|Role||Two-seat night fighter|
|First flight||Spring 1917|
|Primary user||Royal Flying Corps|
The Vickers F.B.25 was a British two-seat night fighter prototype of World War I designed to attack enemy airships. Completed in 1917, it failed in its official flight tests that year and no order for production resulted.
In 1916, Vickers Limited designed a two-seat pusher configuration biplane fighter, the F.B.23, to replace its obsolete Vickers F.B.5 and F.B.9 "Gunbuses". A number of versions of the FB.23 were planned depending on the engine used, with possible powerplants including a 150 hp (119 kW) Salmson water-cooled radial engine, a 150 hp Hart air-cooled radial engine and a 200 hp (149 kW) Hispano-Suiza 8 V-8 engine. The pusher configuration was obsolete however, compared to prospective tractor aircraft such as the Bristol F.2 Fighter, which was both faster than the estimated performance of the F.B.23 and carried a heavier armament, so Vickers abandoned the F.B.23 without an example being built.
Vickers reworked the F.B.23 to form the basis of a two-seat night-fighter, the F.B.25, to compete with the Royal Aircraft Factory N.E.1 to meet a British requirement for a night fighter capable of attacking German airships. The F.B.25 used an identical tail and tail boom assembly to the F.B.23, but had modified wings and a completely new fuselage nacelle.
The F.B.25 was a two-bay biplane with unstaggered wings of equal span. Its nacelle was mounted between the wings, was unusually wide for an aircraft of its type in its day, and accommodated the two-man crew, a pilot and a gunner, in staggered side-by-side seats, with the gunner's seat ahead and to starboard of the pilot's. The gunner was armed with a single 1.59-inch Breech-Loading Vickers Q.F. Gun, Mk II, popularly known as the "Vickers-Crayford rocket gun," which despite its popular name was a lightweight 40 mm single-shot gun that fired shells and had no rocket-launching capability. Its tailbooms converged in elevation to meet at the rear spar of the tailplane. It had a single propeller, mounted in a pusher configuration. The aircraft had an oleo-pneumatic undercarriage, an unusual feature for the time.
Plans called for the F.B.25 to mount a small searchlight in the nacelle's nose, have a nosewheel to reduce the chance of the aircraft turning over during night landings, and use the same 200-horsepower (149-kilowatt) Hispano-Suiza 8 planned for the F.B.23. As design and construction progressed, Vickers made changes; the searchlight and nosewheel were deleted, and as the 200-horsepower engine was unavailable, Vickers substituted a 150-horsepower (112-kilowatt) Hispano-Suiza.
Vickers completed the F.B.25 prototype in the early spring of 1917. Company flight testing revealed poor characteristics. The prototype was sent to Martlesham Heath in June–July 1917 for official testing, and official reports declared that the F.B.25 had poor control characteristics, being "very dangerous" with the engine off, and "almost unmanageable in a wind over 20 miles per hour". The aircraft was condemned as being completely unsuited for use as a night fighter. No further aircraft were built, and the lone F.B.25 later crashed at Martlesham Heath.
- Proposed two-seat fighter. Three versions planned with different powerplants. All unbuilt.
- Two-seat night-fighter based on F.B.23 but with side-by-side seating. One built, powered by 150 hp Hispano-Suiza engine.
Data from War Planes of the First World War:Volume Three Fighters
- Crew: 2
- Length: 28 ft 1 in (8.56 m)
- Wingspan: 42 ft 6 in (12.65 m)
- Height: 11 ft 11 in (3.38 m)
- Wing area: 500 ft² (46.5 m²)
- Empty weight: 1,608 lb (731 kg)
- Loaded weight: 2,454 lb (1,115 kg)
- Powerplant: 1 × Hispano-Suiza water-cooled V-8 engine, 150 hp (112 kW)
- Maximum speed: 86 mph (75 knots, 138 km/h) at 5,000 ft (1,525 m)
- Endurance: 4 hours
- Service ceiling: 11,500 ft (3,506 m)
- Climb to 6,000 ft (1,830 m): 11 min 50 s
- Climb to 10,000 ft (3,050 m): 27 min 10 s
- Aircraft of comparable role, configuration and era
- Bruce 1969, pp. 123-4.
- Bruce 1969, pp. 124–125.
- Williams and Gustin 2003, pp. 85, 93.
- Mason 1992, pp. 107–8.
- Bruce 1969, p. 125.
- Flight of 12 June 1919 reports the aircraft crashed on the way to Martlesham Heath in May 1917
|Wikimedia Commons has media related to Vickers F.B.25.|
- Bruce, J. M. War Planes of the First World War:Volume Three Fighters. London:Macdonald, 1969. ISBN 0-356-01490-8.
- Mason, Francis K. The British Fighter since 1912. Annapolis, Maryland, USA:Naval Institute Press, 1992. ISBN 1-55750-082-7.
- Williams, Anthony G. and Gustin, Emmanuel. Flying Guns: World War I and its Aftermath 1914-32. Ramsbury, UK:Airlife, 2003. ISBN 1-84037-396-2.