J-20 5th Gen Fighter Thread VIII

[kurutoga]

If I understand it right, each update to the F-22/F-35 software requires human test pilot to run all scenarios as regression tests. For example, the so called TR3 is now on every new F-35 but it is not yet fully regression-tested in all scenarios.

I have never heard anything about J-20's software updates. Do we know if the software is being updated?

 

[zbb]

I have great respect for Patchwork and his opinions, but the most he could possibly know is whatever estimates US intel has produced on a particular day. Nobody in the world knows the exact parameters of both aircraft (and they aren't constant values in any case).

I'm willing to accept the idea that J-20/F-22/F-35 are all operating in the same ballpark of VLO, but anything more specific than that is inherently questionable. That doesn't mean he's ignorant or mistaken, far from it, just that he's making generalizations he probably shouldn't.

There have been encounters between J-20s and F-35s over the East China Sea that also involved KJ-500 and E-3 AWACS on each side, so US defense establishment will have some data gathered from such encounters, however limited that may be.

 

[Alfa_Particle]

The consensus elsewhere online seem to be that while the J-20 has a smaller RCS than the su-57, it still has a (much) larger RCS than the F-22,

One thing that I'll say, is that from a purely theoretical perspective, in terms of head-on RCS and assuming that a) both airframes uses the same materials and b) identical RAM composition, the splitter gaps of the F-22's caret intakes are a magnitude more disastrous to it's RCS than the canards.

And spoiler alert: both assumption a) and b) is not true and in reality, the J-20 being decades more modern enjoys a broader application of advanced materials and techniques. But even disregarding these advantages, the J-20 inherently is stealthier than the Raptor at least from head-on.

And note that the majority of the consensus online are from rather ill-informed people.

and that the J-20's canards compromise its stealth.

If you feel like disregarding multiple studies done by multiple different groups of people (CAC et al.), sure.

I know that canards compromising stealth in the general sense has been somewhat debunked

Be a bit more confident and say "completely debunked."

but the J-20's canards specifically do not sit in the same plane as the main wings unlike F-22's main wings and its elevators.

And CAC literally did a study of an aircraft with two versions: conventional wing and a canard delta, and they found that the canards have negligible impact to the aircraft's RCS compared to a conventional wing design, which can be completely eliminated with appropriate measures. I'd be more concerned about the splitter plate gaps.

The J-20 also has 2 smaller wings at the very back that point down.

They're called ventral strakes, which can be made out of composites since they are fixed. Fun fact: non-conductive materials such as CFRP are practically invisible to radar.

Patch once said something like J-20's signature isn't quite on the level of Blk4 F-35s but is similar to early production airframes,

I have no idea who he is, but I feel like I should. However, again from a purely theoretical point of view, in terms of head-on RCS the J-20 should have a larger degree range without RCS spikes horizontally than the F-35 due to the higher wing sweep angle.

 

[Wrought]

There have been encounters between J-20s and F-35s over the East China Sea that also involved KJ-500 and E-3 AWACS on each side, so US defense establishment will have some data gathered from such encounters, however limited that may be.

If one or both sides was not using Luneburg lenses during such encounters, then they deserve to be court-martialed.

That being said, I don't doubt everyone's intelligence division has some reasonable estimate of the real numbers. But anyone using such estimates to draw definitive conclusions like X > Y should put some big qualifiers around their claims at the very least.

I have no idea who he is, but I feel like I should. However, again from a purely theoretical point of view, in terms of head-on RCS the J-20 should have a larger degree range without RCS spikes horizontally than the F-35 due to the higher wing sweep angle.

Patchwork Chimera, he of deep insight and foul language. Gone too soon, alas.

 

[zyklon]

Patchwork Chimera, he of deep insight and foul language. Gone too soon, alas.

Given Patchwork Chimera's depth of knowledge and style of writing, he is almost certainly someone with a security clearance on file at OPM.

Though someone has probably convinced him that it'd behoove him -- professionally speaking -- to post less on Reddit and Twitter.

 

[Biscuits]

I'm curious as to what this forum's opinion is about J-20's RCS compared to the F-22's. The consensus elsewhere online seem to be that while the J-20 has a smaller RCS than the su-57, it still has a (much) larger RCS than the F-22,

What consensus? An absolute dream that something from a few decades ago which US even themselves admit is outdated to make today would have an advantage let alone much more than a 2020s era platform.

and that the J-20's canards compromise its stealth.

Not more than the F-22s rearward control surfaces (essentially back canards) compromise stealth. LM and CAC have a technique marketed as using a computer to control the turning surface in a way that minimises RCS spikes.

I know that canards compromising stealth in the general sense has been somewhat debunked, but the J-20's canards specifically do not sit in the same plane as the main wings unlike F-22's main wings and its elevators. The J-20 also has 2 smaller wings at the very back that point down.

While it's near impossible to know which side is better, in the case of F-22 in particular, it says a lot as an indicator that US doesn't want to get more F-22. However we have no way of knowing where the J-20 stand vs F-35.

Another data point. USAF uses early block F35 to simulate J20s at Nellis.

That might be nothing but face saving coupled with a dose of resource saving. The training planes' parameters would be heavily simulated by software anyways.

 

[ougoah]

You would need to know the source of RF emission to know how to best deflect control surfaces so as to minimise radar return. I doubt very much that LM and/or CAC have any special techniques at doing this since it would require them to have technology which perfectly understands exactly where all emissions are coming from and work out the best compromise between achieving desired movement and minimising reflections. Absolutely not likely.

They would make assumptions based on machine learning from data or fed data on likely positions and get the AI to make educated guesses as to statistical optimums. I think it's better to just deflect as required.

Surely the real challenge of hiding control surfaces from radar other than removing them entirely is in the materials used.

 

[00CuriousObserver]

Keep in mind that J-20 doesn't necessarily need to be stealthier than F-22 or F-35 to achieve its strategic goals.

What China appears to have decided to pursue with the low-rate initial production batches of J-20A is a fighter with a sufficiently small RCS to be hard to detect within the background clutter of any clash relatively near China’s own airspace. In such a scenario, there would be hundreds of non-LO aircraft and missile tracks in the area of operations, as well as intensive EW. The threat of J-20s with long-range PL-15 missiles operating within the background chaos would be a major headache for US planners attempting to protect critical tanker and ISR orbits within useful range of the area of operations.

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(The "J-20A" here just refers to the first LRIP J-20s I think)

I have no idea who he is, but I feel like I should.

You can have a look here:

PLA strike strategies in westpac HIC

 

[Alfa_Particle]

Keep in mind that J-20 doesn't necessarily need to be stealthier than F-22 or F-35 to achieve its strategic goals.

It doesn't, but it likely is.

You can have a look here:

PLA strike strategies in westpac HIC

Good Lord what exquisite writing! I'm in tears. He certainly knows what he's talking about (same thing unfortunately can't be said for some of our rather uh, cough, challenged, cough, NAFO acquaintances), what a shame. I would've loved to interact with him.

Admirable, really. I aspire to be half as skillful with words and information as he is.

Edit: did a bit more reading, and my sincerest thanks to @00CuriousObserver for curating such an exquisite (I'm running out of adjectives, this is the best word to sum his work up) collection of works by an actual professional. A much-needed breath of fresh air compared to the unfortunate slop pushed to my TL on Twitter. Following an extremely detailed and well thought-out two-part analysis with "yeah this s*** blows" had me in tears. Patchwork, if by some unlikely means you're reading this, you've gained a fan.

 

[by78]

Self-explanatory.