The Firestone XR-9, also known by the company designation Model 45, was a 1940s American experimental helicopter built by the Firestone Aircraft Company for the United States Army Air Forces. Only two (the military XR-9B and one civil example) were built.
Development
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) was a design for a single-seat helicopter of pod-and-boom configuration. It had a fixed tri-cycle landing gear and three-bladed main and tail rotors. Power would have been supplied by a 126 hp (94 kW) Avco Lycoming XO-290-5 engine. The Model 45C (XR-9A) was the same helicopter with a two-bladed rotor. Neither of the two helicopters were built. G & A Aircraft was purchased by Firestone in 1943,and was renamed the Firestone Aircraft Company in 1946.

A revised two-seat design the revised Model 45C (or XR-9B) was built with a three-bladed main rotor and two-seat in tandem. The first aircraft procured by the Army Air Forces in 1946, it was powered by an Avco Lycoming O-290-7 engine 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. This differed in having the two occupants side-by-side instead of Tandem as in the 45C, and was equipped with a 150 horsepower (110 kW) Lycoming engine. The prototype was demonstrated at the 1946 Cleveland National Air Races. A four-seat Model 50, with twin tail rotors, was also projected, but the predicted sales boom did not materialise, and Firestone closed its aircraft manufacturing division.












Specifications (XR-9B)
General characteristics
Crew: 1
Capacity: 1 pax
Length: 27 ft 7 in (8.4 m)
Height: 8 ft 6 in (2.6 m)
Gross weight: 1,750 lb (794 kg)
Fuel capacity: 25 US gal (21 imp gal; 95 l) 80 Octane fuel
Powerplant: 1 ? Lycoming O-290-7 4-cyl. horizontally-opposed air-cooled piston engine, 135 hp (101 kW)
Main rotor diameter: 28 ft 0 in (8.53 m)
Performance
Maximum speed: 100 mph (160 km/h, 87 kn)
Cruise speed: 80 mph (130 km/h, 70 kn)
Service ceiling: 10,000 ft (3,000 m)
Rate of climb: 1,000 ft/min (5.1 m/s)