Question

High speed subsonic aircrafts are designed with thick airfoil wings.

(a) True

(b) False

I had been asked this question by my school teacher while I was bunking the class.

Enquiry is from The Supercritical Airfoil topic in portion Subsonic Compressible Flow over Airfoils : Linear Theory, Linearized Supersonic Flow of Aerodynamics

Answer 1

Correct answer is (b) False

To explain I would say: The flow over thin airfoil experiences less perturbation and Cp0 value is negative Cp0 with a smaller magnitude. On the other hand thick airfoils experience higher perturbation resulting in negative of larger magnitude. Thus on seeing the graph, thick airfoil has lower critical Mach number compared to the thin airfoil. This is the reason why high speed subsonic aircrafts make use of thinner airfoils.