Effects of roughness on airfoils
This is a 1927 NACA Technical Memorandum No. 430 from the National Advisory Committee for Aeronautics, a government research report on how surface roughness changes airfoil performance, written for aeronautical engineers and aerodynamics researchers. The three plates are engineering graphs and a wing-section diagram; they plot lift coefficient against drag coefficient for six surface roughness conditions, from perfectly smooth to heavily roughened. A designer might borrow the clean grid-and-curve plotting style, the labelled chord-line diagrams, and the restrained monochrome technical layout.
