Development of a Non-autorotative Airplane Capable of Steep Landing
A 1931 NASA technical report, published in the United States, on developing an airplane that could land steeply without autorotation, aimed at engineers and aeronautical researchers. The pictures are plates of wind-tunnel and model work: a rotor-like test apparatus, a close view of a mounted model with a curved arc and a pivoting blade, and graphs of lift coefficient against angle of attack and of motion traces over time. A designer might draw on the graphs' clean line plots and dashed curve annotations as a restrained technical diagram style.
