The effect of changes in compression ratio upon engine performance
A 1925 NASA technical report on how changing compression ratio affects engine performance, presented as a set of engineering charts. The pictures are plotted graphs of friction horsepower, compression pressure, indicated and brake mean effective pressure, and fuel and air density, with curves labelled by compression ratio and speed. A designer might take the clean grey line-graph style, with dense labelled curves and tidy axis lettering, as a model for technical diagrams.
