Theory of flapping flight
A NACA Technical Memorandum from 1925, issued by the National Advisory Committee for Aeronautics and later catalogued by NASA's Technical Reports Server, presenting a theoretical study of flapping flight for aeronautical engineers. The pictures are plain technical graphs, a wing section profile, and force-curve diagrams drawn in black line and hatched fill, with labelled axes and small numbered plots. A designer could take from them a restrained diagrammatic vocabulary of hatched areas, loop-shaped curves and stacked plots for showing motion cycles and performance data.
