The PAK-FA News, Pics & Debate Thread XXV

just noticed this picture of 056, it seems they cheated us again ;), the yellow hatched area is not treated with RAM, I guess the whole spine is not as well. You can easily see there fasteners holding the composite skin. The thick layer of RAM is under the greyish-white looking top coat, but they seem to use several shades. Some are having a cyan tint, probably to distinguish where RAM has been applied. Have someone noticed it already?

M

I think you are reaching a bit here. I cant see it. (32 yo)

The actual RAM applied on the T-50-6-2 is only on a few spots for testing, its not on the whole aircraft.

I do believe the cyan tint you speak of has previously been used on Yak-130’s, Su-34’s, and Su-30’s. It’s just a common color tone the Russian air force uses.

Yup, 056 is definitely (fully?) RAMed up. Probably accounts for that strange cyan sheen already seen on some parts of 055R, in addition to the light grey edge treatments on the inlet lips and some other edges.

It is something to note that on T-50-6-2 even on the part of the hatch that doesn’t have the thick RAM covering the screws are still treated

just noticed this picture of 056, it seems they cheated us again ;), the yellow hatched area is not treated with RAM, I guess the whole spine is not as well. You can easily see there fasteners holding the composite skin. The thick layer of RAM is under the greyish-white looking top coat, but they seem to use several shades. Some are having a cyan tint, probably to distinguish where RAM has been applied. Have someone noticed it already?

M

The PakFa has small vertical tails simply because it does not need bigger one. It uses differential camber variation in yaw (levcon and close coupled horizontal tail).

The pakFa is certainly closer to a “6th gen” design with no tails on that point than any other known flying design. The J20 use its canards on the same way. Hence the small vertical surface somewhat aero masked by th fuselage and double delta albeit with a smaller aero envelope.

“автоматическое обнаружение в ИК диапазоне воздушных целей (ВЦ) и ракет”

ИК=Инфракрасное=Infrared

I am not so convinced by your theory. Why go with the IR-system for Su-35S, if it has such issues that they don’t want to use it (or more developed version of it) on their 5th gen project? To my knowledge we saw both systems for the first time in 2011. Su-35S’ IR system on the first production plane which made its first flight on May 2011 and 101KS-U on the T-50-3 during the same year. KS-U was also shown on MAKS 2011.

I am a bit skeptical that 101KS-U is actually an UV system, but if it is, it would support one bigger theory. That PAK FA is meant to be operated as a low-altitude fighter.

Reason being that a stealth fighter is harder to detect when it is flying low and ground clutter is aiding its efforts to avoid detection. PAK FA’s primary role is to protect Russian airspace from a violating force and that threat comes from air-based systems like AWACS and fighters. This is very different from the threats that shaped the development of US’ stealth aircraft. For their more offensive-minded doctrine it was (and is) crucial to be able to operate in enemy airspace where the biggest detection threat comes from ground-based radar systems.

I think we can see this difference even in the stealth preferences. In this regard it is interesting to compare YF-23 and PAK FA. Both have a tunnel between the intakes/engines, which from certain angles probably poses a signature management problem. On YF-23 the tunnel was placed on the top of the plane to keep the bottom as simple and clean as possible whereas on the PAK FA the opposite was done. Because for YF-23 the main threat comes from below and for the (hypothetically) low-flying PAK FA the main threat comes from above.

According to current understanding one of the PAK FA’s sensors (101KS-P) is a high-resolution thermal imager specifically to aid low-altitude flying and that would go well with the theory. Having a DIRCM on a fighter aircraft is unusual or even the first? But if PAK FA is to be operated as a low-flyer then it would make a lot more sense as MANPADS would be a substantial threat to an aircraft operating in the hypothesized manner. This is also where 101KS-U as an ultraviolet system fits the picture. As an UV-based MAWS has an advantage over IR-based MAWS on dealing with ground-launched missiles and directing DIRCM, because of the high IR background clutter.

There are of course issues with this kind of employment of the aircraft. Effective range of both missiles and the aircraft itself is diminished and even AAA can threaten an expensive aircraft, but especially on homefield these may not be such big problems.

Not seems probable to me as in orderr to get an advantage from clutter it would need to fly at a really low level, something like Tornado and Su-24 did.
Certainly the final one product is thought as a multirole, although A2A oriented plane, so it would have the capability of operate even at lower quotes than the hyperspecialized F-22A , hence the necessity of a Flir pod and DIRCM.
You are instead right when you talk about a plane able to operate in strict connection with Russian AD network instead than in the offensive air superiority mode you have well depicted for F-22, hence a stealth configuration centered over frontal aspect instead than an all round one.

so any other major differences/changes in the 50-8 prototype besides the pitot tube.
and why did they re-add it? New radar being tested?

Times ago they said it would be the one with the L band radar in the wings, hence the return of pitot.

I am not so convinced by your theory. Why go with the IR-system for Su-35S, if it has such issues that they don’t want to use it (or more developed version of it) on their 5th gen project? To my knowledge we saw both systems for the first time in 2011. Su-35S’ IR system on the first production plane which made its first flight on May 2011 and 101KS-U on the T-50-3 during the same year. KS-U was also shown on MAKS 2011.

Could be a risk management or cost reduction kind of thing as well, just like how f-22 not intergrated with IRST or HMD eventhough these things are available

I think we can see this difference even in the stealth preferences. In this regard it is interesting to compare YF-23 and PAK FA. Both have a tunnel between the intakes/engines, which from certain angles probably poses a signature management problem. On YF-23 the tunnel was placed on the top of the plane to keep the bottom as simple and clean as possible whereas on the PAK FA the opposite was done. Because for YF-23 the main threat comes from below and for the (hypothetically) low-flying PAK FA the main threat comes from above.

That possible i guess , and probably the reason why it got small vertical tail too

Having a DIRCM on a fighter aircraft is unusual or even the first? But if PAK FA is to be operated as a low-flyer then it would make a lot more sense as MANPADS would be a substantial threat to an aircraft operating in the hypothesized manner. This is also where 101KS-U as an ultraviolet system fits the picture. As an UV-based MAWS has an advantage over IR-based MAWS on dealing with ground-launched missiles and directing DIRCM, because of the high IR background clutter.

It rare , but not the first though. And DIRCM would be effective against AAM as well

http://aviationweek.com/awin/northrop-aims-fast-jet-laser-jammer-f-35
http://www.defense-aerospace.com/articles-view/release/3/42557/uk-fast-jet-dircm-reaches-milestone-(july-20).html

so any other major differences/changes in the 50-8 prototype besides the pitot tube.
and why did they re-add it? New radar being tested?

I think T-50-8 is the main aerodynamic test subject of the second stage. It might not have any sensors (except that second stage exclusive one above inflight refueling tube). Certainly there are only placeholders for 101KS-O and 101KS-V and not even that for 101KS-Us. Also there aren’t any radiation stickers next to radiating elements like usually. Now it might be because they just hadn’t added that stuff when the pictures were taken (even the bort number isn’t painted) or maybe 50-8 simply doesn’t have any radiators and it focuses totally on aerodynamics, materials and tests of stability and handling.

It is something to note that on T-50-6-2 even on the part of the hatch that doesn’t have the thick RAM covering the screws are still treated:
[ATTACH=CONFIG]250289[/ATTACH]
Compare that to T-50-1:

You sure that one is IR based rather than UV ? i cant find detail of either anywhere on that page though. But if i have to guess the system probably just IR rather than IIR so there high false alarm rate which is why PAK-FA use UV instead

“автоматическое обнаружение в ИК диапазоне воздушных целей (ВЦ) и ракет”

ИК=Инфракрасное=Infrared

I am not so convinced by your theory. Why go with the IR-system for Su-35S, if it has such issues that they don’t want to use it (or more developed version of it) on their 5th gen project? To my knowledge we saw both systems for the first time in 2011. Su-35S’ IR system on the first production plane which made its first flight on May 2011 and 101KS-U on the T-50-3 during the same year. KS-U was also shown on MAKS 2011.

I am a bit skeptical that 101KS-U is actually an UV system, but if it is, it would support one bigger theory. That PAK FA is meant to be operated as a low-altitude fighter.

Reason being that a stealth fighter is harder to detect when it is flying low and ground clutter is aiding its efforts to avoid detection. PAK FA’s primary role is to protect Russian airspace from a violating force and that threat comes from air-based systems like AWACS and fighters. This is very different from the threats that shaped the development of US’ stealth aircraft. For their more offensive-minded doctrine it was (and is) crucial to be able to operate in enemy airspace where the biggest detection threat comes from ground-based radar systems.

I think we can see this difference even in the stealth preferences. In this regard it is interesting to compare YF-23 and PAK FA. Both have a tunnel between the intakes/engines, which from certain angles probably poses a signature management problem. On YF-23 the tunnel was placed on the top of the plane to keep the bottom as simple and clean as possible whereas on the PAK FA the opposite was done. Because for YF-23 the main threat comes from below and for the (hypothetically) low-flying PAK FA the main threat comes from above.

According to current understanding one of the PAK FA’s sensors (101KS-P) is a high-resolution thermal imager specifically to aid low-altitude flying and that would go well with the theory. Having a DIRCM on a fighter aircraft is unusual or even the first? But if PAK FA is to be operated as a low-flyer then it would make a lot more sense as MANPADS would be a substantial threat to an aircraft operating in the hypothesized manner. This is also where 101KS-U as an ultraviolet system fits the picture. As an UV-based MAWS has an advantage over IR-based MAWS on dealing with ground-launched missiles and directing DIRCM, because of the high IR background clutter.

There are of course issues with this kind of employment of the aircraft. Effective range of both missiles and the aircraft itself is diminished and even AAA can threaten an expensive aircraft, but especially on homefield these may not be such big problems.

so any other major differences/changes in the 50-8 prototype besides the pitot tube.
and why did they re-add it? New radar being tested?

No, no such detail about the aerosol system.

That page has general details about Sukhoi’s work on RCS reduction.
The photo of the Su-30 says “Radar absorbent material”, the one under the Berkut says “RAM, cockpit treatment, S-ducts, frequency selective surfaces”. The T-50 photo just says “All methods”.
Some mention of RCS reduction of radar and other sensor systems.

The document mentions no reduction in thrust, less pressure issues from circular engine duct to flat nozzle exhaust and much smaller system weight.
However it mentions IR reduction is not quiet as high.

Does not specify if PAK-FA will have this system, just mentions it as a direction of work.

The other relevant page from that Sukhoi document:

what does that page say ? and what are those stuff at the bottom ?
for the aerosol system , is there any mentioned of the aerosol consumption rate ?

The document mentions no reduction in thrust, less pressure issues from circular engine duct to flat nozzle exhaust and much smaller system weight.
However it mentions IR reduction is not quiet as high.

Does not specify if PAK-FA will have this system, just mentions it as a direction of work.

The other relevant page from that Sukhoi document:

Talks about IR signature reduction through use of flat nozzles vs circular, and the images below show an aerosol system used to reduce IR.

The flat nozzle is the one tested on the Su-27UB, photos have been available for many years.

the aerosol one is very interesting , what sort of aerosol we are talking about here ? salt water ? will the aircraft have to carry extra aerosol in addition to normal fuel ? what is the consumption rate ? will it be on all the time ? will it reduce thrust ? will PAK-FA use that method to reduce IR signature ?

would you be kind enough to translate what the photo say ?

Talks about IR signature reduction through use of flat nozzles vs circular, and the images below show an aerosol system used to reduce IR.

The flat nozzle is the one tested on the Su-27UB, photos have been available for many years.

would you be kind enough to translate what the photo say ?

It is quite curious that PAK FA apparently uses a simpler UV system for MAWS when Su-35S is already using an IR-based system. http://www.npk-spp.ru/deyatelnost/avionika/126-optiko-elektronnaya-razvedka-.html

You sure that one is IR based rather than UV ? i cant find detail of either anywhere on that page though. But if i have to guess the system probably just IR rather than IIR so there high false alarm rate which is why PAK-FA use UV instead

Which is why that is one aspect of the reported capabilities of the 101KS-suite that I’m skeptical about, and I don’t recall an official source for it either. Possibly it’s just a journalist extrapolation from the fact that the F-22 was (and sometimes still is) widely quoted as having a UV MLD – which is also false, as manufacturer brochures and published raw sensor imagery prove. I could see it being a dual-band IR/UV system though, as some images of 101KS-U hardware have shown a pair of smaller lenses flanking the main one behind the sensor window, but my guess would rather be that they’re laser warning receivers.

It’s just a MAWS – you won’t see much in UV spectrum since its sources are very rare in the nature – usually it’s a Sun or some very VERY hot things, like rocket motor. This makes detection and selection of the threats(i.e. missile) much more simpler than if it worked in IR, but IR has much more of potential and universality, but makes target selection and identification much harder due to the much more complicated “IR picture” of the world.

It is quite curious that PAK FA apparently uses a simpler UV system for MAWS when Su-35S is already using an IR-based system. http://www.npk-spp.ru/deyatelnost/avionika/126-optiko-elektronnaya-razvedka-.html