Time for 100K lbs of AB Thrust?

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
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rowbeartoe

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Unread post05 Sep 2021, 20:44

I may be wrong, but I think the Mig-25/31 had the biggest if not one of the largest engines for a fighter jet. If our NGAD Jet doesn't include engines that can produce 100K+ of AB thrust I'd have to believe a design like the Mig-25/31 would have the space to make such engines now.

That said, I see no reason to use "yesterdays" engines i.e. something that is already 15 years old (F135-PW-100) to put in the NGAD. If they do, I hope that it's a story like the F-14. Meaning they wanted more powerful engines but budget limited them until the F-14a+ aka F-14B and F-14D.

With the F-22 weighing just over 43K empty with 17K internal fuel and 70K of AB thrust, I don't think it's to much to ask for an airframe to now to weigh in the 50K range empty, with 100K of AB thrust and 20K-30K in internal fuel. Obviously the push isn't going to be these specs as much as other higher priority requirements, but usually these things go hand and hand. i.e a request for 70K of full thrust w/o AB for supercruise speed/stealth/etc.

The F-22 prototype engine was 30K with the YF119-PW-100L but the F119 ended up with 35K. So who knows, maybe the NGAD in that was flying last year in 2020 had 90K now (I have no idea), but maybe final production will be over 100K.

Maybe not as soon as 2025 as I think it's possible, but later because of all the hurdles a final fighter bird needs these days with avionic software. Either way, it has to be coming, if we (US) miss the opportunity with the AF and Navy 6th gen, perhaps another country will. Obviously, this isn't the be all end all of best fighter. It's just an evolution possibility looking at the trends since the Jet age.

I'm excited to see what we humans can do! :)
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sferrin

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Unread post05 Sep 2021, 23:22

rowbeartoe wrote:I may be wrong, but I think the Mig-25/31 had the biggest if not one of the largest engines for a fighter jet.


Forget the Mig-31 for the moment. The really weird one is the Mig-25.

https://www.secretprojects.co.uk/thread ... post-32416
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Unread post06 Sep 2021, 18:15

rowbeartoe wrote:I may be wrong, but I think the Mig-25/31 had the biggest if not one of the largest engines for a fighter jet. If our NGAD Jet doesn't include engines that can produce 100K+ of AB thrust I'd have to believe a design like the Mig-25/31 would have the space to make such engines now.


Yes they have massive engines which work different then other fighter engines (lot more efficient at high altitude and high speeds when using AB then ordinary turbojet/turbofan) but NGAD role isn't medium stratosphere interceptor so MiG-25/31 engines are irrelevant as comparison.

NGAD need as best as possible fuel economy and it would be nice to super cruise. Not some super duper max AB thrust. Also NGAD don't need to be heavier then F-22. F-22 is already quite heavy for its size it is 19.7tons, massive MiG-25 is only 300kg heavier and it doesn't use titanium nor composites :shock:

Imagine NGAD with similar size as F-22 but not flat heavy nozzles and replace titanium with composites and aluminium, weight savings can be noticable and it can be used for more fuel.
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Unread post06 Sep 2021, 19:47

sferrin wrote:
milosh wrote:From what I read XA100 and XA101 are F135 size but that doesn't mean they can be use for F-35 without modifications and I gave my option what is problem, size isn't (used to their max capability).

If there is plan to make scaled up XA100/XA101 I didn't know about it.


The XA100/XA101 are the engines that are designed to drop into an F-35. There is also a program for development engines that are not limited to the F135 envelope.

Capturezzz.JPG


From Sept 17, 2018 AvWeek


Hm, so with scaled up XA100/XA101 navy could have interesting single engine interceptor fighter. I don't think USN would be able to find funds for something like NGAD even just with two F135 but some single engined monster fighter which design scream speed is much more optionable.
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Unread post07 Sep 2021, 16:34

milosh wrote:
sferrin wrote:
milosh wrote:From what I read XA100 and XA101 are F135 size but that doesn't mean they can be use for F-35 without modifications and I gave my option what is problem, size isn't (used to their max capability).

If there is plan to make scaled up XA100/XA101 I didn't know about it.


The XA100/XA101 are the engines that are designed to drop into an F-35. There is also a program for development engines that are not limited to the F135 envelope.

Capturezzz.JPG


From Sept 17, 2018 AvWeek


Hm, so with scaled up XA100/XA101 navy could have interesting single engine interceptor fighter. I don't think USN would be able to find funds for something like NGAD even just with two F135 but some single engined monster fighter which design scream speed is much more optionable.


NGAD won't be single-engined. And it will be larger than the F-22 (probably a lot) for fuel. Would not be surprised if it was more like XF-108 in size.
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Unread post07 Sep 2021, 19:29

sferrin wrote:Hm, so with scaled up XA100/XA101 navy could have interesting single engine interceptor fighter. I don't think USN would be able to find funds for something like NGAD even just with two F135 but some single engined monster fighter which design scream speed is much more optionable.


NGAD won't be single-engined. And it will be larger than the F-22 (probably a lot) for fuel. Would not be surprised if it was more like XF-108 in size.[/quote]

I was writing about USN not USAF. NGAD is USAF program and it is quite unrealistic to see something similar on carrier deck. It would be big bird and very costly, NGAD will cost a lot and navalized version noticeable more.

That is why I mentioned single engine fighter interceptor with scaled up next gen engine.
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Unread post07 Sep 2021, 19:55

milosh wrote:That is why I mentioned single engine fighter interceptor with scaled up next gen engine.


USN catapults can handle up to 80,000lb aircraft.
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Unread post07 Sep 2021, 21:11

sferrin wrote:
milosh wrote:That is why I mentioned single engine fighter interceptor with scaled up next gen engine.


USN catapults can handle up to 80,000lb aircraft.


I didn't mean that, but price. NGAD will be quite expensive and now you want naval variant of it? Also if it is massive that is problem of its own, it isn't just stress on capapults but fitting something of F-108 size of deck and hangar.
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Unread post07 Sep 2021, 22:50

milosh wrote:
sferrin wrote:
milosh wrote:That is why I mentioned single engine fighter interceptor with scaled up next gen engine.


USN catapults can handle up to 80,000lb aircraft.


I didn't mean that, but price. NGAD will be quite expensive and now you want naval variant of it? Also if it is massive that is problem of its own, it isn't just stress on capapults but fitting something of F-108 size of deck and hangar.


Carriers are designed for much larger airwings than they currently have. Bigger aircraft as well. The Vigilante was 77 feet long. The A-3D 76 feet with a 72 foot span.
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Unread post08 Sep 2021, 00:38

There is another consideration on carrier aircraft size. Specifically, the Navy has specified the minimum distance between the exhaust nozzles in afterburner and the jet blast deflector. I believe it most recently was set based on the F-14. That was one of the considerations when going from the F-23 to its naval version in order to meet that requirement. Also, in the days of the A-3 and RA-5, the aircraft was attached to the catapult a bridle underneath the center of the aircraft. Later aircraft attach via a more efficient method to a bar on the nosewheel. This shift in methodology is why on carriers after CVN-70 you no longer needed the "horns" at the end of the catapult run. This change in methodology also made the aircraft "sit" a few feet further back on the cat, so that has to be taken into consideration in order to insure that required distance.

Unless something has changed, I don't think there is any great push for the Navy's 6th generation a/c to be a variant of AF's NGAD. Sharing some systems, yes, but not the same airframe. In fact, the sentiment seems to be strongly against that, AFAIK.
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Unread post08 Sep 2021, 02:15

aaam wrote:There is another consideration on carrier aircraft size. Specifically, the Navy has specified the minimum distance between the exhaust nozzles in afterburner and the jet blast deflector. I believe it most recently was set based on the F-14. That was one of the considerations when going from the F-23 to its naval version in order to meet that requirement. Also, in the days of the A-3 and RA-5, the aircraft was attached to the catapult a bridle underneath the center of the aircraft. Later aircraft attach via a more efficient method to a bar on the nosewheel. This shift in methodology is why on carriers after CVN-70 you no longer needed the "horns" at the end of the catapult run. This change in methodology also made the aircraft "sit" a few feet further back on the cat, so that has to be taken into consideration in order to insure that required distance.

Unless something has changed, I don't think there is any great push for the Navy's 6th generation a/c to be a variant of AF's NGAD. Sharing some systems, yes, but not the same airframe. In fact, the sentiment seems to be strongly against that, AFAIK.


Nobody has said it would be the same. It won't be single-engined however. Consider both the Phantom II and the Vigilante used a pair of J79s yet were very different, with different capabilities.
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Unread post08 Sep 2021, 05:15

sferrin wrote:Nobody has said it would be the same. It won't be single-engined however. Consider both the Phantom II and the Vigilante used a pair of J79s yet were very different, with different capabilities.


Completely different versions of J79 from what gather. It's like comparing a 1977 Chevy small block to a 1967 Chevy small block. Sire, you could swap them from one car to the next. But you're going to find it much easier putting an older engine into the older car where it belongs, and likewise the newer engine in the newer car. You never know what kind of mechanical gymnastics you have to pull mixing new/old parts. That 1977 engine was built to tighter tolerances even if they perform in similar fashion. The newer engine generally will enjoy a better lifespan due to it being built on lessons learned over time.

It seems like F-106A borrowed the afterburner section off retired F-105G's that might make my argument largely irrelevant.
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Unread post08 Sep 2021, 13:26

madrat wrote:
sferrin wrote:Nobody has said it would be the same. It won't be single-engined however. Consider both the Phantom II and the Vigilante used a pair of J79s yet were very different, with different capabilities.


Completely different versions of J79 from what gather.


Nope. Both the RA-5C and F-4J used the J79-GE-10. There are other versions of the Phantom and the Vigilante that use other versions of the J79 but it's hardly the show-stopper you're portraying it to be. Could you swap engines literally between aircraft? Don't know. You probably can't swap F100s between F-15s and F-16s but that doesn't change the fact they're both using F100s. Nor does it change the fact that, especially since they're both in design, it would be child's play to make both the NGAD and the USNs aircraft compatible with the same engine.
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Unread post08 Sep 2021, 17:16

sferrin wrote: You probably can't swap F100s between F-15s and F-16s but that doesn't change the fact they're both using F100s. Nor does it change the fact that, especially since they're both in design, it would be child's play to make both the NGAD and the USNs aircraft compatible with the same engine.


Swapping a F100-220 or -229 between F-15 and F-16 use is technically very easy. Remove the nozzle turkey feathers for F-15, uncap the 7th stage compressor bleed for F-16, and change a bit of DEEC /EDU cooling plumbing (ejector cooling for F-15C/D, tank cooling for F-15E and F-16) and you are ready to install.

This has been done occasionally, but the fleets are usually kept separate for programmatic reasons. TCTO retrofits were usually done first on F-16s for single engine safety reasons, so changing fleets can run into configuration and TCTO funding issues, and has to be approved by the USAF engine program manager
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Unread post13 Oct 2021, 23:17

Re: Follow on engine size (NGAD) this is from this weeks AvWeek:

NGAP.JPG
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