Torsional vibration of aircraft engines
A 1932 NACA Technical Memorandum from the National Advisory Committee for Aeronautics, issued for engineers and researchers studying aircraft engine behaviour. The pictures are plain scientific engineering material: typeset diagrams, black-and-white photographs of torsiograph recording devices, and line graphs of vibration amplitude against engine speed. A designer could take from them the stark, measurement-driven look of early technical documentation, with its dense figure captions, labelled cross-sections and dotted-and-solid plotted curves.
