Question

The incorrect difference between airfoil and wings is_______

(a) Presence of induced drag in wings

(b) Different effective angles of attack seen by

(c) Difference in the lift-curve slope

(d) Lift slope of the wing is higher than of airfoil

The question was posed to me during an online exam.

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

Answer 1

Correct choice is (d) Lift slope of the wing is higher than of airfoil

To explain I would say: The finite wing has a lower lift slope than infinite wing (airfoil). This is another difference than the presence of induced drag between wings and airfoil. Also, the effective angles of attack are different for both, being the same only when the lift is zero (at zero lift angle of attack).