Preliminary report on the flat-top lift curve as a factor in control at low speed
A 1928 NASA technical report on aerodynamic lift and control at low airspeed, a technical document for aeronautical engineers and researchers. Its two plots show a lift-to-drag curve and lift and drag coefficients against angle of attack, plus a vector diagram of force directions across a wing section, giving designers a stark graph-paper look of plotted curves, crosses and circles on a grid.
