Bending of beams of thin sections
This is an N.A.C.A. technical memorandum from 1936 on the bending of thin-walled beams, issued by the National Advisory Committee for Aeronautics for aircraft structural engineers. Its pictures are plain black-and-white engineering line diagrams: a semicircular section with downward pressure arrows and reaction forces labelled Q and M0, and a circular tube cross-section marked with a neutral axis, radius, and thin wall thickness. A designer could borrow their clean technical-drawing style, with arrows and labelled dimensions for diagrammatic schematics.
