Boulton Paul Bittern
|Manufacturer||Boulton Paul Limited|
|First flight||February 1927|
Design and development
Designed to Air Ministry Specification 27/24, which called for a single-seat night fighter for use against enemy bomber aircraft, the Bittern design was unusual for its time in that it was a twin-engined shoulder wing monoplane rather than a single-engine biplane.
Two prototypes were built, both very underpowered. As a result, during testing performance was so poor that further development was abandoned.
The first prototype had fixed .303 in (7.7 mm) Vickers machine guns, the second had guns that could be angled from 0-45° upwards so the fighter could attack bombers from below without having to put the aircraft into a climb. The wingspan of the second prototype was increased by about 5 ft (1.5 m).
Specifications (P.31 Bittern J7936)
Data from Boulton Paul Aircraft since 1915
- Length: 32 ft 4 in (9.86 m) 
- Wingspan: 41 ft 0 in (12.50 m)
- Empty weight: 3,215 lb (1,458 kg)
- Gross weight: 4,500 lb (2,041 kg)
- Powerplant: 2 × Armstrong Siddeley Lynx 7-cyl. air-cooled radial piston engine, 230 hp (170 kW) each
- Maximum speed: 145 mph (233 km/h; 126 kn) (J7936) 152 mph (245 km/h) (J7937)
- Endurance: 3¾ hours
- 2 x fixed forward-firing 0.303 in (7.70 mm) Vickers machine-guns (J7936)
- 2 x two 0.303 in (7.70 mm) Lewis machine-guns in revolving barbettes either side of the nose (J7937).
- Night landing flares under the fuselage
- Donald, David, ed. (1997). The Encyclopedia of World Aircraft. Prospero Books. p. 118. ISBN 1-85605-375-X.
- Boulton-Paul P.31 Bittern - night fighter
- The WWII Fighter Gun Debate: Upward firing guns
- Brew, Alec (1993). Boulton Paul Aircraft since 1915. Putnam & Company Ltd. pp. 199–203. ISBN 0-85177-860-7.
- Mason, Francis K. (17 Sep 1992)). The British Fighter since 1912 (1st edition ed.). London: Putnam ; Language English. p. 187. ISBN 0-85177-852-6.