Question

The angle between the chord line and the direction of free-stream velocity is called the angle of attack.

(a) True for airfoil only

(b) True for wing only

(c) True for airfoil and partially true for wings

(d) False

This question was addressed to me during an interview.

This key question is from Downwash and Induced Drag in section Flow over Airfoils over Finite Wing of Aerodynamics

Answer 1

Right choice is (c) True for airfoil and partially true for wings

Easiest explanation: For an airfoil, the angle between the chord line and the direction of free-stream velocity is called the angle of attack. For the wings, the precise name is geometric angle of attack. Hence the given statement is only partially true for a wing.