Preliminary Investigation on Boundary Layer Control by Means of Suction and Pressure with the U.S.A. 27 Airfoil
This is a 1928 NACA technical report on boundary layer control by suction and pressure over a U.S.A. 27 airfoil, issued for aeronautical researchers and wind tunnel engineers. Its pictures are plain line graphs of coefficient of normal force against angle of attack, with hand-drawn curves, gridded axes and fitted labels on the plots. A designer could take from them the clean typeset chart layout of early aerodynamic reports, with precise lettering and curves in thin black and dashed lines.
