage amalgamation.

2. What is really hurting the Flanker is its higher DI AAMs R-27, R-73, R-77? I do not have their respective DI numbers; but I know that the Aim-7 on the Eagle is only 1.8, and on the F-14 it's 2 if loaded under the fuselage and 6 on the stub wing pylon. Aim-9 on the Tomcat's stub wing pylon is an 8, while on the Eagle it's only 2.1?


Oh, there CFT was Computational Fluid Dynamics. That would be other studies done (F-16 HFFM in particular) where a full 3-D computer model was tested digitally to get lift and drag data.

On to your questions.

1. The Flanker has a better ClMax than the Eagle, and it happens at a lower angle of attack. The Tomcat with wings unswept has the best ClMax due to having full span trailing edge slotted flaps and leading edge slats as opposed to leading edge flaps. This gives the wing great airflow management and a better lift curve slope. Things that improve lift curve slope are high aspect ratio, low sweep, and high lift devices. On the Cd front, we see drag areas of 11.55 for the Eagle, 13.73 for the Tomcat, and I found 14.14 works on the Flanker. This drag for the Flanker is what gives me the proper speed, acceleration, climb, and range performance for the thrust, weight, and TSFC that I have to work with. The Flanker may have an elegant upper surface but the lower surface is a mess. The ventrals to not attach to the nacelles so there is a lot of interference drag there. Also, the two verticals are enormous. The whole plane is enormous. There is a lot of raw surface area to produce friction drag. I can't arbitrarily lower the Cd I use because the Flanker "looks slick". I started with a lower value and found the actual performance did not line up with any reference so I had to tweak things until the performance matched.

2. Remember than DI needs to be used in conjunction with reference wing area to get drag area. The DI of 1.8 on the F-15s AIM-7 corresponds to a Drag Area of 0.109 ft^2, while the Tomcat's 2 corresponds to 0.113 ft^2. The DI of an R27 on a MiG-29 is 17. That corresponds to 0.695 ft^2. A loaded Flanker has a LOT of drag. This can even be seen my the actual combat ops of the Su-35 in Syria where they have two R77, two R27ET, and two R73. This is a less impressive load that found on F-16s doing air combat ops (two AIM-9 and four AIM-120).

When I am done with the exhausting Intercept study I will be revamping the beginning of the document and going into more detail about the plane systems and the models I use (and what they are referencing).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 18:12
by f-16adf
Yes, I remember that for improving lift (curve) slope: High aspect ratio (generally low wing sweep angle), and leading edge slats as opposed to leading edge flaps. The slats allow the air to speed up (between the wing and the slat) consequently lowing pressure above the wing. Where as on a low aspect ratio (say a 60 degree delta, Mirage III) the lift slope is smaller, which means a higher AOA is needed for a given lift. And on modern deltas (with FBW) such as the Eurofighter and Rafale; they employ LE slats, I guess trying to maximize CL as much as possible. Don't know why Saab chose LE flaps for the Gripen; but that wing is only at 45 degrees.


The Flanker is so big, I guess you could call it Rodan's bigger brother.


One thing, why does the maneuverability of the F-14 seem to fall apart once generally above about 350knots (maybe wing drag build up while at 22 degrees)? I mean, that wing is very, very good from about 325 and under. But once you put some knots on it, it seems to fall off as quickly as it rose? And as the wings start to go back in the low 400's it gets even worse...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 19:28
by sprstdlyscottsmn
f-16adf wrote:One thing, why does the maneuverability of the F-14 seem to fall apart once generally above about 350knots (maybe wing drag build up while at 22 degrees)? I mean, that wing is very, very good from about 325 and under. But once you put some knots on it, it seems to fall off as quickly as it rose? And as the wings start to go back in the low 400's it gets even worse...


I assume you mean the sustained performance? The wing start to sweep backwards around 0.7M. As that happens you start to lose everything that made the wing great (aspect ratio, sweep, full span trailing edge). The instant performance is due to the G-limits imposed by the NATOPS.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 24 Apr 2017, 22:32
by f-16adf
Yes, I meant sustained. I figured losing full span trailing edge was part of it (kind of similar to a F-100 or a Su-7).


Thanks again-

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Apr 2017, 03:44
by sprstdlyscottsmn
Thanks for the posts f-16adf, it pushed me to finish the F-16 intercept analysis and you all showed me that I need to finish the "prologue" if you will.

No other analysis should be this intensive. three intercepts down, seven to go. Four of them should be simple and boring so they shouldn't take forever.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 03:18
by sprstdlyscottsmn
Ug, so I just did my Stubby intercept mission and it went as expected, but when I was putting up the flight envelope it just looks... off.

blarf.png


I am matching the model I used to generate this matched to following stated performance specs.
25 degree nose up in Mil on takeoff at 300knots at -2.44%
0.6-0.95M @15k in 17.9s at +3.18% (assumed 60% internal and 2 AIM-120)
0.8-1.2M @30k in 61s at +0.08% (achieved by 240-3, same assumed load as above)
max End of (assumed 47000lb total weight)
4600pph at -0.24%
at 32K at +5.47%
at 0.75M at +0.00%
Loaded cruise realtive to F-16 of
10-15K higher at -6.47% (could not get 10k higher)
50kt faster at -0.65% (within resolution nose of my speed measurement)
590nm strike with 2xAIM-120 and 2xGBU-31 with 10 minutes loiter landing with 7k-8k fuel remaining at -4.72% (6670 remaining, all optimum climb, cruise, loiter, and descent)
Sustain 4.59G at 15k at +0.00% (achieved by 240-3)
Top speed in excess of 1.67 at +11.9% (achieved by 240-3, I have 1.87 as peak)
keeping 1.2M drag just over the Mil thrust at 36,000ft for "very minimal burner"

I know there is more than one way to skin a cat to match the performance up, and I think I need to re-adjust for something I read about the F135 making 40K with inlet and exhaust (I measure airflow losses and gearbox losses separately).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 04:02
by doge
I made a video.

It looks quite quick turn.
How about?

original
F-35A https://www.youtube.com/watch?v=2kJOvsQVGhM
F-22 https://www.youtube.com/watch?v=j9DNMI5JsM8
EF-2000 (6:58) https://www.youtube.com/watch?v=9GDFBIPuveU

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 04:49
by sprstdlyscottsmn
Yes, the instantaneous turn is phenomenal, in my model too. I'm more concerned with the bizarre speed limits in my envelope.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 05:47
by garrya
sprstdlyscottsmn wrote:Ug, so I just did my Stubby intercept mission and it went as expected, but when I was putting up the flight envelope it just looks... off.

Image
.

Can you be more specific about what looking off here?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 05:51
by sprstdlyscottsmn
I guess how "pinched" the envelope looks between 1 and 1.4M. Also the accelerations I am seeing are not in line with "recovers energy faster than the F-16" or "F/A-18 with four engines". I am wondering if mart of my problem is the assumption of configuration for acceleration spec? I'll keep digging. But as my list of stated abilities show I am trying to match as many different performance specs as possible as closely as possible.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 07:08
by hornetfinn
sprstdlyscottsmn wrote:Sustain 4.59G at 15k at +0.00% (achieved by 240-3)


I don't think this matters much in this case, but is the 4.59G a typo? IIRC, it was 4.95G.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 12:53
by sprstdlyscottsmn
Yes, it was a typo. 4.95 is my target.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 16:58
by sferrin
doge wrote:I made a video.

It looks quite quick turn.
How about?

original
F-35A https://www.youtube.com/watch?v=2kJOvsQVGhM
F-22 https://www.youtube.com/watch?v=j9DNMI5JsM8
EF-2000 (6:58) https://www.youtube.com/watch?v=9GDFBIPuveU


That F-22 video is pretty obviously slowed down.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 17:07
by gta4
this is a non-slow-down video of F-22:

https://www.youtube.com/watch?v=N_3m5Zx-6Kc

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2017, 18:55
by sferrin
True, that's not slowed down. It's sped up. :roll:

This is what you're looking for:

2:40

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 02:02
by doge
Thanks. retry.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 14:07
by sprstdlyscottsmn
Okay, so I reworked a few of my assumptions and did a bit more research on configurations. While the .6-.95M and sustG are specified with a configuration, the .8-1.2M acceleration is not. Once I changed that loadout and re-worked this so that the numbers work I got a less pinched envelope. Top speed actually came down by .01M but overall it looks better. Acceleration is more in line with pilot reports as well. Honestly the speed is as well. Most reports on the A model power indicate pilots have to pitch up or throttle down to not overspeed and that exceeding 40Kft is easy. This will also help once I get to the B and C models as they still need to be able to hit 1.6M, albeit more slowly and they will have more drag.

My previous set of numbers (not including the top speed because that is open ended) ranged from -6.47% to +5.47% for a total error range of 11.94%. My current numbers range from -3.92% to +0.9% for a total error range of 4.82%. I am much more satisfied.
blarf 2.png

Note: while the F-35 and Su-35 seem to have similar envelopes here, configuration has a lot to do with it. Both are around 50% fuel but the F-35 has two internal AAMs while the Su-35 has six external AAMs and two jamming pods. The Su-35 still has superior acceleration and STR over most the envelope due to its great T/W.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 16:15
by steve2267
sprstdlyscottsmn wrote:Note: while the F-35 and Su-35 seem to have similar envelopes here, configuration has a lot to do with it. Both are around 50% fuel but the F-35 has two internal AAMs while the Su-35 has six external AAMs and two jamming pods. The Su-35 still has superior acceleration and STR over most the envelope due to its great T/W.


Would the F-35 numbers change with four (or six - Block 4) internal AAMs? Yes, but by how much? I am going to hazard a guess that the changes are probably within your error tolerance?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 16:59
by sprstdlyscottsmn
steve2267 wrote:Would the F-35 numbers change with four (or six - Block 4) internal AAMs? Yes, but by how much? I am going to hazard a guess that the changes are probably within your error tolerance?

Adding ~1,400lb to a ~40,000lb airframe, a 3.5% change in sustained G and acceleration. No big deal.

The REASON they are being compared with the loadouts they are is that in my intercept mission they are being compared after the F-35 has fired four of its six AMRAAMs, right before the Su-35s are hit, to show the combat performance of the two planes in the conditions they are in when they are at their physical closest.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 17:41
by garrya
sprstdlyscottsmn wrote: The Su-35 still has superior acceleration and STR over most the envelope due to its great T/W.

I got that Su-35 fly faster and what not but isn't the F-35 supposed to have better acceleration than even the F-16 (which already better than sukhoi) ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 18:09
by gta4
sprstdlyscottsmn wrote:Okay, so I reworked a few of my assumptions and did a bit more research on configurations. While the .6-.95M and sustG are specified with a configuration, the .8-1.2M acceleration is not. Once I changed that loadout and re-worked this so that the numbers work I got a less pinched envelope. Top speed actually came down by .01M but overall it looks better. Acceleration is more in line with pilot reports as well. Honestly the speed is as well. Most reports on the A model power indicate pilots have to pitch up or throttle down to not overspeed and that exceeding 40Kft is easy. This will also help once I get to the B and C models as they still need to be able to hit 1.6M, albeit more slowly and they will have more drag.

My previous set of numbers (not including the top speed because that is open ended) ranged from -6.47% to +5.47% for a total error range of 11.94%. My current numbers range from -3.92% to +0.9% for a total error range of 4.82%. I am much more satisfied.
blarf 2.png

Note: while the F-35 and Su-35 seem to have similar envelopes here, configuration has a lot to do with it. Both are around 50% fuel but the F-35 has two internal AAMs while the Su-35 has six external AAMs and two jamming pods. The Su-35 still has superior acceleration and STR over most the envelope due to its great T/W.


When you adjust the Su-35 model, did you use the 50% fuel of 11500kg?

Here are a few concerns:

Even though Su-27B has an internal fuel of 9400kg, it uses 50% fuel of 5270kg = 2635kg to calculate performance (1000m, 600-1100km/h in 15s).

I don't know how much fuel was used for Su-35, but judging by the experience of Su-27, it probably uses 3000kg fuel+2 short range aam to achieve the "1000m, 600-1100km/h in 13.8s" acceleration.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 18:12
by gta4
garrya wrote:
sprstdlyscottsmn wrote: The Su-35 still has superior acceleration and STR over most the envelope due to its great T/W.

I got that Su-35 fly faster and what not but isn't the F-35 supposed to have better acceleration than even the F-16 (which already better than sukhoi) ?


That is determined by the speed region. form 0.6-0.95 I suppose F-35 has better acceleration.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 18:44
by gta4
To sprstdlyscottsmn:

These data could come in handy.

Su-35 and Su-27 has almost the same aerodynamics design. At M0.85, Su-27 has Oswald efficiency factor 0f 0.71, so the induced drag index should be 1/(pi*aspect ratio*Oswald efficiency factor)=0.129.

It also has a Cd0 of 0.0185 at this mach number.

su-27 cd0 efficiency.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 18:57
by gta4
doge wrote:I made a video.

It looks quite quick turn.
How about?

original
F-35A https://www.youtube.com/watch?v=2kJOvsQVGhM
F-22 https://www.youtube.com/watch?v=j9DNMI5JsM8
EF-2000 (6:58) https://www.youtube.com/watch?v=9GDFBIPuveU


The F-22's turn at 21:46 is more incredible than the clip you are using:
https://www.youtube.com/watch?v=3WHsRBOlPts

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 19:13
by sprstdlyscottsmn
New data is always good.

Please remember everyone, I am not using arbitrary weights or loadouts or altitudes when I say "X has stat Y". I am using a Su-35 with 10,120lb of fuel remaining because that is what was left after it flew 450nm, 95 of it in full afterburner. It has a drag index of 60 and a base CDo of 0.02117 (in light of new data I will have to change some details, but most of the important stuff will stay the same). The Su-35 weighs in at a total of 54,589lb at this time while the F-35 weighs in at 39,398lb. Both planes began their set missions with full fuel. Using my estimated installation losses for both gearbox and airflow restrictions, but still using Sea Level and Static, the T/W of the Su-35 was 0.95 to the F-35s 0.81.

I am not, nor will I be, comparing "Well the Su-27 was calculated at this fuel load so if I take an F-35 to the same fuel load/percentage/fraction it has an acceleration of X." One plane is on a long range escort mission while the other is on a fairly long range intercept. They will end up switching.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 19:55
by gta4
sprstdlyscottsmn wrote:New data is always good.

Please remember everyone, I am not using arbitrary weights or loadouts or altitudes when I say "X has stat Y". I am using a Su-35 with 10,120lb of fuel remaining because that is what was left after it flew 450nm, 95 of it in full afterburner. It has a drag index of 60 and a base CDo of 0.02117 (in light of new data I will have to change some details, but most of the important stuff will stay the same). The Su-35 weighs in at a total of 54,589lb at this time while the F-35 weighs in at 39,398lb. Both planes began their set missions with full fuel. Using my estimated installation losses for both gearbox and airflow restrictions, but still using Sea Level and Static, the T/W of the Su-35 was 0.95 to the F-35s 0.81.

I am not, nor will I be, comparing "Well the Su-27 was calculated at this fuel load so if I take an F-35 to the same fuel load/percentage/fraction it has an acceleration of X." One plane is on a long range escort mission while the other is on a fairly long range intercept. They will end up switching.


OK sounds fair enough. looks like you are using a total pressure recovery of around 0.79 at sea level static for F-35, and 0.9 for Su-35 (1% loss in total pressure recovery results in 1.3-1.5% loss in thrust).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 19:58
by steve2267
sprstdlyscottsmn wrote:The REASON they are being compared with the loadouts they are is that in my intercept mission they are being compared after the F-35 has fired four of its six AMRAAMs, right before the Su-35s are hit, to show the combat performance of the two planes in the conditions they are in when they are at their physical closest.


Oh... I gotcha now. Makes too much sense. Sorry for the suddenly increased density of my noggin.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 20:11
by gta4
sprstdlyscottsmn wrote:I am not, nor will I be, comparing "Well the Su-27 was calculated at this fuel load so if I take an F-35 to the same fuel load/percentage/fraction it has an acceleration of X." One plane is on a long range escort mission while the other is on a fairly long range intercept. They will end up switching.


Sounds reasonable. In fact I am not asking you to use that fuel load to calculate performance, but it is a good way to verify the aerodynamic model (3000 kg fuel and 13.8 s from 600-1100km/h, @ 1000 m).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 20:19
by sprstdlyscottsmn
gta4 wrote:OK sounds fair enough. looks like you are using a total pressure recovery of around 0.79 at sea level static for F-35, and 0.9 for Su-35 (1% loss in total pressure recovery results in 1.3-1.5% loss in thrust).

If I understand what you are saying here, using a loss of 18.97% on the Su-35 (31,900 to 25,847) is a pressure recovery of .85-.87 and the 20.32% thrust loss for the F-35 (43,000 to 34,264) is a pressure recovery of .84-.86.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 22:05
by doge
gta4 wrote:The F-22's turn at 21:46 is more incredible than the clip you are using:
https://www.youtube.com/watch?v=3WHsRBOlPts


Thanks again. Retry again.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 22:43
by gta4
sprstdlyscottsmn wrote:
gta4 wrote:OK sounds fair enough. looks like you are using a total pressure recovery of around 0.79 at sea level static for F-35, and 0.9 for Su-35 (1% loss in total pressure recovery results in 1.3-1.5% loss in thrust).

If I understand what you are saying here, using a loss of 18.97% on the Su-35 (31,900 to 25,847) is a pressure recovery of .85-.87 and the 20.32% thrust loss for the F-35 (43,000 to 34,264) is a pressure recovery of .84-.86.


OK I know. but in fact the uninstalled full A/B thrust of 117S is 30856 lb instead of 31900 lb. 31900 lb is special mode.
(1 kg = 2.204 lb)
117C.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2017, 23:19
by sprstdlyscottsmn
Oh excellent! Given the plethora of new data, I guess I need to bring my analysis to a halt, re-verify my Su-27/35 model, double check any outcome changes, update some tables, then get back to it. Accuracy is a bitch. Thanks fellas!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Jun 2017, 17:22
by gta4
doge wrote:
gta4 wrote:The F-22's turn at 21:46 is more incredible than the clip you are using:
https://www.youtube.com/watch?v=3WHsRBOlPts


Thanks again. Retry again.


This is the most updated F-35 tight turn video:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Nov 2017, 17:39
by sprstdlyscottsmn
So once again I needed to update my performance models to become more flexible. I also strove to streamline the sheet and was quite successful. My 28Mb excel files are being replaced by a 10Mb excel file that does more. I also made a few big decisions regarding the document itself.

Model Validity - I will take a few key parameters that I use to verify my models and will add the standards and the results into the document.

Missions - I decided to combine the CAP and Intercept mission as well as changing the ROE to make it more difficult for the strike fighters. Now instead of generic "Early warning radar detects this at that time" there will be aircraft on CAP that need to detect the aggressors. AWACS may be added, unknown at this time.

Aircraft - I have decided to narrow down the list of aircraft in the study to Strike Fighters that will be operational in the 2020 timframe. This means the removal of the F-15C (gold standard for decades, yes, but no operational strike capability), the F-14D (I only even added this because I wanted to see how it would do, but it is obsolete and out of service for more than a decade already), and the A-10C (seen by many as the gold standard of ground pounding, was only going to be included so show how it fared compared to the rest). I may keep the F-15C and A-10C as a benchmark and compare the Strike Fighters performance against the last dedicated types in service, unknown at this time. This also means that the Su-35S will be the sole aggressor, launching Kh-59MK(2)s itself.

Systems - ECM and ECCM will be taken into account in a greatly simplified manner with levels of ECM and levels of ECCM given to different systems.

Damage - I am estimating missile warhead blast radius and improving the timing of my missile tracking algorithm to allow for better terminal range resolution. I will compare minimum flown distance, final closure rate, blast radius, and a general technological pK (75%-85%) to represent reliability of the systems. This will combine to a new system where an aircraft may sustain damage without being destroyed.

Drop Tanks - after some debate I am deciding that drop tanks will never be dropped due to a combination of historical precedent, logistics, and timing issues.

All that said, the drive that my most current files were on was corrupted so I lost some progress.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Dec 2017, 17:16
by sprstdlyscottsmn
Ugh, every time I think I am "Done" with something. My Su-35 model was flawed in a way not readily apparent, but largely due to the low altitude of the acceleration spec. I will need to go over a few things to see how they changed as a result, but in my preliminary first pass the Strike Eagle was able to outscore the Charlie Eagle baseline due to having a back seater. I may also need to revamp the escort distance, now that I think about it 2 miles is a bit far.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Dec 2017, 02:27
by eloise
sprstdlyscottsmn wrote: I may also need to revamp the escort distance, now that I think about it 2 miles is a bit far.

Don't you mean 200 miles? 2 miles sound like nothing for escort

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Dec 2017, 02:54
by sprstdlyscottsmn
Once the CAP aircraft intercept the aggressors they escort them two miles abreast of them. I think half a mile is more realistic.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Dec 2017, 03:06
by spazsinbad
sprstdlyscottsmn wrote:Once the CAP aircraft intercept the aggressors they escort them two miles abreast of them. I think half a mile is more realistic.

Don't know where you got that information. In my day 'escorting' would be maximum half a nautical mile (1,000 yards) in the rear quarter either side so that escort can roll in to attack aggressor within gun range if need be. Is this more likely?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Dec 2017, 06:28
by eloise
sprstdlyscottsmn wrote:Once the CAP aircraft intercept the aggressors they escort them two miles abreast of them. I think half a mile is more realistic.

I see, i thought you mean escorts only fly with strike formation for 2 miles then went back

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Dec 2017, 08:18
by sprstdlyscottsmn
spazsinbad wrote:
sprstdlyscottsmn wrote:Once the CAP aircraft intercept the aggressors they escort them two miles abreast of them. I think half a mile is more realistic.

Don't know where you got that information. In my day 'escorting' would be maximum half a nautical mile (1,000 yards) in the rear quarter either side so that escort can roll in to attack aggressor within gun range if need be. Is this more likely?


Agreed. I am going with abeam to simulate the jockeying of position. When escort tries a rear quarter they slow down to get abeam or the aggressor wingie drifts behind the escort lead. End result being that if the aggressors are able to see both escorts on a scope before the merge then they isolate the escorts to make it a 1v1 as the additional QRA/Alert-5/Intercept jets are still inbound. But thank you for varifying that half mile is a more realistic distance. Maybe I will set up the aggressors in a 1 mile trail with one escort each at half mile rear quarter. Lead escort is in a bad position then though.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Dec 2017, 15:48
by garrya
Spurt, would it be possible for you to plot their Em diagram at 20K feet on the same graph (like all of them, instead of only F-15E and Su-35 like you did earlier) ?
Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Dec 2017, 16:12
by optimist
Depends what they are escorting. I saw with our transports, they tend to fly low, so they don't throw a big shadow and the escorts are high, their job is to not give the transports position away, yet still be able to protect the asset.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Dec 2017, 17:13
by sprstdlyscottsmn
garrya,

I won't do a proper E-M diagram (increments of 100 to 200 fps) due to how much space that would take on my sheets. As for a basic ITR/STR plot (or any performance plot really) they become difficult to read once you put more than two on the same plot. Putting ten ITR/STR plots on one graph would be unreadable. Overlaying two full E-M diagrams on one graph would be unreadable.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Dec 2017, 17:15
by sprstdlyscottsmn
optimist wrote:Depends what they are escorting. I saw with our transports, they tend to fly low, so they don't throw a big shadow and the escorts are high, their job is to not give the transports position away, yet still be able to protect the asset.

The escort in question here is an intercept. Defending fighters intercepting and escorting aggressor fighters prior to a shooting war.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 27 Dec 2017, 02:15
by sprstdlyscottsmn
Okay, WOW! I was able to make a lot of progress this long weekend. I have completed the CAP/Intercept mission for the F-15E and F-22A. The F-15E has fuel for days and the F-22 almost never needs afterburner. So fun!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2018, 18:10
by sprstdlyscottsmn
QRA mission completed for F-16C, F-35A, F-35B, and F-35C. Working on the F/A-18C performance model and I am trying to model the -402 motors. I have a report that gives a few actual dynamic thrust values, sustained turn rates, and acceleration specs so I am starting there before I de-rate to -400 and then match performance with the NATOPS. Only two Hornets and a Harrier to go before QRA is done and I move on to Strike and Interdiction/CAS.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2018, 18:16
by garrya
sprstdlyscottsmn wrote:Okay, WOW! I was able to make a lot of progress this long weekend. I have completed the CAP/Intercept mission for the F-15E and F-22A. The F-15E has fuel for days and the F-22 almost never needs afterburner. So fun!

Does F-15E carry external fuel tanks in your CAP/intercept missions profile?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2018, 18:37
by sprstdlyscottsmn
garrya wrote:Does F-15E carry external fuel tanks in your CAP/intercept missions profile?

Yes. I have found that operationally the F-15C and E almost always carry the two wing tanks. They do not adversely effect the performance significantly. The F-15E is a heavy bird and it burns a lot of fuel.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2018, 21:39
by viper12
Stupid question ; is there a rule of thumb to estimate dynamic thrust ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2018, 22:35
by sprstdlyscottsmn
viper12 wrote:Stupid question ; is there a rule of thumb to estimate dynamic thrust ?

In my experience, no. I start by estimating how much thrust is lost to the gearbox and airflow issues to get a baseline for "installed thrust". I then found that taking uninstalled thrust, adjusting for density altitude, and subtracting the gearbox and airflow losses give a reasonable baseline installed thrust with altitude, but the adjustments for speed vary dramatically. For example, a J79 makes more thrust when installed in an F-4 pushing it at Mach 2.0 at 30,000ft than it does uninstalled sitting on a test stand at sea level. I have yet to see another motor that does that (other than I assume the J58).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 05:35
by garrya
sprstdlyscottsmn wrote: For example, a J79 makes more thrust when installed in an F-4 pushing it at Mach 2.0 at 30,000ft than it does uninstalled sitting on a test stand at sea level. I have yet to see another motor that does that (other than I assume the J58).

what is the reason for that ? :shock:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 05:40
by sferrin
garrya wrote:
sprstdlyscottsmn wrote: For example, a J79 makes more thrust when installed in an F-4 pushing it at Mach 2.0 at 30,000ft than it does uninstalled sitting on a test stand at sea level. I have yet to see another motor that does that (other than I assume the J58).

what is the reason for that ? :shock:


Ram effect.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 14:39
by sprstdlyscottsmn
My Phanboy response would have been "pure malice and rage.". I mean, have you ever heard a Phantom do a high speed pass? Those motors sound angry!

In all seriousness the J79 was built for speed. Look up a list of planes that had them. F-4, F-104, B-58, (IIRC) A-5. All of them are famous for being fast in their day. The F119 is our modern equivalent.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 16:26
by juretrn
Sprts, are you going to upload those new assessments you made?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 16:34
by mixelflick
sprstdlyscottsmn wrote:
garrya wrote:Does F-15E carry external fuel tanks in your CAP/intercept missions profile?

Yes. I have found that operationally the F-15C and E almost always carry the two wing tanks. They do not adversely effect the performance significantly. The F-15E is a heavy bird and it burns a lot of fuel.


I have often wondered about this. In the 1980's, Eagle's almost exclusively carried a belly/centerline tank. Today, it's almost always 2 wing tanks (we have F-15C's here in central mass, just a few miles away). How is it that two big tanks under those wings don't degrade performance significantly? If I'm not mistaken, they're big (600 gallon) tanks...

I do recall asking an F-15 driver why instead they didn't favor the conformal tanks. His answer made a lot of sense, "I can punch the wing tanks, but not the saddlebags...". :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 17:11
by jetblast16
sferrin wrote:
garrya wrote:
sprstdlyscottsmn wrote: For example, a J79 makes more thrust when installed in an F-4 pushing it at Mach 2.0 at 30,000ft than it does uninstalled sitting on a test stand at sea level. I have yet to see another motor that does that (other than I assume the J58).

what is the reason for that ? :shock:


Ram effect.


Could be caused from the exhaust gas velocity of those engines; and they were high :shock:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 17:13
by jetblast16
I mean, have you ever heard a Phantom do a high speed pass? Those motors sound angry!


Many, many times :wink:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jan 2018, 20:12
by viper12
mixelflick wrote:I have often wondered about this. In the 1980's, Eagle's almost exclusively carried a belly/centerline tank. Today, it's almost always 2 wing tanks (we have F-15C's here in central mass, just a few miles away). How is it that two big tanks under those wings don't degrade performance significantly? If I'm not mistaken, they're big (600 gallon) tanks...


In one Combat Aircraft magazine IIRC, they interviewed some F-15C pilots, and one of them said the drag difference between the 2 wing tanks and the centerline tank configs was minimal or something like that. And yes, all these tanks are 600-gal ones.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Jan 2018, 03:07
by sprstdlyscottsmn
viper12 wrote:
mixelflick wrote:I have often wondered about this. In the 1980's, Eagle's almost exclusively carried a belly/centerline tank. Today, it's almost always 2 wing tanks (we have F-15C's here in central mass, just a few miles away). How is it that two big tanks under those wings don't degrade performance significantly? If I'm not mistaken, they're big (600 gallon) tanks...


In one Combat Aircraft magazine IIRC, they interviewed some F-15C pilots, and one of them said the drag difference between the 2 wing tanks and the centerline tank configs was minimal or something like that. And yes, all these tanks are 600-gal ones.

Confirm. In the -1 I was astounded to see that the center-line carries almost as much drag as both wing tanks and the pylons you need for the AA stores anyway. Very minimal drag increase but a huge boost to fuel.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 21 Jan 2018, 03:14
by sprstdlyscottsmn
juretrn wrote:Sprts, are you going to upload those new assessments you made?

So my assessment is going to be four parts. First will be an analytical assessment of the planes physical and equipment characteristics. Second will be the CAP/QRA mission. Third will be a deep strike with a few large munitions. Fourth will be an Interdiction/CAS scenario with higher numbers of smaller munitions.

I am running the F-15E(229), F-16C(129), F/A-18C(402), F/A-18E, AV-8B, F-22A, F-35A, F-35B, and F-35C through all missions.

I am still working CAP/QRA at the moment. I have the AV-8B and F/A-18E to go. The problem is the model for the F/A-18E is being troublesome to say the least. I have raw hard thrust numbers for 20,000ft from 0.8M to 1.4M and yet it shouldn't ever get past 1.3M. I can't get the drag values to reconcile that. I'm very tempted to fudge the thrust above 1.2 but I just can't bring myself to do it.

Edit: SO I just trying altering one of my many wave drag parameters and it brought the speed I was getting at 20kft down from 1.40 to 1.33. I do not like being so far off but that becomes the one big anomaly between the Curve 1 and Curve 4 lines that I am mimicking from the NATOPS. When the rest seems to line up give or take 0.01M I will take one oddball 0.03M error (2.3% error in top speed). Since I got that to work I should have the SHornet done tonight. If I can do the AV-8B tomorrow I will post what I have done for review.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jan 2018, 18:09
by sprstdlyscottsmn
AV-8B fuel flow is being problematic, and I realized my F-35 and Super Hornet models have inconsistent fuel flow so I will need to button those down.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jan 2018, 18:25
by spazsinbad
I guess you have AV-8B NATOPS & Performance PDFs?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jan 2018, 18:29
by sprstdlyscottsmn
I do, thank you. That is how I know my numbers are so off. I have an idea of how to change the Dynamic TSFC to fix it.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Feb 2018, 15:13
by gta4
Here is a good article about F/A-18E's lift curve and drag polar:
"Flight Test Techniques Employed to Successfully Verify F/A-18E In-Flight Lift and Drag"
AIAA 99-0768
f18 drag polar.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Feb 2018, 18:58
by sprstdlyscottsmn
I'll store that nugget away. I had to redo a little of the profile but I was able to re-run 4 planes yesterday. I'm also trying to mess around with a meaningful maneuverability metric. While the AV-8B+ has a token BVR capability it is by no means an interceptor. The F-35B is a quantum leap.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2018, 12:45
by gta4
This is the lift curve slope from the same article. You can see that Super hornet has VERY STEEP lift curve slope (greater than 0.1/deg), significantly higher than any existing fighter jets.
lift curve slope.jpg
lift curve slope.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2018, 14:41
by sprstdlyscottsmn
A quick review of what is shown vs what isn't shown. Lift curve slope hits nearly .15. that's amazing! We don't know the actual CL or Alpha shown in the graph. Still, I think it's worth updating the lift curve in my model.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Feb 2018, 15:07
by sprstdlyscottsmn
Hey everyone. Quick question. In an air-to-air agility metric I am trying to find something useful to measure. Instead of listing a doghouse plot, right now I am ploting time, radius, speed, and altitude to complete a standard rate 90 degree turn, followed by a "half-pull" (linear portion of CL alpha curve) 90 degree turn, followed by a CL Max 90 degree turn, followed by a max Alpha nose position change. The maneuver starts at 0.8M at 30,000ft and afterburners are engaged the whole time. My thoughts are that these four things measure energy gain during gentle turns, energy loss during modest turns, energy loss during hard turns, and low speed nose pointing. I then measure how much energy has been lost.

So my question is, do these seem like good things to measure? Any ideas of something else that should be measured?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 Feb 2018, 21:40
by rheonomic
sprstdlyscottsmn wrote:So my question is, do these seem like good things to measure? Any ideas of something else that should be measured?


I haven't really been following this thread, but have you looked at any of the fighter agility metrics work done in the early to mid 90s?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 03:11
by sprstdlyscottsmn
rheonomic wrote:
sprstdlyscottsmn wrote:So my question is, do these seem like good things to measure? Any ideas of something else that should be measured?


I haven't really been following this thread, but have you looked at any of the fighter agility metrics work done in the early to mid 90s?

I have now. Looks like what I am tinkering with is similar in nature to the CCT study with the F-5, F-16, and F/A-18. Thanks for the tip.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 03:44
by johnwill
gta4 wrote:This is the lift curve slope from the same article. You can see that Super hornet has VERY STEEP lift curve slope (greater than 0.1/deg), significantly higher than any existing fighter jets.


No surprise there, since the SH has the lowest wing sweep of any modern fighter.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 04:13
by gta4
I think the traditional agility metric (CCT) is good enough:

1) bank 90 degree
2) turn until 180 degree nose pointing change (so the angle changed in flight path is smaller than 180 deg, given the the presence of AOA increase)
3) bank 90 degree to level flight
4) accelerate back to initial speed

Calculate the total time spent. The shoter the better.

At 4500 m, the best performer (I remember) is F-16, which spends only 21-22 seconds. This is because it bleeds less energy in Phase 2.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 05:04
by eloise
sprstdlyscottsmn wrote:. Instead of listing a doghouse plot

I personally like doghouse plot more as we can see turn rate at various speed

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 05:59
by sprstdlyscottsmn
The doghouse plots make themselves at this point, so leaving them in is no big deal. As for the 180, a sustained turn will take the longest to turn but will have 0 acceleration time, while a max AOA turn will have the smallest flight path change but the largest acceleration time, and all the variations in between. There is a lot to consider.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 14:04
by gta4
The main disadvantage of doghouse plot:

You can not get any "dynamic" knowledge of the aircraft, e.g. how long does it take to turn a given angle?

So it may cause some illusion: two jets with similar peak ITR will give you the impression that they have similar first turn capability. However, the one who bleeds energy slower will deplete its turn rate slower, thus has angular advantage right from the start.

A more extreme example: the one who bleeds energy slower, even has lower peak IRT, may still finish the 180 deg turn first.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 14:57
by garrya
gta4 wrote:The main disadvantage of doghouse plot:

You can not get any "dynamic" knowledge of the aircraft, e.g. how long does it take to turn a given angle?

So it may cause some illusion: two jets with similar peak ITR will give you the impression that they have similar first turn capability. However, the one who bleeds energy slower will deplete its turn rate slower, thus has angular advantage right from the start.

A more extreme example: the one who bleeds energy slower, even has lower peak IRT, may still finish the 180 deg turn first.

Don't you get the bleed rate Ps from the chart too?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 Feb 2018, 17:42
by sprstdlyscottsmn
garrya wrote:Don't you get the bleed rate Ps from the chart too?

Not from the charts I can produce. What I have looked at is what ten seconds of turn looks like comparing max CL vs mid range pull to see what the final differences are in rate, radius, and speed.

Another thing that I do put in with my doghouse plots is a deceleration plot representing the maximum CL pull seen in the doghouse.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Feb 2018, 15:51
by gta4
Anyway, do not use 90 deg turn. Use 180 deg turn. I will explain later.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 13 Feb 2018, 17:50
by sprstdlyscottsmn
I've already gone back and re-done the turn as a max CL 180 and a recovery acceleration in a straight line back to the starting speed. I had to re-do one of my algorithms to allow for the "I'm pretty much stalled and can't use all my lift to arrest my decent or I will stay stalled". My previous algorithm caused almost any stall to result in a floating leaf departure all the way to the ground or then AB thrust was enough to arrest the fall.

I am now recording the total CCT, the time to reposition the nose 180 (not the flight path) and the theoretical minimum time to reposition the nose 180 (max AoA pull at the last second to shave a few seconds off the nose position time). I am also recording the total radius of the turn and the altitude lost during recovery.

So far I am seeing some interesting and unexpected results.

The Hornet loses no altitude. I determined this is because it has a wing tank which limits it to 20 AoA, not a max CL pull.
The Super Hornet loses no Altitude. I determined this is because it's stall speed is so low that does not require a dive to recover. It also seems to have more efficient lift generation than the legacy hornet (less drag per lift) from the data I have seen.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 06:51
by steve2267
For giggles and grins, not as a true aircraft agility metric, but more of a system metric, what about calculating minimum time necessary to obtain a HOBS missile solution? This would include minimum time to crank the nose around, combined with HMDS parameters, and the particular HOBS missile carried (e.g. AIM-120, AIM-9x, ASRAAM, IRIS-T, Python 5 etc). 90° off boresight is probably way too little -- some systems may permit the pilot simply to look at 90° and shoot. Perhaps place the bogey at 135° or 180° for such a system agility metric.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 11:39
by gta4
Two agility metrics I came across year ago:
Assume an aircraft starts a turn at M0.8 and maintains a constant AOA in a turn.
Using traditional CCT metric, and assume the AOA limit of an aircraft is alpha_l,
Traverse through all values from 0 to alpha_l with 0.1 deg increment. Calculate the corresponding T1, T2, T4 and T4.

T1: bank 90 degree
T2: turn until 180 degree nose pointing change (so the angle changed in flight path is smaller than 180 deg, given the the presence of AOA increase)
T3: bank 90 degree to level flight
T4: accelerate back to initial speed

Metric 1: Find the AOA that minimize T2. T2 is the metric.
Metric 2: Find the AOA that minimize T_total=T1+T2+T3+T4. T_total is the metric.

Metric 1 evaluates missile fight capability, especially with HOBS missiles.
Metric 2 evaluates gun fight capability.

Fun fact: Those who have good peak ITR may not perform well in Metric1. :mrgreen: :mrgreen: :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 14:46
by sprstdlyscottsmn
steve2267 wrote:For giggles and grins, not as a true aircraft agility metric, but more of a system metric, what about calculating minimum time necessary to obtain a HOBS missile solution? This would include minimum time to crank the nose around, combined with HMDS parameters, and the particular HOBS missile carried (e.g. AIM-120, AIM-9x, ASRAAM, IRIS-T, Python 5 etc). 90° off boresight is probably way too little -- some systems may permit the pilot simply to look at 90° and shoot. Perhaps place the bogey at 135° or 180° for such a system agility metric.

So I had thought about that, and it would certainly skew things in favor of the F-22 and F-35 (T=0), but the higher the off-bore the shot the lower the Pk. Bogeys are also not static.

[quote="gta4']Metric 1: Find the AOA that minimize T2. T2 is the metric.
Metric 2: Find the AOA that minimize T_total=T1+T2+T3+T4. T_total is the metric.[/quote]
This is what I am doing, mostly. I don't have the resources to generate roll rates so that aspect is unfortunately left out. I am turning the flight path 180 degrees at CLmax and then recovering to initial speed. I am measuring total time, time for the nose to reach 180, turn radius, altitude lost, and as a bonus the potential time for the nose to reach 180 if the end of the turn is a max Alpha instead of Max CL pull.

As the configurations are mission based instead of fixed ratio based some aircraft have things skewed in their favor. The -402 powered F/A-18C has more specific excess thrust in the mission configuration than the F-16. That and it's lower Alpha limit (lower than CL max with wing tanks) means it turns just as "slowly" as a CAT-I pull of the Viper but loses less speed.

The F-35B kicks the snot out of the F-35C in total T even though the F-35C is a close second to the F-22 in turning T because the F-35B is 10,000lb lighter under the mission conditions.

The Su-35 performs worse than the F-15C until the bonus alpha pull is added in.

I need to finish this (hopefully this weekend) so I can get the A-A part posted

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 14:59
by gta4
This is what I am doing, mostly. I don't have the resources to generate roll rates so that aspect is unfortunately left out. I am turning the flight path 180 degrees at CLmax and then recovering to initial speed.


This is the biggest difference between your metric and my metric. You should not use max AOA but you need to traverse from 0 to max AOA to find the AOA that minimize T2 or T_total. And AOA remains constant during a turn.

90 deg roll time is hard to calculate but you can safely ignore it because they are significantly smaller than T2 and T4. I have a way to estimate 90 deg roll time if you are interested.

180 deg turn is very important in HOBS missile fight:
two circle.png

Those who have good peak ITR may finish 90 deg turn first, but it is useless because the opponent is not in the HOBS kill zone.
The jet who finishes 180 deg turn first will have the first shot opportunity, and it is always the one with better energy retention.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 15:22
by sprstdlyscottsmn
gta4 wrote:
This is the biggest difference between your metric and my metric. You should not use max AOA but you need to traverse from 0 to max AOA to find the AOA that minimize T2 or T_total. And AOA remains constant during a turn.

90 deg roll time is hard to calculate but you can safely ignore it because they are significantly smaller than T2 and T4. I have a way to estimate 90 deg roll time if you are interested.

180 deg turn is very important in HOBS missile fight:
two circle.png

Those who have good peak ITR may finish 90 deg turn first, but it is useless because the opponent is not in the HOBS kill zone.
The jet who finishes 180 deg turn first will have the first shot opportunity, and it is always the one with better energy retention.


Max AoA is not Max rate of turn for aircraft that have very high max AoA. I've already said that minimizing T_total is done with a sustained turn but minimizing T2 is done with CL max. I can currently set one of three AoA limits (mid pull, CL Max pull, and AoA max pull) and then modulate the G limit as incrementally as I want. It sounds like you want to see the AoA incremented. I don't know how much work that will be to add, but I'll check. I guess if I really think about it I am doing min average radius at constant AoA instead of max average rate at constant AoA.

Also, in your scenario there is a 3-9 line cross. In mine it begins from an escort position, moving in the same direction so in that case (pulling into each other) radius matters. If one fighter has a somewhat higher rate but a larger radius that could only put him in front of the tighter turning fighter faster.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 15:49
by gta4
I've already said that minimizing T_total is done with a sustained turn but minimizing T2 is done with CL max.

The fun fact is, minimizing T2 (or t_total) may require neither Cl_max nor sustained turn. I am confident with that claim because I have done a simulation on Mirage 2000. That is why I made AOA incremented.

Also, in your scenario there is a 3-9 line cross. In mine it begins from an escort position, moving in the same direction so in that case (pulling into each other) radius matters.


So your scenario is not a "head-on merge", that is interesting and very few literature focus on it. I am looking forward to your conclusion.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 15:56
by gta4
http://www.dept.aoe.vt.edu/~mason/Mason ... ownS03.pdf
This is a CFD analysis on F-35 A/B/C. I believe the drag polar is useful to you.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 15:58
by gta4
BTW, I calculated the energy characteristics of F-16C on 5000m. Feel free to review it if you are interested:
viewtopic.php?f=30&t=53852

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 16:34
by sprstdlyscottsmn
gta4 wrote:The fun fact is, minimizing T2 (or t_total) may require neither Cl_max nor sustained turn. I am confident with that claim because I have done a simulation on Mirage 2000. That is why I made AOA incremented.

I can believe it.

I gave something a whirl and my model is not going to be quickly adjustable to be AoA focused. The current setup is CL need based with limits. I tried giving an AoA limit higher than mid pull but lower than CL max pull and it still limited the CL to the mid pull. It will take some diving into the formulas to figure that one out.

gta4 wrote:So your scenario is not a "head-on merge", that is interesting and very few literature focus on it. I am looking forward to your conclusion.


My scenario is about a potential event that starts the shooting war. A 3-9 cross kill em as soon as you can scenario requires hostilities to have already begun. Otherwise my scenario would begin with BVR shots.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 16:38
by sprstdlyscottsmn
gta4 wrote:http://www.dept.aoe.vt.edu/~mason/Mason_f/F35unknownS03.pdf
This is a CFD analysis on F-35 A/B/C. I believe the drag polar is useful to you.

If read this report, and I do have a copy saved as a reference. I disagree with a few of their methods and thus the resulting conclusions.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 18:03
by sprstdlyscottsmn
I think I got it. Reworked how the CL was calculated, by having it calculated (it was a lookup before), and now I can fine tune the turning with an Alpha limit.

0.8M 30,000 init.

F-35C

Min_Radius 35_AoA (CL_Max)

T2 - 14 sec (11.8 sec with last second max AoA pull)
T_total - 61.5s
Radius - 2,569ft
Alt_fin - 27,269ft

Min_T2 27_AoA

T2 - 13.1 sec (10.7 sec with last second max AoA pull)
T_total - 55.5
Radius - 2,988ft
Alt_fin - 30,000ft

Min_T_total 8.6_AoA (Sust G)

T2 - 22.3 sec (17 sec with last second max AoA pull)
T_total - 22.8 sec
Radius - 5,946ft
Alt_fin - 30,000ft

Thanks for the discussion gta4! I think I will include all three as each one has a use. Min Rad for co-direction turn. Min T-2 for opposing direction turn. Min T-total for max energy retention.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 18:33
by gta4
You are welcome.
How did you calculate the last second pull where you need the pitch moment and moment of inertia?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 Feb 2018, 20:23
by sprstdlyscottsmn
gta4 wrote:You are welcome.
How did you calculate the last second pull where you need the pitch moment and moment of inertia?


In an overly simplified, but consistent, way. I record the change of flight path based on the specified turn and overlay that with max AOA. It would take 0.5-1sec to increase the pitch from the specified AoA to the max AoA but the plane will still be turning (and in most cases passing through CL max for best available rate) so I figure it kind of washes out. It's only a first order approximation but I feel pretty confident that I would not gain much more in accuracy for the effort it would take to get a second or third order estimate.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 Feb 2018, 02:00
by quicksilver
zzzzz....

Wake us up when you guys sort this stuff out.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Feb 2018, 03:28
by rheonomic
sprstdlyscottsmn wrote:
gta4 wrote:http://www.dept.aoe.vt.edu/~mason/Mason_f/F35unknownS03.pdf
This is a CFD analysis on F-35 A/B/C. I believe the drag polar is useful to you.

If read this report, and I do have a copy saved as a reference. I disagree with a few of their methods and thus the resulting conclusions.


Skimming it over it looks like an undergrad project where they ran X-35 approximate geometry through a vortex lattice code and added some drag correction, so I wouldn't put much (any?) stock in it.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Feb 2018, 16:20
by sprstdlyscottsmn
I just found an error in the sustained turn formula I used to calibrate the model to reality. The error was not present in the performance calculations. Net result, "calibrated" model gave superior performance than calibration. Only took a few minutes to fix when I tested it, but I have to re-run the missions as it changed fuel flow values. This is why I shouldn't work on this stuff past midnight.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Feb 2018, 19:13
by sprstdlyscottsmn
Hey guys,

If it's not one thing it's everything else. I found that my calibration for Sustained Turn was off ((a-b)/c got put in as (a/c)-b). The fix is not difficult but it takes a bit of time. Sorry for the delay. At this point I debate the value of releasing any comparison document vs just making my calibrated models for when people have questions on performance.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 May 2018, 17:48
by sprstdlyscottsmn
Further update. While I do not have flight manuals for the Rafale or Typhoon, I do have similar information available for them as I have for the Su-35 (except for actual clean Cdos and a lift curve). This has gotten me thinking that maybe I should make this less US focused. I really wanted to have the AV-8B+ to show what a leap in capability the F-35B is, but in the end it is just too poor at the interception and escort aspects. So in effect I am seriously considering altering the planes in test. Potential changes are the addition of Rafale and Typhoon as well as the potential replacement of F-16C with F-16V and SHornet Blk II with Blk III (upgrades begin 2020, it's in the timeline I am looking at). Maybe Hornet C with RACR upgrade? Is that funded somewhere? I know only one person left on the boards cares about this, other than me, so I don't expect the thread to blow up with comments.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 May 2018, 23:50
by viper12
I'd certainly be interested to see your updated analysis, so maybe that brings the number of people who care about it to two. :wink:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 May 2018, 23:59
by sprstdlyscottsmn
Well alright then!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 00:01
by juretrn
I think most members here care, it's just hard to contribute, or even make meaningful comments if aerodynamics is not your field.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 03:30
by garrya
sprstdlyscottsmn wrote:Further update. While I do not have flight manuals for the Rafale or Typhoon, I do have similar information available for them as I have for the Su-35 (except for actual clean Cdos and a lift curve). This has gotten me thinking that maybe I should make this less US focused. I really wanted to have the AV-8B+ to show what a leap in capability the F-35B is, but in the end it is just too poor at the interception and escort aspects. So in effect I am seriously considering altering the planes in test. Potential changes are the addition of Rafale and Typhoon as well as the potential replacement of F-16C with F-16V and SHornet Blk II with Blk III (upgrades begin 2020, it's in the timeline I am looking at). Maybe Hornet C with RACR upgrade? Is that funded somewhere? I know only one person left on the boards cares about this, other than me, so I don't expect the thread to blow up with comments.

That actually great, iam very much interested to see how these 4.5 gen compared, Rafale probably have the best STR at low-medium altitude or so i have heard.
viper12 wrote:I'd certainly be interested to see your updated analysis, so maybe that brings the number of people who care about it to two. :wink:

make it 4 :mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 04:09
by collimatrix
I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 14:57
by mixelflick
collimatrix wrote:I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.


Ditto!

The issue for the general public is this: They've heard everything from it got whipped by an old F-16 with drop tanks to.... it's 2nd only air to air to the Raptor.

So which is it? Or is the truth somewhere in between...??

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 15:09
by sprstdlyscottsmn
collimatrix wrote:I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.


The F-35A is the most "empty" fighter aircraft... possibly ever. With an empty weight of 29,300 lb and a total internal load of 23,500lb (weapons and fuel) and having it's length dictated by the LHA/LHD elevators, it certainly had to make concessions.

Wave drag can be thought at a very high level as fundamentally coming from Area Rule and Fineness Ratio.

The FR is where the F-35 suffers compared to the F-22 (as a directly applicable example). They have similar body width yet the F-35 is a dozen feet shorter. Yet, despite being a dozen feet shorter with a similar body width and shorter wingspan the F-35A manages to have about 2,200lb MORE internal carriage (between fuel and weapons) because it only has a single engine to deal with.

Now, the Area Rule is how smoothly the cross section increases down the length of the plane. Look closely at the F-35A. As the peak of the canopy blends back toward the fuselage the pointed intakes begin. Once the intakes meet the center body the bumps for the A-G weapons bay begins. Once those bumps reach their peak the wing begins. Follow this thought process as you look at the side and bottom views of the F-35A and you will see that it appears to have near flawless area ruling. Look at the bottom. Why doesn't it have a flat bottom like the F-22? It would be cheaper to manufacture and make it roomier in the weapons bays right? Instead it looks like a river coursing over rocks. The lower surface is carefully sculpted.

This is why an F-35A can effortlessly exceed 1.6M if the pilot chose to ignore the limits. Evidence of this? The F-35C has been taken to 1.6M. It has the same engine. It has a much larger wing that contributes to a poorer wave drag (as evidenced by the transonic acceleration times). If the same engine can push the plane with much more wave drag to 1.6M then it can easily push the F-35A beyond that. Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)

The design priorities of the F-35 are to be the perfect plane for the actual missions the F-16 and F/A-18 do in real life. Even ignoring the stealth and systems side of it, just looking purely at payload and performance, it exceeds the capabilities of the teen-series by far.

A clean F-16 is a hotrod, but it is also useless. Send it out on a CAP mission and it sees an increase in form drag and weight from missiles, pylons, fuel tanks, and maybe ECM gear. Send it out for a strike mission and it sees a bigger increase in form drag and weight from bombs and targeting pods in addition to the missiles, pylons, fuel tanks, and ECM gear.

A clean F-35 is not quite as much of a hotrod. Send it out on a CAP mission and it sees the weight of the missiles, no form drag. Send it out on the strike mission and it sees the weight of the bombs, no form drag. No pylon drag, no fuel tank drag, no ECM drag, no targeting pod drag.

Before you even add in the VLO properties, the F-35 is one of the finest warplanes ever designed.

As to the F-16 "dogfight", I will get to that later.

*EDIT* Now it's later. The only people who believe the F-35 lost a dogfight to an F-16D with two empty gas tanks are those who only read the hit pieces and not the test pilots report on the encounter, that was attached to at least one of the hit pieces.

The test was a CLAW test of the AoA region between 20 and 25 degrees AoA. The F-35 in question was not 3F or even unrestricted 3i. What the test pilot commented can best be summed up in a few points.

1. The CLAW begins blending from low AoA logic to high AoA logic in the 20-25 degree region. This should be increased to 35 AoA as at 25 AoA the F-35 still flies as if its at low AoA.
2. At the specified test AoA, the F-35 cannot generate sufficient rate to achieve or maintain an offensive position on the F-16 target. The specified AoA also does not allow sufficient energy retention.
3. Overall control responsiveness felt sluggish, particularly in pitch and yaw. Previous flight tests on later CLAW builds (remember, test was not done using latest CLAW in test at teh time) already demonstrated the safe use of more rapid control deflections.

So to further summarize: Open up and adjust the CLAW, don't fight at 20-25 AoA.

Recall Dolby Hanche talking about how he can rake the nose hard in an F-35 to get angular position and then accelerate quickly to recover the lost energy, an acceleration he states the F-16 would have to drop it's nose to achieve.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 16:58
by zero-one
sprstdlyscottsmn wrote: Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)


Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 17:36
by SpudmanWP
Ton as in 2000lbs

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 18:00
by sprstdlyscottsmn
zero-one wrote:Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs


Hey there zero one.

So AFAIK there is no 1,000 pound ton. There IS a 1,000kg ton (tonne, long ton, or metric ton) which is 2,200 lb.

Russian planes seem equipped only for 500kg and below weapons with the exception of the KAB 1500, a 1,500kg class weapon, and only three can be carried.

European planes only seem to carry LGBs instead of JDAMs, but even looking at "one-ton" LGBs the Tiffy carries a max of 2, the Rafale carries a max of 3, the Tornado carries a max of 2.

A Mk84 weight 2,031lb. Adding the GPS guidance kit to it will only increase the weight. It will not increase the weight beyond 2,200 lb as the GBU-10 LGB weighs in under that. So, being between 2,000 and 2,200 lb I just say "ton" as whether using metric or imperial it isn't far off.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 18:44
by vanshilar
sprstdlyscottsmn wrote:2. At the specified test AoA, the F-35 cannot generate sufficient rate to achieve or maintain an offensive position on the F-16 target. The specified AoA also does not allow sufficient energy retention.


As a minor nit on this. The pilot in the test report directly said "The CLAW prevented such shot opportunities" -- in other words, it wasn't because of fundamental aerodynamic limitations with the F-35 aircraft, but because of the software limitations put in place at that time that it didn't have sufficient rate. One of his recommendations was, of course, to adjust the CLAW parameters to increase that rate -- so it should no longer be an issue now.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 18:54
by sprstdlyscottsmn
vanshilar wrote:As a minor nit on this. The pilot in the test report directly said ...

I appreciate the quote. I don't have my copy of the report on hand.

I don't think the CLAW can change the aerodynamics though. Lift at the AoA is the lift at the AoA. What the CLAW can and does control is the transition and onset rates for pitch, roll, and yaw.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 19:21
by steve2267
I do not know to what extent this plays into the CLAW discussion, but I do recall the test pilot in the "infamous CLAW test" was stated as having a lot of flight time in F-15's, if memory serves, so it is possible he was "fighting" the F-35 as he would an F-15, unless the test had very specific procedures / test cards. The more I think of it, I'll stick with specific test cards, so his F-15 experience probably had little to do with the test. However, more recently, we have had quotes from F-35 pilots stating that one of the reasons the F-35 is waxing everyone's a$$ (my words) is because they have learned how to fly it -- how to take advantage of its strengths and avoid its weaknesses. So it appears quite possible that, as Spurts says above, don't fight the F-35 in the 20-25° AoA regime. Perhaps that regime is not one of the strong suites of the F-35. Either stay below 20° alpha and keep your energy up, or transition up to 35-40° (numbers I pulled out of thin air) to slow down, and out-radius the other guy.

While it appears that the LM flight control wizards were able to open CLAW up and improve those rates, it is possible that fighting the F-35 in that blended control region is not the F-35's strong suite. FWIW.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 22:39
by viper12
sprstdlyscottsmn wrote:There IS a 1,000kg ton (tonne, long ton, or metric ton) which is 2,200 lb.


Just to nitpick a bit, a long ton is actually different, being the heaviest of all tons around ; it's 2,240lb = 1,016kg : https://en.wikipedia.org/wiki/Long_ton

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 09 May 2018, 22:53
by sprstdlyscottsmn
viper12 wrote:
sprstdlyscottsmn wrote:There IS a 1,000kg ton (tonne, long ton, or metric ton) which is 2,200 lb.


Just to nitpick a bit, a long ton is actually different, being the heaviest of all tons around ; it's 2,240lb = 1,016kg : https://en.wikipedia.org/wiki/Long_ton

I did not know that. Thanks! I love learning new random bits.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 10 May 2018, 02:29
by gta4
The most evident proof of F-35's maneuverability limitation in 2015:
Pilots complained about F-35's pitch rate.
Now, who complains F-35's pitch rate? Those airshow moves clearly contradicts that.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2018, 10:23
by collimatrix
Spurts, thank you very much!

Do you mind if I repost your explanation elsewhere?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 11 May 2018, 14:20
by sprstdlyscottsmn
By all means, do.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 May 2018, 20:52
by collimatrix
Further question; why would the F-35 be weaker in the 20-25 AOA range where the F-16 dominates? Is there anything to the idea that the F-35 was optimized for instantaneous turn rate while the F-16 was optimized for sustained turn rate?

Thank you for clarifying the issue of fineness ratio vs area ruling.

F-35C vs F-35A is interesting. The F-35C lacks the little wing root vortex generators that the A has. Presumably it has to generate a lot of lift at a fairly low AOA for carrier operations. Which makes me wonder; what would happen if you put an F-35C wing on an F-35B? STOVL operations require quite a bit of low-airspeed lift too.

One of the things I remember when I read earlier drafts of the operational performance comparison is that the F135 engine has surprisingly uninspiring specific fuel consumption. Given that it's a generation newer than the F100/F110, it should have a higher overall pressure ratio and a hotter turbine inlet temperature. It's also got a rather high bypass ratio. All else being equal, those things should make it an exceptionally efficient engine. But it isn't.

What is your guess as to why that is? I was thinking that the LO features of the nozzle trade away a bit of SFC. But that's just a guess. Could it be something else? Could the compressor have a rather low isentropic efficiency in exchange, say, for compactness, light weight or good throttle response?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 14 May 2018, 21:55
by sprstdlyscottsmn
collimatrix wrote:Further question; why would the F-35 be weaker in the 20-25 AOA range where the F-16 dominates? Is there anything to the idea that the F-35 was optimized for instantaneous turn rate while the F-16 was optimized for sustained turn rate?


We cannot draw the conclusion that the F-16 was also using 20-25 AoA. At no point does the test report indicate the regime the F-16 was using. If anything, we can conclude the F-16 was at less than 25 degrees as that only allows 1G in the CAT-I configuration while 20 degrees is around 7G IIRC.

The F-16 was optimized to reduce speed lost in a max pull. The F-35 is optimized to lose and gain speed as needed.

collimatrix wrote:F-35C vs F-35A is interesting. The F-35C lacks the little wing root vortex generators that the A has. Presumably it has to generate a lot of lift at a fairly low AOA for carrier operations. Which makes me wonder; what would happen if you put an F-35C wing on an F-35B? STOVL operations require quite a bit of low-airspeed lift too.


The F-35C also has full span flaps/flaperons and a large lifting tail. I expect its lift curve looks very different than the F-35A. As for a STOVL C (or big wing B) I doubt it would even be able to operate. Adding 160ft^2 of wing and likely another 60ft^2 of tail is going to add a lot of weight. The C is the heaviest variant and it isn't all in the landing gear and longerons. Think instead of it this way, the difference in weight from the A to the B is all STOVL requirement, now add that weight to the C. It would also then be too wide to operate from small deck carriers.


collimatrix wrote:One of the things I remember when I read earlier drafts of the operational performance comparison is that the F135 engine has surprisingly uninspiring specific fuel consumption. Given that it's a generation newer than the F100/F110, it should have a higher overall pressure ratio and a hotter turbine inlet temperature. It's also got a rather high bypass ratio. All else being equal, those things should make it an exceptionally efficient engine. But it isn't.


There are a LOT of systems on the F-35. That requires a LOT of power. That power comes from the gearbox on the F135. It takes fuel to keep that gearbox adequately powered. I agree that on the surface I would expect the F135/F119 to have a better TSFC than the F100/F110 line. I don;t have enough info here to give a better answer.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 15 May 2018, 05:18
by wrightwing
zero-one wrote:
sprstdlyscottsmn wrote: Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)


Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs


6 2k lb JDAMS

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 May 2018, 17:08
by sprstdlyscottsmn
With my new sheet I'm taking another look at how I was going to be scoring the aircraft. I decided to make a scaled effect list for ECM and a radars ECCM as well as working an assumption of tracking range vs detection range based on advancement of radar technology.

Previously it was a generic "if the radar can detect you then it can track you, and if the ECM can detect the radar in can jam it. Jamming reduces detection range by 50%" I never liked how that was very cut and dry and didn't play in to the intricacies of modern radar and ECM at all. I spent a few days pouring over garrya's blog until I came up with something that I feel better approximates reality but is still simple enough for me to implement.

I know 100% that what I do here is not correct as the truth about ECM and ECCM is extremely classified and anyone who knows how my analysis is wrong will not be allowed to tell me how to make it right.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 29 May 2018, 19:43
by madrat
Actually tonnes/tons should be generally either 2,000 pounds or 1,000 kilograms.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 04 Jun 2018, 18:36
by sprstdlyscottsmn
For the sake of everyone understanding the accuracy that I drive toward for my modeling I am showing the calibrations I used for the Strike Eagle (-229). Clean here refers to no ordnance or CFTs, AA refers to 8 missiles, CFTs, and LANTIRN (configuration found in -1 and also used in actual combat)

I used the clean 40,000ft accelerations to make sure my actual excess thrust is in the correct ballpark.
Mudhen Cal Accel Clean 43-600.PNG


I used the AA 40,000ft accelerations to make sure my supersonic drag model for ordnance is in the correct ballpark.
Mudhen Cal Accel AA 60-700.PNG


I then use the flight envelopes to make sure that my thrust values at key speeds are correct.
Mudhen Cal Env Clean 40-000.PNG

Mudhen Cal Env AA 55-000.PNG


I use the AA STR plot to make sure my thrust values at 20,000ft are calibrated with my dynamic Oswalds Efficiency Factor.
Mudhen Cal Sust AA 55-000.PNG


And I use Max End fuel flows and Max Range Opt Cruise values with AA loading across almost the entire fuel range to calibrate my induced drag and my dynamic fuel flow model.
Mudhen Cal Fuel AA.PNG


Once I get my model to this level of calibration I am confident that I can simulate a wide range of performance parameters including those not found in the FM.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 08:51
by hornetfinn
I really like your approach sprts! :D

This is really educational, thanks a lot!

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 10:31
by Corsair1963
sprstdlyscottsmn wrote:
collimatrix wrote:I am curious if you would be willing to make a post giving your interpretation of the design priorities and general capabilities of the F-35.

When I read your first work in this thread, I had come away with the following impression of the F-35:

-The F-35 doesn't compare so well to the best fourth gen fighters in a guns only dogfight if both are clean and at half fuel.

-Part of this is because the F-35 carries a ridiculous amount of fuel, and because it has internal weapons bays. If the two fighters are given equal internal fuel endurance, and an actual air to air weapon load, the F-35 quickly pulls ahead.

-Still, all those weapons bays and all that fuel have to fit somewhere. The F-35 is a rather stubby, tubby plane with a shape that works very well for stealth and reasonably well for subsonic flight efficiency. However, the F-35 has somewhat unavoidably high wave drag because it just isn't that long and pointy, so its transonic and supersonic performance are less impressive.

I was curious if you might confirm or dispel those general conclusions, and what your overall take on the F-35's aerodynamic priorities is.


The F-35A is the most "empty" fighter aircraft... possibly ever. With an empty weight of 29,300 lb and a total internal load of 23,500lb (weapons and fuel) and having it's length dictated by the LHA/LHD elevators, it certainly had to make concessions.

Wave drag can be thought at a very high level as fundamentally coming from Area Rule and Fineness Ratio.

The FR is where the F-35 suffers compared to the F-22 (as a directly applicable example). They have similar body width yet the F-35 is a dozen feet shorter. Yet, despite being a dozen feet shorter with a similar body width and shorter wingspan the F-35A manages to have about 2,200lb MORE internal carriage (between fuel and weapons) because it only has a single engine to deal with.

Now, the Area Rule is how smoothly the cross section increases down the length of the plane. Look closely at the F-35A. As the peak of the canopy blends back toward the fuselage the pointed intakes begin. Once the intakes meet the center body the bumps for the A-G weapons bay begins. Once those bumps reach their peak the wing begins. Follow this thought process as you look at the side and bottom views of the F-35A and you will see that it appears to have near flawless area ruling. Look at the bottom. Why doesn't it have a flat bottom like the F-22? It would be cheaper to manufacture and make it roomier in the weapons bays right? Instead it looks like a river coursing over rocks. The lower surface is carefully sculpted.

This is why an F-35A can effortlessly exceed 1.6M if the pilot chose to ignore the limits. Evidence of this? The F-35C has been taken to 1.6M. It has the same engine. It has a much larger wing that contributes to a poorer wave drag (as evidenced by the transonic acceleration times). If the same engine can push the plane with much more wave drag to 1.6M then it can easily push the F-35A beyond that. Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)

The design priorities of the F-35 are to be the perfect plane for the actual missions the F-16 and F/A-18 do in real life. Even ignoring the stealth and systems side of it, just looking purely at payload and performance, it exceeds the capabilities of the teen-series by far.

A clean F-16 is a hotrod, but it is also useless. Send it out on a CAP mission and it sees an increase in form drag and weight from missiles, pylons, fuel tanks, and maybe ECM gear. Send it out for a strike mission and it sees a bigger increase in form drag and weight from bombs and targeting pods in addition to the missiles, pylons, fuel tanks, and ECM gear.

A clean F-35 is not quite as much of a hotrod. Send it out on a CAP mission and it sees the weight of the missiles, no form drag. Send it out on the strike mission and it sees the weight of the bombs, no form drag. No pylon drag, no fuel tank drag, no ECM drag, no targeting pod drag.

Before you even add in the VLO properties, the F-35 is one of the finest warplanes ever designed.

As to the F-16 "dogfight", I will get to that later.

*EDIT* Now it's later. The only people who believe the F-35 lost a dogfight to an F-16D with two empty gas tanks are those who only read the hit pieces and not the test pilots report on the encounter, that was attached to at least one of the hit pieces.

The test was a CLAW test of the AoA region between 20 and 25 degrees AoA. The F-35 in question was not 3F or even unrestricted 3i. What the test pilot commented can best be summed up in a few points.

1. The CLAW begins blending from low AoA logic to high AoA logic in the 20-25 degree region. This should be increased to 35 AoA as at 25 AoA the F-35 still flies as if its at low AoA.
2. At the specified test AoA, the F-35 cannot generate sufficient rate to achieve or maintain an offensive position on the F-16 target. The specified AoA also does not allow sufficient energy retention.
3. Overall control responsiveness felt sluggish, particularly in pitch and yaw. Previous flight tests on later CLAW builds (remember, test was not done using latest CLAW in test at teh time) already demonstrated the safe use of more rapid control deflections.

So to further summarize: Open up and adjust the CLAW, don't fight at 20-25 AoA.

Recall Dolby Hanche talking about how he can rake the nose hard in an F-35 to get angular position and then accelerate quickly to recover the lost energy, an acceleration he states the F-16 would have to drop it's nose to achieve.



I guess weasel1962 didn't read this thread....... :wink:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 13:03
by marsavian
So clean and without CFTs the -229 Eagle can supercruise at Mach 1.1 ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 13:41
by sprstdlyscottsmn
Yes, but that doesn't get you anything.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 19:33
by viper12
marsavian wrote:So clean and without CFTs the -229 Eagle can supercruise at Mach 1.1 ?


I also doubt the fuel consumption is worth it. Aircraft designers tend to avoid having the cruise speed in the Mach 0.9-1.2 range IIRC because the fuel efficiency is relatively bad.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 20:53
by playloud
viper12 wrote:
marsavian wrote:So clean and without CFTs the -229 Eagle can supercruise at Mach 1.1 ?


I also doubt the fuel consumption is worth it. Aircraft designers tend to avoid having the cruise speed in the Mach 0.9-1.2 range IIRC because the fuel efficiency is relatively bad.

If you listen to Gripen E fans, they think the jet will be supercruising around at Mach 1.1 all day.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 21:25
by sprstdlyscottsmn
viper12 wrote:
marsavian wrote:So clean and without CFTs the -229 Eagle can supercruise at Mach 1.1 ?


I also doubt the fuel consumption is worth it. Aircraft designers tend to avoid having the cruise speed in the Mach 0.9-1.2 range IIRC because the fuel efficiency is relatively bad.

Not necessarily. Depending on the design at the loadout the optimum cruise speed may very well be a tad over 0.9 at higher altitudes. Eagles and Vipers are great examples of this. The Mudhen with CFTs has an earlier mach for drag divergence (beginning of transonic wave drag) and it still pull 0.86M for best range in an air to air loadout.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 05 Jun 2018, 22:20
by marsavian
sprstdlyscottsmn wrote:Yes, but that doesn't get you anything.


It would allow you to close in on everyone else going subsonic in military power plus allow you to bleed off speed in a turn down to Mach 0.85 while increasing your turn rate at the same time. Seems a useful starting position to begin air combat. Could the -229 still do this supercruise with just 4 body AAMs and the full 8 (+4 wing AAMs) too ?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 02:15
by sprstdlyscottsmn
If you drop the pods an 8 missiles Mudhen would just crack Mach 1 when not above 30,000ft. Less than 1.05M. Drop the CFTs and you are looking at close to 1.1M.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 03:16
by steve2267
sprstdlyscottsmn wrote:If you drop the pods an 8 missiles Mudhen would just crack Mach 1 when not above 30,000ft. Less than 1.05M. Drop the CFTs and you are looking at close to 1.1M.


So... get yourself there a bit quicker... to a gunfight?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 04:35
by Corsair1963
wrightwing wrote:
zero-one wrote:
sprstdlyscottsmn wrote: Also, the F-35C still has enough "oomph" to break Mach 1 with six one-ton JDAMs and four A-A missiles. How many navy planes can even carry that load? (F-35C only) How many fighter aircraft in the world can even carry that load? (F-35A, F-35C, F-15E) And how many of those are single engine? (F-35A/C only)


Hi sprst, Im curious about this line? Its amazing, but were Flankers and other European fighters also taken into account?

Also when we say six 1 ton JDAMs are we talking tonnes 1,000 pound Jdams or tonnes 2,000 poud JDAMs. cause I tried to convert and it seems that there are a few different kinds of tonnes. 1 is equivalent to around 1k lbs and the other is around 2k lbs


6 2k lb JDAMS


F-35CbombedUpOverSea.jpg




https://news.usni.org/wp-content/upload ... 282835.jpg

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 05:03
by sprstdlyscottsmn
steve2267 wrote:
sprstdlyscottsmn wrote:If you drop the pods an 8 missiles Mudhen would just crack Mach 1 when not above 30,000ft. Less than 1.05M. Drop the CFTs and you are looking at close to 1.1M.


So... get yourself there a bit quicker... to a gunfight?

Let me run some numbers on this tomorrow. PM me in the morning to remind me, will ya?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 08:33
by zero-one
F-35CbombedUpOverSea.jpg




https://news.usni.org/wp-content/upload ... 282835.jpg[/quote]

I feel like the C would be the best performing F-35 overall. Though the A will have an edge in most energy related performance metrics.

But if it can break the barrier with this 12,000+ pound load, then it looks like it has plenty of power to go around
By the way, do we have links to support that? It's not that I don't believe it, but it would be nice to post that on basement dweller threads.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 08:39
by spazsinbad
Go here for MOAR: viewtopic.php?f=22&t=53438&p=380737&hilit=d3Lqqewy9II#p380737

HOOK 2017 Update on F-35C testing LM test pilot QUOTE


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 14:01
by steve2267
spazsinbad wrote:Go here for MOAR: viewtopic.php?f=22&t=53438&p=380737&hilit=d3Lqqewy9II#p380737

HOOK 2017 Update on F-35C testing LM test pilot QUOTE



I don't mean to kick a hornet's nest, and I thought we had put this to rest, but since we're quoting...

At the 0:15 mark, he clearly states "and GBU-32's across the board..." which are 1000lb munitions. Did he ever correct himself, or do we know for sure, that these were in fact GBU-31s? (i.e. 2000lb munitions)

Hell, even if they are 1000lb bombs, it is still impressive to be hauling that load past the barrier.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 14:44
by sprstdlyscottsmn
steve2267 wrote:
spazsinbad wrote:Go here for MOAR: viewtopic.php?f=22&t=53438&p=380737&hilit=d3Lqqewy9II#p380737

HOOK 2017 Update on F-35C testing LM test pilot QUOTE



I don't mean to kick a hornet's nest, and I thought we had put this to rest, but since we're quoting...

At the 0:15 mark, he clearly states "and GBU-32's across the board..." which are 1000lb munitions. Did he ever correct himself, or do we know for sure, that these were in fact GBU-31s? (i.e. 2000lb munitions)

Hell, even if they are 1000lb bombs, it is still impressive to be hauling that load past the barrier.

The image is definitively GBU-31s on the wings.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 16:01
by sprstdlyscottsmn
steve2267 wrote:
sprstdlyscottsmn wrote:If you drop the pods an 8 missiles Mudhen would just crack Mach 1 when not above 30,000ft. Less than 1.05M. Drop the CFTs and you are looking at close to 1.1M.


So... get yourself there a bit quicker... to a gunfight?

So, CFTs and 8 missiles brings a Mudhen to 1.01M. Drop the CFTs and operate as a heavy F-15D and it goes up to 1.04M. Drop the pylons and go with belly missiles only, 1.08M. Now we are speaking purely in terms of academics as Eagles don't fly without the wing pylons.

Let's say for a moment a "Heavy D" Strike Eagle is in a CAP at 32,000ft. 8AAMs, no CFTs, wing tanks.

Contact. 100nm out. Visual needed asap. Still 3,000lb of fuel in the drop tanks. What do you do? Best Cruise? Full Mil? AB? Keep tanks vs punch them?

Keep tanks.
- Best Cruise 0.86M @ 41,000ft. (Baseline)
- - 7 min to climb to 41,000ft at schedule speed. 5.3 min at cruise. 12.3 min total
- - 946lb fuel to climb to 41,000ft at schedule speed. 554lb in cruise. 1,500lb total (still have ~1,500 in tanks)
- - 56nm covered in climb. 44nm in cruise

- Full Mil 1.02M @ 32,000ft.
- - 10.75 minutes to cover distance. 93 seconds saved
- - 2,790lb fuel consumed. 1,290lb more than baseline (tanks nearly empty)

- AB 1.4M @ 50,000ft
- - 3.25 minutes to SS climb. 4.7min in cruise. 261 seconds saved
- - 4,180lb of fuel in climb, 4,464 in cruise. 8,644 lb of fuel consumed in total. 7,144lb more than baseline

Punch tanks.

- Full Mil 1.03M @ 32,000ft
- - 10.45minutes to cover distance. 111 seconds saved
- - 2,848lb of fuel consumed in addition to 3,000lb dropped.

- AB 1.4M @ 50,000ft.
- - 2.75 minutes to SS climb. 5.13min in cruise. 265 seconds saved
- - 3,647lb of fuel in climb, 4,631lb in cruise. 8,305 lb of fuel consumed in addition to the 3,000lb dropped.

So as we can see these limited Full Mil dashes can save time over longer distances (roughly a third of the time saved over a high altitude SS dash) but they also consume roughly a fifth as much extra fuel as using AB. I suppose it makes a nice tool for the toolbox.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 16:16
by steve2267
Thanks for running the numbers.

Apparently I mis-read an earlier comment and thought that to get those low SS cruise numbers, the Mudhen had to jettison all tanks, CFTs, pylons, and missiles... hence the query about going to a gunfight. My bad.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 16:54
by sprstdlyscottsmn
steve2267 wrote:Thanks for running the numbers.

Apparently I mis-read an earlier comment and thought that to get those low SS cruise numbers, the Mudhen had to jettison all tanks, CFTs, pylons, and missiles... hence the query about going to a gunfight. My bad.

You did not really misread anything. The 1.1M+ SC number does indeed require a completely clean airframe.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 19:52
by splittingatoms
sprstdlyscottsmn wrote:
steve2267 wrote:
sprstdlyscottsmn wrote:F-15 related numbers


How does an F-35A compare in this scenario, assuming its internally loaded and has a similar fuel state? Does a quick hit of burner and then limited mil-power "supercruise" compare favorably? I won't presume to dictate the best scenarios...you're far better than I. I'm just interested to see the real world implications of a clean airframe and high fuel fraction.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 06 Jun 2018, 20:36
by sprstdlyscottsmn
splittingatoms wrote:How does an F-35A compare in this scenario, assuming its internally loaded and has a similar fuel state? Does a quick hit of burner and then limited mil-power "supercruise" compare favorably? I won't presume to dictate the best scenarios...you're far better than I. I'm just interested to see the real world implications of a clean airframe and high fuel fraction.

I don't have an updated F-35A model yet. My previous model shows a full Mil dash reaching 1.048M and using 2,300lb fuel over 10.1 minutes to cover the 100nm. AB dash takes 7.95 minutes, 4,461lb fuel. Again, my F-35A model is less accurate than my F-15E model right now.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 07 Jun 2018, 23:47
by sprstdlyscottsmn
Fixed my Post Stall effects to better simulate the "flat plate" drag of an aircraft at high AoA. The Strike Eagle is heavy too. Too heavy.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 13:25
by Dragon029
You need to get a copy of the new AIAA tech paper: "F-35 Aerodynamic Performance Verification"; I'm skimming it now and it appears to have a fair bit of F-35 flight test data, including altitude vs mach flight envelope charts, lift coefficient vs aoa charts, fuel flow vs mach number, etc; a lot of the charts don't specify which variant they're talking about, and the charts generally don't have their axis fully labelled, but they do show curves and test points for specified altitudes, airspeeds, etc on grids whose intervals, etc can be estimated.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 14:04
by gta4
Dragon029 wrote:You need to get a copy of the new AIAA tech paper: "F-35 Aerodynamic Performance Verification"; I'm skimming it now and it appears to have a fair bit of F-35 flight test data, including altitude vs mach flight envelope charts, lift coefficient vs aoa charts, fuel flow vs mach number, etc; a lot of the charts don't specify which variant they're talking about, and the charts generally don't have their axis fully labelled, but they do show curves and test points for specified altitudes, airspeeds, etc on grids whose intervals, etc can be estimated.


I can't find it using google scholar. Can you show us the link please?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 14:30
by Dragon029
https://arc.aiaa.org/doi/pdf/10.2514/6.2018-3679

Without buying it you can't really see much; I'm hesitant to post the full thing, because when you buy and download a copy it has your membership details (like full name) attached to the document (which I can remove from the pages, but I'm not 100% certain there isn't metadata tagging me in it).

Anyway, here's some of the charts - the flight envelope one appears to resemble an F-16C (with an F100-PW-229) with a gross weight of about 30,000lb and a DI of something like 70.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 15:16
by Dragon029
In part of the document there's also a little chart included as part of a diagram; zoomed in it appears to show an F-35 E-M chart. The chart comes from a Figure outlining the process of calculating F-35 flight performance data, so AFAIK it's not based on flight test data, just wind tunnel, propulsion testing, etc data from early / mid stages of SDD.

I don't know what gross weight it represents, I don't know which F-35 variant it represents, etc, but I still think it's interesting:

What I'm seeing here is a minimum turn radius of a little over 2000ft (achieved between Mach 0.3 and Mach 0.7), a max instantaneous turn rate of about 20 deg/s at Mach 0.7 and +8Gs, with a specific excess power of -2500ft/s. Max sustained turn rate is shown at about 12 deg/s at Mach 0.8, +6Gs and a turn radius of something like 4250ft.

Again, there's a lot of unknowns about what exactly we're looking at here, but maybe one of you might be able to deduce some additional details from what we're seeing here.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 15:40
by sprstdlyscottsmn
What I see is that it represents an A model based on the 9G limit. I see that it does not do 9G to corner so it has a tapering feature similar to the F-16. If the Envelope Chart also shows in A model, then it seems as though the E-M chart represents an altitude of ~19,000ft based on ultimate speed (just past 1.4M) but with a higher Drag Index than the envelope chart (1.25M at Ps-0 for EM vs ~1.29M at Ps=0 for Envelope) but at a lighter weight than the Envelope chart (min speed of 0.2M in E-M vs min speed 0.25M in Envelope).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 17:01
by gta4
Wait! Cruise at Mach 1.4?
What does PA cruise mean?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 17:10
by sprstdlyscottsmn
gta4 wrote:Wait! Cruise at Mach 1.4?
What does PA cruise mean?

Don't get hung up on it. Think of it as measuring the fuel flow while at the throttle setting needed to sustain that speed and altitude.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 18:05
by gta4
The se[ value at 19000 ft is amazing.
Accurate prediction 2 year ago:
F-35 will have very good subsonic SEP
viewtopic.php?f=55&t=52510

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 19:48
by quicksilver
gta4 wrote:Wait! Cruise at Mach 1.4?
What does PA cruise mean?


Powered Approach

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 02 Jul 2018, 19:57
by spazsinbad
"...B. Test Matrix
The F-35 Aerodynamics and Propulsion teams entered the flight test phase of the SDD program with a high-fidelity
wind tunnel, analytical database. Extensive work was accomplished to ensure that all forces and moments identified
in the force and moment bookkeeping system were well-defined from wind tunnel testing and CFD. This was
particularly important when objectives were difficult to achieve from testing. The comprehensive nature of the
preflight databases was key to successfully verifying aircraft performance requirements with a minimal matrix of
flight test maneuvers.

The matrix of dedicated aircraft performance flight test maneuvers was designed to minimize required test flights.
At the same time, it continued to provide the data necessary to verify the KPP performance requirements and validate
the performance databases for all phases of flight. The goal was to validate a credible collection of the databases that
formed the basis of the performance products provided to the operator (e.g., flight manual, pilot checklist, performance
on the glass). The IFTPWG balanced fidelity in the final databases with the cost of testing and analysis. Its members
were constantly evaluating and refining the test matrices due to programmatic pressure to reduce flight test costs and
shorten the schedule. In the end, the number of dedicated test points flown for any one variant was roughly half the
number used for previous fighter aircraft. Table 2 summarizes the test points for clean configuration...."
&
"...Aerodynamics data for the aircraft in an up-and-away configuration (i.e., gear up) were standardized to the nearest
database breakpoint Mach number, 36,089-foot pressure altitude, a constant center of gravity, and a set of engine
operating parameters generally consistent with cruise conditions. The altitude serves as the baseline condition for the
aerodynamics database. Aerodynamics data for the aircraft in a powered-approach configuration (i.e., gear down)
followed that process but was modified due to the difference in typical operating altitudes between an up-and-away
and a powered-approach configuration; the latter occurs nearer to sea level so that sea level serves as the baseline for
powered-approach configuration aerodynamics. All aerodynamics standardization was completed holding test α
constant because the databases are a function of α, rather than of CL ..."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 02:59
by sprstdlyscottsmn
Okay, so I took the last few weeks off to help a board member develop some turn performance stuff, but now I am back at it. Examples of metrics being looked at currently are "Escort gone wrong" a co-direction, co-speed, closest altitude, 3-9 break into each other from half a mile. Both parties are executing a 180 and firing along the way. I will be scoring the odds of no one dies, red force only dies, blue force only dies, and both parties die. I will also do a BVR joust where I will be looking at the same odds only there will be no evasive maneuvers as the complexity goes through the roof. I will also to a 3-9 cross from 1/4 mile at the end of the joust into a break. The aircraft to include seem to change monthly, with the retirement of the Hornet, the funding of Block III- Super Hornet, the sale of the F-16V. BTW, I will be representing the most advanced versions of the aircraft found around the globe, meaning I will need to see what I really need to change to turn an F-15E into an F-15SA. Hmm, does this mean I still include Swiss F/A-18s?

*EDIT* It takes a long time to validate a performance model right now, between 20-40 hours. Then another 10 or so to run the model through the mission sets. I am halfway through F-15E mission sets and I don't know what will change to make it an F-15SA. I am already assuming APG-81 and EPAAWS. I'll have to look back at an old comparison I did to see what the impacts of the F110 will be.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 08:12
by Dragon029
sprstdlyscottsmn wrote:What I see is that it represents an A model based on the 9G limit. I see that it does not do 9G to corner so it has a tapering feature similar to the F-16. If the Envelope Chart also shows in A model, then it seems as though the E-M chart represents an altitude of ~19,000ft based on ultimate speed (just past 1.4M) but with a higher Drag Index than the envelope chart (1.25M at Ps-0 for EM vs ~1.29M at Ps=0 for Envelope) but at a lighter weight than the Envelope chart (min speed of 0.2M in E-M vs min speed 0.25M in Envelope).


Nice note; for comparison, here's an F-16C (F100-PW-229, GW 22,000lb, DI=0) at 20,000ft:

Image

That's <9 deg/s sustained and 17.1 deg/s instantaneous vs ~12 deg/s and ~20 deg/s.

Also, maybe I'm missing something, but doesn't the envelope show a min speed of about Mach 0.15 rather than Mach 0.25?

That would mean that the E-M chart F-35A is both draggier and heavier than the envelope aircraft, which suggests even greater performance (as the envelope should be newer / real world data vs old calculated semi-real world data in the E-M chart; it's also unlikely that the envelope aircraft is an F-35B or F-35C if it's lighter and less draggy than an (albeit combat loaded) F-35A).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 08:40
by garrya
Dragon029 wrote:]

Nice note; for comparison, here's an F-16C (F100-PW-229, GW 22,000lb, DI=0) at 20,000ft:

Image

That chart is for Mil power, Max AB look like this
Capture.PNG

So comparing F-35 and F-16 F-110 GE129 ( DI=0)
ITR = 20°/s for f-35 and 17.4°/s for F-16
STR = 12 °/s for f-35 and 12.5°/s for f-16

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 10:24
by Dragon029
Woops, that does sound more realistic.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 14:59
by sprstdlyscottsmn
Dragon029 wrote:
Also, maybe I'm missing something, but doesn't the envelope show a min speed of about Mach 0.15 rather than Mach 0.25?


You have to look up at 19,000ft on the Envelope. No worries.

Garrya, ITR like a Hornet and STR like a Viper seems to be holding up.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 15:18
by gta4
Still wondering what are the details of the "mach 1.4 PA cruise". That would become some decent data on airshow brochure.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 15:41
by Dragon029
Where did "mach 1.5 PA cruise" come from? As quicksilver already mentioned, PA cruise means powered approach, with the 'cruise' aspect indicating that it's flying level with landing gear down, like in a circuit. On the flight envelope diagram those marks only exist down in the bottom left between Mach ~0.18 and Mach 0.4 at 5000ft.

As for the regular 'cruise' marker at Mach 1.5, it's my understanding that 'cruise' in this context doesn't exclude afterburner usage; it's just maintaining a constant airspeed and altitude for the purposes of measuring things like tail deflections, the thermal and vibratory environment, etc.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 15:44
by steve2267
sprstdlyscottsmn wrote:
Dragon029 wrote:
Also, maybe I'm missing something, but doesn't the envelope show a min speed of about Mach 0.15 rather than Mach 0.25?


You have to look up at 19,000ft on the Envelope. No worries.

Garrya, ITR like a Hornet and STR like a Viper seems to be holding up.


That an airshow clean Viper can only slightly out turn an F-35 (12.5°/sec vs 12°/sec) also seems to hold.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 19:54
by garrya
sprstdlyscottsmn wrote:
Garrya, ITR like a Hornet and STR like a Viper seems to be holding up.

How does its ITR compare with Mirage, F-14 at similar altitude? Inferior or superior?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 03 Jul 2018, 20:50
by quicksilver
Dragon, he asked, what does 'PA cruise' mean? I dont think he intended the statement about mach and his question about PA cruise to be connected.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 15:55
by sprstdlyscottsmn
In realizing that one of my big problems is constantly shifting the goal posts for what I want to compare based on what my model can do, I am deciding to instead do the full document writeup with everything except the performance analysis first so that my scope is clearly defined. So, in that effort, I have some decisions to make regarding the configurations of the planes in the analysis. I would like your collective input. As I am looking at the most advanced variants of each fighter, this leaves me with the following for the teen series.

F-15SA
F-16V
F/A-18E Blk III

Now, the F-15SA and B3 SHornet will have CFTs, but what about the F-16V. Several foreign customers use CFTs, and several foreign customers have purchased/are purchasing F-16Vs new or as upgrades. Only Singapore seems to already have CFTs and an upgrade plan to F-16V. No documentation for the F-16V I have seen has ever mentioned CFTs. Do I just go ahead and put CFTs on the F-16V?

Also, has anyone actually purchased CFTs for the Typhoon or Rafale? I am doing TR3 Tiffy and Rafale M for my comparison as well.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 17:10
by SpudmanWP
The official F-16V LM Product Card has CFTs.

https://www.lockheedmartin.com/content/ ... rd2016.pdf

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 17:40
by sprstdlyscottsmn
Perfect! Thanks Spud.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 17:58
by SpudmanWP

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 18:57
by sprstdlyscottsmn
So, I kept looking at orders. Everytime I looked up a news article about the F-16V and who bought it I never saw mention of CFTs. I honestly never even thought to go to the manufacturers website as I was so focused on who bought them.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 18:59
by garrya
garrya wrote:How does its ITR compare with Mirage, F-14 at similar altitude? Inferior or superior?

So for my question earlier, i can't find 20k ft diagram for either F-14 or Mirage, only 15k ft chart are available
Mirage 2000.JPG

At 15k ft:
Mirage 2000 with 2 missiles
Maximum STR: 13 deg/sec
Maximum ITR: 23.9 deg/sec

F-14D with 8 missiles
Maximum STR: 12.3 deg/sec
Maximum ITR: 18 deg/sec


Comparing with F-35 chart at 19k ft
Maximum STR: 12 deg/sec
Maximum ITR: 20 deg/sec
Image

At first glance, F-35 values are smaller, but we should note that data are measured at 4000 ft higher where air are thinner, this affect STR and ITR negatively.
For example when altitude changed from 15k ft to 20k ft
F-16 ITR changed from 19.1 deg/sec => 17.4 deg/sec ( a reduction of around 8.9%)
F-16 STR changed from 15 deg/sec => 12.5 deg/sec ( a reduction of around 16.67%)

F-16.JPG


In short, assuming there are similar degradation due to altitude, F-35 STR is better than both Mirage 2000 and F-14D, however, its ITR is not as good as Mirage 2000. So F-35 agility is somewhere between F-16 and Mirage 2000

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 19:32
by SpudmanWP
sprstdlyscottsmn wrote:So, I kept looking at orders. Everytime I looked up a news article about the F-16V and who bought it I never saw mention of CFTs. I honestly never even thought to go to the manufacturers website as I was so focused on who bought them.


The problem stems from the FMS announcements not having any details beyond avionics (no mention of pylons or EFTs either).

Http://www.dsca.mil/major-arms-sales/go ... ft-support
http://www.dsca.mil/major-arms-sales/go ... figuration
http://www.dsca.mil/major-arms-sales/sl ... n-aircraft
http://www.dsca.mil/major-arms-sales/go ... figuration

I think they are just considered part of the stock sale like pylons & EFTs.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 22:45
by geforcerfx
Do the new Block 70s come with the 132 to like the block 60 did?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 22:55
by SpudmanWP
Depends:
Bahrain = F-110-GE-129
Slovenia = no decision yet
Greece = Existing engines in the upgrade.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 16 Jul 2018, 23:24
by steve2267
I red recently somewhere, but precisely where I do not recall, that the Block 70 is available with 29,000lb engines, 32,000lb engines, and that it can go all the way up to a 36,000lb class GE motor and a 37,000lb class P&W motor. While a 32,000lb P&W motor is available, I think all recent Viper buys have specified either the GE-129 or GE-132.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jul 2018, 02:52
by viper12
SpudmanWP wrote:Depends:
Bahrain = F-110-GE-129
SlovAKIA = no decision yet
Greece = Existing engines in the upgrade.


Fixed for you.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jul 2018, 04:19
by SpudmanWP
viper12 wrote:Fixed for you.

Sorry, too much PCP (Pre-Coffee Posting) and autocorrect :doh:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jul 2018, 06:37
by juretrn
Slovenia buying fast jets... Oh man, good one. We had problems deciding whether to buy those 20 Patria AMVs.
Our military has what, 800 million € budget? Won't get us far with buying those jets...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Jul 2018, 10:13
by viper12
Well, Slovakia isn't exactly a powerhouse either with its defense spending of €1.082B : https://en.wikipedia.org/wiki/Slovak_Armed_Forces

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jul 2018, 16:36
by sprstdlyscottsmn
Going through the shell document to write that up as completely as I can without having the aircraft models finished to force me to have a bound scope of data. I currently only have models for the Su-35S, F-15C (-220) F-15E (229) and F-15SA (-129) finished. I keep changing scope so I never progress. In working the scope I realized I needed to add the European missiles to my missile simulation, which led me to realize there are errors there too. Missile guidance is not trivial and I commend the folks who do this for a living.

I really want to finish this project so I can get back to work on another project of mine.

Going to start the guidance over from scratch. I don't know if I'm having a mental breakthrough or a mental breakdown.

"The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't.
In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too may be corrected by the GEA. However, the missile must also know where it was.

The missile guidance computer scenario works as follows. Because a variation has modified some of the information the missile has obtained, it is not sure just where it is. However, it is sure where it isn't, within reason, and it knows where it was. It now subtracts where it should be from where it wasn't, or vice-versa, and by differentiating this from the algebraic sum of where it shouldn't be, and where it was, it is able to obtain the deviation and its variation, which is called error."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jul 2018, 20:46
by spazsinbad
MISS Ile Jibber JABber…. WMV audio only.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jul 2018, 23:20
by sprstdlyscottsmn
First time I heard that I could feel my IQ drop 10 points.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jul 2018, 23:39
by spazsinbad
:bang: :devil: Yeah but I understood it. MOroNIC huh. :doh: :mrgreen: Typical RAN FAA sprog fiter jet Pilote/AWI briefing.... :roll:


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jul 2018, 05:26
by firebase99
That missile nonsense is a joke right? its true intention is satire/sarcasm correct?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 20 Jul 2018, 06:03
by spazsinbad
Way! Dood it's for non-English speaker consumption to translate into their lingo for immediate unnerstanning. Comprende?

Some chalkboard retarded briefing for youse: viewtopic.php?f=22&t=27661&p=297644&hilit=retards#p297644

Scroll down from here for more: viewtopic.php?f=57&t=22125&p=243463&hilit=chalkboard#p243463

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jul 2018, 06:17
by garrya
Saw BiO posted this in Keypub
F-35 Aerodynamic Performance Verification
After completing all flight test analysis and obtaining the F-35 JPO’s concurrence, we used the validated
aerodynamics databases to calculate the KPP mission performance for each variant. The results showed that each of
the variants exceeded the JCS requirement for mission range by more than 10 percent
Image

https://arc.aiaa.org/doi/abs/10.2514/6.2018-3679

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 25 Jul 2018, 06:28
by spazsinbad
DOWNLOAD here for the 1.85Mb PDF cited above: download/file.php?id=27757 (PDF 1.85Mb)
VII. Conclusion [F-35 Aerodynamic Performance Verification]
On the F-35 program, we successfully implemented a modeling and simulation-based approach to aerodynamic performance verification. Applying conservatism to performance calculations early in the program protected against potential uncertainties in configuration, weight, or aerodynamics levels. Our rigorous process controlled aircraft weight growth and helped to ensure that the performance of the final F-35 design met the KPP requirements of the program specification. The efforts of a government/contractor team culminated in delivering a credible, flight test-based aerodynamics and performance database that accurately represents the performance of the F-35. This will be applicable for not only specification verification but also the operational performance products used by the fleet."

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 26 Jul 2018, 14:04
by mixelflick
garrya wrote:Saw BiO posted this in Keypub
F-35 Aerodynamic Performance Verification
After completing all flight test analysis and obtaining the F-35 JPO’s concurrence, we used the validated
aerodynamics databases to calculate the KPP mission performance for each variant. The results showed that each of
the variants exceeded the JCS requirement for mission range by more than 10 percent
Image

https://arc.aiaa.org/doi/abs/10.2514/6.2018-3679


Damn she has some legs and with new engines, will only be getting longer..

Was it LM's intention to exceed the design spec this dramatically? Or was it based on feedback from pilots? I recall hearing LM giving the pilots the choice of having an internal gun or more fuel, and the Marine/Navy pilots chose more fuel...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 28 Jul 2018, 20:38
by sprstdlyscottsmn
I have mission profiles worked out for CAP and DCA, working on Deep Strike and Interdiction/CAS. Deep strike is posing a challenge in that I want to incorporate a threat of S-400 so I need to figure out how many battalions to use and where to put them and where Su-35s on CAP will go. Afterall, if I am wanting to show the Operational differences I need to include threat avoidance routing or threat countering (AARGM added to loadout on top of standoff or direct attack munitions). I am adding a more detailed printout of flight envelopes and turning performances that will cover four different loadouts and weights ranging from clean at 60% internal fuel to the highest drag loadout that results in MGTOW and then using 60% initial fuel. The idea is to show how different aircraft degrade in performance for different missions. I will also have a measurement of combat cycle times under a specific air to air loadout (that is also used in the envelope charts) as additional standardized data. I will also standardize some of the combat actions such that I will be able to calculate various odds of success. The final result should be unrecognizable from the first comparison I posted years ago. When I have finished the F-15SA (first plane in the comparison) I will post the full document so that everyone knows what to expect, after which I will only have to make models and run scenarios.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 03:14
by garrya
sprstdlyscottsmn wrote:I have mission profiles worked out for CAP and DCA, working on Deep Strike and Interdiction/CAS. Deep strike is posing a challenge in that I want to incorporate a threat of S-400 so I need to figure out how many battalions to use and where to put them and where Su-35s on CAP will go. .

Is this a good start?
http://www.fmn.dk/temaer/kampfly/Docume ... 160509.pdf

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 03:48
by fbw
@sprstdlyscottsmn- How do you model for thrust throughout the entire flight envelope for engines that all specifications and inlet performance is not OSINT? There are a few for which the entire thrust envelope is available, what about engines like the F135?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 05:30
by steve2267
spazsinbad wrote:DOWNLOAD here for the 1.85Mb PDF cited above: download/file.php?id=27757 (PDF 1.85Mb)
VII. Conclusion [F-35 Aerodynamic Performance Verification]
On the F-35 program, we successfully implemented a modeling and simulation-based approach to aerodynamic performance verification. Applying conservatism to performance calculations early in the program protected against potential uncertainties in configuration, weight, or aerodynamics levels. Our rigorous process controlled aircraft weight growth and helped to ensure that the performance of the final F-35 design met the KPP requirements of the program specification. The efforts of a government/contractor team culminated in delivering a credible, flight test-based aerodynamics and performance database that accurately represents the performance of the F-35. This will be applicable for not only specification verification but also the operational performance products used by the fleet."


When I clicked on the download linky... I get:
You are not authorised to download this attachment.


Phutt the wuk? I guess my F-16.net clearance dunn got revoked...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 06:27
by eloise
F-35 service celling is a bit low?
F-35 Flight Envelope.png

0mtW1Ho.jpg

l8ezy2d.png

hShD2pN.jpg

HlnGtu8.jpg

pXAy6Jc.png

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 08:27
by magitsu
steve2267 wrote:Phutt the wuk? I guess my F-16.net clearance dunn got revoked...

LM asked Dragon029 to remove the AIAA papers. He contacted the f-16.net mods and now it seems you were too late, they already removed them.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 10:11
by spazsinbad
:doh: There was a window at least for a day to download the files - some people are just slow eh. :drool:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Aug 2018, 19:15
by sprstdlyscottsmn
An example of what the flight envelope stuff looks like.

Capture1.PNG


Clean: DI 0; 41,900lb
Air: CFT, 2xAIM-9X, 2xAIM-120D, 2xWing pylons and launchers, ATP, IRST21; DI 62; 60,300lb
Ground: CFT, 2xAIM-9X, 2xAIM-120D, 2xEFT, 2xSLAM-ER, 4xWing pylons and launchers, ATP, IRST21; DI 99; 64,700lb.
Max: CFT, 2xAIM-9X, 2xAIM-120D, 2xEFT, 2xHARM, 4xSDB I pallets, 4xWing pylons and launchers, ATP, IRST21; DI 176; 69,700lb.

OWS may impede some of the heavier loads transonic max G, but in general this is what it would look like. We don't know what the OWS does on the FBW Eagles.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 01 Sep 2018, 14:49
by doge
eloise wrote:F-35 service celling is a bit low?

I found a Figure that marked beyond 50K ft. (but, I’m not sure what this Fig.5 test means...)
F-35 50K (F-35 System Development and Demonstration Flight Testing at Edwards Air Force Base and Naval Air Station Patuxent River).jpg

(Thank you Dragon029 who shared pdf! :D )

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Sep 2018, 18:46
by sprstdlyscottsmn
Life has taken me away from the analysis for a while. I am currently working on making a quick and Dirty SAM analysis for determining routing impacts and mission success rate impacts. It is not forgotten. The S400 is a complicated system.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 17 Sep 2018, 20:21
by energo
sprstdlyscottsmn wrote:Life has taken me away from the analysis for a while. I am currently working on making a quick and Dirty SAM analysis for determining routing impacts and mission success rate impacts. It is not forgotten. The S400 is a complicated system.


Not at all. They say it goes twice as high and twice as far as the S300, so it's a simple extrapolation:

https://www.youtube.com/watch?v=GUeWu1Ar3rw&t=8


.
.
.
:mrgreen:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 00:54
by madrat
Define S-400, because it's basically a bastardized label considering the Russians promised all sorts of products that never materialized.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 06:08
by wrightwing
energo wrote:
sprstdlyscottsmn wrote:Life has taken me away from the analysis for a while. I am currently working on making a quick and Dirty SAM analysis for determining routing impacts and mission success rate impacts. It is not forgotten. The S400 is a complicated system.


Not at all. They say it goes twice as high and twice as far as the S300, so it's a simple extrapolation:

https://www.youtube.com/watch?v=GUeWu1Ar3rw&t=8


.
.
.
:mrgreen:

Which missile in each series? The S-300V4 has a 400km range, too.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 14:15
by sprstdlyscottsmn
madrat wrote:Define S-400, because it's basically a bastardized label considering the Russians promised all sorts of products that never materialized.

That's why it's complex. I'm trying to figure out a way to manage four different missiles and a gun system. I'm starting with each missiles having a range and altitude based Pk as a reference then adjusting that based on the speed of the target airframe.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:03
by ricnunes
eloise wrote:F-35 service celling is a bit low?
Image


You made an interesting question.
Could it be that the F-35 in that test (or set of tests) was carrying it's full (internal) weapon payload, namely 2xAMRAAMs plus 2xGBU-31s? Such payload could limit the F-35's ceiling, no?

What I find interesting about the diagram above is again (and again, because I've brought the subject before) the F-35's maximum/top speed, which as we all know here is Mach 1.6 (also "shown" by the diagram)
However if we look at the Mach 1.6 top speed, this clearly seems to me to be an "artificial limit".
Looking at the diagram, I believe that the F-35 flight envelop can clearly be expanded in terms of maximum speed, namely at altitudes around 35,000-40,000 ft (or perhaps even slightly higher).

Moreover, there's the LM maximum speed spec of 1200 mph (which should be TAS) for the F-35 and together with this, I found this great airspeed/mach calculator from one of NASA's webpages:
https://www.grc.nasa.gov/www/k-12/airplane/mach.html

Using the calculator on the webpage above, one can calculate that on planet Earth (yes, you can calculate air and mach speed on Mars too, :mrgreen: ) the 1200 mph speed at an altitude of 40,000 corresponds to mach 1.817 while at an altitude of 35,000 ft it corresponds to mach 1,808 which could somehow "confirm" my "thesis" that the F-35 actual top/max speed at altitude is/could be Mach 1.8.
Beside compared to other flight profiles from other fighter aircraft, if we extend the F-35's profile on the above diagram ("break" the artificial barrier) the "1G Sustained Flight" lines should meet at around Mach 1.8, no? (another indication that the F-35 top speed could indeed ending up being Mach 1.8)

Regarding the calculator above and when reading the webpage's text, it seems that it models supersonic speeds (as opposed to the other well known web based airspeed calculator which only models subsonic flight) since it takes into account factors such as compressibility during supersonic flight and it even seems to take into account hypersonic flight (which obviously is not the case here).
Just for checks and for example, using the following airspeed calculator (which only models subsonic flight):
http://www.hochwarth.com/misc/AviationCalculator.html
1200 mph (TAS) at an altitude of 40,000 ft corresponds to Mach 2.092 while using the NASA calculator this same speed and altitude corresponds again to Mach 1.817

But and by the way, is there something that could be wrong with my reasoning above?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:14
by sprstdlyscottsmn
Unfortunately it is very common for top speeds to be listed as a Mach number, and then the MPH that said Mach number would correlate to at sea level. That is what has happened here.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:23
by steve2267
Why the infatuation with whether the F-35 can go faster than 1.6 Mach?

The speed limit is 1.6 Mach, as defined by the aircraft spec, and clneared by flight testing. Can a pilot go faster? Unless the CLAW automagically deploy speed brakes or limit the throttle, then probably yes, but then he is a test pilot. Flutter? Would suck to have a wing or stabilator or vertical fin depart the airfrane. Control issues due to shock locations & interactions?

ricnunes wrote:But and by the way, is there something that could be wrong with my reasoning above?


Dynamic pressure.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:24
by ricnunes
sprstdlyscottsmn wrote:Unfortunately it is very common for top speeds to be listed as a Mach number, and then the MPH that said Mach number would correlate to at sea level. That is what has happened here.


Yes, but that does't explain why there's a clear artificial speed limit at mach 1.6 at altitude on the F-35's flight profile diagram, does it?

Moreover, that 1200 mph value comes from LM itself (and not from some "wild" media source) so wouldn't it be that extrapolating the Mach 1.6 value at sea level and come up with the value kinda of an "unprofessional" move by LM itself?
And if this was the case, I would expect that LM would simply remove should value by now since it's a "wrong value" but they haven't, by the contrary.
I would guess/imagine that such value by a manufacturer would be aircraft's the structural speed limit instead (or something close it).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:25
by sferrin
wrightwing wrote:
energo wrote:
sprstdlyscottsmn wrote:Life has taken me away from the analysis for a while. I am currently working on making a quick and Dirty SAM analysis for determining routing impacts and mission success rate impacts. It is not forgotten. The S400 is a complicated system.


Not at all. They say it goes twice as high and twice as far as the S300, so it's a simple extrapolation:

https://www.youtube.com/watch?v=GUeWu1Ar3rw&t=8


.
.
.
:mrgreen:

Which missile in each series? The S-300V4 has a 400km range, too.


S-300V4 is a completely different system than the S-300/S-400.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 15:26
by ricnunes
steve2267 wrote:Why the infatuation with whether the F-35 can go faster than 1.6 Mach?


Because if you look at any other fighter aircraft flight profile diagram both "sustained flight" lines meet naturally on a roughly rounded edge - This simply doesn't happen with the F-35.
(which is an indication that the Mach 1.6 is an artificial limitation and not an actual one)


steve2267 wrote:Dynamic pressure.


Care to expand?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 16:13
by sprstdlyscottsmn
ricnunes wrote:
steve2267 wrote:Why the infatuation with whether the F-35 can go faster than 1.6 Mach?


Because if you look at any other fighter aircraft flight profile diagram both "sustained flight" lines meet naturally on a roughly rounded edge - This simply doesn't happen with the F-35.
(which is an indication that the Mach 1.6 is an artificial limitation and not an actual one)

Just because you don;t see it in the charts doesn't mean it isn't there. It's actually true on MOST fighters. It is not a thrust/drag limit, it is a design specification and a placard limit. It's not that flight at higher speeds isn't possible, it's just prohibited. With CFT mounted stores the F-15E is only AUTHORIZED to fly to 1.4M. Care to venture a guess of how fast a -229 powered F-15E can haul four CFT mounted Mk-84s if the pilot ignored that restriction? ~1.65M. At the authorized limit of 1.4M the Mudhen would still be pulling a 0.03G acceleration (1ft/s^2) on a STD+10degC day at 36,000ft. Artificial limits are all around, just accept this and move on.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 17:16
by steve2267
ricnunes wrote:
steve2267 wrote:Dynamic pressure.


Care to expand?


Dynamic pressure is the total pressure the free stream exerts on a structure or vehicle as it moves through the air. In the US, it is typically expressed as lbs/ft^2 (at least it was in the rocket business), though possibly in psi. (In the rest of the world, it should be N/m^2, but for all I know, the Europeans use kg/m^2).

I expect that the limits of the F-35 airframe, whether constrained by an artificial placard or not, are related to a specified dynamic pressure in lbs/ft^2, whether that be 1200mph at some altitude at standard temperature, or a Mach number at 36,000 ft at a standard day. Thinking about this some more... it is probable that the JSF program specified the boundaries of the flight envelope, and LM converted those velocities at whatever altitude and atmospheric conditions to a dynamic pressure, then designed the aircraft to perform up to that dynamic pressure limit, which may occur at 1200mph or some Mach number.

Having said all this... the F-35 has a very useful top end of 1.6 Mach. Be happy. Give it a rest. (Please)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 17:46
by blindpilot
ricnunes wrote:...
However if we look at the Mach 1.6 top speed, this clearly seems to me to be an "artificial limit".
...
But and by the way, is there something that could be wrong with my reasoning above?


First a qualifier. My bachelors degree work was aeronautical-"structures" (think JW's stuff, wings breaking off etc.) and not pure "aero/fluids." (Post grad studies not applicable here). That said ....

When aircraft are designed, limits are "baked into" the design to some extent. The design limits dictate certain design decisions. Those decisions can, and often do, create real and not "artificial" performance limits. Supersonic aero also is not driven by the same fluid dynamics as subsonic flow. (More power = Mo thrust against parasitic drag)

An example. The SR-71 speed limits were not aero limited. The internal structure was designed and "built" to thermal expansion limits. While perhaps not technically the case, a good way to look at this is to see the airframe stretching as it gets warmer, and at some point the cockpit sub-unit connections exceed the joint expansion dimensions, and the crew capsule would "fall out" of the hotter airframe, even though the SR-71 itself could perhaps go even faster. That's a design limit that is very much NOT artificial. (that's second/third generation - F-104/F-4 etc. thinking)

So can the F-35 exceed Mach 1.6? Probably, but that is also not an artificial number. All the design parameters, such as skin thermal durability, or control surface size and orientation, were set for the design limits. These things are not "artificial."

FWIW MHO,
BP

PS another interesting fact on thermal effects. The SR-71 actually came back more durable than before the last flight due to annealing effect. Flying made the structure stronger. There seems (from reports) to be a similar effect to the F-35 stealth materials. The material durability is improved with flight. But this doesn't mean it can't be "melted"' beyond those effects.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 18:02
by sprstdlyscottsmn
blindpilot wrote:
ricnunes wrote:...
However if we look at the Mach 1.6 top speed, this clearly seems to me to be an "artificial limit".
...
But and by the way, is there something that could be wrong with my reasoning above?


First a qualifier. My bachelors degree work was aeronautical-"structures" (think JW's stuff, wings breaking off etc.) and not pure "aero/fluids." (Post grad studies not applicable here). That said ....

When aircraft are designed, limits are "baked into" the design to some extent. The design limits dictate certain design decisions. Those decisions can, and often do, create real and not "artificial" performance limits. Supersonic aero also is not driven by the same fluid dynamics as subsonic flow. (More power = Mo thrust against parasitic drag)

An example. The SR-71 speed limits were not aero limited. The internal structure was designed and "built" to thermal expansion limits. While perhaps not technically the case, a good way to look at this is to see the airframe stretching as it gets warmer, and at some point the cockpit sub-unit connections exceeding the joint expansion dimensions, and the crew capsule would "fall out" of the hotter airframe, even though the SR-71 itself could perhaps go even faster. That's a design limit that is very much NOT artificial.

So can the F-35 exceed Mach 1.6? Probably, but that is also not an artificial number. All the design parameters, such as skin thermal durability, or control surface size and orientation, were set for the design limits. These things are not "artificial."

FWIW MHO,
BP

You bring up an excellent aspect to consider.

Fixed Intakes

The inlet design would have been heavily influenced by the need to handle speed up to Mach 1.6. Why design the inlet to be efficient at 1.8M when 1.6M was the design specification? Bragging rights?

"Way to go! we have a 1.8M inlet on a 1.6M plane, too bad flutter will rip off the verticals at 1.65M"

I am NOT saying flutter will cause a structural problem at 1.65M. What I AM doing is expanding on the example BP gave. Every aspect of the design that deals with shockwave formation was designed to a 1.6M specification.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 18:33
by blindpilot
sprstdlyscottsmn wrote:...
You bring up an excellent aspect to consider.

Fixed Intakes ..... Every aspect of the design that deals with shockwave formation was designed to a 1.6M specification.


Exactly, and it brings to the forefront aspects of modern design. The days of designing F-104 "man in a missile", or F-4 "with enough power even a brick can go Mach 2" .. those days are over. We have the ability to go as fast as you want ... see X-15 et al. Just tell Lockheed or Boeing how fast you want, and they will build it .. for a price (see current hypersonic developments).

Modern design is extremely complicated. The decisions from material choice to wing design, to engine choices are all part of a fabric woven into a specific set of target performance requirements. This began even with 4th gen designs, and is even more true in 5th gen designs. We will not be strapping rockets on the tail of the F-35 as we once did with the F-104.

Thanks Spurts,
BP

PS. This reminds me of a conversation JW and I had with others two years ago, on how fast was the B-58.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 18:51
by sprstdlyscottsmn
blindpilot wrote:
PS. This reminds me of a conversation JW and I had with others two years ago, on how fast was the B-58.

I remember that conversation. I recall posting something along the lines that AFAIK all J79 powered airframes were thermal/structural/flutter limited, never drag limited (clean).

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 18 Sep 2018, 19:09
by steve2267
Lest we forget about SWAT (circa 2007?) where engineer's were getting big dollar bonuses for every pound (oz?) weight saved. Designing for a speed above 1.6 Mach would have surely added more weight... possibly a lot more as those sorts of changes tend to have a cascading effect.

Was it Gums that mentioned a thermal limit on the Viper's canopy? I recall reading somewhere that one of the reasons Stubby's canopy hinges at the front was that design saved weight. I wonder what sort of weight penalty might have had to have been paid for a canopy thermal limit of 1.8 or 2.0 Mach?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 00:48
by jetblast16
Speaking of J79s lol..


Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 02:17
by h-bomb
steve2267 wrote:Lest we forget about SWAT (circa 2007?) where engineer's were getting big dollar bonuses for every pound (oz?) weight saved. Designing for a speed above 1.6 Mach would have surely added more weight... possibly a lot more as those sorts of changes tend to have a cascading effect.

Was it Gums that mentioned a thermal limit on the Viper's canopy? I recall reading somewhere that one of the reasons Stubby's canopy hinges at the front was that design saved weight. I wonder what sort of weight penalty might have had to have been paid for a canopy thermal limit of 1.8 or 2.0 Mach?


Actually an LM engineer on an interview stated the forward hing was a maintenance wish list item. With that you can pull the entire ejection system without having to remove the canopy. It was a labor saving feature. I am sure someone here can explain the joy or canopy alignment.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 03:15
by johnwill
sprstdlyscottsmn wrote:You bring up an excellent aspect to consider.

Fixed Intakes

The inlet design would have been heavily influenced by the need to handle speed up to Mach 1.6. Why design the inlet to be efficient at 1.8M when 1.6M was the design specification? Bragging rights?

"Way to go! we have a 1.8M inlet on a 1.6M plane, too bad flutter will rip off the verticals at 1.65M"

I am NOT saying flutter will cause a structural problem at 1.65M. What I AM doing is expanding on the example BP gave. Every aspect of the design that deals with shockwave formation was designed to a 1.6M specification.


So what would it take to clear the F-35 for 1.8, if it could get there? The usual suspects - flutter, loads, flight control, store separation, engine, thermal, etc would all have to be analyzed and flight tested. Chances are, flutter would not be a problem, since the most critical mach numbers are usually between 0.9 and 1.2 at low altitudes. Loads and flight controls are interconnected. If the structure is strong and stiff enough, flight controls can maintain their effectiveness. If not, loss of control causes loads to greatly increase and fail the structure. A possible problem would be reduced or reversed aileron effectiveness, where wing twist would cause a reversed roll moment on the airplane. The solution is to reduce or remove roll commands from the ailerons and add them to the horizontal tails, which don't lose as much effectiveness at higher machs. A more likely problem is loss of rudder effectiveness or reversal, because there is no other way maintain directional control. Store separation, engine, and thermal effects are someone else's problem.

The only way I can see this happening is with an increased thrust engine.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 04:17
by marsavian
The F-35 also appears to generally have a 0.2M speed deficit to other fighters at lower altitudes too. It maybe able to out-turn (including the AoA), out-climb, out-accelerate, out-last (with its high fuel load) most other military planes but it will not be out-running most if not all of its supersonic opposition. If it's spotted and chased it will have to stand and fight. Small price to pay for the overall great package it is in so many spheres of combat.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 05:08
by glennwhitten
I believe I read the F 35 has a top speed of M 1.67. Considering the fact that the F 35 holds its weapons and fuel internally, it should be faster than the F 18 with a top speed of M 1.8. No one complains of the F 18 top speed much.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 05:31
by SpudmanWP
The F-18's performance varies greatly when armed.

Image

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 08:51
by hythelday
glennwhitten wrote: No one complains of the F 18 top speed much.


Evefyone did when F-14 was still in service :D

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 09:08
by hornetfinn
marsavian wrote:The F-35 also appears to generally have a 0.2M speed deficit to other fighters at lower altitudes too. It maybe able to out-turn (including the AoA), out-climb, out-accelerate, out-last (with its high fuel load) most other military planes but it will not be out-running most if not all of its supersonic opposition. If it's spotted and chased it will have to stand and fight. Small price to pay for the overall great package it is in so many spheres of combat.


If it can out-accelerate the opposing aircraft, then it will create more space between the two until the opposing aircraft can get to higher speed than what the F-35 is going. Then it will slowly crawl closer unless the speed difference is rather large. High internal fuel load in F-35 means that it can likely go at high speed for longer time than opposing aircraft. I'd say that F-22 is currently the only operational fighter jet that might be able to do that in real world combat situation. MiG-31 has the top speed, but might just take too long to accelerate to high enough speed to catch a speeding F-35. It would be also extremely difficult to keep an eye for that F-35 given it has VLO stealth and great SA.

Of course this is just one-on-one situation. In real world combat that situation is not likely happening as F-35s will have superior SA and cooperation with their avionics and VLO stealth. I doubt any sane opposing fighter pilot would try to catch a lonely F-35 as that would likely mean being trapped by other F-35s and other networked assets.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 09:21
by popcorn
Any aircraft chasing. F-35 is going to eat a missile launched .in over-the-shoulder mode.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 09:36
by gta4
marsavian wrote:The F-35 also appears to generally have a 0.2M speed deficit to other fighters at lower altitudes too. It maybe able to out-turn (including the AoA), out-climb, out-accelerate, out-last (with its high fuel load) most other military planes but it will not be out-running most if not all of its supersonic opposition. If it's spotted and chased it will have to stand and fight. Small price to pay for the overall great package it is in so many spheres of combat.


No, It does not need to stop and fight. It can Just use LOAL shot of aim9x against a chasing plane.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 10:03
by gta4
In fact F35 welcomes anyone who dare to chase, because the chaser needs To engage into afterburner which makes it an easy target for DAS. When an aim9x is launched in LOAL mode, it engages the target head on, resulting in extended range and PK rate. However, the chaser needs to shoot F35 with its missile's tail chase mode, as you know it shrinks missile's range and PK rate significantly.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 11:11
by ricnunes
@blindpilot, steve2267 and sprstdlyscottsmn,

First of all thanks for the replies, they make sense.

Yes, some of you have definitely far better knowledge than I have about aerodynamics (and as such thanks again for your replies), so I guess you'll have to excuse be if I'm being a bit of a "pain in the a$$" about this subject (and as such not "giving this a rest", just yet :mrgreen: ) but I have the following point/question which I would like to address (and for which I would really appreciate a reply on your part) which BTW was a point/question that I probably should have mentioned earlier:
- Yes, it's indeed a fact that the F-35 was designed with a top speed of Mach 1.6 in mind and as such I understand the designer/manufacturer when developing an aircraft will design it for such top speed and likely not more.
However, isn't the top speed of Mach 1.6 for the F-35 a top speed with full internal weapon which is a quite heavy payload of 2x2000lb (usually GBU-31s) plus 2xAMRAAMs?
This I believe, is my main point for "keeping up" this subject. Yes, I understand that weapon payload is internal and as such shouldn't produce Parasitic drag but it adds weight and as such should produce lift-induced drag, right? Even thou the lift-induced drag is reduced at higher speeds, it should still be present (namely around Mach 1.6-1.8 ), no?

I guess that my point/question above could be "subdivided" into the next two "sub-points":
1- I also don't think that the F-35 will be cleared (if possible) to fly above Mach 1.6 while carrying it's full internal weapons loadout of 2x2000lb (usually GBU-31s) plus 2xAMRAAMs but how about when carrying 4xAMRAAMs (only)? Or only 2XAMRAAMs or even clean (although this last one - clean - is kinda useless in the real world).
2- My second point which in some part is related to the points above, is that with previous fighter aircraft generations the top speed requirement was for a clean aircraft like for example Mach 2 for the F-16 or Mach 2.5 for the F-15 or Mach 1.8 for the F/A-18, etc... (but again please correct me if I'm wrong). So in case I'm not wrong, when the JSF/F-35 was designed it's maximum speed was for a full internal weapons load (albeit internal) which was kinda the opposite when compared to previous generations of fighter aircraft hence why and probably the main reason why I'm "speculating" if the F-35 could have its top speed increased/expanded since there's still a room for lower/lighter internal weapons load? (this is more a question than an affirmation, BTW).

Finally, someone also brought up the intakes. But regarding this, I think that the difference between Mach 1.8 and Mach 1.6 (or Mach 1.67 tested) isn't that big so I'm a bit skeptical on the impact that the F-35 intakes may have on preventing the F-35 to reach Mach 1.8. Besides, wasn't a F-16 tested with DSI and it still managed to reach Mach 2.0 (basically it's top speed or very close to it, this without DSI)?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 11:21
by ricnunes
SpudmanWP wrote:The F-18's performance varies greatly when armed.



You chart is very interesting indeed Spudman.
It shows that with a weapons payload of 2xAIM-9s (certainly wingtip mounted) plus 2xAMRAAMs (certainly mounted on the fuselage) which shouldn't have a big impact on drag does ends up having quite "big" impact on top speed which in this case seems to be around Mach 1.57 as opposed to Mach 1.8 on a clean aircraft.
I guess that this is one more thing that makes me "digress" about the F-35's top speed.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 11:54
by hythelday
According to your logic F-35 even with max internal load would go faster than 1.6M once it burns enough fuel.

FYI test airframes have been flown, and remained controllable, at AoA significantly higher than operatinal planes are capped. One could also keep posting fantasies how F-35 has a secret button to override this in order to surprise the opposition.

The alternative is to take multiple flight test and weapon separation reports that are available to the public and accept the fact that 1.6M is the limit, since 1) it fulfills requirements 2) operational 1.6M is still faster than all but one western fighter (I do not remember who was it, but one senior member of this forum once posted that the fastest Eagle has ever flown in combat was 1.45M)

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 12:00
by ricnunes
hythelday wrote:According to your logic F-35 even with max internal load would go faster than 1.6M once it burns enough fuel.


For what's worth, I don't think that any fighter aircraft reaches its maximum speed with full fuel (but again, I could be wrong).
Or I guess that I could put this into another perspective, this one as an honest question: Is the maximum speed spec/requirement a requirement for a fully (100%) fueled aircraft?


hythelday wrote:FYI test airframes have been flown, and remained controllable, at AoA significantly higher than operatinal planes are capped. One could also keep posting fantasies how F-35 has a secret button to override this in order to surprise the opposition.


Now that you mentioned AoA, isn't there a possibility that a F-35 with a full internal weapons load (2x2000lb bombs plus 2XAMRAAMs) needs to fly at higher AoA compared to a F-35 with less internal weapons (lets say 2xAMRAAMs) this due to weight and as such have less impact on top speed?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 13:29
by element1loop
ricnunes wrote:1- I also don't think that the F-35 will be cleared (if possible) to fly above Mach 1.6 while carrying it's full internal weapons loadout of 2x2000lb (usually GBU-31s) plus 2xAMRAAMs but how about when carrying 4xAMRAAMs (only)? Or only 2XAMRAAMs or even clean (although this last one - clean - is kinda useless in the real world).


If there's no weight or ISA info it's all guessing.

I'd default presume no internal weapons in that case, not the other way.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 14:19
by Dragon029
Speaking of speed differences; I'd encourage people here to do the maths of how long it'd take (with something like a 0.2 or 0.4 Mach difference) to close in for a tail-aspect shot (noting that when engaging a fighter from behind your missile's range is greatly diminished).

For example - say you have an F-35 that's falling back at a full on Mach 1.6, a Su-35 sees it with his IRST and gives chase at an average speed of Mach 2.0 (time to accelerate, etc does matter, but in an alternate scenario you might have an F-35 accelerating to run from a Su-35 that's apparently spotted him and is already supersonic).

And let's say that the Su-35's weapon of choice is an R-77 with a 110km head-on range. For a tail-chase, let's say he has to get within 40km of the F-35 to get a hit (assuming the seeker can get a lock through the stealth & ECM).

So with a closing speed of Mach 0.4, and the requirement to get within 40km, Su-35 is burning roughly 1950lb of fuel per minute in afterburner with a max fuel capacity of 25,400lb.

You then have to consider - how much fuel did both jets start with? Do they have tanker support? How far from home is each jet when the chase begins? Is the F-35 alone and flying back to an undefended tanker (unlikely), or is (2/3 of the way back) the F-35 going to be passing by some other F-35s, or F-22s or F-15Cs, etc during this chase?

Simplifying things though; let's just say both jets can afford to burn 1/3 of their total internal fuel capacity in this chase - both jets will (somewhat coincidentally) have about 4.5 minutes in max afterburner.

So a Mach 0.4 difference, a chase time of 4.5 minutes, an engagement distance of 40km - under this scenario, if the F-35 is initially about 75km away, the Su-35 will never get the chance to launch his R-77; they'll both burn 1/3 of their fuel but the Su-35 will only get 35km (19nmi) closer to the F-35. If the Su-35 begins to chase the F-35 at something like 100nmi (185km) then after expending all that fuel he'll only get within about 150km (80nmi; not even within the R-77's head-on engagement range).

And that's with the Su-35 managing Mach 2 with R-77s - if he's only going Mach 1.8 then he's only going to close 16km (9nmi) despite burning ~8500lb of fuel.

Supercruising can let you burn about half as much fuel, but it also limits your speed - if a Typhoon were to supercruise after an afterburning F-35 and again both jets had 1/3 of their total internal capacity to burn, the Typhoon would initial lose about 8km / 4nmi to the F-35 and then close another ~50km for a total closure of around 40-50km - better than the Su-35, but it's still only an extra ~5-15km closer.

ricnunes wrote:For what's worth, I don't think that any fighter aircraft reaches its maximum speed with full fuel (but again, I could be wrong).

...
Now that you mentioned AoA, isn't there a possibility that a F-35 with a full internal weapons load (2x2000lb bombs plus 2XAMRAAMs) needs to fly at higher AoA compared to a F-35 with less internal weapons (lets say 2xAMRAAMs) this due to weight and as such have less impact on top speed?

No supersonic aircraft can reach its maximum speed with full fuel; the second after you refuel you're no longer at 100% and no plane can just instantly snap to Mach 2 or whatever. Technically speaking though, something like an E-2D or CH-53 on the other hand might be able to reach its top speed while refueling if SOPs are broken.

As for AoA, a jet with a lighter internal load will certainly have an easier time reaching its top speed, but at those speeds the AoA difference is going to be nearly negligible.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 14:40
by sferrin
Coalition fighters trying to run down aircraft fleeing to Iran during Iraqi Freedom illustrate the difficulty well.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 14:53
by marsavian
I am considering the spotting to occur WVR, after the opponents have been vectored in the general direction and got lucky or if the F-35 decides to initiate the merge for operational reasons, it has to either finish the job or out last the opponent in fuel. No doubt about it, the F-22 has more options in this case.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 15:04
by element1loop
Given the title “F-35 Performance Flight Test points” contains no full description of the normalized test conditions (NET of many tests) we could be looking at a genuine performance graph, yes, but it may be one for ISA +25, full fuel, ballasted for MTOW.

Which would easily explain why the service ceiling not being met anywhere along the curve. Any FL500 ceiling needs an ISA indication, plus a weight, to know what it’s actually representing. As temp increases significantly over ISA, the ceiling will decrease below the nominal FL500 'ceiling'. But FL500 will not be the true performance ceiling as there’s always a flight-stability factor built into the certified ceiling, at all ISA values and weights, to open the envelope out a bit, for practical flight control margin purposes.

So the airframe’s true ceiling may be FL540 at ISA, but the jet may limit itself in a nav-cruise mode to the FL500 certified envelope, regardless. Service ceiling will be met at ISA, for it to meet service requirement, but in this graph it doesn’t do that. Which means it’s probably at close to max weight, or else normalized to a significantly higher than ISA atmosphere, or both.

So we can conclude the graph is not showing a full fuel state and and empty payload, at ISA. That ain't it. It’s showing some other undisclosed condition, so we can’t decide much based on what it is displaying.

So that's all that can be said here, IMO.

The other point mentioned is AOA induced drag, which will be a fairly negligible factor for the F-35's high-high cruising speed with weapons. The Teens are severely affected by loading, but not due to increased AOA so much, but due to the high-drag from all the lumpy bits.

With the F-35A you don’t have that problem at all, it’s a very clean lift-body with clean short wings. So even if you added maximum internal payload of 5,700lb, that weight increase is still only 8.14% of the total 70,000 lb MTOW (my figures are about 2 to 3 years old here, I need to update the spreadsheet).

In that state TOW is 52,949 lb with 17,051 lb payload available.

So the AOA increase for the High-High area of the envelope is still going to be just a very small fraction of 1 percent AOA increase, at that higher speed. Thus the F-35A will still be able to use 100% of its speed envelope, given it's not being limited by drag or by the engine (the envelope makes clear it is not engine speed-limited).

But a teen fighter definitely can not get anywhere near its max speed performance at comparable combat weapon and fuel loads as the F-35A.

So why quibble about the speed envelope at all? The F-35A will in fact be capable of being much faster than teen fighters in combat trim by far, i.e. Eagle reached max M=1.45 in combat trim to date? F-35A will beat that!

So factor that into any above scenarios about MiG31s silly enough to chase an F-35A, etc. Without a doubt the current teens are far more vulnerable in any such situation, plus they can be tracked and fired on by what follows and they have higher drag, and far less fuel if they EJETT.

As far as I can determine, the F-35A will not be suffering in performance anywhere compared to any of the teens in that sort of situation, it would be in a far better place to deal with that than an Eagle.

2c

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 15:11
by element1loop
Dragon029 wrote:You then have to consider - how much fuel did both jets start with? Do they have tanker support? How far from home is each jet when the chase begins? Is the F-35 alone and flying back to an undefended tanker (unlikely), or is (2/3 of the way back) the F-35 going to be passing by some other F-35s, or F-22s or F-15Cs, etc during this chase?


And the only way they 'know' it's there at 70 km is via VHF and GCI, not self-tracking.

Now, describe what occurs when the Su35 has a HOBS LOAL SLAMMER closing with it, in that scenario, with ~40km separation ...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 15:23
by gta4
The tail chase range of R77 is only 5km at low altitude.

Surprise?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 15:25
by gta4
The tail chase range of R77 is only 5km at low altitude.

Surprise?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 16:27
by element1loop
um ... can someone remind me why the F-35 is running away from the Su35 again? :?:

I'm stuffed if I can remember why this makes sense.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 16:51
by blindpilot
marsavian wrote:The F-35 also appears to generally have a 0.2M speed deficit to other fighters ...


As others have pointed out well, I'll just say it bluntly.

That is an assertion on your part that is flat wrong! The assumptions are not true. Therefore all that follows that statement is false.

Part of the design process, was looking at actual aircraft performance in the real world with real load outs. Part of the design process was looking at actual speeds and acceleration profiles aircraft in combat actually flew. (see the F-15/F-35 pilot's witness that she never exceeded Mach 1.5 in her 2,000 hours of flying the F-15)

As also noted by others there is a difference between accelerating from Mach .8 to Mach 1.2 and stretching from Mach 1.6 to that last ".2"(or even another .5) Mach. It can take minutes which seem like hours to reach that last top end speed. Another great analogy would be a 200 meter sprinter with an unmatched top end speed, will find the "4.2 40 yard dash" wide receiver has already scored a touchdown, by the time he gets fast enough to start making up the initial lead. Nice that he's so fast ... but ... the other guys already scored the touchdown. Give us a call when you reach top speed, we'll be the ones celebrating on the side lines.

But all of that is academic anyway. Because the witness of former F-16 and F-15 pilots is clear. It is "FASTER" than the other fighters when armed with weapons. The Mach 1.6 speed is not a speed that just happened when they finished the design. It is a considered design point, that would perform in the real world "better" than current fighters (possible F-22 exception).

MHO,
BP

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 17:24
by blindpilot
ricnunes wrote:@blindpilot, steve2267 and sprstdlyscottsmn,

First of all thanks for the replies, they make sense.

....
... hence why and probably the main reason why I'm "speculating" if the F-35 could have its top speed increased/expanded since there's still a room for lower/lighter internal weapons load? (this is more a question than an affirmation, BTW).


Let's look at the phrase "if the F-35 could."

There is a difference between what the design on paper could be adjusted to, and what the aircraft built and coming off the assembly line, can be made to achieve. Even the F-16 when given the bigger engine, had to have it's "Big Mouth" inlet redone ... in the design and manufacturing. Without that change the "Big Mouth" F-16 would not have seen a performance enhancement from the "MO POWER !" engine. (which coincidentally had to be installed at the assembly line.)

Modern designs are intricately woven balances that ideally are right on target. If not then the design is bad.

The easiest example- weight and structural life. In fact the latest reports of three times life on the test article for the F-35 tells me one thing. THE F-35 DESIGN MAY BE TOO HEAVY! If it doesn't break then it's too heavy. It could be made lighter and have the desired life. That's the interrelationship of design elements to performance.

So - "could it?" Probably so at the margins. But if it does, then that part of the design is "bad." The design targets are the exact performance desired. If you want something else. Ask Lockheed. They can do Mach 2, or even Mach 3, or hypersonic. The customer seems to be getting exactly what they asked for with the F-35, according to test reports. That on it's own is remarkable for a fighter aircraft design.

MHO,
BP

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 18:17
by eloise
blindpilot wrote:Because the witness of former F-16 and F-15 pilots is clear. [b]It is "FASTER" than the other fighters when armed with weapons.

I have to disagree with this,
According to manual armed F-16, F-15, F-14 and even F-4 are all faster than F-35.
F-14D with 4 AIM-7 and 4 AIM-9 will have top speed of Mach 1.9
HlnGtu8 (1).jpg


F-16 with drag index = 50 will reach top speed at Mach 1.9
pXAy6Jc (1).png


F-4E with 2 wing tanks and 4 AIM-7 top out at near Mach 1.8
0mtW1Ho (1).jpg


Top speed of F-15C with 4 AIM-7 and 4 AIM-9 and centerline pylon is Mach 2.1
igVWcMY.png

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 18:32
by marsavian
Add Su-30/Su-35/MiG-31/MiG-35 to that list and Typhoon can do Mach 1.8 with its three slim tanks and AAMs. If F-35 gets in a merge it will have to fight its way out but it can do that fine. Even on a bombing interdiction it has 2 AMRAAM and an internal cannon, it can defend itself more than adequately with its angles and high energy/acceleration.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 19:32
by sprstdlyscottsmn
Those planes have higher top speeds, yes, but they take so long to get there and burn so much fuel that it is not OPERATIONALLY useful. That is why no F-15 driver has ever gone over 1.5M in actual combat.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Sep 2018, 19:50
by steve2267
eloise wrote:I have to disagree with this,
According to manual armed F-16, F-15, F-14 and even F-4 are all faster than F-35.
F-14D with 4 AIM-7 and 4 AIM-9 will have top speed of Mach 1.9


I am going to have to disagree with your disagreement.

When 9/11 occurred, and the F-15's scrambled from Otis AFB -- when the Eagle drivers could see the smoke over NYC from 130 miles away at 30,000 ft, do you think they went as fast as they could? Or do you think they "held back?"

9/11 Stories: The Fighter Pilots Who Got The Call
September 07, 2011 by Michael May

DAN NASH (NASTY): I’m Lt. Col. Nash, Dan Nash, call sign is "Nasty."

TIM DUFFY (DUFF