Part-throttle operation and control of a piston-ported two-stroke cylinder
This is a 1943 NASA technical report, NACA Technical Note No. 919, on part-throttle operation and control of a piston-ported two-stroke engine, issued through the NASA Technical Reports Server. The pictures are plain engineering line graphs on squared paper, with curves plotted against engine speed in r.p.m. and labelled with figure captions. A designer might take from them the clean, restrained vocabulary of mid-century technical charts: dense gridlines, dotted data points, and tidy labelled curves.
