Operational Performace Comparison: Viper, Beagle, and Stubby

The F-35 compared with other modern jets.
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bumtish

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Unread post13 Aug 2014, 11:08

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.
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Unread post13 Aug 2014, 14:34

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.
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Unread post13 Aug 2014, 15:57

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....
Attachments
SuperHornetTurnCapabilitiesChartTEXT.gif
SuperHornetTurnRateNATOPS.gif
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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Unread post14 Aug 2014, 01:22

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)
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Unread post14 Aug 2014, 01:32

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.
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Unread post15 Aug 2014, 00:14

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.
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Unread post15 Aug 2014, 00:47

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.
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Unread post15 Aug 2014, 01:09

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.
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Unread post15 Aug 2014, 02:12

delvo wrote:What does "aircraft get bounced" mean?


Engaged by enemy aircraft.
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Unread post15 Aug 2014, 04:24

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.
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Unread post15 Aug 2014, 07:56

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?
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Unread post15 Aug 2014, 15:24

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.
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Unread post15 Aug 2014, 19:24

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.
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Unread post16 Aug 2014, 00:55

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.
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Unread post16 Aug 2014, 02:58

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.
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