The wave drag of arbitrary configurations in linearized flow as determined by areas and forces in oblique planes

"The wave drag, based on linearized theory, of any lifting or non-lifting planar or nonplanar object in a steady supersonic flow is shown to be identical at a fixed Mach number to the average wave drag of a series of equivalent bodies of revolution. The streamwise gradient of area, measured normal to the free stream, at a section of each of these equivalent bodies of revolution is given by the sum of two quantities: 1. the streamwise gradient of area, measured in parallel oblique planes tangent to the Mach cones, along the given object. 2. A term proportional to the resultant force on the object measured in the same oblique planes" (p. 1).