So you are equating theoretical research an mock-ups (none of which were fighters) to 30+ years of operational experience?

Like everything in US vs USSR, there was tons of overlap and ironies. Did they field a stealth jet ? No. They concentrated on water. But.. one of the major scientific breakthroughs on radar refraction, Pyotr Ufimtsev’s 1962 paper Method of Edge Waves in the Physical Theory of Diffraction was came from the Moscow Institute for Radio Engineering. This unclassified paper found its way into the US via the USAF’s System Command’s Foreign Technology Division in 1971. Ufimtsev’s paper helped Lockheed’s Skunk Works’ in its ECHO 1 computer program designed to predict radar cross sections (RCS).

Many of the designs tendered for the MFI (also sometimes called I-90 [fighter-90s]) program often incorporated low-observable features like canted tails and internal weapons’ bays. Yakolev’s MFI submission had canted intakes much like the F-22. Sukhoi also had a stealthy bomber program, the T-60S, of which very little credible information has surfaced.

The T 60S was first planned in 1984

This debate is absolutely fruitless for many reasons, and the most important one is the fact that nobody on this forum and nobody outside the lockheed martin and sukhoi biro knows the exact RCS of the PAK FA and F-22.

They invest billions of dollars on R&D and test the RCS using the most complicated calculations and big anechoic chambers, and all over the net we have guys making “educated” points using just photos and some PC calculations.

Till recently we had “internet experts” claiming that only F-22 has smaller RCS than F-35 and they explained that with “this and that” as a rule of a thumb.
Now we know that more “roundish” F-35 has even smaler RCS than F-22 from certain aspects.

Here is my rule of the thumb, If you don’t want to look stupid, don’t talk about RCS of VLO plane! I don’t!

And just one more thing regarding your comparison using photos:

[ATTACH=CONFIG]2509TTACH]

Even though they look similar from the front, PAK FA doesn’t have even close inlet curvature like YF-23 does.
Because of the much shorter front landing gear PAK FA is leaned forward when on the ground. That way much of the engine face is blocked and the engine itself looks like it is placed much higher in relation to the inlet. In the level flight that is not the case.

[ATTACH=CONFIG]25096/ATTACH]

Anyway, if the ingenieurs from the Sukhoi claim that serial PAK FA will have similar frontal RCS to F-22, it is most certain that they have solved the engine face problem one way or another.
I just hope that they deliver what they promise.

I agree. But for most people, they believe its a foregone conclusion that the Raptor has better stealth than the Pak Fa. And it rarely gets challenged.

You should try different tactics, this one is too cringe

^ There is the under/offcenter intake/wing engine design of the Pak Fa and YF 23.

And then here is the Raptor. The Raptor is an entirely different design. Where the intake S veers into the center of the fuselage. And then goes into the engine. This is why the Raptor has a conventional look.

Not sure what you are cringing about…

Raptor huge vertical tail affect side aspect RCS mostly while PAK-FA inlet design affect front aspect RCS. For bow tie stealth design, frontal aspect are more important.

From one Raptor vs YF 23 report. http://www.globalsecurity.org/military/systems/aircraft/f-23.htm

The YF-23 was stealthier than the F-22 Raptor. The two ruddervators reduce the Radar Cross Signature of the YF-23 significantly.

One of the main reasons I believe the Pak Fa is stealthier than the Raptor.

Firstly, a small corner reflector in the luneburg lens or a chaff clound can have RCS thoundsands times bigger than an F-22 eventhough physically they are alot smaller. In term of stealth attribute: shaping and material play much more important roles than physical size. If 2 object have the same shape and made from same material then yes the smaller object will have smaller RCS if we assuming both object are still in optical region in respect to radar wavelength. But J-20 and PAK-FA do not have similar shape, a slight different in size ( they are at most 20-25% different ) doesnot offset the advantage in shaping.

Secondly, i dont have to prove anything and certainly not to you. I said ” i think ” not ” iam sure ” ,and my post is the answer to the question Y-20 bacon asked me.If he wanted your opinion, he would have asked for it. Maybe if you stopped being immature and defensive every time someone talk about PAK-FA design trade off, people would have care about your opinion.

Firstly, a small corner reflector in the luneburg lens or a chaff clound can have RCS thoundsands times bigger than an F-22 eventhough physically they are alot smaller.

Over exaggeration. Stealth technology is not magic. And common sense would dictate that if it were true, no engineering team would handicap themselves like that.

In term of stealth attribute: shaping and material play much more important roles than physical size.

Is there a ratio or something ? Probably. What is it ? How do you know how much more important it is ? The shape and size are very much intertwined.

But J-20 and PAK-FA do not have similar shape, a slight different in size ( they are at most 20-25% different ) doesnot offset the advantage in shaping.

First. Just because you think that you’ve spotted something, does not mean that the Pak Fa has a “disadvantage in shaping”.

And 2nd,that is a ridiculous claim to make. The Sukhoi engineers would not get the shaping so wrong that it would be visible to the naked eye and would make an aircraft 25% larger in size, have a smaller RCS.

Secondly, i dont have to prove anything and certainly not to you. I said ” i think ” not ” iam sure ” ,and my post is the answer to the question Y-20 bacon asked me.If he wanted your opinion, he would have asked for it. Maybe if you stopped being immature and defensive every time someone talk about PAK-FA design trade off, people would have care about your opinion.

This is the Pak Fa thread. You cant expect to make claims out in the open for all to see, about the Pak Fa without them being challenged. PM him next time.

In term of shaping i think J-20 got a stealthier design than PAK-FA, at least from frontal

Sigh… Anyone who says this can’t expect to be taken seriously.

and I don’t think anyone has got close enough to the intake to confirm or deny what could be a possible engine face sighting. (if that’s where you are going)