How well did F-22 meet the original ATF objectives?

[disconnectedradical]

In the end I think the F-22 for the most part can meet the mixed supercruise/subsonic combat radius requirement, but where it falls short is the subsonic combat radius. I wonder if this is the result of the F-22 aerodynamics and F119 being optimized for supersonic flight and is not quite as efficient when subsonic.

Combat radius of 800 nautical miles on internal fuel would be really challenging, and even with the F-23 which allegedly has more fuel than the F-22, it may not be enough. I do wonder if the F120 may have allowed the F-22 or F-23 to reach that combat radius, since it can increase bypass ratio at subsonic speeds.

[f119doctor]

In the end I think the F-22 for the most part can meet the mixed supercruise/subsonic combat radius requirement, but where it falls short is the subsonic combat radius. I wonder if this is the result of the F-22 aerodynamics and F119 being optimized for supersonic flight and is not quite as efficient when subsonic.

Combat radius of 800 nautical miles on internal fuel would be really challenging, and even with the F-23 which allegedly has more fuel than the F-22, it may not be enough. I do wonder if the F120 may have allowed the F-22 or F-23 to reach that combat radius, since it can increase bypass ratio at subsonic speeds.

I really doubt that the F120 would have been an efficient subsonic cruiser, even with the variable bypass.

In low bypass supercruise mode, it was a 3 stage fan and a 4 stage high compressor and I doubt the OPR exceeded 20:1. This means a relatively cool compressor discharge, allowing more fuel to burned up to the turbine inlet temperature limit, good for supersonic thrust. Almost a self cooled J79 engine cycle with the minimum bypass air around the core.

In high bypass mode, a significant amount of air bypassed after the 2nd stage of the fan, and the core driven 3rd stage had to unloaded with variable vanes both in front of the 3rd stage and in front of the core inlet so the two bypass flows could flow aft together, if I understood the operation correctly. The higher bypass flow at lower Fan pressure ratio is good for subsonic SFC, but it would tend to lower OPR at that condition even further, which is bad for SFC.

As I noted in a post elsewhere in this forum, I remember GE reporting in AvWeek their supercruise fuel flow numbers in the YF-22 at M1.58, 43K. The YF119 couldn’t do this speed at Mil power, but I remember hitting the exact same flight point at Min AB, burning 1000 lbs/hr less fuel flow per engine. Not supercruise, but more efficient!

[disconnectedradical]

It seems like the only way the F-22 can meet the 800 nmi subsonic combat radius requirement is with external tanks. Otherwise you'll probably need a bigger aircraft. I also wonder if maybe the F119 design erred too much on the side of supercruise at the cost of subsonic TSFC.

What's interesting is that reading about F-22 design history, the weight of the original design would have been even more because they had swept trapezoid wings instead of the current diamond wings.

[Roscoe]

[Rant]
wrightwing has it right. I was at Edwards during the Dem-Val and was originally set to be assigned as one of the Ops Engineers (last minute change to work B-2 instead). As it was described to me at the time, the airframe guys and the engine guys were separated for primary proprietary reasons but program competition as well. I've read so many interweb posts saying that the YF-23 was "obviously" better or that the "RCS was clearly lower" that it blows my mind.

First off, the RCS data was never released below the TS level so no one would have a clue (and those that did signed paper to never discuss). Second, program comparisons have also never been made public so everything is pure speculation.
[/Rant]

[charlielima223]

[Rant]
wrightwing has it right. I was at Edwards during the Dem-Val and was originally set to be assigned as one of the Ops Engineers (last minute change to work B-2 instead). As it was described to me at the time, the airframe guys and the engine guys were separated for primary proprietary reasons but program competition as well. I've read so many interweb posts saying that the YF-23 was "obviously" better or that the "RCS was clearly lower" that it blows my mind.

First off, the RCS data was never released below the TS level so no one would have a clue (and those that did signed paper to never discuss). Second, program comparisons have also never been made public so everything is pure speculation.
[/Rant]

I think all these people's misconceptions often come from their perceived notions of the aircraft. The unusual design often leads people to think that the YF-23 was a more stealthy design (mostly in IR spectrum IMO). When Lockheed Martin a few years ago released a conceptual notion of a 6th gen fighter that had similarities to the YF-23... that on further justified/cemented their belief...

You're absolutely correct that NO ONE outside of the programs truly know how the YF-22 and YF-23 compared to each other. Even former test pilot Paul Metz who flew the YF-23 and later the EMD F-22 doesn't draw direct comparisons between the two because he can't. All he will say is that Lockheed made a better presentation at the end which had an effect on which aircraft was picked.

[jetblast16]

I heard or read, again more stuff that has trickled down on to the Internet, that the YF-23 had exceptional supersonic turn performance...

[disconnectedradical]

While I've also heard the YF-23 has great supersonic turn performance, I've also heard that at least in some parts of the supersonic envelope, the YF-22 was even better at supersonic sustained turn, and I'd imagine that the F-22 with the more refined aerodynamics is an even bigger beast in this area.

[rowbeartoe]

Whatever the ATF objectives, this video just shows how capable the F-22 vs the F-35 is in regards to low altitude unarmed maneuvers. That said, the F-35 does a great job too imo. Obviously, airshows are not everything. Still a great video.

[maz]

The F-22 is no doubt the most capable air dominance fighter. It failed to meet range and cost projections. The range requirements could have easily been achieved but increasing internal fuel volume. Simply make the F-22 appear "fatter". This extra fuel comes at the expense of extra structural weight and drag. In hindsight more fuel should have been fitted even if it resulted in 10% extra weight and the supercruise speed dropping by 10%. The F-22 is very short ranged for such a large and heavy aircraft.

I think it should have been cancelled like the Navy A-12 Avenger II and Army RAH-66 Comanche. The USAF never would have missed the F-22. AESA equipped Eagles would have done the job perfectly fine just like the Super Hornet did for the Navy.

Had the US Navy not gone with the low budget option Super Hornet their fleet would probably be significantly smaller today. If the F-22 was cancelled the USAF would actually be more powerful today. The F-15C wouldn't have been disintegrating in the air due to budget constraints.

Cancelling the F-22 program wouldn't have been a waste as all of the research and development would be reused on the next program. Usually when you do something twice it is much easier the second time.

[mixelflick]

The Raptor's final chapter has yet to be written, it's going to be around for a long time yet. And all i hear about now is its "short range". On internal fuel alone, it can cover the same ground as an F-15C with 2 bags.... which is NOT insignificant. I'd say the engineers did pretty damn good, especially given all of the changing requirements etc etc...

It's rather unfair as well: The aircraft is perceived to be on its way out, so all the talk now is about its supposed deficiencies. For an aircraft that had its legs chopped off, weapons and sensors un-funded etc..... it's still the most fearsome thing flying.

Even if you're flying an AESA equipped Eagle..... you're toast. There is no escape, and I'm talking 4 of them vs. 1 Raptor. Have heard that from airshow pilots many times (on both sides of the fence). So let's give credit where credit is due - they did damn good meeting performance requirements (except when they changed them). Even then, I would take a Raptor vs. anything else flying.

Hands down, full stop.

[disconnectedradical]

The F-22 is no doubt the most capable air dominance fighter. It failed to meet range and cost projections. The range requirements could have easily been achieved but increasing internal fuel volume. Simply make the F-22 appear "fatter". This extra fuel comes at the expense of extra structural weight and drag. In hindsight more fuel should have been fitted even if it resulted in 10% extra weight and the supercruise speed dropping by 10%. The F-22 is very short ranged for such a large and heavy aircraft.

It's not the structure, the F-22 already carries as much fuel as an F-15C with a centerline tank. The issue is that the F119 being optimized for supercruise is not great when it comes to subsonic TSFC. If more range is really needed, rather than making the fuselage fatter, it would be better to make it a bit longer. That way you have a bit more maneuver drag but your cruise drag would not have much impact.

I think it should have been cancelled like the Navy A-12 Avenger II and Army RAH-66 Comanche. The USAF never would have missed the F-22. AESA equipped Eagles would have done the job perfectly fine just like the Super Hornet did for the Navy.

Had the US Navy not gone with the low budget option Super Hornet their fleet would probably be significantly smaller today. If the F-22 was cancelled the USAF would actually be more powerful today. The F-15C wouldn't have been disintegrating in the air due to budget constraints.

Cancelling the F-22 program wouldn't have been a waste as all of the research and development would be reused on the next program. Usually when you do something twice it is much easier the second time.

The whole F-22 versus upgraded F-15 debate has already been done to death in the 1990s, and even during the budget cuts after the Cold War, the vastly greater capabilities of the F-22 made it a better value than upgraded F-15s with AESA. No need to debate it again because you'll just reach the same conclusions. F-15C falling apart is BECAUSE we didn't buy enough F-22s to replace them because in 2009 we were more focused on the Middle East than against China or Russia. The F-15EX happened only because coincidentally, the production line is kept alive by foreign orders and we are just piggybacking of of that. So this cancellation talk is using current circumstances to make historical decisions. If Rumsfeld and Gates weren't hell bent on stopping the F-22 production at 187, then we wouldn't be having this problem.

The F-22 is also much further along than the A-12 at similar timeframe so canceling it would have been a massive waste. The USAF would not have been massively more capable without the F-22, quite the opposite considering the difference in capability and survivability compared to even upgraded F-15s. There's a reason that even the new F-15EX will not be the spearhead unlike the F-22 and F-35.

[Roscoe]

I think all these people's misconceptions often come from their perceived notions of the aircraft. The unusual design often leads people to think that the YF-23 was a more stealthy design (mostly in IR spectrum IMO).

First off, IR signature wasn't a thing back then (we weren't even capable of measuring it worth a damn given it's dependance to atmospheric conditions and background "clutter") so I firmly doubt that was a differentiator. Secondly, an aircraft's RCS is rarely congruent with visual appearance because a lot of it is materials. So those speculating that the YF-23 was stealthier than the YF-22 because it looks "cooler" don't really have a clue.

[eloise]

First off, IR signature wasn't a thing back then (we weren't even capable of measuring it worth a damn given it's dependance to atmospheric conditions and background "clutter") so I firmly doubt that was a differentiator.

With all due respect, didn’t they use the Airborne Turret Infrared Measurement System III (ATIMS III) and Threat Infrared Generic Emulation Radiometer (TIGER) pod to measure F-22 infrared signature back then?

6E7FB5A2-12B4-47E5-BC5E-E871589AB504.png (12.53 KiB) Viewed 1633 times

Secondly, an aircraft's RCS is rarely congruent with visual appearance because a lot of it is materials. So those speculating that the YF-23 was stealthier than the YF-22 because it looks "cooler" don't really have a clue.

I haven’t seem the scattering chart of either YF-22 or YF-23 wouldn’t the elimination of corner reflector (using V tail) is beneficial for side aspect RCS? Assuming RAM and RAS would be quite similar and unlikely that the whole wing can be transparent to radar wave

[eloise]

There was an interview where F-14 pilot claimed he could detect YF-22 from pretty far on IRST as well
Here it is
Thats also fit with manual data if that F-22 was supersonic, though to be fair, I’m not sure if YF-23 fair any better?. May be the much longer duct help if IRST look up from lower altitude

[milosh]

Secondly, an aircraft's RCS is rarely congruent with visual appearance because a lot of it is materials. So those speculating that the YF-23 was stealthier than the YF-22 because it looks "cooler" don't really have a clue.

F23 did had advantage in materials. It would use lot more composites then F22. And NG had quite good knowledge about stealth and composites because of ATB program.