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The Saunders-Roe A.36 Lerwick was a British flying boat built by Saunders-Roe Limited (Saro). It was intended to be used with the Short Sunderland in Royal Air Force Coastal Command but it was a flawed design and only a small number were built. They had a poor service record and a high accident rate; of 21 aircraft, 10 were lost to accidents and one for an unknown reason. ==Design and development== Air Ministry Specification R.1/36 (to meet Operational Requirement 32) was issued in March 1936 to several companies that had experience in building flying boats.〔Buttler p. 236〕 The specification was for a medium-range flying boat for anti-submarine, convoy escort and reconnaissance duties to replace the Royal Air Force's biplane flying boats such as the Saro London and Supermarine Stranraer. The specification called for a cruise speed of and a weight of no more than .〔Buttler p. 136〕 Designs were tendered by Saunders-Roe (S.36), Supermarine (Type 314), Blackburn Aircraft (b. 20) and Shorts. The Blackburn B.20 was a radical design that offered much better performance, by reducing the drag associated with a flying boat hull and so a prototype was ordered to test the concept. Of the other designs the Supermarine was the first choice with Saro and Shorts tied in second place. The Supermarine was ordered "off the drawing board" i. e. without requiring prototypes to be produced and flown first. Supermarine's commitment to the Spitfire meant that work was not expected to start for two years and so the Ministry looked to the other designs. Saunders-Roe had redesigned the S.36 in the meantime—replacing low hull and gull wing with a deep body and high wing—and the Supermarine order was transferred to the S.36.〔Buttler p. 137〕 The contract was issued in June 1937 to buy 21 of the S.36, receiving the service name Lerwick (after the town of Lerwick). The aircraft was a compact twin-engined, high-winged monoplane of all-metal construction. The Lerwick was of all-metal construction, with a conventional flying boat hull, a planing bottom and two stabilising floats, carried under the wings on long struts. It was powered by two Bristol Hercules radial engines and initially had twin fins and rudders. For defence, the Lerwick was equipped with three powered gun turrets. The nose turret had a single 0.303 inch Vickers K gun; the other two had 0.303 Browning machine guns, two guns in the Nash & Thomson FN.8 turret in the dorsal position and four in the Nash & Thomson FN4.A turret at the tail.〔London 2003, p. 172.〕 Offensive weapons were a total of of bombs or depth charges – four or eight bombs, or four depth charges, carried in two streamlined nacelles behind the engines, similar to the Martin PBM Mariner.〔Buttler p. 145〕〔London 2003, p. 173.〕 The first three aircraft were used as prototypes, with the first being launched on 31 October 1938, after numerous delays during design and construction. The Lerwick was immediately found to be unstable in the air, on the water and not suited to "hands off" flying. The latter was a major problem in an aircraft designed for long-range patrols. Numerous adjustments, including the addition of a greatly enlarged single fin and an increase in the wing angle of incidence, failed to remedy its undesirable characteristics, which included a vicious stall and unsatisfactory rates of roll and yaw.〔Bowyer 1991, p. 149.〕 In service, several aircraft were lost because of wing floats breaking off, suggesting this was a structural weakness. Persistent problems with the hydraulics resulted in bomb doors sometimes dropping open during flight.〔London 2003, p. 185.〕 On one engine the Lerwick could not maintain height, nor could it maintain a constant heading, as the controls could not counter the torque of one engine on maximum power.〔London 2003, p. 183.〕 An engine failure would inevitably see the aircraft flying in slowly descending circles. On one occasion, the loss of an engine forced a Lerwick to make an emergency landing in the Caledonian Canal. The aircraft was then towed to Oban at the end of a string of coal barges.〔(【引用サイトリンク】url=http://www.georgian.net/422sqdrn/18.htm ) 〕 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「Saro Lerwick」の詳細全文を読む スポンサード リンク
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