The Aerodynamic Effect of a Retractable Landing Gear
This is a 1933 NACA Technical Note, issued by the National Advisory Committee for Aeronautics, reporting wind-tunnel research on how a retractable landing gear changes an aircraft's aerodynamic drag. It was written for aeronautical engineers and aircraft designers. The two photographs show a Lockheed Altair with its wheels extended beside a hangar, and the same aircraft mounted in a large wind tunnel, which a designer might use as reference for aircraft profiles and engineering documentation.
