The effects of partial-span plain flaps on the aerodynamic characteristics of a rectangular and a tapered Clark Y wing
This is a 1938 NASA technical report, published in the United States, testing how partial-span plain flaps change the lift and drag of rectangular and tapered Clark Y wings for aircraft designers. The pictures are engineering graphs of coefficient curves against angle or flap deflection, plus a line drawing of a wing with a flap labelled with its chord and angle. A designer could take from them the clean plotting conventions of technical charts, with dense gridlines, marked data points and labelled curves.
