The Effect of Surface Irregularities on Wing Drag. 3; Roughness
This NASA technical report from 1938 studies how surface roughness on aircraft wings raises drag, with results presented as charts and test photographs for aeronautical engineers. Its graphs plot drag increase against airspeed and roughness position, while the photographs show sandpaper-grain textures and a wind-tunnel test wing, offering a designer reference for how rough surfaces read in measured form.
