Twisting of thin walled columns perfectly restrained at one end
This is a 1938 NACA technical memorandum on the torsion of thin-walled columns held fixed at one end, issued by the National Advisory Committee for Aeronautics for engineers and aircraft structure analysts. Its two plates are engineering line diagrams: hatched cross-section and twisted-solid figures, plus an elliptical section with labelled dimensions and angles, offering a designer clean, technical schematic line work with dense hatching and dimension callouts.
