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The Hawker Hart was a British two-seater biplane light bomber aircraft of the Royal Air Force (RAF). It was designed during the 1920s by Sydney Camm and manufactured by Hawker Aircraft. The Hart was a prominent British aircraft in the inter-war period, but was obsolete and already side-lined for newer monoplane aircraft designs by the start of the Second World War, playing only minor roles in the conflict before being retired. Several major variants of the Hart were developed, including a navalised version for the Royal Navy's aircraft carriers. Beyond Britain, the Hart would be operated by a number of foreign nations, including Sweden, Yugoslavia, Estonia, South Africa, and Canada. ==Design and development== In 1926, the Air Ministry stated a requirement for a two-seat high-performance light day-bomber, to be of all-metal construction and with a maximum speed of 160 mph (258 km/h). Designs were tendered by Hawker, Avro and de Havilland.〔Lewis 1974, p. 146.〕 Fairey, who had sold a squadron's worth of its wooden Fox bomber in 1925, was not at first invited to tender to the specification, and was only sent a copy of the specification after protesting to the Chief of the Air Staff, Hugh Trenchard.〔Jarrett ''Aeroplane Monthly'' May 1995, p. 13.〕〔Taylor 1974, p. 196.〕 Hawker's design was a single-bay biplane powered by a Rolls-Royce F.XI water-cooled V12 engine (the engine that later became known as the Rolls-Royce Kestrel). It had, as the specification required, a metal structure, with a fuselage structure of steel-tube covered by aluminium panels and fabric, with the wings having steel spars and duralumin ribs, covered in fabric. The crew of two sat in individual tandem cockpits, with the pilot sitting under the wing trailing edge, and operating a single .303 in (7.7 mm) Vickers machine gun mounted on the port side of the cockpit. The observer sat behind the pilot, and was armed with a single Lewis gun on a ring mount, while for bomb-aiming, he lay prone under the pilot's seat.〔Jarrett ''Aeroplane Monthly'' June 1995, pp. 30–32.〕 Up to 520 pounds (240 kg) of bombs could be carried under the aircraft's wings.〔Mason 1991, p. 170.〕 ''J9052'', the prototype Hart, first flew in June 1928, being delivered to the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath on 8 September. It demonstrated good performance and handling, reaching 176 mph (283 km/h) in level flight and in a vertical dive.〔Jarrett ''Aeroplane Monthly'' May 1995, p. 14.〕〔Mason 1994, p. 205.〕 The competition culminated in the choice of the Hawker Hart in April 1929. The de Havilland Hound was rejected due to handling problems during landing and because of its part-wooden primary structure. While the Avro Antelope demonstrated similar performance and good handling, the Hart was preferred as it was far cheaper to maintain, a vital aspect to a programme during defence budget constraints that the British armed forces faced during the 1920s. The Fairey Fox IIM (which despite the name was effectively an all-new aircraft), delayed by Fairey's late start on the design compared to the other competitors, only flew for the first time on 25 October 1929, long after the Hart had been selected.〔 A total of 992 aircraft were built as Harts.〔 It became the most widely used light bomber of its time and the design would prove to be a successful one with a number of derivatives, including the Hawker Hind and Hector, being made. There were a number of Hart variants made, though only slight alterations were made. The Hart India was a tropicalised version of the aircraft; the Hart Special was a tropicalised Hawker Audax, a Hart variant, with desert equipment; a specialised Hart Trainer was also built which dispensed with the gunner's ring. Vickers built 114 of the latter model at Weybridge between 1931 and June 1936.〔Lewis 1974, pp. 176, 233.〕 The production Hart day bomber had a single 525 hp (390 kW) Rolls-Royce Kestrel IB 12-cylinder V-type engine; a speed of 184 mph (296 km/h) and a range of 470 mi (757 km).〔 It was faster than most contemporary fighters, an astonishing achievement considering it was a light bomber, and had high manoeuvrability, making the Hart one of the most effective biplane bombers ever produced for the Royal Air Force. In particular, it was faster than the Bristol Bulldog, which had recently entered service as the RAF's front line fighter. This disparity in performance led the RAF to gradually replace the Bulldog with the Hawker Fury.〔Lewis 1974, p. 176.〕 Demand was such that production was spread out among a wide selection of aircraft companies. Of the 962 built in the United Kingdom, Hawker produced 234, Armstrong Whitworth 456, Gloster 46, Vickers 226, and 42 were produced in Sweden under licence by ASJA who built 18, Götaverken who built 3, and the Central Workshops of the Air Force (CVM) who built 21.〔("Hawker Hart." ) ''aeroflight.co.'' Retrieved: 4 December 2012.〕 1004 Harts were produced.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hawker Hart」の詳細全文を読む スポンサード リンク
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