Measurements of the Air-flow Velocity in the Cylinder of an Airplane Engine
A 1939 NACA technical report, compiled from NASA's Technical Reports Server, presenting measurements of air-flow velocity inside an aircraft engine cylinder for engineers and aerodynamics researchers. The pictures are plain line graphs with numbered curves plotted against engine speed, crank angle and throttle setting, with labelled intake, compression, expansion and exhaust phases. A designer could take from them the restrained grid-and-curve vocabulary of mid-century engineering documentation, with hand-lettered annotations and dashed reference lines.
