Razor sharp leading edges...

[Externet]

Hi.

Which drag coefficient is greater; a rounded leading edge or a razor

sharp leading edge for a given wing/keel ?

[J.C.MacSwell]

Hi.

Which drag coefficient is greater; a rounded leading edge or a razor

sharp leading edge for a given wing/keel ?

 

Even for a symmetrical foil and 0 degrees angle of attack a razor sharp leading edge is not ideal simply due to the extra wetted surface required although is is not bad otherwise. So it is higher drag than the optimal shapes.

 

At any angle of attack it is poor both in terms of lift and drag and will stall much earlier.

[Skye]

What about supersonic?

[J.C.MacSwell]

What about supersonic?

 

Very different circumstances. Not my area, but I think sharp may be advantageous.

 

I know that sharper is advantageous at the leading edge of a hyrofoil or rudder near the surface to a depth dependant on the velocity. The pressure at the stagnation point of a rounded/blunter section is not "recovered" by a corresponding drop/suction aft of the leading edge so it just amounts to increased drag.