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.

But the flat lower surface is not optimal from an aerodynamic perspective, and it is rarely used in modern designs. 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 flat bottom simplifies angle measurements on propellers, and makes for easy construction of wings. The airfoil has a thickness of 11.7 percent and is flat on the lower surface aft of 30 percent of chord. The profile was designed in 1922 by Virginius E.

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.

Allerdings hat das Clark-Y weitaus bessere Allroundeigenschaften vor allem bei niedrigen Re-Zahlen. Ähnliche Verbreitung fanden nur Profile aus der vierstelligen NACA-Serie z.

Das Profil Clark-Y ist vermutlich das bekannteste und am häufigsten eingesetzte Flügelprofil der Geschichte.

Flat bottom airfoil