J-20 5th Gen Fighter Thread VIII

enroger

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Speaking of which, I've heard that the J-20's canards are made of carbon fiber-reinforced bismaleimide resin matrix. Since it's non-conductive, it should be close to invisible against radar waves.

Any idea on how true it is?

Not sure how well can composites handle mechanical load as we know canards needs to handle fare amount of aerodynamic load. So far I've only seen composites used in skin. Also, if canards are invisible to radar then why the stealth treatment on the edge?
 

taxiya

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Not sure how well can composites handle mechanical load as we know canards needs to handle fare amount of aerodynamic load. So far I've only seen composites used in skin.
Composite has been used everywhere except the structure inside the wing. It is even used for the wingbox (section joining the wings under the fuselage) in MC21. C-919 also has a parallel program of composite wingbox but opted aluminium for the moment.

Also, if canards are invisible to radar then why the stealth treatment on the edge?
A material being radar transparent is not the same thing of stealth of the aircraft. The canard has metal axis and machnics to connect to the fuselage. Transparent material exposes the internal metal structure. It is WORSE for RCS reduction to use a naked composite component than a well-shaped metal piece. So the surface of the composite material has to be treated no less than metal to conceal the internal metal skeleton.

In short, using composite material has nothing to do with stealth unless the whole aircraft including engine and radar are made of plastics.
 

taxiya

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Speaking of which, I've heard that the J-20's canards are made of carbon fiber-reinforced bismaleimide resin matrix. Since it's non-conductive, it should be close to invisible against radar waves.

Any idea on how true it is?
A full composite component only makes itself stealth but worsens the overall stealth of the aircraft by exposing irregular metal structures behind it. It also accumulate static electrical charges that put the aircraft in danger, F-35's inadequate treatment is an example. So most of exterior composites would be conductive by various means to counter the two drawbacks.
 
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Jono

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The pilot named Chen Xinhao is the same one mentioned in the report from 2020. At the time the official report didn’t specify the type of aircraft used, but it was widely speculated to be J-20. This is official confirmation.


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May I ask how a pair of J-20 could take down 17 targets when each one could only carry 6 AA missiles at most in 2020?
 

Alfa_Particle

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A full composite component only makes itself stealth but worsens the overall stealth of the aircraft by exposing irregular metal structures behind it. It also accumulate static electrical charges that put the aircraft in danger, F-35's inadequate treatment is an example. So most of exterior composites would be conductive by various means to counter the two drawbacks.
Very interesting

If you don't mind me asking, aren't there only the main wings behind the canards? What's the irregular metal structures?

And what's the risk of accumulating charges? Frying the avionics onboard?

Edit: nevermind, saw your comment earlier. The wording made me think it's behind the canards, not in it.
 

reservior dogs

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A full composite component only makes itself stealth but worsens the overall stealth of the aircraft by exposing irregular metal structures behind it. It also accumulate static electrical charges that put the aircraft in danger, F-35's inadequate treatment is an example. So most of exterior composites would be conductive by various means to counter the two drawbacks.
For the canopy, they did the gold plating on the glass to reduce the radar signature. Do you think they do something similar by putting a layer surrounding the inside metal components to reduce the radar signature?
 

taxiya

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For the canopy, they did the gold plating on the glass to reduce the radar signature. Do you think they do something similar by putting a layer surrounding the inside metal components to reduce the radar signature?
I am inclined to think they have a layer in the composite. The coating of canopy works because of its shap is gentle curve. Simple coating on irregular components won't help.
 

taxiya

Brigadier
Registered Member
Very interesting

If you don't mind me asking, aren't there only the main wings behind the canards? What's the irregular metal structures?
I see you got the idea, but still good to show an example of a horizontal stablizer, everything in the red cycle and the fuselage are metal.
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And what's the risk of accumulating charges? Frying the avionics onboard?
Yes, that is one of the risks. To a lesser extent interference with electronics even if not frying them. Another is setting fire of fuel by generating sparks.

Edit: nevermind, saw your comment earlier. The wording made me think it's behind the canards, not in it.
 
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