Ring Wing
 

Hello,

I've heard that a ring wing is twice as efficient as a corresponding planer wing.

Does anybody know any reference to ring wings?

(No aerodynamics books, as far as I know, discuss them. Why?)

Thank you very much.

Re: Ring Wing
 

Ring wings are more efficient, because of a lower induced drag. They are not used anymore because it is not practical and hard to manufacture. Some references can be found in Hoerner, Fluid dynamics drag.

Re: Ring Wing
 

Slightly different question.

Is any information on "box wings" available anywhere?

Re: Ring Wing
 

Some References on ring wing:

(1)The aerodynamics of A Ring Airfoil, H,J, Stewart, Quarterly of Applied Mathematics, Vol.2, p136, July, 1944

(2)The Ring Airfoil in Nonaxial Flow, H.S. Ribner, Journal of the Aeronautical Sciences, p.529, Sept. 1947

(3)Theoretical Wave Drag and Lift of Thin Supersonic Ring Airfoils, H. Mirels, NACA TN1678, August, 1948

(4)Calculation of the Pressure Distribution and Streamline Pattern around a Ring Wing using Finite Difference Methods, M. J. Wagner, AIAA paper 0645, 1983

(5)Ring wing for an Underwater Missile, H. August and E. Carapezza, J. of Aircraft, vol.33, No.4, Aug 1996. p 830-832 (and also in p.837-839)

It looks like ring wings are still alive in torpedoes! See (5).

Regards,

Nishikawa