Noise from propellers with symmetrical sections at zero blade angle, II
This is a 1938 NACA technical report from the NASA Technical Reports Server, a scientific paper on propeller noise, written for aeronautical engineers and researchers. Its pictures are monochrome engineering drawings: a propeller blade plan and section outline with dimension lines, polar directivity diagrams plotting noise pressure in grids, and a graph of distance and velocity against time with an exponent scale. A designer could borrow the clean diagram conventions, the radial polar grid layouts, and the thin technical line work for schematic or infographic styling.
