Question

The incorrect choice for the general lift distribution for a finite wing is ________

(a) Circulation is assumed a Fourier series

(b) 0 ≤ θ ≤ 2π

(c) Coordinate transformation is for spanwise direction to θ

(d) Coefficient of lift depends on aspect ratio directly

I got this question during an interview for a job.

The query is from Prandtl’s Classical Lifting-Line Theory topic in section Flow over Airfoils over Finite Wing of Aerodynamics

Answer 1

Correct option is (b) 0 ≤ θ ≤ 2π

To elaborate: For a general lift distribution of a finite wing, the circulation is assumed a Fourier series from the expression obtained for elliptic lift distribution. The transformation involves spanwise coordinate transformed to θ, where 0 ≤ θ ≤ π. Using this the lift coefficient obtained depends directly on the aspect ratio.