The pressure distribution over a square wing tip on a biplane in flight
This is a 1931 NACA technical note from the NASA Technical Reports Server, a government aeronautics report on pressure distribution over a square biplane wing tip in flight. Its pictures are plain engineering graphs with ruled grids, labelled axes and lettered curves, showing rib and wing coefficients; a designer might take from them a restrained diagrammatic style built on thin black lines, grid structure and minimal typography.
