Circulation Measurements About the Tip of an Airfoil During Flight Through a Gust
This is an NACA technical note from 1939 by the National Advisory Committee for Aeronautics, written for aerodynamics engineers and researchers, reporting measurements of circulation about an airfoil tip while the wing passes through a gust. The pictures are dense engineering plots of velocity and circulation traces against chord position, a few grid-ruled graphs with labelled curves, a table of gust-passage velocity lines, and a photograph of a wing on a whirling arm with hot-wire probes, offering a designer little beyond the graph-paper layouts and the stark technical line style.
