J-20 5th Gen Fighter Thread IV (Closed to posting)

[Air Force Brat]

hook!

Well I guess a guys got to dream, my dream girl is to see Lockmart bring back the F-22, every queen deserves a loyal following and a few dreamers, so I won't tell you where that is on the probability scale, if you promise not to tell me where mine is????? AFB

After seeing your Avatar, maybe someone could put the Raptor up for the AFB, I am so analog it stinks, I think I've got my tippy toe in the electronic age??? Brat

 

[Engineer]

This is written by one of SAC's engineers, which talked about their tri-surface design that competed with J-20. The most important piece of knowledge in the text is that PLAAF gave a requirement that China's forth-generation must be able to fly in 60° AoA. From this, we can see the capability of J-20.

CAC's proposal uses canard configuration right from the beginning, but SAC's original proposal was a traditional layout with LERX. The traditional layout was found to be uncontrollable between 40° ~ 45° AoA and didn't meet the requirement. So, SAC modified the design to include canards, resulting in a tri-surface layout that remained controllable up to 65° AoA. So once again, a configuration with canard proved to be superior to a traditional layout.

Tags: 4-th generation aircraft designs; 601; AoA requirement; China; Shenyang; canard layout; tri-surface layout; 李天传记

 

[andyhugfan]

This is written by one of SAC's engineers, which talked about their tri-surface design that competed with J-20. The most important piece of knowledge in the text is that PLAAF gave a requirement that China's forth-generation must be able to fly in 60° AoA. From this, we can see the capability of J-20.

CAC's proposal uses canard configuration right from the beginning, but SAC's original proposal was a traditional layout with LERX. The traditional layout was found to be uncontrollable between 40° ~ 45° AoA and didn't meet the requirement. So, SAC modified the design to include canards, resulting in a tri-surface layout that remained controllable up to 65° AoA. So once again, a configuration with canard proved to be superior to a traditional layout.

Great find. But how does this compare to other 4th and 5th gen. fighters?

 

[siegecrossbow]

It now appears that earlier reports of the J-20 capable of 90 degree controllable AOA are greatly exaggerated. On the other hand, 65 degree controllable AOA is not too shabby either.

Something I found for reference:

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NASA reported that in one phase of the project, Dryden Flight Research Center "research pilots Bill Dana and Ed Schneider completed the envelope expansion flights in February 1992. Demonstrated capabilities included stable flight at approximately 70 degrees angle of attack (previous maximum was 55 degrees) and rolling at high rates at 65 degrees angle of attack. Controlled rolling would have been nearly impossible above 35 degrees without vectoring."[3] Performance figures were not listed for other phases.

 

[plawolf]

It now appears that earlier reports of the J-20 capable of 90 degree controllable AOA is greatly exaggerated. On the other hand, 65 degree controllable AOA is not too shabby either.

Something I found for reference:

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Good job giving some context to what 60 degrees AoA means, but something to remember is that the 65 degrees figure was for SAC's loosing fifth gen bid, and 60 degrees AoA was the bare minimum the proposals had to hit, with SAC's triplane offering bettering that target.

The 60 degree figure gives a ballpark idea, and while 90 degrees does sound like too much of a stretch in light of that target, it still cannot be entirely ruled out altogether either since it would not be beyond the rely of possibility for a target to be exceeded by so much, and the scale model approximation for a J20 that some radio controlled plane enthusiasts built eariler certainly demonstrated that the J20 configuration is easily capable of 90 degrees AoA or better.

 

[Engineer]

Great find. But how does this compare to other 4th and 5th gen. fighters?

In comparison, F-35 recently demonstrated flight at 50° AoA, while F-22 is capable of maintaining controlled flight in excess of 60°. In the case of F-22, the control at AoA limit is most likely achieved through thrust vectoring, not via aerodynamics as is the case with J-20. This should reflect better aerodynamics on the J-20.

 

[Engineer]

Good job giving some context to what 60 degrees AoA means, but something to remember is that the 65 degrees figure was for SAC's loosing fifth gen bid, and 60 degrees AoA was the bare minimum the proposals had to hit, with SAC's triplane offering bettering that target.

The 60 degree figure gives a ballpark idea, and while 90 degrees does sound like too much of a stretch in light of that target, it still cannot be entirely ruled out altogether either since it would not be beyond the rely of possibility for a target to be exceeded by so much, and the scale model approximation for a J20 that some radio controlled plane enthusiasts built eariler certainly demonstrated that the J20 configuration is easily capable of 90 degrees AoA or better.

I agree that J-20 is likely to be able to exceed 60° AoA or even 65° AoA in controlled flight. However, I have to say 90° AoA is completely unrealistic since there would be no forward movement of the aircraft.

 

[AssassinsMace]

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Here's a video I found on the Chinese boards about thrust-vectoring and maybe something to do with the 2003. Very little I could hear that I understand. Supposedly something at the 28 min mark. They showed Raptor's TVC then a mock-up that I wasn't sure was Chinese or Russian. The people in the back looked Asian I think.

 

[Quickie]

It now appears that earlier reports of the J-20 capable of 90 degree controllable AOA are greatly exaggerated. On the other hand, 65 degree controllable AOA is not too shabby either.

Something I found for reference:

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The above research has very much to do with using TVC to achieve the stated objective. Achieving the same objective without using TVC, a.k.a China's fifth gen JXX proposal, will require a very different approach in the design of the aircraft to begin with.

 

[ahadicow]

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Here's a video I found on the Chinese boards about thrust-vectoring and maybe something to do with the 2003. Very little I could hear that I understand. Supposedly something at the 28 min mark. They showed Raptor's TVC then a mock-up that I wasn't sure was Chinese or Russian. The people in the back looked Asian I think.

This video seem to be made long ago, definitely before revealing of J-20 and J-31. The speaker claimed that China had already made 3D TVC nozzles. He further claimed the engines with those nozzles were already proven on the test frame of 606 and 624 institute. And "we are bit more agile than those(Su-37)."

Liu Da Xiang is a member of Chinese Acadamy of Engineering.

Professor of Beijing University of Aeronautic and Aerospace(BUAA)
Chief designer of GTE

China Gas Turbine Establishment (GTE) is an aeronautical research organization specializing in the advanced study of aero propulsion technology, product development and engine certification tests. The establishment is subordinated to China Aviation Industry Corporation I (AVIC I).