Question

Which is not a feature of the first new NACA airfoil (GA(W)-1 or the Whitcomb airfoil) developed?

(a) Large leading-edge radius

(b) Higher symmetry

(c) Higher maximum lift coefficient

(d) Cusped trailing edge

The question was asked in a job interview.

My question comes from Modern Low Speed Airfoils in section Incompressible Flow over Airfoils of Aerodynamics

Answer 1

Right choice is (b) Higher symmetry

The best explanation: The larger leading edge radius gave a reduced peak in pressure coefficient at the leading edge. The trailing edge was cusped which increased camber, thus decreasing symmetry. These features reduced flow separation and gave a higher value of maximum lift coefficient.