Clark Y airfoil

Clark Y is the name of a particular airfoil profile, widely used in general purpose aircraft designs, and much studied in aerodynamics over the years.

For many applications the Clark Y has been an adequate airfoil section; it gives reasonable overall performance in respect of its lift-to-drag ratio, and has gentle and relatively benign stall characteristics.

The Clark YH airfoil is similar but with a reflexed (turned up) trailing edge producing a more positive pitching moment reducing the horizontal tail load required to trim an aircraft.

[1] The Clark Y was chosen as its flat bottom worked well with the design goal of a low radar cross-section.

The Clark Y has found favor for the construction of model aircraft, thanks to the flight performance that the section offers at medium Reynolds number airflows.