Question

The incorrect statement in relation to the fundamental equation of Prandtls lifting line theory is_____

(a) Geometric AoA is sum of effective AoA and induced AoA

(b) Integro-differential equation

(c) Γ is known

(d) Finite wing design, geometric AoA and free-stream velocity is known

The question was asked in quiz.

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

Answer 1

Correct answer is (c) Γ is known

To explain: The fundamental equation of Prandtls lifting line theory simply states that the geometric angle of attack is the sum of effective angle of attack and induced angle of attack. In mathematical form, it is an integro-differential equation where Γ is unknown and wing design, geometric AoA and free-stream velocity is known.