J-35A fighter (PLAAF) + FC-31 thread

[ZeEa5KPul]

You are doing eyeballing again.
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Studies on J-20 has shown that the ventral fines is more stealthier than baseline fuselage without them modeled on F-35 (therefor J-35 too) from the side. The reason is because J-20 does not thave horizontal and vertical stablizer acting as a perfect reflector. F-22 has that problem too, mind you. The same study also said that without treatment canard aircraft is 1.27dB worse in L band but 0.68dB better in C band than baseline. With proper treatment it is ignorable.

People should read actual scientific paper instead of eyeballing and following self designated expert. The "cannard bad, ventral fin bad" is becoming something like urban legend or UFO.

[addition]
For people holding such idea a similar question can be thought of. F-22 has the inlet gap that add one edge and one gap (on each side) similar to canard that suppose to worsen its RCS. Yet nobody held the belief that F-35 is stealthier than F-22 partitularly in the frontal area, but when it comes to J-20 vs. J-35 the non-issue becomes a concern.

There is one stealth feature on the J-35A absent in the J-20. The intake edge on the J-35A aligns with the wing on the opposite side of the fuselage, you can see that in the second picture by78 posted here: J-35A fighter (PLAAF) + FC-31 thread.

There's no such alignment on the J-20: J-20 5th Gen Fighter Thread VIII

 

[00CuriousObserver]

Ayi:

It's quite interesting that the first J-20 units being converted are now widely expected to also receive mixed batches of J-35As. These two units not only have already begun receiving the J-35A, but are also set to continue receiving more J-20As in the near future.

This suggests that the Air Force may view both the J-35 and the J-20A as a kind of "5.5th generation" fighter, and sees good reason to prioritize equipping its tip-of-the-spear units with them—sharpening the spear, so to speak.

However, prioritizing these cutting-edge aircraft comes with no small number of challenges: they’ll need to explore and refine new maintenance and operational procedures, develop tactics and techniques through R&D, and help draft new training manuals. Considering that these elite frontline units already bear significant responsibilities in routine air and sea sovereignty enforcement operations, the burden on their shoulders is anything but light.

Even so, the performance of the J-35A appears to be impressive enough that these units believe the mixed-unit setup is "worth it"—likely a reflection of the confidence inspired by what might be the most stealth-optimized tactical aircraft in human history to date.

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Yeah, it will speed up the refinement of training doctrines and combat capability generation.

 

[gelgoog]

It seems like a bad idea to me.
It will make maintenance and training more complicated. Both aircraft also likely have huge range disparities.

 

[taxiya]

There is one stealth feature on the J-35A absent in the J-20. The intake edge on the J-35A aligns with the wing on the opposite side of the fuselage, you can see that in the second picture by78 posted here: J-35A fighter (PLAAF) + FC-31 thread.

There's no such alignment on the J-20: J-20 5th Gen Fighter Thread VIII

There seems to be such alignment in case of J-35A, but once again this is another eyeballing. Whether this alianment is really about improving RCS or only about air flow control or both and how much RCS improvement its has should be based on research paper and I would caution to draw conclusions from it.

From the same paper I understand that the idea of having these edges to align is that reflection of the smaller edge (intake) would be buried by the larger edge (wing) when incoming radio wave hit them. With fuselage in between them blocking one from the other, they act independently. That alignment of J-35A would not make much difference if there is any. They would act independently to the incoming radar waves. Also note, the intake edges are on different planes from the main wings, if they are exposed from the same direction from above or below (when it supposedly has advantage), they act as two emitting sources, not one.

Another principle of edges except main wings (dictated by aerodynamics) is that it is preferred that thier angle to fuselage are less than 90 degrees, so radio wave reflected from them will not go outwards but bounced to the fuselage and then somewhere else. For this principle J-20's intake angle is adaquate.

My thought here is not supported by test data but merely understanding of principles. The more I read the paper the more I believe it is too complicated subject for simplistic judgement.

Not related to your post but something I have to say is, I remember that there were lots of CAC fanboys bashing SAC 10 years ago when J-20 was chosen by PLAAF, now I sense some "revenge" like atmosphere to pick every design differences from J-35 to beet J-20. These differences are nothing new and have been used by westerners to argue the "inferiority" of J-20 10 years ago. The whole thing of "A is better than B" was and remains more ego driven than technology driven.

 

[latenlazy]

There seems to be such alignment in case of J-35A, but once again this is another eyeballing. Whether this alianment is really about improving RCS or only about air flow control or both and how much RCS improvement its has should be based on research paper and I would caution to draw conclusions from it.

From the same paper I understand that the idea of having these edges to align is that reflection of the smaller edge (intake) would be buried by the larger edge (wing) when incoming radio wave hit them. With fuselage in between them blocking one from the other, they act independently. That alignment of J-35A would not make much difference if there is any. They would act independently to the incoming radar waves. Also note, the intake edges are on different planes from the main wings, if they are exposed from the same direction from above or below (when it supposedly has advantage), they act as two emitting sources, not one.

Another principle of edges except main wings (dictated by aerodynamics) is that it is preferred that thier angle to fuselage are less than 90 degrees, so radio wave reflected from them will not go outwards but bounced to the fuselage and then somewhere else. For this principle J-20's intake angle is adaquate.

My thought here is not supported by test data but merely understanding of principles. The more I read the paper the more I believe it is too complicated subject for simplistic judgement.

I know that there were lots of CAC fanboys bashing SAC 10 years ago when J-20 was chosen by PLAAF, now I sense some "revenge" like atmosphere to pick every design differences from J-35 to beet J-20. These differences were nothing but used by westerners to argue the inferiority of J-20 10 years ago and have been debated to death.

The broader point you’re highlighting here is that there is not one but many different strategies for reducing return reflections, so a handful of visual heuristics is simply insufficient to understand the engineering that went into RCS reduction and how effective they were. Sometimes you’re not trying to reflect the EM radiation in an aligned angle with primary shapes but into a hotspot where you’ve concentrated some radar absorbing structures.

 

[ZeEa5KPul]

Noted. I didn't mean to belittle or even comment seriously on the RCS reduction engineering of the J-20 and certainly not get into a food fight over which is the better plane. I'm very happy they're both in service with the PLAAF. I just noticed this edge alignment property since there's been such a deluge of high quality photos of the J-35A recently.

Incidentally, when I was playing the same game with the J-20, I noticed that if you extend a line segment along the edge of the intake, you hit exactly the outer trailing corner of the canard - rather where the corner would be if it weren't clipped. I doubt that's a coincidence.

 

[latenlazy]

Noted. I didn't mean to belittle or even comment seriously on the RCS reduction engineering of the J-20 and certainly not get into a food fight over which is the better plane. I'm very happy they're both in service with the PLAAF. I just noticed this edge alignment property since there's been such a deluge of high quality photos of the J-35A recently.

Incidentally, when I was playing the same game with the J-20, I noticed that if you extend a line segment along the edge of the intake, you hit exactly the outer trailing corner of the canard - rather where the corner would be if it weren't clipped. I doubt that's a coincidence.

I would simply suggest that you’re just not going to learn very much chasing edge alignments outside of primary shapes. Edge alignments take care of reflections at large orders of magnitude but if you’re chasing very low RCS what matters most is the additional reduction measures for reflections at small orders of magnitude, and that’s just going to involve a whole lot more engineering strategies than just edge alignments. If it was all edge alignment dependent then stealth planes would have stuck to faceted shapes like the F-117.

 

[AndrewS]

Ayi:

It's quite interesting that the first J-20 units being converted are now widely expected to also receive mixed batches of J-35As. These two units not only have already begun receiving the J-35A, but are also set to continue receiving more J-20As in the near future.

This suggests that the Air Force may view both the J-35 and the J-20A as a kind of "5.5th generation" fighter, and sees good reason to prioritize equipping its tip-of-the-spear units with them—sharpening the spear, so to speak.

However, prioritizing these cutting-edge aircraft comes with no small number of challenges: they’ll need to explore and refine new maintenance and operational procedures, develop tactics and techniques through R&D, and help draft new training manuals. Considering that these elite frontline units already bear significant responsibilities in routine air and sea sovereignty enforcement operations, the burden on their shoulders is anything but light.

Even so, the performance of the J-35A appears to be impressive enough that these units believe the mixed-unit setup is "worth it"—likely a reflection of the confidence inspired by what might be the most stealth-optimized tactical aircraft in human history to date.

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Yeah, it will speed up the refinement of training doctrines and combat capability generation.

But the 7th Brigade is located in the interior?

So it doesn't have any routine duties and can focus on tactics development?

 

[AndrewS]

It seems like a bad idea to me.
It will make maintenance and training more complicated. Both aircraft also likely have huge range disparities.

Mixed brigades would likely result in better training, because any airstrike or air-to-air will comprise different aircraft types.

Yes, maintenance will be more complicated and cost more with mixed brigades.

But for frontline units, mixed units is how the airbases will be operating in wartime.

For rear-area units, they will likely have to deploy to another airbase.

So there's no point optimising for the lower cost maintenance with a single aircraft type, and then finding out the maintenance structure isn't sufficient for a wartime deployment structure.

Plus a lot of the maintenance will be performed by the volunteer conscripts who are paid barely anything?

EDIT. And given the number of new J-20 and J-35 that are likely to come into service, I'm expecting mixed units to become 2 brigades. So you get 20-24 J-20 plus 20-24 J-35

 

[taxiya]

I didn't mean to belittle or even comment seriously on the RCS reduction engineering of the J-20 and certainly not get into a food fight over which is the better plane.

I knew and I want to once again say that the last paragraph of my post (the ranting part) is not aimed at you but a observation of the past months in this forum.