J-20... The New Generation Fighter II


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latenlazy

Colonel
I remain very unconvinced that we can determine if anything has VLO coatings simply from the colour and shade of an aircraft.
Well, that's why I was skeptical, the engine nozzles are very unique, and there was some chatter about it being an IR suppressant when the pictures first came out. It took that picture of the blackhawk rotor to make me think there was some credibility to it though.
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Well, that's why I was skeptical, the engine nozzles are very unique, and there was some chatter about it being an IR suppressant when the pictures first came out. It took that picture of the blackhawk rotor to make me think there was some credibility to it though.
Hmm.. The most I will say about the nozzles is that they are indeed unique, in that they are serrated like the F-35's nozzle so the engineers have clearly given some thought to the rear aspect radar sig management (as opposed to say the current T-50 prototypes). But I'm not willing to go beyond that. The fact the blackhawk helicopter is painted in a similar shade to the J-20's engine nozzle means nothing. If say the F-22's nozzles were painted in a similar colour the argument would be a small fraction stronger, though still very weak imho. It's not like there is a universal RAM or IR reduction material "colour"...

But I don't know enough about IR reduction to say any more.
 

latenlazy

Colonel
Hmm.. The most I will say about the nozzles is that they are indeed unique, in that they are serrated like the F-35's nozzle so the engineers have clearly given some thought to the rear aspect radar sig management (as opposed to say the current T-50 prototypes). But I'm not willing to go beyond that. The fact the blackhawk helicopter is painted in a similar shade to the J-20's engine nozzle means nothing. If say the F-22's nozzles were painted in a similar colour the argument would be a small fraction stronger, though still very weak imho. It's not like there is a universal RAM or IR reduction material "colour"...

But I don't know enough about IR reduction to say any more.
It's not really a painting as it is a coating. Two very different processes.
 

kyanges

Junior Member
Thanks for the replies, and I think you're all right. I'm trying to avoid over generalizing, and I know the opinions vary widely depending on who is asked.

Actually what really got me was when it seemed every and any suggested design compromise was having the legs cut out from under it. I just couldn't see if there was any sort of consensus rising out of the discussions aside from agreeing that nothing is known. Though now that I think of it, there really isn't any other way discussions on the J-20 could go, considering how little is concrete. Debates are bound to be intense.

I'll try again in an even more conservative fashion:

-It's probably around 20 meters long.
-???
-???

That about covers it, right? :p .
 
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MiG-29

Banned Idiot
I think John is saying that the canards could serve, in the case of the J-20, as moving LERX.
That is right, the LEVCON is only a canard that instead of been separated physically, is blended into the wing, the LEVCON due to its leading edge swept will generate vortices like any LERX or Canard but because it lacks a trailing edge it won`t generate a down wash.
Canards do control the vortices they generate however they also generate a downwash.
The LEVCON then has one basic advantage it can control the lift on the wing without killing as much lift as a canard does.
On a canard cases its down wash is turbulent flow, not laminar, this will kill some lift at the wing and also its Vortices are bursting first thus canards have a drag disadvanatge, the Su-35 has eliminated the canard in favour of TVC but T-50 has not, however it does not use a canard but a LEVCON.
In the case of the LCA, it improves lift without increasing the size or drag in a way a canard would had.
 

latenlazy

Colonel
Thanks for the replies, and I think you're all right. I'm trying to avoid over generalizing, and I know the opinions vary widely depending on who is asked.

Actually what really got me was when it seemed every and any suggested design compromise was having the legs cut out from under it. I just couldn't see where anyone stood on a given issue. Though now that I think of it, there really isn't any other way discussions on the J-20 could go, considering how little is concrete. Debates are bound to be intense.

I'll try again in an even more conservative fashion:

-It's probably around 20 meters long.
-???
-???

That about covers it, right? :p .
Hah, pretty much :p
 

siegecrossbow

Brigadier
Staff member
Super Moderator
Thanks for the replies, and I think you're all right. I'm trying to avoid over generalizing, and I know the opinions vary widely depending on who is asked.

Actually what really got me was when it seemed every and any suggested design compromise was having the legs cut out from under it. I just couldn't see if there was any sort of consensus rising out of the discussions aside from agreeing that nothing is known. Though now that I think of it, there really isn't any other way discussions on the J-20 could go, considering how little is concrete. Debates are bound to be intense.

I'll try again in an even more conservative fashion:

-It's probably around 20 meters long.
-???
-???

That about covers it, right? :p .
If huzigeng, the eyewitnesses at CAC, and the satellite photo-fanatics are to be trusted then yes.
 

kyanges

Junior Member
That is right, the LEVCON is only a canard that instead of been separated physically, is blended into the wing, the LEVCON due to its leading edge swept will generate vortices like any LERX or Canard but because it lacks a trailing edge it won`t generate a down wash.
Canards do control the vortices they generate however they also generate a downwash.
The LEVCON then has one basic advantage it can control the lift on the wing without killing as much lift as a canard does.
On a canard cases its down wash is turbulent flow, not laminar, this will kill some lift at the wing and also its Vortices are bursting first thus canards have a drag disadvanatge, the Su-35 has eliminated the canard in favour of TVC but T-50 has not, however it does not use a canard but a LEVCON.
In the case of the LCA, it improves lift without increasing the size or drag in a way a canard would had.
What's an advantage of a Canard over a LEVCON? Any?


EDIT:
@latenlazy, siegecrossbow:

Noted. :) .
 

MiG-29

Banned Idiot
The equation doesn't tell you anything without the required data. The Cd is different for different aircraft wings. This is in addition to different Cds for different aircraft bodies.
what about boundary layer? The J-20 has a larger cross section and a longer fuselage body, i know for you it does not translate into area but for it does for air, more area exposed more radar signature, more drag.

Example F-35 and J-20 i know you will claim the J-20 is different but basicly both are the same type of aircraft seen frontally, however the J-20 is larger, this means more drag and a larger radar signature.
The F-22 has also a smaller area exposed to air and a shorter body fuselage so then times area in the equation will mean more area exposed.




Then the J-20 needs more thrust due to a larger body and heavier weight, unless it has engines like the F-119, F-135 or the new Russian T50 or I129 the J-20 won`t reach the same performance
 
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MiG-29

Banned Idiot
What's an advantage of a Canard over a LEVCON? Any?


EDIT:
@latenlazy, siegecrossbow:

Noted. :) .
LEVCONs are not control surfaces as canards are, a canard can pitch the aircraft as a tailplane does, a LEVCON can only stall or increase the wing lift moving the center of lift of the main wing as canards do this by it self is pitch control but they are not pitch or roll control surfaces like tailplanes or elevons, the T-50 uses its tailplanes as roll and pitch control and wing trailing edge flaps and the LCA it uses its wing elevons (trailing edege flaps) as pitch and roll control.
 
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