This is a discussion on J-20... The New Generation Fighter III within the Air Force forums, part of the China Defense & Military category; Originally Posted by MiG-29 It`s incredible your ability to say the speed of those aircraft just at naked eye wow, ...
red herring, as you are now trying to divert attention away with F-22. Paul Metz never flew the J-20, so while what he says regarding the F-22 may be true, his statements are also meaningless on the J-20. The simple matter is that you claimed canard needs large deflection for trim, and that claim turned out to be wrong based on the video evidences that we have seen; evidences such as this, this, and this.
As far as the J-20 is concerned, Dr. Song was able to achieve high lift and low drag with the current configuration through the clever combination of aerodynamic devices, while achieving excellent stealth characteristics. His own statement is as follow:
The design team made a future fighter proposal based on the points raised by this article. The proposal employs lift-body LERX canard configuration. It is unstable in both the lateral and yaw directions. The proposal employs small aspect ratio wings with medium back sweep angle, relatively large dihedral canards, all moving vertical stabilizers far smaller than those on conventional fighter aircraft, and S-shaped belly intakes. According to our assessment, the proposed aircraft will have excellent supersonic drag characteristics, high AOA lift characteristics, high AOA stability and controllability, and excellent stealth characteristics.
Last edited by MiG-29; 10-09-2012 at 01:59 PM.
this, this, and this already shows your claim about canard requiring wild deflection to maintain trim to be false.
Stealth features does not automatically mean reduced aerodynamic efficiency. The F-22 is an excellent counter-example, being an aircraft with stealth features and also only aircraft in service that is able to supercruise at Mach 1.7. Like the F-22, the J-20 has excellent aerodynamics as well as stealth characteristics, as explained by Dr. Song.
As to the claim that canard increases RCS, it is merely a myth which has been repeated ad nauesum.
Last edited by Engineer; 10-09-2012 at 02:03 PM.
And yes, I did read what he wrote, no where did he say that drag will increase RCS or that canard will flap uncontrollably up and down during Mach 1.2.
In fact, use your logic, when the air craft is flying supersonic, any large movement by the canard will result in extreme movement by the air craft, or maybe even break it apart.
Also in fact, you do know any aircraft with canard does have many other surfaces to control pitch and yaw right? So you don't even NEED to use canard at all to make a movement, in fact this is exactly what Eurofighter Typhoon have done. The fly by wire system on Thphoon is designed to minimise the canard RCS in flight, maintaining the elevon trim and canards at an angle to minimise RCS, aka making them as flat as possible during level fight.
So I ask you again, in that article where did Paul Metz says drag = more RCS? Where did Paul Metz say canard will make large movement during high speed?
All aircraft experience a loss of control effectiveness at supersonic speeds. To generate the same maneuver supersonically as subsonically, the controls must be deflected further.
simple like that, if you want to believe up to you, more deflection higher RCS.
2. Did you not read canard is NOT THE ONLY control surface on a jet? The Typhoon have written into their FBW software to let other control surface to do more to control the movement of the jet, and minimize the movement of the canard itself. This is done just for RCS, I am pretty sure J-10 and J-20 uses similar FBW software as well.
Find us the DIRECT actual evidence, talk is cheap.
Stealth design calls for a conic region in front of the plane in which RCS remains low. For example:
For full aspect stealth, the aft region also has reduced RCS:
You can read more about it here. If you want to see what the RCS for an actual plane looks like, Carlo Kopp's website has some plots showing the RCS profile of J-20 based on simulations.
In any case, an aircraft does not need to fly directly at a radar to be stealthy. An aircraft with its nose pointing away from a radar source is still stealthy, as long as the radar remains in the conic region. Similarly, the aircraft is still stealthy when flight control surfaces deflecting a few degrees. The effects on RCS will be negligible as long as deflection remains small. Large deflection such as 10° or 20° only occurs when the aircraft is maneuvering, which would mean the aircraft is already seen and any talk about RCS would be pointless.
Last edited by Engineer; 10-09-2012 at 02:40 PM.
Looks like I'm going to have to step in here again. Let's calm things down and stop this topic. I can see where this is heading from previous arguments. You are not going to convince the other side. Everyone has already stated their case, let's move on. Any more posts on this issue will be deleted.
If correct that 2001 & 2002 are now both at Yanglian ... then this must be an older image or .... ????
(image from: http://www.f y j s.cn/bbs/htm_data/27/1210/814904.html)
2003 prototype? It's too hard to tell at this point IMHO.
It just looks like a canopy with a cover over it, it could be any aircraft under there. To present that as evidence of another J20 is just trying too hard.
More J20 prototypes will undoubtably appear in due time. No need to force the issue. All we need to do is be patient.