Effect of periodic changes of angle of attack on behavior of airfoils
A 1922 NASA technical report on how airfoils behave when their angle of attack changes periodically, written for aeronautical engineers and researchers. The pictures are plotted graphs of lift coefficient against drag coefficient and angle-of-attack curves, with fitted lines, data points marked by symbols, and labelled figure numbers. A designer could take from them the restrained look of technical charts: fine grid lines, varied point markers, and curves that rise and flatten.
