The drag of infinite swept wings with an addendum

Abstract

The drag of an infinite swept wing is found in terms of the drag of a related unswept wing having the same relative position of transition. Results in incompressible flow are expressed in terms of a 'sweep factor'. Detailed calculations are made for wings of RAE 101 and 104 sections and the factor appears to have a reasonably universal character not very dependent on shape or Reynolds number if transition takes place early, but strongly dependent on thickness. Results are given as a series of curves and an empirical formula is given for the sweep factor in terms of thickness-chord ratio, angle of sweep and point of transition. A few results are given for compressible flow over an RAE 101 section at sweep angles of 0° and 45°; these show the effect of sweep in delaying the compressibility drag rise.