Airplane stability calculations and their verification by flight tests
This is a 1922 technical report from the NASA Technical Reports Server, a sober engineering document on airplane stability calculations checked against flight tests, aimed at aeronautical engineers and researchers. The two pictures are line diagrams: a family of sloping curves labelled with angles from -10 to +10 degrees, and a force diagram with vectors, a curved path and axes meeting at an origin. A designer could take from them the clean, spare vocabulary of early technical drawing, with thin single-weight lines, serif labels and angled graph lines.
