Acceleration

Unread postPosted: 19 Nov 2016, 20:21
by garrya
So i was reading the article posted here
viewtopic.php?f=55&t=27253&start=60
one thing that strikes me as odd is when pilot talks about acceleration of F-35
-Since I can slow down fast I can point my plane at my enemy for longer before the roles are reversed. The backside is that you loose energy, but it's not really a problem. The plane has so much engine power and low drag that the acceleration is awesome. With a F-16 I would have had to dive to gain as much speed after a hard turn.

Basically , he implied that F-35 accelerate much better than F-16 ( which i think could well be true at subsonic speed). Then there is also this
Image


. But then i also saw another old chart today , and it abit weird because according to the chart , even the fastest version of F-35 still accelerate slower than F-16 , even at dogfight speed
Image
So which is true then ???

Re: Acceleration

Unread postPosted: 19 Nov 2016, 20:58
by count_to_10
Could he be talking about an F-16 with weapons and tanks, and maybe at a higher fuel fraction?
Or maybe the reported charts for the F-35 are performance degraded in some way.

Re: Acceleration

Unread postPosted: 19 Nov 2016, 21:30
by optimist
I remember during early testing. The f-16 chase plane needed to hit the burner, to keep up with the f-35 during it's non burner acceleration.

Re: Acceleration

Unread postPosted: 19 Nov 2016, 21:49
by steve2267
optimist wrote:I remember during early testing. The f-16 chase plane needed to hit the burner, to keep up with the f-35 during it's non burner acceleration.

There's a video around where LM Chief Test Pilot Beesley remarks that F-16 chase needs to keep "tapping his burner" to keep up.

Re: Acceleration

Unread postPosted: 21 Nov 2016, 00:57
by steve2267
I have been unable to find the video in which I recall Jon Beesley stating the F-16 chase plane needs to keep tapping burner just to keep up.

I am reminded that I have read that the F-35 possesses F-16 like acceleration and F-18 like maneuverability.

However, Google appears to be strong with me today:

F-35 Lightning II Flight Tests
15 June 2007 by Eric Hehs
<snip>
How has your impression of the F-35 changed in subsequent flights?

(Jon Beesley, then Lockheed Martin Chief Test Pilot for the F-35, replies)
"I continue to be impressed with the performance of the aircraft. The F-16s flying chase don't have near the fuel capacity or payload capability as the F-35. The Lightning II does very well in comparison. For example, the F-35 often forces the chase aircraft into afterburner when it is in military power.

The airplane's handling qualities continue to be very good throughout the flight envelope. When I raise the landing gear, the airplane flies very smoothly. The landing gear is sequenced, which is unique for a fighter. The nose gear comes up first, then the main gear follows. The gears drop down in reverse order. Another strong impression is that the airplane wants to fly a lot faster than we are allowed to fly at this point in the flight test program. Most of the time we fly at about thirty to forty percent of available thrust. This airplane can go out to high subsonic speeds very easily without using afterburner."
<snip>
Source:http://www.codeonemagazine.com/f35_article.html?item_id=33


Flying The F-35: An Interview With Jon Beesley, F-35 Chief Test Pilot
September 10, 2010 Author not listed
<snip>
"The acceleration of the aircraft in the subsonic envelope is very similar to the acceleration performance of an F-16 with a centerline tank on board. Often in chase situations the F-16 chase aircraft will need to select afterburner during the climb. The most impressive part of this is the performance of the F-35 with full internal weapons (two 2000-pound JDAMs; 2 AIM 120s) is changed very little."
<snip>
Source:http://www.dailyairforce.com/234/flying-the-f35-an-interview-with-jon-beesley-f35-chief-test-pilot/


Google-fu of "f-35 f-16 frontal comparison" and clicking on [ Images ] from the Google results led me to a few graphics from other f-16.net threads:

F-35 & F-16 (Block 50 +) - Comparison of frontal view. (viewtopic.php?f=55&t=15061&)hilit=frontal+profile
Image

and

Image

With a little imagination, I think, to a first order estimate anyway, the x-section area of an F-35 is on the order of the x-section area of a clean F-16 (no missiles, no wing drop tanks) with a centerline tank, a configuration to which Beesley referred above.

However, if this graphic scales all aircraft correctly,from the thread Frontal profile comparisons - F-35 vs other jets (viewtopic.php?t=18478)
Image

the F-35 would appear to have a greater cross-sectional (frontal) area than an F-16 with a centerline droptank, which to me, makes the F-35 performance even more impressive.

Lastly, here is an interview with U.S. Air Force test pilot Lt. Col. Hank “Hog” Griffiths:
Latest From F-35 Tests
8/20/2010 by Guy Norris
<snip>
"Even when loaded internally with two 2,000lb GBU-31 Joint Direct Attack Munitions and two AIM-120 AMRAAMs, Griffith says the sheer power of the Pratt & Whitney F135 is evident. “The engine has a lot of thrust. It’s been fun to outrun the F-16 (chase aircraft). They can’t keep up. If we go to full military power the F-16 has to go to afterburner to keep up.”
<snip>
Source: https://justinwrites.wordpress.com/2010 ... -35-tests/


From the thread What's the F-35's VCS compared to other aircraft (viewtopic.php?f=22&t=41954 )
Image

So, to the original question, I do not see a conflict between the two graphics posted. With regard to the first graphic, where pilots were comparing F-35 performance to other aircraft they had flown, a combat configured F-16C will have a minimum of two wing tanks, plus at least two AIM-120s, and possibly a Lantirn or other sensor pod, and another couple bombs. I think it is clear that an F-35 will regain airspeed (i.e. out-accelerate) an F-16C in that configuration.

As to the second graphic, that is saying that a stripped F-16 with no missiles and no tanks will accelerate slightly faster than an F-35. The pilot quotes I found all stated that the F-16 chase planes all had to keep tapping burner to keep up with the F-35. Typically these chase planes have no missiles (it's a flight test, not a combat or combat training sortie) and either two wing tanks or a single centerline tank. Beesley specifically compared the F-35 acceleration to being like an F-16 with a single centerline tank. I would expect an F16 with a single centerline tank (e.g. an F-35 per Beesley) to accelerate faster than a viper with two bags on the wings, but be slightly slower than an F-16 without any tanks.

In summary, without hard numbers / flight test data, all anecdotal evidence in the form of pilot quotes / interviews points to the F-35 having F-16 like acceleration. (Which is nothing to sneeze at.)

Re: Acceleration

Unread postPosted: 21 Nov 2016, 17:14
by playloud
I spoke to an F-35 pilot at Nellis the other day during the airshow. He was a former Viper pilot. He said he has out-accelerated an F-16 that was carrying nothing but a centerline tank (both planes flying the say speed, and got into full burner at the same time). He said if the F-16 was completely clean, he believes the acceleration would be very similar to the F-35.

Edit: This also jives with the bar graph above.

Re: Acceleration

Unread postPosted: 24 Nov 2016, 16:42
by steve2267
New Fighter Jet: Controversial Future of the U.S. Fleet
David Majumbar November 7, 2008
<snip>
In terms of aerodynamic performance, the F-35 is an excellent machine, Beesley said. Having previously been only
the second man ever to have flown the F-22 Raptor, Beesley became the first pilot ever to fly the F-35 in late 2006.
As such, Beesley is intimately familiar with both programs. According to Beesley, the four current test pilots for F-35
have been most impressed by the aircraft's thrust and acceleration. In the subsonic flight regime, the F-35 very
nearly matches the performance of its' larger, more powerful cousin, the F-22 Raptor, Beesley explained. The
"subsonic acceleration is about as good as a clean Block 50 F-16 or a Raptor- which is about as good as you can
get." Beesley said.
<snip>
Source:http://www.livescience.com/3032-fighter-jet-controversial-future-fleet.html



An oldie but a goodie quote. Found this perusing some other threads. Article previously linked by (at least) spaz.

Note date of article is 2008. The context of the quote then is from early in the flight test phase (SDD?), so I assume Beesley's comment at this time would be for performance of an F-35A without weapons loaded. If so, then unloaded F-35A accelerates like clean F-16 Block 50. If not, and this comment came from Beesley flying an F-35A with a full internal load (2xAIM120 + 2x2000lb bombs), then that would be even more impressive. Reading between all sorts of lines, it seems like unloaded F-35A <> clean F-16 Block 50, and loaded F-35A <> F-16 Block 50 with single centerline tank. Still nothing to sneeze at.

Put this post in the FWIW file. (Probably not much).

Re: Acceleration

Unread postPosted: 24 Nov 2016, 18:05
by blindpilot
Interesting conversation here, but I would add one note of caution. Aeronautical cross section is not the same as a frontal slice view, or even RCS related cross section.

Consider a heavily area ruled fighter like the F-105. Because of the well designed "wasp waist" the visual wing and tail section pieces on the frontal cutout view actually do not exist as an aero cross section. The fuselage is pinched at that point to be exactly less cross section added by those elements, maintaining the constant cross section flow of the leading nose cross section.

Even this varies by speed, wing loading, AoA and weight (induced drag).

Not only are the pretty black card board frontal cross section views less than fully useful, they can be misleading. At best these pictures give us a general relative size comparison, which may not translate to drag directly.

Just saying.

BP

Re: Acceleration

Unread postPosted: 24 Nov 2016, 18:14
by steve2267
blindpilot wrote:Interesting conversation here, but I would add one note of caution. Aeronautical cross section is not the same as a frontal slice view, or even RCS related cross section.

Consider a heavily area ruled fighter like the F-105. Because of the well designed "wasp waist" the visual wing and tail section pieces on the frontal cutout view actually do not exist as an aero cross section. The fuselage is pinched at that point to be exactly less cross section added by those elements, maintaining the constant cross section flow of the leading nose cross section.

Even this varies by speed, wing loading, AoA and weight (induced drag).

Not only are the pretty black card board cross section views less than fully useful, they can be misleading. At best these pictures give us a general relative size comparison, which may not translate to drag directly.

Just saying.

BP


You make very good points, BP. I was being lazy and just threw up some images I could quickly find to try to illustrate an approximate frontal view comparison between the F-16 and the F-35. If I hadn't been so lazy, I would have photocropped the images to just show the F-35 and F-16.

In a way, though, the cardboard cutout image highlights your point. IF the cardboard cutout image is to scale... how much more impressive the F-35 acceleration performance is, if it compares favorably to the F-16. The F-35 would seem to have a much larger cross-sectional area and would therefore "seem" to have to be a LOT draggier. Bigger engine aside, the aero guys seem to have worked some real magic to minimize transonic drag on the F-35. I think sgtmac even noted this when he stated (somewhere here on F-16.net) that the F-35 appears to have been carefully area ruled as he noted that when "one bump" was diminishing, another "bump" began to grow.

Re: Acceleration

Unread postPosted: 24 Nov 2016, 18:40
by smsgtmac
steve2267 wrote:
New Fighter Jet: Controversial Future of the U.S. Fleet
David Majumbar November 7, 2008
<snip>
In terms of aerodynamic performance, the F-35 is an excellent machine, Beesley said. Having previously been only
the second man ever to have flown the F-22 Raptor, Beesley became the first pilot ever to fly the F-35 in late 2006.
As such, Beesley is intimately familiar with both programs. According to Beesley, the four current test pilots for F-35
have been most impressed by the aircraft's thrust and acceleration. In the subsonic flight regime, the F-35 very
nearly matches the performance of its' larger, more powerful cousin, the F-22 Raptor, Beesley explained. The
"subsonic acceleration is about as good as a clean Block 50 F-16 or a Raptor- which is about as good as you can
get." Beesley said.
<snip>
Source:http://www.livescience.com/3032-fighter-jet-controversial-future-fleet.html
livescience.com-New Fighter Jet Controversial Future of the US Fleet.pdf



An oldie but a goodie quote. Found this perusing some other threads. Article previously linked by (at least) spaz.
...


Keep in mind today’s F-35A is more than a half a ton lighter than the aircraft Beesley described as having sub-sonic acceleration on par with the Raptor. In 2008, the “non-weight optimized” AA-1 was the only bird flying.
(http://www.dote.osd.mil/pub/reports/FY2 ... Report.pdf)

Estimates at the time of the SWAT effort were that in driving out the excess weight as needed for the F-35B, the “other variants” would lose about 1300 lbs as well.
http://www.airspacemag.com/military-avi ... 17183/?all

The last DOT&E report that talked about F-35A weight changes characterized the F-35A objective weight target NTE weight baseline aircraft as AF-72. All that come afterwards (until more goodies earn their way past the weight police) should be almost exactly the same weight. From FY14 DOT&E Report Pg. 46:
Weight management of the F-35A is important for meeting air vehicle performance requirements and structural life expectations. These estimates are based on measured weights of components and subassemblies, calculated weights from approved design drawings released for build, and estimated weights of remaining components. These estimates are used to predict the weight of the first Lot 7 F-35A aircraft (AF-72), planned for delivery in August 2015, which will be the basis for evaluating contract specification compliance for aircraft weight.
- According to these reports, the program has reduced weight by 16 pounds in CY14 (from January to October estimate). The current estimate of 29,016 pounds is 355 pounds (1.2 percent) below the planned not-to-exceed weight of 29,371 pounds.
- The program has demonstrated positive weight management of the F-35A over the past 38 months, showing a net loss of 123 pounds in the estimates from August 2011 to October 2014. The program will need to ensure the actual aircraft weight meets predictions, as well as continue rigorous management of the actual aircraft weight beyond the technical performance measurements of contract specification in CY15 through the balance of SDD to avoid performance degradation that would affect operational capability.
(
http://www.dote.osd.mil/pub/reports/fy2014/pdf/dod/2014f35jsf.pdf)

Re: Acceleration

Unread postPosted: 24 Nov 2016, 18:41
by blindpilot
steve2267 wrote:
blindpilot wrote:Interesting conversation here, but I would add one note of caution. Aeronautical cross section is not the same as a frontal slice view, or even RCS related cross section.

... At best these pictures give us a general relative size comparison, which may not translate to drag directly.

Just saying.

BP


You make very good points, BP. I was being lazy and just threw up some images I could quickly find to try to illustrate an approximate frontal view comparison between the F-16 and the F-35. If I hadn't been so lazy, I would have photocropped the images to just show the F-35 and F-16.

In a way, though, the cardboard cutout image highlights your point. IF the cardboard cutout image is to scale... how much more impressive the F-35 acceleration performance is, if it compares favorably to the F-16. ...


Indeed the design (heavily computer aided) is impressive.

Full disclosure - my aero degree is in structures (breaking things and materials) and not fluid dynamics beyond aero 101 stuff, so take my comment with the appropriate allowances.

BP

Re: Acceleration

Unread postPosted: 24 Nov 2016, 19:27
by steve2267
I attended a pilot "talk" given by an F-22 / F-15 driver. (This was something through the FAA Wings program, if memory serves.) Two things stuck in my head. One, as an F-22 pilot, flying against the F-15 was like "clubbing baby seals." The second may not be attributable to him, but to an F-117 pilot quote -- I can't recall -- but the sentiment was that given the choice between being invisible or being super-maneuverable, the pilot chose invisibility, every time.

Take an F-16, stir in a little A-7, bake, then sprinkle on a generous helping of F-117. What do you get? An F-35.

Re: Acceleration

Unread postPosted: 24 Nov 2016, 19:39
by count_to_10
steve2267 wrote:I attended a pilot "talk" given by an F-22 / F-15 driver. (This was something through the FAA Wings program, if memory serves.) Two things stuck in my head. One, as an F-22 pilot, flying against the F-15 was like "clubbing baby seals." The second may not be attributable to him, but to an F-117 pilot quote -- I can't recall -- but the sentiment was that given the choice between being invisible or being super-maneuverable, the pilot chose invisibility, every time.

Take an F-16, stir in a little A-7, bake, then sprinkle on a generous helping of F-117. What do you get? An F-35.

Your missing quite possibly the most important part: the sensor fusion on the F-35 makes the pilots the next best thing to omniscient. So what do you add in to represent that?

Re: Acceleration

Unread postPosted: 24 Nov 2016, 19:53
by steve2267
count_to_10 wrote:
steve2267 wrote:I attended a pilot "talk" given by an F-22 / F-15 driver. (This was something through the FAA Wings program, if memory serves.) Two things stuck in my head. One, as an F-22 pilot, flying against the F-15 was like "clubbing baby seals." The second may not be attributable to him, but to an F-117 pilot quote -- I can't recall -- but the sentiment was that given the choice between being invisible or being super-maneuverable, the pilot chose invisibility, every time.

Take an F-16, stir in a little A-7, bake, then sprinkle on a generous helping of F-117. What do you get? An F-35.

Your missing quite possibly the most important part: the sensor fusion on the F-35 makes the pilots the next best thing to omniscient. So what do you add in to represent that?


X-wing.

I tried to argue in the nickname thread that the F-35 should be called the X-wing. I mean, if you're going to be master of the Jedi Transition, ruler of Star Wars Canyon... you might as well grab the name while it is open.

May the Force be with you.

:mrgreen: :devil:

Re: Acceleration

Unread postPosted: 26 Nov 2016, 06:58
by playloud
Adding a Stubby vs Rhino comparison.

Re: Acceleration

Unread postPosted: 27 Nov 2016, 21:55
by Gums
Salute!

Thread is bout accel, and I have flown two jets with awesome accel. Nevertheless, the total capabilities of the weapon system and the envisioned threat needs to be considered.

The Viper accelerated about like the VooDoo I flew back in the mid-sixties. Imagine unloading at 20K and 0.9M in a 20 - 30 deg climb, then passing the mach still climbing and getting to 1.33M about when reaching level and then back up to 50,000 freeking feet in another minute and a half or so. That was our climb schedule back in 1966. In the Viper I would have my solo stud ( clean A model) start at 400 KIAS and then light burner and do a 90 deg turn pulling 3 gees and roll out. So at 5,000 feet he would wind up at about 700 knots and 1.1M or so.

Accel is great in and of itself, and the Stubbie without external stores is gonna be as good as the Raptor. Remember that the Viper is drag limited a lot more than weight limited. It was very obvious to us in those early days when we flew with those huge wing tanks, and the centerline not so much.

Slightly off topic but I gotta go with Steve. Sorry Count. So from Steve:

Take an F-16, stir in a little A-7, bake, then sprinkle on a generous helping of F-117. What do you get? An F-35.


To be honest, adding the A-7D to the mix is one good thing to consider. As a SLUF/Viper dude I feel well-qualified to speak from the peanut gallery. Thing to remember is it was veeeery slugish and had a huge RCS. Nevertheless, it remained the permier bomb truck until the early 80's.

The F-35 is more like the SLUF WRT avionics/nav/sensors. Especially the nav. Biggest difference is the neat radar - AESA, isn't it? Our SLUF dar was really good for A2G and terrain following/avoidance and such. The Viper DAR was good A2G without TF or TA modes, but that was all. A2A radar in the Viper was like an Eagle or Hornet ( only had a few dozen hours in those sims, but the avionics were accurate if not the aero, ditto for the F-20 sim).

@Count

Talk to any Viper pilot that flew the SLUF first. Ditto for Double Ugly folks that came to we lowly mudbeaters in the SLUF.

Our SA was way beyond anything else we had flying in the tactical environment except the 'vaark. We had super radar for ground map, TF and TA and beacon-bombing. We had a great INS with a doppler system, so we could takeoff with a 2 nin alignment and then do an airborne INS alignment using that doppler. Or we could go pure doppler or pure INS or another two mixed modes. Neat huh? And then the biggest bonus - the projected map display.

see the attached PMDS article from the Fighter Weapons Review. It was the template for my address to the DMA folks at the St Louis facility that produced our maps on 35 mm film for our gizmo. No kidding. I got to meet the gnomes that did all the good work.

The two biggest fears of a fighter/attack pilot is running outta gas and knowing where you are. In the SLUF we had all bases covered, but getting away from the enema in A2A was a problem, heh heh.
++++++++

I like the overall F-35 implementation now. It is not a bomb truck like the SLUF or Bone or Buff. But the sucker will likely get in and hit and get out. It will also help other friendly folks. I would like to try it myself.

Hope all had a great Thanksgiving here in the states and across the world, holiday or not.

Gums opines...

Re: Acceleration

Unread postPosted: 23 Jul 2019, 10:42
by doge
Perhaps, I Excavation, dug up the Questions that everyone is also secretly interested in. 8) (I'm a digging Man.)
https://www.instagram.com/stories/highl ... 094008342/ (This is a DEMO team account.)
We have F-35 crew chief Staff Sgt John Baker here to answer your questions.

Q: what's the best part of the F-35 to you and what is the best part of flying it.
A: The best part of the F-35 is the engine!

Q: What mach number does the F-35 go up to.
A: Top speed is 1.6 Mach!

Q: Is it true that the F-35's acceleration is very comparable to the F-22's?
A: Very comparable.

The F-35 has the largest single engine motor out of any fighter (43,000lbs of thrust)
The F-22 is a twin engine fighter with 70,000 lbs of thrust.

Re: Acceleration

Unread postPosted: 24 Jul 2019, 19:24
by wooster
"The F-35 doesn’t have the altitude, doesn’t have the speed [of the F-22],
but it can beat the F-22 in stealth,” Hostage told me

Acceleration times from Mach 0.8 to Mach 1.2 were extended by eight seconds, 16 seconds
and 43 seconds for the A, B and C-models respectively. The baseline standard used for the
comparison was a clean Lockheed F-16 Block 50 with two wingtip Raytheon AIM-120 AMRAAMs.

1. Acceleration may be on part with an F-22, but even my pickup truck can beat either
jet 0-60mph. You can twist things around if you want to get the desired shock and awe
affect of a public comment on acceleration. Acceleration is great until you run out speed.

2. Per the above, acceleration is being compared to a dirty F-16 and not clean as people
here always suggest. I know they call it clean, but being loaded with 2 amraams isn't
by definition clean. Yes, drag is small on the amraam.

Re: Acceleration

Unread postPosted: 24 Jul 2019, 19:35
by sferrin
wooster wrote: I know they call it clean, but being loaded with 2 amraams isn't
by definition clean. Yes, drag is small on the amraam.


Do you honestly think it's enough to care about?

Re: Acceleration

Unread postPosted: 24 Jul 2019, 19:52
by sprstdlyscottsmn
According to the FM, wingtip AIM-120Bs have a DI of 0. Still a clean aircraft.

Re: Acceleration

Unread postPosted: 25 Jul 2019, 06:23
by element1loop
wooster wrote:1. Acceleration may be on part with an F-22, but even my pickup truck can beat either
jet 0-60mph. You can twist things around if you want to get the desired shock and awe
affect of a public comment on acceleration. Acceleration is great until you run out speed.


But who needs more air speed than that?

>1.6 = more heat = much higher fuel burn rate = seriously reduced range = much less useful

Speed mattered when "Speed is Life" = 3rd and 4th gen thinking

5th-gen = "Not Being Tracked is Life" = If you are not seen then high speed does not even matter much.

Acceleration, to a useful speed, is more important to getting somewhere fast, and then being still able to dominate the air and loiter when you arrive. The fight is mostly transonic, where unseen high acceleration is the most important ability after agile turning.

Or ... Accel + Alt + VLO + DAS + MDF + Radial Distance = LIFE . . . Always choose Stealth

Re: Acceleration

Unread postPosted: 25 Jul 2019, 23:19
by johnwill
sprstdlyscottsmn wrote:According to the FM, wingtip AIM-120Bs have a DI of 0. Still a clean aircraft.


That's because the baseline DI = 0 for F-16 includes wing tip missiles. DI is the incremental drag effect of external stores above a defined baseline. Of course the drag effect of tip missiles is very small, as you say. One reason the effect is small is the launcher and missile combine to increase the aspect ratio, which generally reduces the AoA a tiny amount, for less induced drag.

Drag Index is based on 1g flight at 0.80 mach. It is not intended to provide accurate drag increments at all conditions, but is intended to help estimate cruise range for various store loadings.

Re: Acceleration

Unread postPosted: 25 Jul 2019, 23:22
by sprstdlyscottsmn
johnwill wrote:That's because the baseline DI = 0 for F-16 includes wing tip missiles. DI is the incremental drag effect of external stores above a defined baseline. Of course the drag effect of tip missiles is very small, as you say. One reason the effect is small is the launcher and missile combine to increase the aspect ratio, which generally reduces the AoA a tiny amount, for less induced drag.

Drag Index is based on 1g flight at 0.80 mach. It is not intended to provide accurate drag increments at all conditions, but is intended to help estimate cruise range for various store loadings.

Right, while not physically clean the FM considers tip missiles to be part of a Basic Airframe.

Re: Acceleration

Unread postPosted: 26 Jul 2019, 04:00
by firebase99
sprstdlyscottsmn wrote:
johnwill wrote:That's because the baseline DI = 0 for F-16 includes wing tip missiles. DI is the incremental drag effect of external stores above a defined baseline. Of course the drag effect of tip missiles is very small, as you say. One reason the effect is small is the launcher and missile combine to increase the aspect ratio, which generally reduces the AoA a tiny amount, for less induced drag.

Drag Index is based on 1g flight at 0.80 mach. It is not intended to provide accurate drag increments at all conditions, but is intended to help estimate cruise range for various store loadings.

Right, while not physically clean the FM considers tip missiles to be part of a Basic Airframe.


I believe its also a balance issue for the Viper.

Re: Acceleration

Unread postPosted: 26 Jul 2019, 17:27
by sprstdlyscottsmn
It flies fine without them, but they do help with flutter and wing bending moments with the AIM-120 helping more than the AIM-9. This is why the AIM-120 is always on the wingtips while the AIM-9 is on the outboard pylon.

Re: Acceleration

Unread postPosted: 26 Jul 2019, 21:54
by johnwill
The structural design of the launcher / tip area is controlled by the abrupt twanging (sorry, technical term) the missile gets while ejecting a 2000 lb bomb from station 3 or 7 in a 4g pullup. The loads and stresses in that condition are much higher than any 9g turn or 6g roll.

Another severe case is jettisoning a 370 tank at 1.6 mach. The shock waves from the tank sweep over the missile, launcher, and tip as the tank pivots downward and falls away. It was checked in flight test, but I don't know if it ever has happened in service.

Re: Acceleration

Unread postPosted: 26 Jul 2019, 22:12
by sprstdlyscottsmn
:notworthy:
johnwill wrote:The structural design of the launcher / tip area is controlled by the abrupt twanging (sorry, technical term) the missile gets while ejecting a 2000 lb bomb from station 3 or 7 in a 4g pullup. The loads and stresses in that condition are much higher than any 9g turn or 6g roll.

Another severe case is jettisoning a 370 tank at 1.6 mach. The shock waves from the tank sweep over the missile, launcher, and tip as the tank pivots downward and falls away. It was checked in flight test, but I don't know if it ever has happened in service.

:notworthy:

Re: Acceleration

Unread postPosted: 27 Jul 2019, 07:38
by charlielima223
element1loop wrote:
Speed mattered when "Speed is Life" = 3rd and 4th gen thinking

5th-gen = "Not Being Tracked is Life" = If you are not seen then high speed does not even matter much.



I cant remember where I read or heard it but it was from an F-22 pilot talking about their experience in the F-22. It went something along thr line of...
Flying above 50000 feet supercruising close to mach 2 and being stealthy, I can see everything but no one and nothing can touch me. I can give someone a bad day without knowing I was there and be on my way out before they even know what is going on.


Stealth and SA are a must in the world of 5th gen capabilities but having speed is indeed a bonus...

https://fas.org/man/dod-101/sys/ac/docs ... 991378.htm

Its ability to supercruise will allow the F-22 larger patrol areas, and permit the Raptor to enter and exit hostile areas in quick fashion, reducing the time a pilot spends over an enemy's territory," he said. "The capabilities of an F-22 aircraft will be a great benefit to our warfighters.


Flying fast in terms of the F-22 also means that they use less fuel...
https://www.safie.hq.af.mil/Portals/78/ ... 154531-787

Re: Acceleration

Unread postPosted: 27 Jul 2019, 08:54
by spazsinbad
charlielima223 wrote:
charlielima223 wrote:...Flying fast in terms of the F-22 also means that they use less fuel...
https://www.safie.hq.af.mil/Portals/78/ ... 154531-787

This PDF illustrates flying 'slightly faster' during CORONET MISSIONS (when ARF x many times is carried out) does not imply flying faster generally means 'fuel is saved'. One would have to have the DASH ONE/NATOPS figures to work this out OK.
"...FLY FAST, SAVE GAS?
Two F-22 CORONET demonstrations showed flying at a faster airspeed, including during air refueling, not only reduces transit time, but also saves fuel. In January 2014, Maj Sterling Boyer and Mr. Don Reese, working with TACC and the AOS, developed the concept of flying and air refueling F-22 CORONETs at 335 KIAS, closer to F-22 maximum range airspeed and within boom limits, instead of the standard 310 KIAS. The first demonstration flew 12 F-22s with KC-10 and KC-135 tanker support from Langley to Hickam, then on to Kadena, measuring a range of factors including fuel use, flight hours, and aircraft stability. Results indicated significant savings not only in flight time, but also net fuel, which could have a large impact if the method is applied across the fleet...."

Re: Acceleration

Unread postPosted: 27 Jul 2019, 16:37
by smsgtmac
In Speed vs. Stealth, if indeed they are at odds with each other, Stealth wins at any speed point.
https://elementsofpower.blogspot.com/20 ... -wins.html

Re: Acceleration

Unread postPosted: 28 Jul 2019, 04:29
by element1loop
Higher speed does not reduce burn rate, it just improves specific-consumption in terms of allowing a slightly better range achieved (if drag is low enough at speed) for a full fuel load than a lower speed does (obviously there's a cross-over speed where that's no longer true ... i.e. high-speed cruise). Unlikely to hold true for the F-35 due to its ample frontal cross-section as speed rises.

I'd be OK with slower dash and more stealth, loiter and maneuver time when I get there (especially as DAS-type sensor nets proliferate).

charlielima223 wrote:Its ability to supercruise will allow the F-22 larger patrol areas, and permit the Raptor to enter and exit hostile areas in quick fashion ...


The F-35A is more likely to enter a minute or two later and stay for 20 to 30 minutes - good mix, IMO.

Re: Acceleration

Unread postPosted: 28 Jul 2019, 07:17
by charlielima223
Over Syria, F-22s have already been shown to be valuable forward ISR assets. F-22s flying forward or with strike packages and then staying around to provide information to follow on aircraft and assist in C&C. The F-35s more comprehensive and advanced sensor suite makes it better in this regard. Im sure the Raptors ability to quicky accelerate or supercruise will give it some advantages if it needs to respond to a pop up threat. Much like how in Afghanistan Vipers, Mudhens, Rhinos, and Bones had larger AORs than the A-10 because they could respond and quickly go from point A to point B (granted in a premissive environment).

Re: Acceleration

Unread postPosted: 28 Jul 2019, 23:25
by doge
I came up with a sudden. 8) (!) My mediocre F-35 tactics opinion or idea...

First of all. (Organize.)
    ・F-22's subsonic Radius is about 590 nmi. (...It should be.) I think that the radius at the time of Super Cruise is about 460 nmi. (maybe.)
    ・F-35's Radius is known to be 669~max 760 nmi.
The difference in its Radius is up to about 300 nmi. (760-460=)

So, I came up with... 8)
At the expense of "Fuel" of its Radius 300 nmi, Is it possible for F-35 to approach F-22's mission/tactics, or to close the gap between?

In other words, I want to use fuel with a radius of 300 nmi for the afterburner and make F-35 a "pseudo" Raptor.

If it's possible use the idea of gaining speed at the expense of this radius and making it the same as the F-22 Super Cruise radius, The F-35 should be able to become a "pseudo" F-22 raptor.

Anxiety factor here...
    ・In the afterburner, is Fuel consumption too intense too much?
    ・Is a Fuel with a Radius of 300 nmi not enough for an afterburner? Not enough fuel?
    ・With a fuel of Radius 300 nmi, How long time can the F-35 sustain supersonic speed?
    ・Isn't it realistic...?
I have no idea at all... :shrug:
This is my mediocre idea who is a mediocre person. :notworthy:

Re: Acceleration

Unread postPosted: 29 Jul 2019, 01:46
by spazsinbad
MEDIOCRE you ain't - you have the best avatar known to the web for starters. 8) Without answering your questions I would generalise that this sort of fuel equation can only be known from flight manual fuel usage figures. We could all work out details with imagined figures but that is all they would be <garbage in> <garbage out> Why an 'ersatz F-22'? It's an F-35.

Re: Acceleration

Unread postPosted: 29 Jul 2019, 03:05
by steve2267
I'm about to grab a beer, so I'll grab a napkin too.

In round numbers -- and I better use crayon while I'm at it -- out and back 300nm is 600nm. This is about an hour, maybe a little more, of flying time at cruise for an F-35. From some numbers that Spurts was throwing around... an hour of cruise from an F-135 is on the order of 4500lbs. (Prolly somewhere between 3500 and 5500lbs.) So... you've got "4500lbs" of gas to play with for your pseudo-Raptor mission. I know the F-35 afterburner is "staged" and articles have mentioned a "min burner" usage... but even in "min burner," I'm guessing an F135 will still drink the gas quickly, but how quickly? Don't have the Dash One that Spaz refers to... so we're kinda stuck.

TEG (ThatEngineGuy) had some decent rule-of-thumb SFC numbers for modern gas turbine engines in terms of lbs gas / lb thrust / per minute (or per hour). Multiplying by thrust numbers for the F135 seemed to give hourly burn rates comparable to Spurts numbers. FWIW.

Re: Acceleration

Unread postPosted: 29 Jul 2019, 04:26
by viper12
I'll use the numbers posted there : https://www.hs.fi/kotimaa/art-200000613 ... 1bd4a3b646

There's 11,089kg/h for mil thrust, 10.2kg/s for afterburner. The new KPP has been given as 63 seconds for accelerating from Mach 0.8 to Mach 1.2. Assuming it's at 30,000ft, Mach 1.2 equals 707 knots TAS.

Let's suppose that after that acceleration, you can maintain Mach 1.2 with mil thrust or barely more than that, so the 11,089kg/h =~ 24,450lb/h fuel consumption would be a good approximation. The number that floats around for normal cruise is some 5,000lb/h, and it's probably around Mach 0.9.

With a very napkinesque assumption, let's say the acceleration between 0.9 and 1.2 Mach is constant (and is the same as between Mach 0.8 and Mach 1.2), so it's 3.74 knots TAS per second ; integrate that between Mach 0.9 and Mach 1.2, and you've covered 29,230 knots-second, or 8.12nm, in those 47.25 seconds. The fuel needed for that acceleration, assuming it's full afterburner, would be around 1,063lb.

In comparison, staying at Mach 0.9 would have covered 6.96nm in that time, and burned 65.6lb of fuel. So you flew an extra 1.16nm, pretty much negligible for the rest of the calculations. And roughly an extra 1,000lb of fuel for the acceleration over staying at Mach 0.9.

At Mach 1.2, you got k1 = 707/24,450 = 0.0289nm/lb of specific range, while you got k2 = (3/4)*707/5,000 = 0.106nm/lb at Mach 0.9. So the question is when do we have x/k1 + 1,000 = (x+600)/k2, as that's the condition for equal total fuel burn for accelerating and then sustaining Mach 1.2, while covering an extra 600nm at Mach 0.9.

So you got x*k2 = (x+600)*k1 - 1,000*k2*k1 => x*(k2-k1) = 600*k1 - 1,000*k2*k1 => x = [600*k1 - 1,000*k2*k1]/(k2-k1) = [17.34 - 3.063]/0.0771 =~ 185nm.

So it means you that if you accelerate from Mach 0.9 to Mach 1.2 (about 8nm), then fly at that speed for 185nm, you've burned the same quantity of fuel as flying some 792nm at Mach 0.9.

Now one important thing to note ; the thing used around 7,464lb of fuel, so you probably don't want to fly at that speed for too long considering the reserves.

Re: Acceleration

Unread postPosted: 29 Jul 2019, 23:06
by doge
spazsinbad wrote:

Thank you very much! :notworthy: I'm extremely happy you said that so about me. :thanks:
"F-35 is not F-22".I think so, too. I tend to have excessive expectations for the F-35 due to my strong desires or aspirations. My bad point. :doh:

steve2267 wrote:

Thank you very much for touching my idea! :notworthy:
Even it's a mini-afterburner will consume lot of fuel, I think so too. The words "Afterburner is Wasteful fuel" or "Afterburner is dripping of fuel" I see a lot on the web.

viper12 wrote:

Thank you very much for doing complicated calculations! :notworthy:
Calculation is a difficult area for me. :doh: However, I understand that I consume a lot of fuel by that. After all, afterburner seems better not to use for a long time.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 00:02
by viper12
It's not just afterburner that gulps fuel ; with the assumptions made above, the specific range at Mach 0.9 is about 3.7 times better than at Mach 1.2, which means you burn 3.7 times less fuel to cover a given distance. Fuel consumption between idle (or nearly) and military power has a pretty big gap apparently on the F-35.

It's basically like switching from a light hybrid car to a sports car in terms of worsening the fuel consumption, and as the old saying goes, there's never too much fuel on a plane...unless it's on fire. :mrgreen:

Re: Acceleration

Unread postPosted: 30 Jul 2019, 00:52
by wrightwing
viper12 wrote:It's not just afterburner that gulps fuel ; with the assumptions made above, the specific range at Mach 0.9 is about 3.7 times better than at Mach 1.2, which means you burn 3.7 times less fuel to cover a given distance. Fuel consumption between idle (or nearly) and military power has a pretty big gap apparently on the F-35.

It's basically like switching from a light hybrid car to a sports car in terms of worsening the fuel consumption, and as the old saying goes, there's never too much fuel on a plane...unless it's on fire. :mrgreen:

The standard cruise speed for the F-35 is between M.95 and .97. It doesn't require AB to maintain M1.2, though. We'd need to calculate fuel burn at MIL power.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 01:20
by quicksilver
“The standard cruise speed for the F-35 is between M.95 and .97.”

What does “standard cruise speed” mean? Where does that term come from? When is that speed used (in a mission profile) and for what purpose?

“It doesn't require AB to maintain M1.2...”

Not according to the people who fly it. There’s a previous thread on this.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 09:09
by wrightwing
quicksilver wrote:“The standard cruise speed for the F-35 is between M.95 and .97.”

What does “standard cruise speed” mean? Where does that term come from? When is that speed used (in a mission profile) and for what purpose?


Where does cruise speed come from, and what is it's purpose?
“It doesn't require AB to maintain M1.2...”

Not according to the people who fly it. There’s a previous thread on this.

Actually, it is according to the people who fly it.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 11:37
by quicksilver
Still waiting...

Tell us where ‘standard cruise speed’ comes from, and who (not Steve O’Bryan some years ago who was wrong or misquoted) said the jet does 1.2 in mil.

We can pull out the old thread if you’d like...or I can give you the answer...

At altitude, F-35 requires afterburner (or a dive in mil) to achieve supersonic flight. If one ‘unloads’ the jet (a routine practice in fighter aircraft) it will do so much more quickly; the downside is one does not always have some altitude to give away to do so). Once you take the jet out of AB, it will start to decelerate to a subsonic number. The good news is that the decel rate is fairly slow comparatively speaking. In some jets, in some configurations, a similar action (pulling the throttle to mil from ab) is like using the speed brake.

Back to ‘standard cruise speed’; where did you get that? Only ‘standard cruise speed(s)’ I ever learned were ‘max range’ and ‘max endurance’ — everything else was a circumstantial expedient. Where did your claim wrt F-35 ‘standard cruise speed’ come from?

Re: Acceleration

Unread postPosted: 30 Jul 2019, 13:39
by quicksilver
“Where did your claim wrt F-35 ‘standard cruise speed’ come from?”

I’m guessing you read it on the internet someplace (not named f-16.net).

Apart from the fact that my F-35-flying neighbors and former colleagues have told me the reality (...years ago), for most fighter aircraft, the general problem with ‘cruising’ in that (claimed) Mach number range (.95-.97) would be that it puts the jet in the middle of drag divergence — where small increases in Mach number above ‘max range’ require significantly disproportionate increases in fuel flow. Therefore ‘cruising’ (sustained flight) in that Mach range — while possible — is circumstantial, not ‘standard’. In common terms, you’re using a s___load of fuel to go just a tiny bit faster.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 15:49
by steve2267
Hey QS, while this will vary with altitude and conditions, have your former colleagues driving Lightnings stated how fast the jet will true out at, at max Mil power setting?

More of a curiosity question than anything. And, of course, may be privileged info...

Re: Acceleration

Unread postPosted: 30 Jul 2019, 16:45
by sprstdlyscottsmn
steve2267 wrote:Hey QS, while this will vary with altitude and conditions, have your former colleagues driving Lightnings stated how fast the jet will true out at, at max Mil power setting?

More of a curiosity question than anything. And, of course, may be privileged info...

"In full war equipment operates F-35 effortlessly 10,000 to 15,000 feet higher than our F-16 can, without using afterburner. The speed in 'cruises' is without further 50 to 80 knots higher. " I think it was Dobly that said that. I only have it credited as "Norwegian test pilot"

Re: Acceleration

Unread postPosted: 30 Jul 2019, 18:28
by playloud
sprstdlyscottsmn wrote:
steve2267 wrote:Hey QS, while this will vary with altitude and conditions, have your former colleagues driving Lightnings stated how fast the jet will true out at, at max Mil power setting?

More of a curiosity question than anything. And, of course, may be privileged info...

"In full war equipment operates F-35 effortlessly 10,000 to 15,000 feet higher than our F-16 can, without using afterburner. The speed in 'cruises' is without further 50 to 80 knots higher. " I think it was Dobly that said that. I only have it credited as "Norwegian test pilot"

Major Morten “Dolby” Hanche

https://nettsteder.regjeringen.no/kampf ... elt-annet/

Re: Acceleration

Unread postPosted: 30 Jul 2019, 18:38
by sprstdlyscottsmn
Thought so, thanks for the confirmation.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 20:14
by quicksilver
steve2267 wrote:Hey QS, while this will vary with altitude and conditions, have your former colleagues driving Lightnings stated how fast the jet will true out at, at max Mil power setting?

More of a curiosity question than anything. And, of course, may be privileged info...


No. Details generally not public. I don’t ask; they don’t offer.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 21:15
by quicksilver
LtCol Hank Griffiths, who commanded the test squadron at EDW some years back said this on the matter —

“What we can do in our airplane is get above the Mach with afterburner, and once you get it going ... you can definitely pull the throttle back quite a bit and still maintain supersonic, so technically you're pretty much at very, very min[imum] afterburner while you're cruising," Griffiths said. "So it really does have very good acceleration capabilities...”

DT test guy...not prone to spin or hyperbole. Just the facts.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 21:51
by steve2267
quicksilver wrote:LtCol Hank Griffiths, who commanded the test squadron at EDW some years back said this on the matter —

“What we can do in our airplane is get above the Mach with afterburner, and once you get it going ... you can definitely pull the throttle back quite a bit and still maintain supersonic, so technically you're pretty much at very, very min[imum] afterburner while you're cruising," Griffiths said. "So it really does have very good acceleration capabilities...”

DT test guy...not prone to spin or hyperbole. Just the facts.


Based on your knowledge and experience, wouldn't "very very min[imum] afterburner" still drink fuel at a rather prodigious rate? (Though far less than max burner.) I am guessing the motor is still burning a substantial amount of fuel more than max Mil. But what does this piston popper know?

Re: Acceleration

Unread postPosted: 30 Jul 2019, 21:57
by sprstdlyscottsmn
Of course. Using min burner to hold 1.2M vs Mil power to hold .99M is going to be in the ballpark of 2-3 times the fuel flow. Actual Drag may not be as high at 1.2M as would be expected relative to .99M. .99M is near maximum trans-sonic wave drag while 1.2M is usually well on the way back down to the steady supersonic condition. 300% fuel flow for 120% speed? no one is going to think that's a good plan. Even moreso that 0.99M is probably 150% fuel flow compared to 0.93-0.95. Max R and Max Mil can be very different fuel flows for a small change in speed.

Re: Acceleration

Unread postPosted: 30 Jul 2019, 23:47
by quicksilver
steve2267 wrote:
quicksilver wrote:LtCol Hank Griffiths, who commanded the test squadron at EDW some years back said this on the matter —

“What we can do in our airplane is get above the Mach with afterburner, and once you get it going ... you can definitely pull the throttle back quite a bit and still maintain supersonic, so technically you're pretty much at very, very min[imum] afterburner while you're cruising," Griffiths said. "So it really does have very good acceleration capabilities...”

DT test guy...not prone to spin or hyperbole. Just the facts.


Based on your knowledge and experience, wouldn't "very very min[imum] afterburner" still drink fuel at a rather prodigious rate? (Though far less than max burner.) I am guessing the motor is still burning a substantial amount of fuel more than max Mil. But what does this piston popper know?


Jets burn prodigious amounts of JP in mil — F-22 included. Operationally, sometimes you just need the speed... :wink:

Re: Acceleration

Unread postPosted: 31 Jul 2019, 01:00
by Corsair1963
It will be interesting to see how the XA100 or XA101 would change the above debate??? :|

Re: Acceleration

Unread postPosted: 31 Jul 2019, 01:26
by viper12
sprstdlyscottsmn wrote:Of course. Using min burner to hold 1.2M vs Mil power to hold .99M is going to be in the ballpark of 2-3 times the fuel flow.


Isn't that figure a bit high ? The Finnish specs sheet gave around 24.4K lb/h for mil power and some 81K lb/h in afterburner for the F-35A, so in the worst case scenario, minimum afterburner would be close to full afterburner, at 73.2 lb/h or so.

Re: Acceleration

Unread postPosted: 31 Jul 2019, 03:10
by spazsinbad
playloud wrote:
sprstdlyscottsmn wrote:
steve2267 wrote:Hey QS, while this will vary with altitude and conditions, have your former colleagues driving Lightnings stated how fast the jet will true out at, at max Mil power setting?

More of a curiosity question than anything. And, of course, may be privileged info...

"In full war equipment operates F-35 effortlessly 10,000 to 15,000 feet higher than our F-16 can, without using afterburner. The speed in 'cruises' is without further 50 to 80 knots higher. " I think it was Dobly that said that. I only have it credited as "Norwegian test pilot"

Major Morten “Dolby” Hanche

https://nettsteder.regjeringen.no/kampf ... elt-annet/

English Transration Reference here: viewtopic.php?f=55&t=27497&p=295008&hilit=Hanche+right+stuff#p295008

Earlier 'gabriele' posted the original link: viewtopic.php?f=22&t=27186&p=289639&hilit=Hanche+right+stuff#p289639
part from Google Transrate: "...In full war equipment operates F-35 effortlessly 10,000 to 15,000 feet higher than our F-16 can, without using afterburner. The speed in 'cruises' is without further 50 to 80 knots higher. In the F-16, I must use afterburner and take running speed before a missile shot. F-35 "cruiser" both faster and higher. Therefore, I am ready to shoot far anytime.

F-35 also has more fuel than we are accustomed to, it carries the load inside and is not as dependent on afterburner. Therefore we are left with more range than the F-16 and similar aircraft can achieve. "Combat radius" for the F-35 is between 30% and 70% longer than we get with the F-16! The extra range comes in handy in our elongated country. Range may alternatively be replaced in endurance over a given area...."