You two keep arguing over trivial stuff, which I find annoying. If you are done, I would like to hear Dr. Somnath's response. He made a provocative post and let's see if he's changed his mind.
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Reply to J-20 and Rafale canards comparison
1. The J-20 Mighty Dragon does not need a saw-tooth design at the rear of the canard, because the J-20 canard is made of composite material, shaped to deflect radar away from transmitter, RAM-coated (which Rafale lacks), and the canard-fuselage intersection is specifically designed to deflect radar. In conclusion, the J-20 canard is very stealthy.
The claim that the J-20 canard gap is a corner reflector is not true. Go ahead and try to draw a ray trace diagram to show a corner reflector. You cannot. It is a surface discontinuity as a tiny radar source. This kind of surface discontinuity is also seen in the T-50/Pak-Fa's airfoil gap and main wing control surfaces for the F-22, J-20, and T-50/Pak-Fa.
In my opinion, the Rafale canard design is clearly inferior. The Rafale built a thick structure to avoid a continuity gap. The round Rafale nose (which is not shaped) and the attendant large canard bridge are terrible for stealth. I think they designed it this way for structural integrity. [I'll label the problems on the Rafale later tonight when I return]
T-50/Pak-Fa Front Airfoil Gap Back-end is not shaped to deflect radar
T-50/Pak-Fa front airfoil gap will reflect radar when it bounces off the back end.
Another look at T-50/Pak-Fa radar-reflecting back-end of front airfoil gap.
Notice the subtle angled curve of the J-20 Mighty Dragon canard back-end to deflect radar.
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2. J-20 slightly-rounded LERX is a minor criticism. It can be easily fixed. It is trivial.
3. The third point about the angle of the J-20's wings is without merit. I have already written a post to compare the planform alignment of the J-20, F-22, and T-50/Pak-Fa. It is silly to argue for more planform alignment angles on the J-20.
The shape of the main wings is designed to match the aerodynamics of an aircraft. The J-20 has canards and its wing shape is the most appropriate aerodynamically for the aircraft. The guiding design principle is "form follows function" and not why don't you copy design features from other planes.
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Explanation of corner reflector (a 90 degree angle):
Illustration of corner reflector on T-50/Pak Fa
For example, let me illustrate why the T-50's uneven underside is not stealthy.
The uneven underside on the T-50/Pak-Fa third prototype creates a natural 90-degree angle. This allows enemy radar to reflect off the fuselage, bounce off the inside-face of the air-inlet, and return to the transmitter/detector for detection.
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Off-topic: Nice try Mr. Somnath. However, this nit-picking won't work. You need to find a major flaw to grab people's attention. The only major flaw on the J-20 is the round engine nozzles. The J-20 engine nozzles are serrated like the F-35, but they are clearly not as stealthy (in both radar and infrared wavelengths) as the F-22.
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French Rafale is a very non-stealthy 4th generation fighter
Mr. Somnath picked a terrible example in the French Rafale when he attempted to illustrate a perceived deficiency in the J-20 Mighty Dragon canard design. The French Rafale is not to be emulated in any way in the design of a 5th generation stealth fighter. The round shielding to hide the canard gap is far less stealthy than the J-20 canard's elegant back-end to deflect radar.
