Wind-tunnel investigation of NACA 23012, 23021, and 23030 airfoils with various sizes of split flap
This is a 1939 NACA technical report from the National Advisory Committee for Aeronautics, issued by the NASA Technical Reports Server collection, presenting wind-tunnel test results for airfoil sections with split flaps for aviation engineers. The pages are dense engineering graphs of lift, drag and pitching-moment coefficients plotted against angle of attack, with small inset drawings of each airfoil profile and its deflected flap. A designer might take from them only the stark grid-paper charts and the sharp wedge-shaped wing silhouettes, useful as a clean technical graphic vocabulary.
