Experimental research on air propellers
A 1918 NASA Technical Reports Server publication of experimental research on air propellers, issued as a technical report for aeronautical engineers and researchers. The first plate is a dense grid-backed graph of propeller performance curves, with rising and falling lines plotted across labelled axes. The second shows an apparatus of a motor-driven test stand, with a bracketed frame, a small horizontal rig and a pair of sensing vanes, rendered as a clean line drawing. A designer could take the graph's sweeping curves as a source of flowing diagrammatic lines and the stand drawing as a plain technical sketch with strong black shapes.
