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The Armstrong Whitworth F.K.8 was a British two-seat general-purpose biplane built by Armstrong Whitworth during the First World War. The type served alongside the better known R.E.8 until the end of the war, at which point 694 F.K.8s remained on RAF charge. ==Design and development== The aircraft, originally designated the F.K.7, was designed by Dutch aircraft designer Frederick Koolhoven as a replacement for the Royal Aircraft Factory B.E.2c and the Armstrong Whitworth F.K.3. It was a sturdier aircraft than the F.K.3, with a larger fuselage and wings, and was powered by a 160 hp (110 kW) Beardmore water-cooled engine.〔Bruce 1982, pp.100-101.〕 The undercarriage used oleo shock absorbers and the observer was equipped with a Scarff ring mounting for a .303 in (7.7 mm) Lewis machine gun. No armament was initially provided for the pilot. The rudder featured a long, pointed horn-balance.〔Bruce 1982, pp. 100–101.〕 The type was fitted with very basic dual controls, enabling the observer to control the aircraft in the event of the pilot becoming incapacitated by enemy action.〔Munson 1967, p. 31.〕 The first example, ''A411'', flew in May 1916 and was delivered to the Royal Flying Corps' Central Flying School at Upavon on 16 June.〔 Because its rival, the Royal Aircraft Factory R.E.8 was still an unknown quantity, it was decided that 50 of the Armstrong Whitworth design, which was redesignated F.K.8., would be ordered for the RFC.〔 The production aircraft which followed were identical in most respects to ''A411'', with the addition of a forward-firing .303 in (7.7 mm) Vickers machine gun to port of and slightly behind the engine. The Armstrong Whitworth gun synchronising mechanism was incomplete at the time the first example ''A2636'' had arrived in France and some early production F.K.8s may have used the Arsiad interrupter gear instead. The Armstrong Whitworth mechanism (like other early mechanical synchronising systems) proved unreliable and was later replaced by the Constantinescu gear.〔Bruce 1982, p. 101.〕 From the fifth production aircraft the rudder balance was shortened and the shape of the vertical tailfin was modified.〔Bruce 1982, p. 102.〕 F.K.8s had teething troubles, the oleo undercarriage was unable to withstand rough use on the frontline airfields, tailskids frequently broke and the original radiators blocked up quickly.〔 Following instructions issued on 30 April 1917, some F.K.8s were refitted with simplified vee-undercarriages from Bristol F.2 Fighters. This soon led to a temporary shortage of these undercarriages and the practice had to be discontinued until May 1918, after which several F.K.8s were fitted with revised undercarriages.〔Bruce 1982, pp. 102–103.〕 Most production F.K.8s had modifications to the wings, gunner's seat and the exhaust system. The tall inverted vee radiators incorporated improved tubes which reduced the blockages. On later aircraft the nose cowling was redesigned.,〔Bruce 1982, p. 103.〕 and smaller box radiators were standardised. In service the F.K.8 (nicknamed the "Big Ack") proved to be effective and dependable, being used for reconnaissance, artillery spotting, ground-attack, contact-patrol and day and night bombing.〔 It was reputedly easier to fly than the R.E.8, and was sturdier, but its performance was even more pedestrian, and it shared the inherent stability of the Royal Aircraft Factory types. While the pilot and observer were placed reasonably close together, communication between the two lacked the "tap on the shoulder" intimacy of the Bristol Fighter, or for that matter, the R.E.8. The F.K.13 seems to have been the designation of a reconnaissance version of the F.K.8 but it may have been a project.〔Bruce, J. M. ("Letter from J.M.Bruce to ''Flight'', 15 May 1953, p. 612." ) ''flightglobal.com'', 15 May 1953. Retrieved: 7 December 2009.〕 A total of 1,650 were built. 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「Armstrong Whitworth F.K.8」の詳細全文を読む スポンサード リンク
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