Crank case scavenging of a two-stroke-cycle engine
A 1928 technical memorandum from the NASA Technical Reports Server, originally issued by an aeronautical research body for engine engineers studying two-stroke crankcase scavenging. Its pictures are engineering line drawings and graphs: plotted curves of percentages and volumes against cubic centimetres, a sectioned valve and fuel meter with labelled parts, and port-shape diagrams. A designer could take from them a sparse, numbered, technical-diagram vocabulary of graph grids, leader lines and cutaway apparatus.
