Question

Cl vs Cd is called as _______________

(a) drag polar

(b) parasitic drag

(c) total drag

(d) no significance

This question was posed to me during a job interview.

I need to ask this question from Pressure Coefficient topic in section Inviscid & Incompressible Flow of Aerodynamics

Answer 1

The correct answer is (a) drag polar

For explanation I would say: It is called drag polar and it gives the relation between the lift and drag of the aircraft. It describes the amount of lift generated per drag produced. Cl/Cd ratio must be high. The amount of lift generated should be more with relatively less drag.