TAKING as basic requirements such fundamental characteristics as can be largely separated from the problem of wing design or assumed as attributes of the complete airplane, the author discusses the independent variables consisting mainly of the geometrical characteristics that can be varied to obtain maximum performance without changing the basic requirements. He develops a weight and a drag equation, each founded on the chosen basic requirements and including in the simplest possible form the combined effect of the independent variables.
The terms in these equations are defined and the equations are applied to a low-wing monoplane in power and gliding fight and to a rectangular-wing
biplane in gliding flight. The results are tabulated in some instances but are principally shown on charts. The accuracy of the results obtained is stated to depend largely upon the proper choice of approximations with an appreciation of their limitations. Certain reservations as to the accuracy of the equations are stated. The reduction to practice of the drag equation is discussed, and this is followed by comments on wind-tunnel research and flight-test data. Interesting points, bearing directly on practical design and having general application throughout the particular ground covered in the paper, are presented. Various contributing and supplementary data are given in appendixes.