F-35 internal fuel, range

[disconnectedradical]

Wouldn’t have gone down this off-topic rabbit hole if Corsair wasn’t peddling his opinions and potato arguments in the face of evidence the whole time.

Back on topic. I went back to try to find the sources for the 7% range improvement with the F135 ECU.

https://breakingdefense.com/2023/03/air ... tor/?amp=1

However, RTX (parent of P&W) state in an article in December 2022 that 7% is when F135 ECU is paired with the new Collins EPACS cooling system, which I’m guessing can provide much more cooling with existing bleed air. Interesting the article isn’t available anymore and I had to dig through web archives to find it.

https://web.archive.org/web/20230725162 ... ing-system

This may be another question for f119doctor but how much does bleed air cooling affect raw performance or TSFC? Previously I thought it was mainly the engine durability that got hit.

[f119doctor]

Bleed air is the worst possible (but often necessary) hit on engine performance, especially if it is taken from the aft end of the high compressor. You take power from the turbine to drive the compressor, input that power into the compressed air plus any compressor inefficiencies, then you throw part of that energy away in the bleed air instead feeding it back into the turbine flow path and out the exhaust for thrust. More fuel with higher turbine temperatures are required to offset the bleed loss, impacting TFSC, turbine life, and thrust once you reach the turbine temperature limit.

On the F-16, they take bleed air off the back end of the high compressor at low power settings, then transition to a mid compressor bleed at higher power settings to reduce the amount discarded work and minimize the impacts. But this adds complexity and possible failure modes.

I don’t know all what is going into the F135 ECU. I believe it includes a redesigned high compressor that was developed under a Navy funded fuel burn reduction program. This improves the efficiency of the HPC, which lowers both compressor discharge temperature and turbine inlet temps and improves TFSC. I don’t know if the HPC airflow capacity has been increased to offset higher bleed flow or what improvements are slated for the combustor, high and low turbines that make up the F135 Power Module that might improve efficiency and temperature capability of the engine.

[Corsair1963]

Wouldn’t have gone down this off-topic rabbit hole if Corsair wasn’t peddling his opinions and potato arguments in the face of evidence the whole time.

Back on topic. I went back to try to find the sources for the 7% range improvement with the F135 ECU.

https://breakingdefense.com/2023/03/air ... tor/?amp=1

However, RTX (parent of P&W) state in an article in December 2022 that 7% is when F135 ECU is paired with the new Collins EPACS cooling system, which I’m guessing can provide much more cooling with existing bleed air. Interesting the article isn’t available anymore and I had to dig through web archives to find it.

https://web.archive.org/web/20230725162 ... ing-system

This may be another question for f119doctor but how much does bleed air cooling affect raw performance or TSFC? Previously I thought it was mainly the engine durability that got hit.

Talk about calling the kettle black...

[ericchase88]

:: Removed by moderator ::

[disconnectedradical]

I don’t know all what is going into the F135 ECU. I believe it includes a redesigned high compressor that was developed under a Navy funded fuel burn reduction program. This improves the efficiency of the HPC, which lowers both compressor discharge temperature and turbine inlet temps and improves TFSC. I don’t know if the HPC airflow capacity has been increased to offset higher bleed flow or what improvements are slated for the combustor, high and low turbines that make up the F135 Power Module that might improve efficiency and temperature capability of the engine.

Back in 2017-2018 when the F135 upgrades were still Growth Option 1.0 and 2.0, P&W talked about a power module upgrade that gives 6-10% thrust improvement and 5-6% range improvement. This was from the Navy's F135 Fuel Burn Reduction and Air Force's Component and Engine Structural Assessment Research (CAESAR) programs, which I think goes even further back to the XTE68/LF1 in the early 2010s. I think this is what became the F135 ECU, and the argument that it's a lower risk and cost upgrade option makes sense because the components have been tested for quite a long time now.

https://www.flightglobal.com/pratt-and- ... 72.article

Interesting is that even back in 2017-2018 when it was Growth Option 1.0, they were discussing about improved PTMS for Block 4.

https://www.prattwhitney.com/en/newsroo ... option-1-0
https://www.ainonline.com/aviation-news ... e-upgrades

What's interesting is that back then, Growth Option 2.0 was supposed to be the XA101 3-stream adaptive engine, but in 2020 that changed to the XA101 being an entirely new design and GO2 being dropped altogether. I'm not sure what caused that to change, maybe going with a 3-stream architecture required so many changes that basing it on the F135 is no longer worth it and it's better to go clean sheet?

Talk about calling the kettle black...

No, you ignored all the data presented to you because it doesn't fit your opinion and kept pushing generalizations or misrepresentations of what people have said.

[botsing]

Which facts, specifically?

Probably the fact that this person (ericchase88) is part of a troll farm.

Just when harmony is resolved on this topic (or any topic), this person randomly walks in and starts pushing nonsensical polarizing views to bring it to discourse again.

I've reported this person.

[ericchase88]

It is simple FACT that carrying external stores have big impact on drag. This applies to all fighters. Yet the F-22 fanboys on this thread make unsupported claim that somehow with big external stores like fuel tanks and pods it can exceed performance of clean F-35, like somehow the Raptor is magic and doesn’t care about laws of physics. And ignore statements from test pilots like Jon Beasley.

The angular fuel tanks and pods are supposed to try to not ruin the stealth, but it will badly hurt aerodynamics. Hard to see how F-22 with these external stores can exceed performance of clean F-35 like the fanboys keep claiming with no evidence at all! They’ll say anything to argue that the F-22 is better.

Me and others who call out the F-22 fanboys polluting an F-35 thread are then attacked.

[F-16ADF]

I don't know the drag index of the stealthy fuel tanks, so I am leaving that out of my post. Though the streamlined IR pods probably don't have much drag, that's my guess. I would rather see the IR system near or under the radome, but they say there is no room.

Now I have a question I would like answered. And applying the same criterion. If 2 air to air missiles and pylons 'cripple' the performance of a jet; Then is the F-35's performance greatly reduced or impaired when carrying the 2 external aim-9X aams and their double canted pylons?

[ericchase88]

As said many times, the tanks and pods are much bigger and more angular than missiles. Meant to reduce RCS not be aerodynamic, so drag impact is much bigger. I don’t know why this is so hard to see?

And F-35 don’t need external fuel tanks it has much better range than F-22 (what this thread is about), yet F-22 needs the fuel tanks for range and the pods for IRST that F-35 already have. Yet it comes with big tradeoffs in performance and the sensor fusion will never be as good as F-35.

The performance isn’t crippled, but mounting external stores clearly affect performance, which is why an F-22 with those external stores will lose much of the advantage compared to a clean F-35 which has very good transonic acceleration!

[F-16ADF]

That is your opinion. Do you have a T.0. 1F-35-1-1 or T.0. 1F-22-1-1 to prove your point?

I am guessing the drag index of an aim-9x missile is 4 or 5. After all, the IRIST missile in the Greek F-16 manual has a drag index of 4. And what about those double canted pylons? The standard LAU-129 is a 6. My guess is the F-35's are equal or more. And no I do not have an F-35 manual to prove my point just as you do not have the Drag Index for the streamlined IR pods -you are guessing. So the F-35's drag index with 2 external aams, by way of my estimation is 20-25. Just as the drag index of a Viper with 4 aams, 2 aim-120 and 2 aim-9 is 22. If the Viper is incapacitated with 4 missiles, then the same criterion must be applied to the F-35?

Again, you don't have a manual for F-22 or the IR pods, just as we don't have one for the F-35 and its external aams. What you are doing is guessing, and then applying it is a truism.

Eyeball the drag of the 2 wing tanks for the F-15, and do the same for the centerline tank. And then compare your 'eyeball' figures to the actual numbers in the flight manual.

[Corsair1963]

That is your opinion. Do you have a T.0. 1F-35-1-1 or T.0. 1F-22-1-1 to prove your point?

I am guessing the drag index of an aim-9x missile is 4 or 5. After all, the IRIST missile in the Greek F-16 manual has a drag index of 4. And what about those double canted pylons? The standard LAU-129 is a 6. My guess is the F-35's are equal or more. And no I do not have an F-35 manual to prove my point just as you do not have the Drag Index for the streamlined IR pods -you are guessing. So the F-35's drag index with 2 external aams, by way of my estimation is 20-25. Just as the drag index of a Viper with 4 aams, 2 aim-120 and 2 aim-9 is 22. If the Viper is incapacitated with 4 missiles, then the same criterion must be applied to the F-35?

Again, you don't have a manual for F-22 or the IR pods, just as we don't have one for the F-35 and its external aams. What you are doing is guessing, and then applying it is a truism.

Eyeball the drag of the 2 wing tanks for the F-15, and do the same for the centerline tank. And then compare your 'eyeball' figures to the actual numbers in the flight manual.

Neither do you have any facts. Yet, we do know "external stores" (pylons, tanks, pods, missiles, etc.) have a detrimental impact on performance. Nor have we seen any "reason" to believe the F-22s new stealthy stores. Have made some type of major aerodynamic break thorough in that regard. Which, would be "required" to support your claims

As a matter of fact, their bulky angular appearance makes such claims seem very much a suspect.

[disconnectedradical]

Hello how many times do we have to say it. There is "no hard data" just wild speculation from members like you....

Making informed estimates based on hard data from a comparable aircraft is not “wild speculation”, just because you want to ignore it since it doesn’t fit your opinion.

So are you saying that USAF is purposely lying by calling them “Low Drag Tank and Pylon”? This is some actual “wild speculation”.

Neither do you have any facts. Yet, we do know "external stores" (pylons, tanks, pods, missiles, etc.) have a detrimental impact on performance. Nor have we seen any "reason" to believe the F-22s new stealthy stores. Have made some type of major aerodynamic break thorough in that regard. Which, would be "required" to support your claims

As a matter of fact, their bulky angular appearance makes such claims seem very much a suspect.


IMHO

“Angular” doesn’t mean much, it’s the incidence angle of the plane from the - airflow. An angular but pointed and chiseled tip, like the AIRST pods, would be quite aerodynamic. If anything, this is you making a wild speculation without understanding fluid mechanics.

Again, are you saying that USAF is purposely lying by having “low drag” in the name?

[hkultala]

Hello how many times do we have to say it. There is "no hard data" just wild speculation from members like you....

Making informed estimates based on hard data from a comparable aircraft is not “wild speculation”, just because you want to ignore it since it doesn’t fit your opinion.

You posted range numbers from marketing power points, I posted fuel fraction calculations and comparisons of engine bypass ratios.

You keep assuming that the new tanks must have magically low drag because they are called "low drag tanks".

Those fuel fraction calculations and bypass ratio numbers are much harder data than the marketing range numbers in those power points and the belief that the new tanks must have low drag in all flight conditions because they are called "low drag tanks"

The physics of this universe and all actual hard numbers show that those tanks must have considerable effect on drag.

[Corsair1963]

Hello how many times do we have to say it. There is "no hard data" just wild speculation from members like you....

Making informed estimates based on hard data from a comparable aircraft is not “wild speculation”, just because you want to ignore it since it doesn’t fit your opinion.

You posted range numbers from marketing power points, I posted fuel fraction calculations and comparisons of engine bypass ratios.

You keep assuming that the new tanks must have magically low drag because they are called "low drag tanks".

Those fuel fraction calculations and bypass ratio numbers are much harder data than the marketing range numbers in those power points and the belief that the new tanks must have low drag in all flight conditions because they are called "low drag tanks"

The physics of this universe and all actual hard numbers show that those tanks must have considerable effect on drag.

Yes, like I said these new tanks would have to be groundbreaking in regard to aerodynamics. In order to achieve what some of the Raptor Supporters are claiming. I've seen nothing to support such a claim....

While I have "no doubt" they offer reductions in RCS compared to existing designs. I don't see such an improvement is aerodynamic qualities...

[F-16ADF]

That is your opinion. Do you have a T.0. 1F-35-1-1 or T.0. 1F-22-1-1 to prove your point?

I am guessing the drag index of an aim-9x missile is 4 or 5. After all, the IRIST missile in the Greek F-16 manual has a drag index of 4. And what about those double canted pylons? The standard LAU-129 is a 6. My guess is the F-35's are equal or more. And no I do not have an F-35 manual to prove my point just as you do not have the Drag Index for the streamlined IR pods -you are guessing. So the F-35's drag index with 2 external aams, by way of my estimation is 20-25. Just as the drag index of a Viper with 4 aams, 2 aim-120 and 2 aim-9 is 22. If the Viper is incapacitated with 4 missiles, then the same criterion must be applied to the F-35?

Again, you don't have a manual for F-22 or the IR pods, just as we don't have one for the F-35 and its external aams. What you are doing is guessing, and then applying it is a truism.

Eyeball the drag of the 2 wing tanks for the F-15, and do the same for the centerline tank. And then compare your 'eyeball' figures to the actual numbers in the flight manual.

Neither do you have any facts. Yet, we do know "external stores" (pylons, tanks, pods, missiles, etc.) have a detrimental impact on performance. Nor have we seen any "reason" to believe the F-22s new stealthy stores. Have made some type of major aerodynamic break thorough in that regard. Which, would be "required" to support your claims

As a matter of fact, their bulky angular appearance makes such claims seem very much a suspect.

Good. Then the fact of the matter remains we all DO NOT KNOW. As I said earlier, please answer my above question:

Do the 2 external aim-9x aams on the the double canted pylons have, and as you just stated above in your reply, a "detrimental" impact on performance of an aircraft such as the F-35?