Drag of Prestone and Oil Radiators on the YO-31A Airplane
This NACA technical note from 1935, issued by the National Advisory Committee for Aeronautics, reports wind-tunnel tests of radiator drag on the YO-31A military biplane for engineers and aeronautical researchers. The photographs show the aircraft mounted on struts in a test tunnel with its radiators exposed, and the cowl and fairing outline drawing gives a designer a clear sense of how engineering documents presented streamlined forms in plain technical line.
