Aerodynamics thread

[Inst]

@Air Force Brat ,

My point is that the canards act a little like stabilons because of the X-wing canard set-up. That means the J-20 has less need for tailfins than an F-35 or F-22, to the extent that it might be practical to ditch tailfin yaw control and rely on canards and TVC instead.

As for the "beauty" of the J-20, I don't see it. The design reminds me more of the A5M of the IJA, i.e, it's a necessary transition but it's not an A6M Zero. The J-20 has problems insofar as it has way too many aerodynamic devices; you have chines on the nose, lerx in front of the canards, lerx behind the canards, canards, delta, lifting body, ventral strakes, tailfin. It's not elegant; it's like if someone decided to throw in everything they knew about aircraft into it and hope it flies well, which it seems to do.

Reducing yaw control is not necessarily a bad thing if the plane is still flyable without it, if other elements of maneuverability are enhanced, as seen with the X-36 demonstrator.

 

[PhilFYW]

Guys,

Is there any aerodynamics benefits of using tails compared to canards?
Multiple canard layout concepts surfaced JSF and ATF, but they are not received; therefore I guess US do have the technology to use canard layout. Is there thus any aerodynamic reasons for such choices?

Thank you!

 

[gelgoog]

Guys,

Is there any aerodynamics benefits of using tails compared to canards?
Multiple canard layout concepts surfaced JSF and ATF, but they are not received; therefore I guess US do have the technology to use canard layout. Is there thus any aerodynamic reasons for such choices?

There was some US govt. contractor who (in)famously said that "the optimum location for a canard is on someone else's plane".
Yes there were such programs like the

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and the

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.

Some of the design concepts for the future F/A-XX also have canards. Commonly mentioned reasons not to use canards include: instability, energy bleeding, reduction in stealth. Although proponents claim that the instability is the main advantage (it allows for more maneuverability), they also claim the stealth reduction can be minimized with active control by the fly-by-wire system.

Other modern designs like the Su-57 do not have canards but they have other moveable surfaces which achieve similar results. Plus they also typically have engine TVC.

The interesting bit starts at 0:35.

 

[PhilFYW]

How is instability enhanced through lack of canards? Also how to canards contribute to energy bleeding? The Eurocanards seems to have general superior sustained turn rates compared to similiar generation tailed fighters.

 

[PhilFYW]

Also what are the benefits of LEVCONS over LERXs and canards? Do they have better vortex generation over the other 2?

 

[Deino]

Guys ... can we reserve this thread for general PLAAF-related questions and not for "anything that comes into my mind"??

We have a dedicated aerodynamics thread in the general section... please continue there.

Best,
Deino

 

[PhilFYW]

Is there any other aerodynamics thread? I searched and seemed to be only able to find this one. Is it alright to give me the name of the other thread so that I could find it more easily?

Thanks!

 

[Air Force Brat]

Is there any other aerodynamics thread? I searched and seemed to be only able to find this one. Is it alright to give me the name of the other thread so that I could find it more easily?

Thanks!

Nyet Komrade! this is the only aerodynamics thread, started at the insistence of the unknowing and willingly ignorant who have no interest in aerodynamics and seem oblivious to the fact that aerodynamics are the "secret sauce" of the Su-57, J-20, J-31, F-35, and F-22,, so if you are still hanging out, post away. This thread was started to keep these extremely interesting discussions to a minimum on the J-20 thread, where some folks just want to see more pretty pictures, LOL!

 

[PhilFYW]

According to the J-20 design article by Dr Song Wei Chong, canards enhances lift significantly more greatly compared to LERXes, possessing a maximum lift coefficient of almost twice as much. This can be seen from the attached picture.

As seen in the picture, canards generate a maximum lift coefficient of around 0.35 while LERXes generate a maximum lift coefficient of around 0.2. Is there any reason so, considering canards and LERXes are both vortex generators, and neither couples "more" vortexes compared to the other?

Thanks in advance for any answers!

 

[Air Force Brat]

According to the J-20 design article by Dr Song Wei Chong, canards enhances lift significantly more greatly compared to LERXes, possessing a maximum lift coefficient of almost twice as much. This can be seen from the attached picture.

As seen in the picture, canards generate a maximum lift coefficient of around 0.35 while LERXes generate a maximum lift coefficient of around 0.2. Is there any reason so, considering canards and LERXes are both vortex generators, and neither couples "more" vortexes compared to the other?

Thanks in advance for any answers!

There is indeed an easy explanation, canards are an airfoil and contribute to total aerodynamic lift, tails provide negative lift, canards provide positive lift!

Canards are also much more aerodynamically shaped, they are a forward mounted small wing, the vortex created that enhance lift of the main wing is the "gravy", so yes canards provide greater total lift than the LERX's, although I do like the LERX, I think its amazing...

so having said that, we also must concede that canards while providing more lift, also add considerably more "DRAG"! fact of life, make lift, create drag!