Tests in the Variable Density Wind Tunnel to Investigate the Effects of Scale and Turbulence on Airfoil Characteristics
A 1931 NACA technical report on wind tunnel tests of how Reynolds number, scale and turbulence change airfoil lift and drag, issued by the National Advisory Committee for Aeronautics for aeronautical engineers and researchers. The pictures are plain graphs of coefficients against Reynolds number and angle of attack, with airfoil profile outlines drawn at the top and inside a plot. A designer might take the clean grid-and-curve layout and the thin airfoil silhouettes as a restrained technical diagram style.
