Preliminary biplane tests in the variable density wind tunnel
A 1928 NACA Technical Note reporting preliminary wind tunnel tests of biplane wings in the variable density tunnel, issued by the National Advisory Committee for Aeronautics for aeronautical engineers and researchers. Its pages are engineering graphs of moment coefficients, lift-to-drag ratios, polar curves and profile drag plotted against lift coefficient for biplanes at several stagger angles. A designer might take from them the plain, grid-based chart style of 1920s technical drawing, with hand-inked curves, dense tick labels and small circular data markers.
