Question

Which is the wrong implication of the elliptical lift distribution for a wing?

(a) Circulation varies elliptically along span

(b) Span length does not affect circulation

(c) Lift is zero at the tips

(d) Maximum lift is at the center

The question was posed to me during an interview.

This is a very interesting question from Prandtl’s Classical Lifting-Line Theory in portion Flow over Airfoils over Finite Wing of Aerodynamics

Answer 1

The correct option is (b) Span length does not affect circulation

Best explanation: The elliptical lift distribution comes from the elliptical distribution of circulation along the span. The lift (or circulation) involves span length in the governing equations and hence the wrong statement. Lift is zero at the wing tips and maximum at the center.