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Gloster F.9/37
Gloster F.9/37
Role Fighter
Manufacturer Gloster Aircraft Company
Designer George Carter
First flight 3 April 1939
Primary user Royal Air Force (intended)
Number built 2

The Gloster F.9/37, also known as the Gloster G.39, was a British twin-engined design from the Gloster Aircraft Company for a cannon-armed fighter to serve with the Royal Air Force planned before the Second World War. The F.9/37 was rejected in favour of other designs.

A development of the F.9/37 as a night fighter, for a new Air Ministry Specifications F.29/40 – known unofficially as the "Gloster Reaper" – was dropped so that Gloster would be able to concentrate on existing work and on the nascent British jet projects.

Design and development

Gloster had designed a twin-engined turret-fighter for specification F.34/35 but the single engine design from Boulton Paul (Boulton Paul Defiant) for F.9/35 was seen to cover both requirements and the F.34/55 design dropped. Less than two years later, F.9/37 for a "twin-engined single-seat fighter with fixed armament" was issued.[1]

The F.9/37 was designed under the direction of W. G. Carter, his first for Gloster, to F.9/37 (hence the name) as a single seat fighter carrying an armament of four 0.303 in (7.7 mm) Browning machine guns and two 20 mm Hispano cannon in the nose.

A prototype (military serial number L7999) with 1,060 hp Bristol Taurus T-S(a) radial engines flew on 3 April 1939,[2] and demonstrated excellent performance, its maximum speed of 360 mph (580 km/h) being the best recorded by a British fighter at the time.[2] Test flights revealed that the prototype was very manoeuvrable and "a delight to fly."[3] However, after being badly damaged in a landing accident in July 1939, it was re-engined with 900 hp Taurus T-S(a)-IIIs in 1940, which resulted in reduced performance. A second prototype (L8002) with 880 hp Rolls-Royce Peregrine I liquid-cooled in-line engines flew on 22 February 1940,[2] it proved capable of 330 mph (530 km/h) at 15,000 ft (4,570 m).[4]

F.18/40 and F.29/40

Specification F.18/40, for a dedicated night fighter, with both nose- and turret-mounted guns, led to Gloster submitting a design based on the F.9/37, fitted with Rolls-Royce Merlin engines, a dorsal four-gun turret and Airborne Interception (AI) radar.[5] This received support from the Air Staff who saw it as superior to the Bristol Beaufighter and the Air Ministry ordered one of the F.9/37 prototypes to be converted to the new specification as F.29/40.[6]

Unofficially known as the "Gloster Reaper", it inherited the admirable handling characteristics of the F.9/37, and despite being judged superior to other designs, including turreted variants of the Beaufighter and de Havilland Mosquito, the Reaper was terminated.[6] The project was terminated in May 1941, so that Gloster could concentrate on other work, especially its work on jet aircraft.

Specifications (L7999 with Taurus engine)

Data from The British Fighter since 1912[2]Gloster Aircraft since 1917[7]

General characteristics

  • Crew: 1
  • Length: 37 ft ½ in (11.29 m)
  • Wingspan: 50 ft ½ in (15.26 m)
  • Height: 11 ft 7 in (3.53 m)
  • Wing area: 386 ft² (35.9 m²)
  • Empty weight: 8,828 lb (4,013 kg)
  • Loaded weight: 11,615 lb (5,280 kg)
  • Powerplant: 2 × Bristol Taurus T-S(a) 14 cylinder radial engine, 1,000 hp (746 kW) each
  • Propellers: 3-bladed metal Rotol variable pitch [7] propeller, 1 per engine
    • Propeller diameter: 10 ft (3.04 m)


  • Maximum speed: 360 mph (313 knots, 580 km/h) at 15,000 ft (4,570 m)
  • Service ceiling: 30,000 ft (9,150 m)
  • Rate of climb: 2,460 ft/min[8] (12.5 m/s) at 15,000 ft
  • Wing loading: 30.1 lb/ft² (147 kg/m²)
  • Power/mass: 0.172 lb/hp (0.283 kW/kg)
  • Climb to 28,000 feet (8,500 m): 19 min, 36 sec


See also



  1. King, H. F. "From Mars to Javelin: F.9/37 (Taurus engines)." Flight, 27 May 1955, p. 275.
  2. 2.0 2.1 2.2 2.3 Mason 1992, p. 279.
  3. Green 1961, p. 51.
  4. James 1987, p. 236.
  5. Morgan 1992, p. 360.
  6. 6.0 6.1 Buttler 2004, p. 62.
  7. 7.0 7.1 7.2 James 1987, pp. 233–234.
  8. Green and Swanborough 1994 [page needed]


  • Bowyer, Michael J.F. Interceptor Fighters for the Royal Air Force 1935-45. Wellingborough, UK: Patrick Stephens Ltd., 1984. ISBN 0-85059-726-9.
  • Buttler, Tony. Secret Projects: British Fighters and Bombers 1935 -1950 (British Secret Projects 3). Leicester, UK: Midland Publishing, 2004. ISBN 1-85780-179-2.
  • Green, William. War Planes of the Second World War, Volume Two: Fighters. London: MacDonald & Co. (Publishers), 1961.
  • Green, William and Gordon Swanborough. The Complete Book of Fighters. New York: Smithmark, 1994. ISBN 0-8317-3939-8.
  • James, Derek N. Gloster Aircraft since 1917. London: Putnam, 1987, First edition 1971. ISBN 0-85177-807-0.
  • Mason, Francis K. The British Fighter Since 1912. Annapolis, Maryland: Naval Institute Press, 1992. ISBN 1-55750-082-7.
  • Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Chancellor Press, 1994. ISBN 1-85152-668-4.
  • Morgan, Eric B. "The Gloster F.9/37" Twentyfirst Profile Volume 1, No. 12, March 1992. New Milton, Hampshire, UK: 21st Profile Ltd., 1992.

External links

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