J-20 5th Gen Fighter Thread VIII

ZeEa5KPul

Colonel
Registered Member
Anybody know why the flat panels on the J-20 fuselage have serrated edges?
There's always some gap between any two panels and the difference in conductivity between the aircraft's skin and the air creates a reflective boundary. If this boundary is a straight line, the radar wave would reflect back to the source, like a long wave coming from the sea striking a wall. The serrations scatter the waves away from the source.
 

THX 1138

Junior Member
Registered Member
Serrated edges in contrast to.... square/non-serrated edges?

Yes. I was wondering why those panels have zig-zag edges instead of straight edges.


There's always some gap between any two panels and the difference in conductivity between the aircraft's skin and the air creates a reflective boundary. If this boundary is a straight line, the radar wave would reflect back to the source, like a long wave coming from the sea striking a wall. The serrations scatter the waves away from the source.

Interesting. I had no idea the gap between two panels would have an effect on radar reflection.
 

Blitzo

Lieutenant General
Staff member
Super Moderator
Registered Member
Yes. I was wondering why those panels have zig-zag edges instead of straight edges.

It is a general visible design features on stealth aircraft that you do not want edges which are 90 degrees to incoming RF waves, but rather you want to deflect them.

On virtually all stealth aircraft (not only J-20), you can see serrations across panels and edges on an aircraft.
 

siegecrossbow

General
Staff member
Super Moderator
J-20 test pilot Li Gang regales the reporter with the tale of one of the toughest challenges during the test flight process — simulating emergency missile launch under extreme battlefield conditions. The missile must be ejected from the main weapon bay while the prototype is simultaneously performing a fast roll and a high G turn.

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YouTube link.

 

siegecrossbow

General
Staff member
Super Moderator
"Simulating emergency missile launch" <- Not an actual launch of a dummy round?
How is simulation dangerous? No, it is the launch of a missile under high G/high toll rate conditions. Test Pilot Li Gang explicitly stated that there was the danger of the missile accidentally striking the aircraft after it leaves bellybay, since the J-20 hasn’t attempted this IRL prior to the test.
 
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by78

General
Interesting comparison of both the J-20 vs the J-20A's profile and as it seems, the new version's radome (below) has not only a more beak-like shape (2nd image) but seems to be also quite different from below.

(Image modified on an image posted by @CadderVoyager from Weibo)

View attachment 119812
View attachment 119813

This reminds me of a Chengdu
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that might have something to do with the resigned nose. The patent is on a new nose cone shape that reduces drag in both subsonic and supersonic regimes. From mach 1.2 to mach 2, a drag reduction of around 10% can be achieved. Although the tip of the new nose design has a greater cross-sectional area that increases initial resistance, a more refined transition/curvature from the tip to the aft results in a net reduction in drag.

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pevade

Junior Member
Registered Member
Interesting comparison of both the J-20 vs the J-20A's profile and as it seems, the new version's radome (below) has not only a more beak-like shape (2nd image) but seems to be also quite different from below.

(Image modified on an image posted by @CadderVoyager from Weibo)

View attachment 119812
View attachment 119813
Wasn't there a scientific paper that was published showing that the beak like design would reduce drag? I remember seeing it posted in this forum.
 
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