Pressure Drop in Radiator Air Tubes
A 1921 NASA technical report, published by the National Advisory Committee for Aeronautics, presenting measurements of pressure drop across radiator air tubes tested in a closed wind tunnel. Its pictures are engineering line graphs plotting pressure drop in pounds per square foot against distance from the rear face in inches, with curves for several air-flow speeds marked M and labelled key panels. A designer might draw on their clean grid layouts, dashed-and-solid line styles, and tidy boxed legends as a plain technical chart vocabulary.
