Fatigue Testing of Wing Beam by the Resonance Method
This is a 1938 NACA technical note, issued by the National Advisory Committee for Aeronautics, reporting fatigue tests of aircraft wing beams using resonance-driven vibration. Its audience is aeronautical engineers and testing staff rather than general readers. The photographs are plain black-and-white documentary shots of test hardware: a rotating armature, an electromagnet housing, a beam end fitting with terminals, and a laboratory rig with load gear and instrument panels. A designer might take from them the industrial look of 1930s machinery, with its bolted castings, exposed fittings and utilitarian detail.
