Progress towards a method for the measurement of the components of the drag of a wing of finite span

Abstract

A theory is developed to relate the total drag of a wing of finite span - or other, more general lifting system - to measurements in a single transverse section of its wake. The theory is an extension of that due to Betz, for the measurement of profile drag, and is expected to provide a basis for the resolution of the total drag into vortex and profile drag components. Some results obtained in a first exploratory survey of the wake of a rectangular wing, of aspect ratio 6, are included, to indicate the nature of the experimental problems presented by the technique. But firm conclusions concerning the definition with which the drag components can be obtained will have to await the results of two further surveys.