Pressure-Distribution Measurements at Large Angles of Pitch on Fins of Different Span-Chord Ratio on a 1/40-Scale Model of the U. S. Airship "Akron."
This is a 1937 NASA technical report on pressure distribution over fins of differing span-chord ratio, tested on a 1/40-scale model of the U.S. airship Akron, prepared for aeronautical engineers. The two photographs show fin shapes set side by side and a single fin mounted on the model's hull, with plain grey tones and no decoration; a designer could take from them the tapered, swept-back fin silhouettes and the clean, technical look of engineering documentation.
