The Compressibility Burble and the Effect of Compressibility on Pressures and Forces Acting on a Airfoil
This is a 1939 NACA technical report, issued by the National Advisory Committee for Aeronautics for aeronautical engineers and researchers, on compressibility effects on airfoils. Its pictures are schlieren photographs of airflow around a wing section in a wind tunnel, showing dark bands, shock lines and support wires against grey fields that a designer could use for abstract fluid or motion textures.
