The autogiro was the first aircraft to successfully employ rotary lift technology.  It was developed in Spain during the early 1920’s by a talented aviator named Juan de la Cierva.  The vehicle was similar to fixed wing aircraft in many respects, and used a conventional engine to provide forward thrust.  The rotor blades on the autogiro were not mechanically powered, but as the name suggests, rotated autonomously as airflow rushed over the surface of the blades.  The faster the aircraft moved forward, the more momentum built up in the rotor assembly, eventually providing lift for the vehicle.  The autogiro was a revolutionary aircraft, and was the forerunner of the modern day helicopter.

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Harold Pitcairn purchased the American manufacturing rights to the autogiro in the late 1920’s, and started the Autogiro Company of America.  The company spent a great deal of time and money improving the autogiro, and was credited with a number of important patents that would eventually be used in helicopter design.  In the fall of 1930 the company engaged in a contract to purchase engines from the Chevrolet Aircraft Corporation.  Below are some interesting documents that relate to Louis Chevrolet’s participation in the Pitcairn PAA-2 autogiro project.