Canards vs Levcons

[utubekhiladi]

lets discuss about pros and cons of canards and levcons.

- thanks

 

[pmaitra]

Good topic of discussion UTK.

Some pointers:
Canard
Levcon - Leading Edge Vortex Controller

Did not find a better definition of Levcon. Hopefully, we will get more inputs.

 

[p2prada]

There really aren't many functional differences as such. These are just design solutions to achieve the required aerodynamic states.

Considering LEVCONS are part of the PAKFA, IMHO, the radar returns may be lesser than Canards. Perhaps the aerodynamic qualities of Canards are greater at low altitudes as compared to LEVCONS. N-LCA uses them for primarily landing while PAKFA probably uses them for an entirely different purpose.

 

[indian_sukhoi]

Btw, Do Su-35s has levcons fitted?. Read somehwere that levcons effects on aircraft intakes?



Although, Canards increase RCS of an aircraft. Typhoon and Rafale canards are controlled by software which reduces its RCS.
Another set back is that increase drag and kill lift. The MKIs and Typhoons face a lot of drag, Thats why the new Su-35s doesn't have any canards.

Has P2P already said, Naval Aircrafts could use canards for short landing. Canards can be usefull as brakes better than aircraft tail.

 

[Twinblade]

There really aren't many functional differences as such. These are just design solutions to achieve the required aerodynamic states.

Considering LEVCONS are part of the PAKFA, IMHO, the radar returns may be lesser than Canards. Perhaps the aerodynamic qualities of Canards are greater at low altitudes as compared to LEVCONS. N-LCA uses them for primarily landing while PAKFA probably uses them for an entirely different purpose.

The few reasons why Canards impart a higher RCS, from what I can see is,

a) Canards are in not the same plane as the main wing (JAS-39, Rafale, Typhoon) and hence provide an additional edge for radar reflections.

Furthermore most canards designs (as in the euro birds) are not optimised for planform alignment. with the exception of YF-23 naval variant which had proper planform alignment.

A LEVCON on the other hand can be both edge aligned as well as planform aligned.

b) Any moving surface in the front aspect will have a seam, a gap with the adjacent surface, and any surface imperfection will bounce back em waves. A canard will have the widest seam considering the degree of movement and the bending forces it will experience. A levcon might be able to get away (strictly in my opinion only) with lower a smaller surface gap and your regular leading edge managing the highest tolerance in finish. A conventionally designed fighter has the option of hiding the seams of its moving surfaces behind the main wing, while a canard does not give you that option.

Just my 2 cents.

 

[p2prada]

Rafale, hides the seams.

So, stealthy.

4th generation aircraft have never been stealth optimised to the extent 5th gen are.

Cannot say the same for J-20 though.

 

[Kshithij]

Levcons are foldable leading edges of the wings. The difference between a canard and Levcon are:
1) canard is a different entity from the wing and lies in a plane horizontal to the wing
2) There is also a few inches of distance between canards and wings which adds to the length of the plane.
3) Levcons can be folded to be a crank that provides lift or unfolded as a barrier that increases drag for landing.
4) Levcons can be used effectively in double delta wings but canards may be able t work only in a smooth delta wing
5) Most importantly, Levcons can't be controlled in 3D but ca only flap up and down whereas canards can be controlled in 3D where it can flap up and down and also rotate. However, the differential flapping up and down of levcon can change the lifts of the wings and help in maneuverability. Canards, however are much better suited for maneuvering
6) Canards add drag while reducing the lift of the wings. Levcons can be folded to make it a part of the wing and avoid any reduction of lift or undue drag