The Unsteady Lift of a Finite Wing
A 1939 NASA technical report on the unsteady lift of finite wings, issued as an engineering document for aerodynamics researchers and aircraft designers. The four pictures are diagrams of circulatory flow around a wing section, basic and transformed flow patterns with bound and wake vortices, a top and front view of inflow vectors, and a lift-function chart for an oscillating airfoil plotted against wavelength and aspect ratio. A designer might borrow the concentric streamline loops and the clean, minimal line-diagram style for technical or schematic graphics.
