J-20 5th Gen Fighter Thread VIII

taxiya

Brigadier
Registered Member
even with the new engines, are you confident that the J-20A is stealthier and has superior kinematic performance? Stealth coating effectiveness is largely gatekept, but from the shape alone, one can reasonably conclude that the F-22 is likely stealthier from the front and rear (I think Wang Haifeng or Yang Wei also said in a video posted on this forum that the J-20 is less stealthy from the rear). As for kinematics, the J-20 is likely at parity for supercruise performance, but without TVC, it's likely still not supermaneuverable like the F-22 or Su-57
F-22 being generally stealthier than J-20 is a dead horse that never stay dead.:mad: I suggest you read some study papers such as
1766959648231.png

It is true that the rear RCS of J-20 is worse than F-22 due to the shape of the nozzle, this is well-known. The rest of RCS of J-20 and F-22 are equal except two areas.

1. untreated bare metal canard increase RCS in L band HH polarization.
2. F-22 is worse than J-20 in 75 to 90 degrees (0 degree is head on), because of the reflector effect of the horizontal and vertical stablizers.

The old fashioned stealth coating like RAM on F-22 is gatekeeping like you said, not decisive. But recent coating and especially stealth structure (meta material) makes huge difference, that is reducing the dependence on shape for the same RCS. Example is the extra RCS caused by canard (aft edge) of J-20 is nearly eliminated by such structure according to the paper.

While J-20 can mitigate the shortcoming of canard, F-22 can never do it to the side RCS because of its shape.

I always strongly object eyeballing complex science and engineering subject in which things are often not what they seem instinctly just like optic illusion in everyday life.
 

Alfa_Particle

Senior Member
Registered Member
F-22 being generally stealthier than J-20 is a dead horse that never stay dead.:mad: I suggest you read some study papers such as
View attachment 167087

It is true that the rear RCS of J-20 is worse than F-22 due to the shape of the nozzle, this is well-known. The rest of RCS of J-20 and F-22 are equal except two areas.

1. untreated bare metal canard increase RCS in L band HH polarization.
2. F-22 is worse than J-20 in 75 to 90 degrees (0 degree is head on), because of the reflector effect of the horizontal and vertical stablizers.

The old fashioned stealth coating like RAM on F-22 is gatekeeping like you said, not decisive. But recent coating and especially stealth structure (meta material) makes huge difference, that is reducing the dependence on shape for the same RCS. Example is the extra RCS caused by canard (aft edge) of J-20 is nearly eliminated by such structure according to the paper.

While J-20 can mitigate the shortcoming of canard, F-22 can never do it to the side RCS because of its shape.

I always strongly object eyeballing complex science and engineering subject in which things are often not what they seem instinctly just like optic illusion in everyday life.
Also, it should be kept in mind that flat, rectangular nozzles actually have a higher RCS as the walls form 90° angles. 2D TVC improves frontal RCS (and sideward if you're tailless) by making the rear fuselage more flush, and marginally and improves IR signatures, but not rearward RCS.
 

Tomboy

Senior Member
Registered Member
Also, it should be kept in mind that flat, rectangular nozzles actually have a higher RCS as the walls form 90° angles. 2D TVC improves frontal RCS (and sideward if you're tailless) by making the rear fuselage more flush, and marginally and improves IR signatures, but not rearward RCS.
F-22 and even F-35 still have better rearward stealth by virtue of having a stealthy augmentor and also a better LOAN nozzle in the case of F-35 than J-20.
 

karaway

Just Hatched
Registered Member
In the case of J-20A I find it difficult to believe that this notion will stand.

Better pray we get J-20As with WS-15s in Zhuhai then. Then we might find out.
Actually, it's hard to say.

The J20A is the most advanced fighter aircraft of the PLAAF.

Sending out the J20A equipped with a new type of engine to participate in the air show might not be in line with the conservative style of the PLAAF.
 

Tomboy

Senior Member
Registered Member
Actually, it's hard to say.

The J20A is the most advanced fighter aircraft of the PLAAF.

Sending out the J20A equipped with a new type of engine to participate in the air show might not be in line with the conservative style of the PLAAF.
Well, J-20 was first shown off in 2016 before it even entered service
 

karaway

Just Hatched
Registered Member
Well, J-20 was first shown off in 2016 before it even entered service
WS15 has just entered mass production, and it still needs time to go through the first half of the bathtub curve.

The PLAAF is always more cautious when it comes to new engines, isn't it?

Of course, I also hope to see the J20A equipped with the new engine participate in the Zhuhai Airshow.
 
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