The Firestone XR-9, also known by the company designation Model 45, is 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-9Rotocycle by the Army)[1] was a design for a single-seat helicopter of pod-and-boom configuration.[2] 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.[3] 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,[3]
and was renamed the Firestone Aircraft Company in 1946.[4]
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,[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.[3] 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.[3] The prototype was demonstrated at the 1946 Cleveland National Air Races.[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]
Variants
Model 45B
Unbuilt single-seat helicopter with three-bladed rotor, Army designation XR-9.
Model 45C
Unbuilt single-seat helicopter with two-bladed rotor, Army designation XR-9A.
Model 45C (revised)
Tandem two-seat helicopter powered by an Avco Lycoming O-290-7 engine and two-bladed rotor, one built as the XR-9B, later re-designated the XH-9B.
Model 45D
Side-by-side two-seat helicopter for civil market, one built.
Model 50.
Four-seat version, not built.
XR-9
Army designation for the unbuilt Model 45B
XR-9A
Army designation for the unbuilt Model 45C
XR-9B
Army designation for the Model 45C (revised), later redesignated XH-9B
^Bridgman, Leonard, ed. (1947). Jane's all the World's Aircraft 1947. London: Sampson Low, Marston & Co. pp. 230c=231c.
^The Illustrated Encyclopaedia of Aircraft. London: Orbis Publications.
Bibliography
Andrade, John. U.S. Military Aircraft Designations and Serials since 1909. Hinckley, Leicastershire, UK: Midland Counties Publications, 1979. ISBN0-904597-22-9.