Vertical descent of the autogiro
A 1932 technical report from the NASA Technical Reports Server on the vertical descent of the autogiro, a rotary-wing aircraft, with no stated audience beyond aeronautical engineers. Its single figure is a labelled line graph plotting a quantity against 1/F, with curves marked a through d on a grid of ruled axes. Designers might borrow its plain engineering chart style, with clean grid lines, lettered curve labels and sparse annotation, for technical diagrams.
