|
The Airco DH.9A was a British single-engined light bomber designed and first used shortly before the end of the First World War. It was a development of the unsuccessful Airco DH.9 bomber, with a strengthened structure, and crucially, replacing the underpowered and unreliable Siddeley Puma engine of the DH.9 with the American Liberty engine. Colloquially known as the "Ninak" (from the phonetic alphabet treatment of designation "nine-A"), it served on in large numbers for the Royal Air Force following the end of the war, both at home and overseas, where it was used for colonial policing in the Middle East, finally being retired in 1931. Over 2,400 examples of an unlicensed version, the Polikarpov R-1 was also built in the Soviet Union, the type serving as the standard Soviet light bomber and reconnaissance aircraft through the 1920s. ==Design and development== The DH.9A was planned as an improved version of the existing Airco DH.9. The DH.9 was a disappointment owing to its underpowered and unreliable engines, and the DH.9A was planned to use much more powerful engines to resolve this. As the Rolls-Royce Eagle engine used in the successful DH.4 was unavailable in sufficient quantities, the new 400 hp (298 kW) American Liberty engine was chosen instead. As Airco was busy developing the Airco DH.10 twin-engined bomber, detailed design was carried out by Westland Aircraft. The DH.9 was fitted with new, longer span wings, and a strengthened fuselage structure.〔Jackson 1987, p. 107.〕 The first prototype flew in March 1918, powered by a Rolls-Royce Eagle as no Liberty engines were yet available.〔Bruce 25 May 1956, p. 643.〕 The prototype proved successful, with the first Liberty-engined DH.9A flying on 19 April 1918, and deliveries to the Royal Air Force starting in June.〔Bruce 25 May 1956, p. 644.〕 By the end of the war, a total of 2,250 DH.9As had been ordered, with 885 being built by the end of the year. As it was decided that the DH.9A would be a standard type in the postwar RAF, the majority of outstanding orders were fulfilled, with 1,730 being built under the wartime contracts before production ceased in 1919. While the existing aircraft were subject to a programme of refurbishment, a number of small contracts were placed for new production of DH.9As in 1925–26. These contracts resulted in a further 268 DH.9As being built. The new production and refurbished aircraft included batches of dual control trainers and six experimental aircraft powered by 465 hp Napier Lion engines, which reached a maximum speed of 144 mph. The Soviet Union built large numbers of an unlicenced copy of the DH.9A, the R-1. After the production of 20 DH.4 copies, followed by about 200 copies of the DH.9 powered by the Mercedes D.IV engine (also designated the R-1) and a further 130 powered by the Siddeley Puma (designated R-2), a copy of the DH.9A, powered by the M-5 engine, a Soviet copy of the DH.9A's Liberty entered production in 1924.〔Alexandrov and Petrov 1998, pp. 55–56.〕 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「Airco DH.9A」の詳細全文を読む スポンサード リンク
|