Behavior of aviation engines at different air densities
A 1922 technical report from NASA's Technical Reports Server, a scanned aeronautical engineering paper on how aviation engines perform as air density changes with altitude. It is aimed at engineers and aviation researchers. The two pictures are graphs: one plots altitude in kilometres against humidity and horsepower decrease with families of crossing lines, and the other plots the temperature of a mixture against a percentage scale with shaded regions and a cooling-by-evaporation bracket. A designer might take the clean grid-and-curve diagram style, its labelled axes and shaded zones as a model for technical charts.
