Increasing the compression pressure in an engine by using a long intake pipe
A 1924 NASA technical report on raising engine compression pressure by lengthening the intake pipe, published as a series of engineering charts. The three figures are plotted graphs of final compression pressure in pounds per square inch against engine speed in r.p.m. and intake pipe length in inches, with curves for each speed. A designer could take from them the clean monochrome plotting style, dense dashed guide lines, and labelled axes typical of mid-century engineering graphs, one drawn on its side for the rotated third figure.
