J-20 5th Gen Fighter Thread VI

[Blitzo]

Canards of the J-20 always reminds me of the Naval YF-23 proposal (Canards, all-moving tails).

For me a J-20 v2.0 that looks like it would be extra cool. One of my personal favorites is off-course the tailless X-36.

NATF-23 proposal

X-36

The canards on J-20 don't really look like those of the Northrop NATF proposal or that of the X-36.

The trailing edge of the J-20s canards and its position relative to the plane of the wing for J-20 are both entirely different from Northrop's NATF proposal or X-36.


But considering how few stealth aircraft concepts there are with canards I suppose merely having canards would be enough to evoke a sense of familiarity...

 

[Air Force Brat]

The canards on J-20 don't really look like those of the Northrop NATF proposal or that of the X-36.

The trailing edge of the J-20s canards and its position relative to the plane of the wing for J-20 are both entirely different from Northrop's NATF proposal or X-36.


But considering how few stealth aircraft concepts there are with canards I suppose merely having canards would be enough to evoke a sense of familiarity...

The dihedral of the NATF is so great that it is almost "bizarre" in appearance, there is no doubt some degree of RCS reduction as well as getting that wing tip vortices above the main wing are the drivers here.

no doubt....

 

[by78]

Comparison photo...

 

[Inst]

I am afraid that Rafale is not taking the same approach. Compare them at the right angle and photographing vantage point.
Rafale is close-coped canard, while J-20 is far-coped canard closer to Eurofighter. The two configurations work very differently. I would guess that it would be very difficult/meaningless for Rafale to do the same while maintaining its canard at that vertical position.

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But the coplanar doesn't really help that much; it's RCS reducing, but it still creates two flat planes.

As for close-coupled vs long-coupled, the Eurofighter apparently copied the J-20's LERX long-coupled set-up. I suspect the trick is that the LERX between the main body and the canards cancels out much of the disadvantages of long-coupled (control) canards vs close-clouped canards.

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Strictly speaking, the Rafale is lerx canard lerx delta like the J-20 if you look at how the nose changes into the canards.

 

[Xizor]

But the coplanar doesn't really help that much; it's RCS reducing, but it still creates two flat planes.

As for close-coupled vs long-coupled, the Eurofighter apparently copied the J-20's LERX long-coupled set-up. I suspect the trick is that the LERX between the main body and the canards cancels out much of the disadvantages of long-coupled (control) canards vs close-clouped canards.

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Strictly speaking, the Rafale is lerx canard lerx delta like the J-20 if you look at how the nose changes into the canards.

Rafale does not have an "lerx-canard" . All i can see at the root of the canard is an un-aerodynamic structure. But feel free to cite a good source linking the same and equating Rafale with the J-20 , whether it be in the case of the "Lerx- canard" or the canard configuration.

 

[taxiya]

Strictly speaking, the Rafale is lerx canard lerx delta like the J-20 if you look at how the nose changes into the canards.

I am not sure what you want to say about this. The first "lerx" of Rafale (nose change to canards) is certainly not in J-20. J-20's lerx is like the second "lerx" of Rafale, from the front most of wing root to the air-intake. But because of the difference of long and short coped canards, their function is fundamentally different. The difference of their lerx would be like talking about F-18 and J-20.

I use quotation mark in Rafale's case is because I am not sure if they are lerx, at least regarding the ones in front of the canards.

 

[Deino]

Don't you think this discussion fits better here?

https://www.sinodefenceforum.com/aerodynamics-thread.t5907/

 

[siegecrossbow]

Screenshot of J-20 opposing J-16/J-10C with AWAC support in a recent exercise.

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Original video from which the screen cap is taken.

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[Inst]

You can clearly see that there are lerx in front of both the wing and the canards.

I just find it amusing that people dislike the Rafale-J-20 comparison; Westerners dislike it because they don't want to think of the J-20 as maneuverable, the Chinese dislike it because they don't like the idea of the J-20 not being wholly original (when the J-20 is basically an aerodynamic hodgepodge of all the ideas that have been tried). And yes, they differ in tail-setup (Rafale is single vertical tail, J-20 is V-tail with all-moving tails), close-coupled vs long-coupled, and the presence of ventral fins on the J-20.

As far as the hodgepodge comment goes, that's why I argue that the J-20 should ditch the tailfin and the ventral strakes. There are way too many aerodynamic devices on the J-20; if you compare it to the F-35, it has ventral fins which the F-35 lacks, it has the lerx canard lerx delta which the F-35 lacks (only having a trapezoidal wing with a lerx, and you have all-moving tails. The J-20 can definitely trim down once TVC comes online.

 

[Inst]

The lines being formed by the Rafale canards clearly show that there's a slight anhedral-dihedral in the close coupled canards.

As for the J-20's long-arm lerx canard lerx, compare the Rafale in a high-G maneuver:

You can see here that the canards are clearly generating vortices.

In this picture, it appears it's only the LERX generating vortices.

As another point of comparison, here's where the J-20 appears to create a complete body mist due to vortex generation.

However, if you compare it to the Rafale's vortex eneration, the tips of the canards seem to not be generating vorteces. So it's still questionable as to whether Lerx Long-Arm Canard Lerx Delta gets you the benefits of at least a conventional close-coupled canard with lerxes.