Russian Su-57 Aircraft Thread (PAK-FA and IAF FGFA)

[Hyperwarp]

They abandoned the f-22/Su-47 style bay because the Su-57's intake position does not allow for it. Sure they could have designed a fighter similar to the F-22 in layout and structure and decided against it for whatever reason. But it's illogical to assume that those reasons were to improve the fighter to another level. They never demonstrated the ability to build an F-22 level fighter and Su-47 was not selected for various reasons. It makes no sense to say that because the bay layout is done in Su-47 therefore they could easily have gone with that option for Su-57. The compromises involved are mysterious to us but i'm not the one making conclusions. The size and fit conclusion I made was based off known width of R-77 and a fair estimate of bay width. I have doubts two can R77s can fit. 3 is impossible.

It is the other way around. Early PAK-FA proposal had a large S-Duct. It was like a hybrid between the F-22 and production proposal of the YF-23 (F-23A EMD?). Unfortunately I can't find the patent for this early version. Maybe Trident (Tirdent) can locate it. But it would eliminate the dual weapons bay arrangement. With a large S-Ducts they could only have one large weapons bay and perhaps one small weapons bay. The intakes have to be widely seperated if they wanted to have 2x large and deep enough weapons bays. These are design choices depending on requirements. They have to compromise. This means the Su-57 will have exposed compressor blades and requires a complicated blocker to shield them similar to the X-32.

 

[Hyperwarp]

The 2 1000 lbs limitation comes in because the F22 would still have 2 Aim 120's for self defense in the same bay. If you just wanted to run a bombing run you could add more JDAMS but if Air defense was not an issue you can also carry additional external stores. Another factor is that the missiles used by the Chinese and Russians tend to be a bit bigger in size meaning that the same ordinance takes up more room.
F22 was canceled more for political issues.

Whole point is, the F-35 can carry LBG, NSM, JSOW, 2000 lbs JDAM and more internally. F-22 cannot. After all, F-22 is for air-dominance.

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F35 has much smaller weapons load outs. in an Air to Air configuration 2 Aim 9 side winders and 6 Aim 120 for the Raptor. even if you add in another rail option which has been offered F35 is still only able to carry 6 missiles internally. F35 will be more reliant on External stores than F22, A feature the J20 and SU57 seem to ignore.

I am unclear what you mean here. J-20 has been spotted with 4x external fuel tanks but not weapons. Su-57 on the other hand has been testing external weapons stores for some time using dummies.

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Deeper perhaps but the YF23 weapons bays were more restricted as it combined The Aim 9 and Aim 120 into the same bay this resulted in a load out of 3 Aim 120 with 2 Aim 9 missiles. To correct this for there proposal of changes between the YF23 and a offered F23 Northrop wanted to add a second weapons bay in front of the YF23's bay this would have lengthened the fuselage by 2.5 feet making a 70 foot long fighter, increasing drag on the bird but still wouldn't have resulted in a equal payload to the Raptor

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True, with the F-23A EMD in its basic configuration had 6x AAM vs 8x AAM of the F-22, but the primary weapons bay was deeper than the F-22 leaving more room for the future including A-to-G munitions. From what I was told, one of the USAFs disapproval of the YF-23 was its weapons bay arrangement especially the weapons release mechanism. One AMRAAM sits on top of the other and if one gets jammed you literally lose 2 (

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). This is not a problem with F-22.

 

[ougoah]

It is the other way around. Early PAK-FA proposal had a large S-Duct. It was like a hybrid between the F-22 and production proposal of the YF-23 (F-23A EMD?). Unfortunately I can't find the patent for this early version. Maybe Trident (Tirdent) can locate it. But it would eliminate the dual weapons bay arrangement. With a large S-Ducts they could only have one large weapons bay and perhaps one small weapons bay. The intakes have to be widely seperated if they wanted to have 2x large and deep enough weapons bays. These are design choices depending on requirements. They have to compromise. This means the Su-57 will have exposed compressor blades and requires a complicated blocker to shield them similar to the X-32.

Yes it was a compromise. They wanted to keep this sort of design for performance but could not use the F-22 bay layout. I wanted to point out how ridiculous that Drive article was. Su-57 bays are not anything to be "liked" as they have put it. If they really wanted to fit 6 missiles into bays, they will eventually be able to anyway with new MRAAMs. 4 R77s is pretty much the current limit. Side bays are questionable... I don't think they exist but some think otherwise because fan art has indicated this and they've taken it and ran. It's not unlikely for the Russians to self promote. After all they did claim that Su-35 is better than F-22 and scared it away in Syria and S-200 damaged an F-35. So believe what you want I guess.

CoG does affect the fighter more with the chosen layout. That much is hard to deny. Whether they've worked around it to make the effects negligible is another issue. We'll likely never see any of these 5th gen fighters actually perform and be able to evaluate their performance. What we do know is India is no longer interested in FGFA officially and has abandoned their project for whatever reasons. Too early to suppose what those reasons are but if they never buy Su-57 down the line while not getting F-35 or another 5th gen fighter from another country, it would be fair to say Su-57 was disappointing enough for them to ignore it despite requiring a 5th gen fighter. On top of this, consider the excitement and certainty behind the FGFA abilities before this reveal.

 

[Gloire_bb]

4 R77s is pretty much the current limit.

Yes, there will be 4, as far as known.
No, these aren't r-77. R-77 was never developed to be carried inside, to begin with.
There are two separate developments specifically for a main bay, articles 170 and 180, respectively.
About fast bays - after published patents and confirmations by Butowski - well, hard to do anything. Wait until they'll actually be pictured.

 

[Tirdent]

They abandoned the f-22/Su-47 style bay because the Su-57's intake position does not allow for it.

Which leads to the question of why they abandoned the Su-47/F-22 intake configuration then - according to teh Internetz, an s-duct is THE universal remedy to all RCS problems after all I'd say the cause-effect relationship is precisely the other way round - the desired bay layout drove the intake ducting (the fact that a short, straight duct has attractions in terms of volume contribution and pressure loss not withstanding - though the blocker required for RCS will work against the pressure loss advantage).

Sure they could have designed a fighter similar to the F-22 in layout and structure and decided against it for whatever reason. But it's illogical to assume that those reasons were to improve the fighter to another level.

Well, deviating from a tried-and-tested template for any OTHER reason sounds very illogical to me. Why re-invent the wheel if the result ends up worse than the established alternative?

It makes no sense to say that because the bay layout is done in Su-47 therefore they could easily have gone with that option for Su-57.

Why not? As mentioned, a very similar fuselage layout with s-ducts and side-by-side main bays is *known* to have been in the running at one point during Su-57 development - it was rejected in favour of the design we see today.

Here's the concept Hyperwarp refers to:



The fuselage configuration is indeed very YF-23 like (though even more reminiscent of Northrop's pre-Dem/Val DP110 iteration), even if the wings and tail are clearly different.

The size and fit conclusion I made was based off known width of R-77 and a fair estimate of bay width. I have doubts two can R77s can fit. 3 is impossible.

I don't know what information you were working off, but the best available estimates for the Su-57 bay dimensions are 4.2m long by 1.0m wide and 0.6m deep each, give or take 0.1m perhaps (which makes them not too different to one half of the F-22 and J-20 main bay in width and length). A R-77 with rear fins folded confirmedly fits into a 0.3m x 0.3m cross section box...

4 MRAAMs is the default for now, but if the Russians ever decide that 6 are required, it should be about as straightforward an upgrade as they come.

 

[Tirdent]

One for all and I don't know if certain members still not know it or deliberately ignore this since they do not want to accept it:
The T50's intake geometry is different and it has another solution added (a blocker - which was not installed in the very first prototypes) in comparison to the F-22/-35, J-20, FC-31 and so on.

Also the YF-23 did NOT have this flaw, it was in fact even more stealthy than the YF-22.

So in the end I'm also not a greatest fan of the T50, but we should not argue with wrong arguments.

It's not completely incorrect, even though the proposed EMD F-23 configuration had very aggressive s-ducts, a small section of the engine fan face is visible from directly ahead:



I suspect the RCS contribution might have been aligned with one of the YF-23 planform's 8 inherent spikes (the reason why it was nicknamed after a spider) and hence may not have required treatment. Alternatively, it is entirely possible that a blocker was planned for - the IGVs on the YF120 engine are certainly interesting:

 

[Hyperwarp]

One possible reason for the YF-23 having better overall RCS reduction was due to the tail. It used ruddervators instead of the conventional tail of the YF-22. The vertical tail of the YF-22 was gigantic (

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). It looks hideous compared to this beauty (

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).

It is possible the YF-22 had better frontal RCS reduction than the YF-23, but overall YF-23 should have been better. When it came to IR signature reduction it seems the YF-23 was well ahead of the YF-22. I think there was a recent revelation about this on how far ahead it was (Apologies for the lack of reference). But at the end of the day, what mattered most to the USAF was who can reliably deliver a 5th gen aircraft within the timeframe and budget. After all, YF-22 fullfilled all the ATF requirements and the production F-22 supposed to have exceeded the requirements. On the other hand, I wouldn't be surprised if Northrop-Grumman botched the production or at least cause severe delays of a hypothetical F-23A. The weapons release mechanism was worrisome.

Anyway, back on topic:

 

[Tirdent]

The (Y)F-23 configuration had a number of basic advantages in terms of RCS. There were fewer major planform angles (= fewer RCS spikes), fewer moving parts (fewer weapons bay & landing gear doors), no BL diverter gaps on the intakes (advanced bleed on the YF-23, DSI on the F-23), better masking of the exhaust nozzles and I'm sure the butterfly tail also helped.

About the only aspect where the (Y)F-22 did better according to crude layman's LO rules was the single piece canopy - which suggests the RCS advantage of this technology isn't as big as it is sometimes made out to be. Apparently the benefit is not sufficiently clear-cut that it was universally considered worth the weight penalty over a separate windshield and canopy, depending on whether you asked Lockheed's or Northrop's design teams (even though the latter clearly placed more emphasis on LO overall).

 

[Jura The idiot]

Apr 8, 2018

two PAKFAs to take part in the Victory Day Parade this year:

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and:

(now I was lucky to quickly find the flyover; starts at 01:07:20 or so in

)

 

[zaphd]

Yes it was a compromise. They wanted to keep this sort of design for performance but could not use the F-22 bay layout. I wanted to point out how ridiculous that Drive article was. Su-57 bays are not anything to be "liked" as they have put it. If they really wanted to fit 6 missiles into bays, they will eventually be able to anyway with new MRAAMs. 4 R77s is pretty much the current limit. Side bays are questionable... I don't think they exist but some think otherwise because fan art has indicated this and they've taken it and ran. It's not unlikely for the Russians to self promote. After all they did claim that Su-35 is better than F-22 and scared it away in Syria and S-200 damaged an F-35. So believe what you want I guess.

CoG does affect the fighter more with the chosen layout. That much is hard to deny. Whether they've worked around it to make the effects negligible is another issue. We'll likely never see any of these 5th gen fighters actually perform and be able to evaluate their performance. What we do know is India is no longer interested in FGFA officially and has abandoned their project for whatever reasons. Too early to suppose what those reasons are but if they never buy Su-57 down the line while not getting F-35 or another 5th gen fighter from another country, it would be fair to say Su-57 was disappointing enough for them to ignore it despite requiring a 5th gen fighter. On top of this, consider the excitement and certainty behind the FGFA abilities before this reveal.

The tandem bay allows for a smaller fuselage frontal cross section, which means a lower drag design. In this old vid Boeing using roughly the same main bay configuration in one of its 6th gen concepts. So by no means an inferior design if your airframe has the length for it.