Boulton & Paul P31 Bittern
The Bittern, designed to meet the requirements of Specification 27/24 for a night fighter, was one of the earliest single-seat twin-engined fighter monoplanes and was intended as a bomber formation interceptor. Powered by two 230hp Armstrong Siddeley Lynx seven-cylinder radials, the first of two Bittern prototypes was flown in 1927, with shoulder-mounted wings carrying mid-set uncowled engines. Armament was two fixed forward-firing 7.7mm Vickers guns in the sides of the forward fuselage.
The second prototype differed with a redesigned wing of constant chord and thickness, overall span being increased by approximately 1.52m and the leading edge carrying Handley Page slots. Six pairs of V-type struts braced the outer wings to the engine nacelles and fuselage. Townend cowling rings were fitted to the engines which were lowered on the wings. In place of the fixed Vickers, two Lewis guns of similar calibre were mounted in barbettes on the fuselage sides forward and below the wing leading edge. These enabled the weapons to be elevated between 0° and 45°. Interconnected with a ring sight attached to an elevating hoop pivoted at the cockpit sides, the guns had no traverse, but their arrangement enabled bombers to be attacked from below. Although advanced in concept, the Bittern was seriously underpowered, with inadequate performance and its development was abandoned.
Engines: 2 x 230hp Armstrong Siddeley Lynx
Take-off weight: 2041 kg / 4500 lb
Wingspan: 12.5 m / 41 ft 0 in
Length: 9.75 m / 31 ft 12 in
Max. speed: 233 km/h / 145 mph