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The Polikarpov I-5 was a single-seat biplane which became the primary Soviet fighter between its introduction in 1931 through 1936, after which it became the standard advanced trainer. Following Operation Barbarossa, which destroyed much of the Soviet Air Forces (VVS), surviving I-5s were equipped with four machine guns and bomb racks and pressed into service as light ground-attack aircraft and night bombers in 1941. They were retired in early 1942 as Soviet aircraft production began to recover and modern ground-attack aircraft like the Ilyushin Il-2 became available. ==Development== The 1928 Five-Year Plan ordered the Tupolev design bureau to develop a mixed-construction (metal and wood/fabric) biplane fighter powered by a Bristol Jupiter VII engine with the first prototype completed by 1 September 1929. The new fighter was designated I-5 (''Istrebitel''—Fighter), but had the internal Tupolev designation of ANT-12. Concurrently, Nikolai Nikolaevich Polikarpov's group was tasked with creating a wood-construction aircraft designated as the Polikarpov I-6 to the same specification. The I-5 design, begun by Pavel Sukhoi, under the supervision of Andrei Tupolev, lagged because the Tupolev bureau was preoccupied with large bombers. As the result the I-5 and I-6 projects were unified in 1929 under Polikarpov's leadership, although neither project met its specified completion date.〔Shavrov〕 Nikolai Polikarpov was arrested by the OGPU in September 1929 for the crime of industrial sabotage for these failures and sentenced to death, although this was commuted to ten years imprisonment in a labor camp. In December 1929 the OGPU gathered a number of aircraft engineers together at Butyrka prison, including Polikarpov, and formed the Internal Prison Design Bureau (''Konstruktorskoye Byuro Vnutrenniya Tyurma''—KB VT) under the leadership of Dmitry Pavlovich Grigorovich. The KB VT was transferred to quarters on the grounds of Factory (''Zavod'') Nr. 30 in Moscow-Khodinka in early 1930.〔Gordon and Dexter, p. 4〕 Shortly afterwards Polkarpov replaced Grigorovich as the head designer when his concept for the I-5 was approved by the OGPU. The full-scale mock-up was approved on 28 March 1930 and the first prototype, designated VT-11 (''Vnutrenniya Tyurma''—Internal Prison), was completed a month later.〔Gordon and Dexter, p. 13〕 It made its first flight on 30 April 1930 and was fitted with an imported supercharged Jupiter VII. It was painted in silver with a red cheat line; a red "VT" was superimposed on the red star on the rudder. The second prototype, known as the VT-12, had a Jupiter VI engine, and took to the air on 22 May, bearing the name "Klim Voroshilov." The two prototypes also differed in minor details regarding the shape of the tail and the construction of the landing gear. All this meant a slight difference in weight and performance between the two prototypes was present, with the second being slightly heavier and faster, while the first had a slight range advantage and a higher service ceiling. The third prototype, designated as the VT-13 and inscribed with "A Gift for the XVIth Congress of the Party", was powered by a Soviet-built M-15 engine with a NACA cowling, but this proved to be unreliable and was not put into production.〔 The second prototype passed its State acceptance trials on 13 August 1931 and was ordered into production a month later on 13 September. One problem noted during the trials was a tendency to make an uncontrolled 180° turn when landing in light winds. Shortening the landing gear by and moving them cured the problem. The engineer who suggest the change was awarded the Order of the Red Star for his ingenuity. Ten pre-production aircraft had already been ordered and they were assembled between August and October. They all had imported engines fitted, but trialled various small improvements for the production aircraft that included cooling vents for the crankcase, introduction of a pitot tube and static vent in the starboard upper wing, a faired headrest for the pilot, and a metal propeller whose pitch could be adjusted on the ground.〔Gordon and Dexter, pp. 13, 16, 20〕 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「Polikarpov I-5」の詳細全文を読む スポンサード リンク
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