Span-Load Distribution as a Factor in Stability in Roll
This is a 1932 NACA technical report from the NASA Technical Reports Server, a government aeronautics research publication for engineers studying aircraft wing stability in roll. The pictures show a wing section diagram with lamination and leading-edge layout, a wind tunnel test setup with equipment on a bench, a wind tunnel interior with a vertical test vane, and a line chart of angle of attack against sweep for two wing sections. A designer could take the clean technical line diagrams and graph styling as reference for plain engineering figures.
