Theory of automatic control of airplanes
A 1939 NACA technical note on the theory of automatic control of airplanes, issued by the NASA Technical Reports Server collection for aeronautical engineers and researchers. Its single picture is a line graph of response against time, with one curve for undamped motion and others for damping ratios 0.20, 0.70 and 1.00 labelled as critically damped. A designer could borrow its clean engineering-chart style, with thin black curves on a white grid and sparse labelling, for diagrams of oscillation settling over time.
