Question

How lift and drag ratio can be expressed in a relation?

(a) Dividing the lift coefficient by the drag coefficient

(b) Dividing the lift coefficient by the moment coefficient

(c) Dividing the drag coefficient by the lift coefficient

(d) Dividing the drag coefficient by the moment coefficient

I had been asked this question by my college director while I was bunking the class.

My question is from Airfoil Characteristics topic in chapter Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Correct option is (a) Dividing the lift coefficient by the drag coefficient

The explanation is: The lift-drag ratio is used to express the relation between lift and drag, and is obtained by dividing the lift coefficient by the drag coefficient. We can get the maximum lift coefficient by the drag coefficient for a given airfoil. The characteristics of any airfoil section can conveniently be represented by a graph showing the lift-drag ratio.