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XR-9
Firestone XR-9B.jpg
Role Utility helicopter
Manufacturer Firestone Aircraft Company
First flight March 1946
Primary user United States Army Air Forces
Number built 2

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.

DevelopmentEdit

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.[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]

VariantsEdit

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
XH-9B
XR-9B re-designated in 1948.

OperatorsEdit

United States
United States Army Air Forces

SurvivorsEdit

The sole Model 45D is in non-display storage at the Army Aviation Museum at Fort Rucker, Alabama. It is painted as an XR-9 46-001.

Specifications (XR-9B)Edit

Data from The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985)

General characteristics
  • Crew: 2
  • Length: 27 ft 0 in (8.23 m)
  • Main rotor diameter: 28 ft 0 in (8.53 m)
  • Height: 8 ft 6½ in (2.60 m)
  • Gross weight: 1750 lb (794 kg)
  • Powerplant: 1 × Avco Lycoming O-290-7 flat-four engine, 135 hp (101 kW) each

Performance

  • Cruise speed: 80 (approx) mph (129 (approx) km/h)
  • Service ceiling: 10,000 ft (3050 m)

See alsoEdit

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ReferencesEdit

NotesEdit

  1. "Short Hop Helicopter". Popular Science, April 1946.
  2. Andrade 1979, p. 171.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Merriam 2002, p. 64
  4. Lambermont 1958
  5. <AAHS Journal, Winter 2003, p. 316.

BibliographyEdit

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