Tests of oil scraper piston ring and piston fitted with oil drain holes
This is a 1922 NASA technical report on engine tests, issued for aeronautical engineers and researchers. The first picture is a dimensioned engineering drawing of a Liberty 12 piston with oil drain holes and a notched ring groove, and the second is a scatter plot with fitted trend lines of oil consumption against engine speed. A designer could take from them the plain line-drawing style of technical sectional views and the clean dual-axis chart layout for data graphics.
