Note on the Katzmayr effect on airfoil drag
This is a 1925 NACA technical note on the Katzmayr effect, an aerodynamic study of how changing wind conditions alter airfoil drag, issued by the National Advisory Committee for Aeronautics for engineers and researchers. The first picture is a dense page of plotted curves and graph lines with labelled axes and angle markings, while the second is a clean line diagram of an airfoil section with lift and drag force vectors and a sloping wind direction, offering a designer crisp technical graph and vector-arrow material.
