Question

The lift per unit span for a thin, cambered airfoil with Γ=10\(\frac {m^2}{s}\), ρ∞=1.0255\(\frac {kg}{m^3}\), V∞=10\(\frac {m}{s}\) is____

(a) 0

(b) 102.55\(\frac {N}{m}\)

(c) 102.55N

(d) 55\(\frac {N}{m}\)

This question was posed to me during an online exam.

My query is from The Cambered Airfoil topic in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

The correct option is (a) 0

The best I can explain: The lift per unit span is given by the formula L’=Γρ∞V∞ by Kutta-Joukowski Theorem. Putting the respective values given in the question, L’=102.55\(\frac {N}{m}\) (unit is N/m, not N).