The Nature of Air Flow About the Tail of an Airplane in a Spin
This is a 1932 NACA technical note, issued by the National Advisory Committee for Aeronautics in the United States, for aircraft engineers and researchers studying spin behaviour. Its photographs are plain black-and-white wind-tunnel and model shots: a tail fin with smoke-like airflow traced in white, dashed lines marking the flow boundaries, and a labelled aircraft test photograph. A designer could take the clear diagrammatic use of streamer smoke and dashed guide lines to show invisible air movement.
