Experiments with an Airfoil Model on which the Boundary Layers are Controlled Without the Use of Supplementary Equipment
A 1931 NACA technical note from the National Advisory Committee for Aeronautics, issued as an aerodynamics report on wing sections for engineers and researchers. Its pictures show a photograph of a dark internal-circulation airfoil model and a labelled line drawing of the airfoil's cross-section with numbered slot or suction points along the upper surface and a chord line dimensioned at 8 inches.
