Experiments with three horizontal empennages
This NACA technical memorandum from 1927, issued by the National Advisory Committee for Aeronautics as a report for aeronautical engineers, records wind-tunnel tests of three horizontal tail surfaces (empennages) on aircraft models. The pictures are plain engineering graphs with curves plotted on grids of lift and drag coefficients against angle of attack and sideslip angle beta, with marked data points and labelled curve families. A designer might take from them only the look of dense technical charts: fine gridlines, tick labels, legend keys and paired curves on shared axes.
