The vortex theory and its significance in aviation
A 1930 NASA technical memorandum on fluid vortex theory and its aviation applications, published as an engineering reference for aeronautical researchers. The pictures are plain black-and-white technical diagrams of streamlines, concentric vortex rings, and shear flow, with labelled figures and small geometric sketches of deforming particles. A designer might take from them the clean hand-drawn logic of flow lines and concentric rings as a source for abstract patterns or diagram-style graphics.
