Wind-tunnel measurements of air loads on split flaps
A 1934 technical report of wind-tunnel measurements of air loads on split flaps, issued by NASA's technical reports series for aeronautical engineers and researchers. Its one picture is a pair of stacked line graphs on gridded paper, with several dashed and solid curves falling from left to right across numbered axes, presenting measured test data rather than decorative art. A designer could take from it the restrained vocabulary of engineering plots: fine grid rules, varied line dash patterns, and tightly clustered data curves.
