Propeller Vibrations and the Effect of the Centrifugal Force
This is a 1935 NACA technical note, a report issued by the National Advisory Committee for Aeronautics, on propeller vibration and centrifugal force, written for aeronautical engineers. The pictures are plain photographs of test rigs in a wind tunnel hall, showing a propeller mounted on a stand and a motor and frame set-up, with a few line graphs of vibration mode shapes. A designer could take little from them beyond the look of 1930s engineering test apparatus, with its black machinery, trestles and steel bracing.
