The effect of small variations in profile of airfoils
This is a 1931 NASA technical report on aerofoil research, produced for aeronautical engineers and researchers, presenting wind-tunnel test data on how small changes in airfoil profile shape affect lift and drag. The pictures are plain engineering line graphs with black curves, circle and cross plot markers, and grid paper, showing coefficient plots against angle of attack, percent of chord, and lift coefficient; a designer might take from them only the clean, minimal chart vocabulary of technical data graphics.
