Close this search box.

Gloster F.9-37

The Gloster F.9-37, also known as the Gloster G.39, was a British twin-engine design from the Gloster Aircraft Company for a cannon armed heavy fighter to serve with the Royal Air Force, planned before the Second World War.

Gloster had designed a twin-engined turret-fighter for specification F.34/35 but the single-engined Boulton Paul Defiant for F.9/35 was seen to cover both requirements and the F.34/35 design dropped.

Less than two years later, F.9/37 for a “twin-engined single-seat fighter with fixed armament” was issued.

The F.9/37 was designed under the direction of George 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.

Intended for dispersed production by semi-skilled labour, the structure broke down into sub-assemblies.

A prototype (military serial L7999) with 1,060 hp Bristol Taurus T-S(a) radial engines flew on 3 April 1939 and demonstrated excellent performance, its maximum speed of 360 mph (580 km/h) being the best recorded by a British fighter at the time.

Test flights revealed that the prototype was very manoeuvrable and “a delight to fly”.

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 reduced its performance.

A second prototype (L8002) with 880 hp Rolls-Royce Peregrine I liquid-cooled, inline engines flew on 22 February 1940; it proved capable of 330 mph (530 km/h) at 15,000 ft (4,600 m).





37 ft 0.5 in (11.290 m)


50 ft 0.5 in (15.253 m)


11 ft 7 in (3.53 m)

Wing area

386 sq ft (35.9 m2)

Empty weight

8,828 lb (4,004 kg)

Gross weight

11,615 lb (5,268 kg)


2 × Bristol Taurus T-S(a),

14-cylinder air-cooled sleeve-valve radial piston engines,

1,000 hp (750 kW) each


3-bladed Rotol, 10 ft (3.0 m) diameter variable pitch metal propellers


Maximum speed

360 mph (580 km/h, 310 kn) at 15,000 ft (4,572 m)

Service ceiling

30,000 ft (9,100 m)

Rate of climb

2,460 ft/min (12.5 m/s) at 16,000 ft (4,877 m)

Time to altitude

28,000 ft (8,534 m) in 19 minutes 36 seconds

Wing loading

30.1 lb/sq ft (147 kg/m2)


0.172 lb/hp (0.105 kg/kW)



Four 0.303 in (7.7 mm) Browning machine guns

Two 20 mm Hispano cannon


Provision for 20 lb (9.1 kg) bomb carriers.



Share on facebook