Clark-Y
Clark-Y is the name of a particular aerofoil profile, widely used in general purpose aircraft designs, and much studied in aerodynamics over the years. The profile was designed in the 1922 by Virginius E. Clark. For many applications the Clark-Y has never been bettered, it gives good overall performance in respect of its Lift-to-drag ratio, and has gentle and relatively benign stall characteristics.
The Lockheed Vega is one example of the Clark-Y in practice.