A NOTE ON THE MEASUREMENT OF THE INDUCED DRAG FACTOR (k) OF A GLIDER

Abstract

There appears to be a good case for treating lift dependent drag as being composed of two separate terms varying C^2. One is purely the induced drag (with a k value to cover non-ellipticity of lift distribution) which is inversely proportional to aspect ratio. The other is the variation of wing profile drag coefficient and is independent of aspect ratio. In the Reynolds Number range normaly used by gliders and for Wortmann wing sections, it appears that this variation of wing profile drag coefficient contributes a slope of about 0.0038 to the Cd/C1^2 plot.