Originally developed by G & A Aircraft with the co-operation of the United States Army Air Forces' Air Technical Service Command, the G & A Model 45B (designated XR-9 Rotocycle by the Army)[1] was a design for a single-seat helicopter of pod-and-boom configuration.

The first aircraft procured by the Army Air Forces in 1946,[3] it was powered by an Avco Lycoming O-290-7 engine[3] and first flew in March of that year.

A civil version, the Model 45D was also built and flown, in anticipation of a postwar boom in aircraft sales.

[5] A four-seat Model 50, with twin tail rotors, was also projected,[3] but the predicted sales boom did not materialise, and Firestone closed its aircraft manufacturing division.

[3] The sole Model 45D is on display (without blades installed) at the United States Army Aviation Museum at Fort Novosel, Alabama.