Page 82 - Understanding Flight

CH03_Anderson 7/25/01 8:56 AM Page 69

Wings 69

Fig. 3.11. Piper Cherokee 140 with a “Hershey Bar” wing. (Photo courtesy of Albert
Dyer.)

Fig.3.12. The Republic P-47 with an elliptic wing shape. (Photo courtesy of the U.S.
Air Force Museum.)

diverted, and thus the lift, changes along the span. In classical
aerodynamics it can be shown that the lift of the most efficient wing
tapers from the root to the tip in an elliptical fashion. It can be shown
that keeping the downwash velocity, and therefore the angle of attack
of the wing, constant along the trailing edge minimizes the induced
drag. So the elliptical-lift distribution is obtained by shaping the wing
so that the amount of air diverted tapers in an elliptical fashion. This