Question

When the lift becomes zero, the center of pressure of the cambered airfoil is at which point on the airfoil (consider given lengths are from the leading edge)?

(a) Quarter-chord length

(b) Mid-chord length

(c) 0 (i.e. at the leading edge)

(d) ∞ (i.e. the point does is not on the airfoil)

I have been asked this question in semester exam.

I would like to ask this question from The Cambered Airfoil in portion Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Correct option is (d) ∞ (i.e. the point does is not on the airfoil)

To explain: The center of pressure of a cambered airfoil will leave the airfoil and move at a very large distance away from the airfoil. This is one reason why the aerodynamic center is preferred over the center of pressure since it is always at the quarter-chord but the later keeps on changing with the angle of attack.