A simple approximate method is given for the calculation of isentropic irrotational flows past symmetrical airfoils, including mixed subsonic-supersonic flows. The method is based on the choice of suitable values for the streamline curvature in the flow field and the subsequent integration of the equations of motion. The method yields limiting solutions for potential flow. The effect of circulation is considered. A comparison of derived velocity distributions with existing results that are based on calculation to the third order in the thickness ratio indicated satisfactory agreement. The results are also presented in the form of a set of compressibility correction rules that lie between the Prandtl-Glauert rule and the von Karman-Tsien rule (approximately). The different rules correspond to different values of the local shape parameter square root sign YC sub a, in which Y is the ordinate and C sub a is the curvature at a point on an airfoil. Bodies of revolution, completely supersonic flows, and the significance of the limiting solutions for potential flow are also briefly discussed.
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