Tests in the variable-density wind tunnel of the NACA 23012 airfoil with plain and split flaps
This is a 1939 NACA technical report of wind-tunnel tests on the NACA 23012 airfoil, issued by the US National Advisory Committee for Aeronautics for aeronautical engineers and researchers. Its four plots chart section drag, pitching moment, angle of attack and lift coefficient for plain and split flaps set at several deflection angles, with measured curves drawn as dense families of lines on gridded graph paper that a designer could borrow for technical diagram layouts.
