Propeller Tests to Determine the Effect of Number of Blades at Two Typical Solidities
A 1939 NASA technical report on propeller tests, issued by NASA's Technical Reports Server and aimed at aeronautical engineers, comparing how the number of blades affects performance at two typical solidities. The page shows photographs of test propellers: a two-blade propeller with spinner, three plain blade forms in profile, and several propeller hubs in black and white. A designer could take from it the clean, technical look of mid-century engineering documentation, with simple grid-free photographs of isolated objects on pale paper.
