The Characteristics of a Family of Rooftop Aerofoils Designed at their Drag-Rise Condition in Viscous, Compressible Flow Part I I: Off Design Conditions

SUMMARY The problems of computing and of presenting off-design variations of profile drag for the new family of rooftop aerofoils described in Ref.1 are examined by considering as a typical example a 50% rooftop section designed at a Mach number (Mdes > of 0.7 and having a thickness-chord ratio (t/c> of 0.1. Profile drag results are presented in two ways: (a> as a set of polar curves of CD vs CL for a range of Mach numbers, and (b) as contours of C D in the CL-M plane. Boundaries for rear separation, drag rise, and peak local Mach number equal to 1.2, are shown. For sections of given t/c and Mdes the present results indicate that the minimum drag anywhere along the flight locus M'CL = constant is obtained by choosing the particular section which has its design point on this locus.