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The Platt-LePage XR-1, also known by the company designation PL-3,〔Francillon 1990, p.49.〕 was an early American twin-rotor helicopter, built by the Platt-LePage Aircraft Company of Eddystone, Pennsylvania. The winner of a United States Army Air Corps design competition held in early 1940, the XR-1 was the first helicopter tested by the USAAF, flying in 1941. The flight testing of the XR-1 proved troublesome, and although continued testing showed that the design had promise, other, improved helicopters were becoming available before the XR-1 was ready for service. As a result, the development of the aircraft was terminated in 1945. ==Design and development== Developed during 1939 from an earlier, unsuccessful design, the PL-1,〔Charnov 2003, p.171.〕 the Platt-LePage Model PL-3 was the winner of a 1940 design competition, held under the terms of the Dorsey-Logan Act, for the supply of a helicopter design to the United States Army Air Corps.〔Leishman 2006, p.32.〕 Platt-LePage's submission was judged by the Army to be superior to its competitors, which included a helicopter submitted by Vought-Sikorsky, and autogyros developed by Kellett and Pitcairn. 〔 Following the selection of the Platt-LePage design in May 1940, a contract for the construction of a prototype and a static test airframe was issued in July of that year.〔 The contract specified delivery of the flying prototype in January 1941, however the aircraft was not completed until three months later than the contract schedule,〔 a delay that led to Sikorsky receiving Dorsey-Logan Act funding for development of its design, which became the XR-4.〔Pattillo 2000, p.142.〕 In its design, the XR-1 bore a strong resemblance to the Focke-Wulf Fw 61, a helicopter developed by Henrich Focke in Germany that, flown by Hanna Reitsch, had impressed Platt-LePage co-founder Wynn LePage during a tour of Europe.〔Francillon 1990, p.48.〕 The XR-1 was powered by a Pratt & Whitney R-985 radial engine, mounted in a buried installation within the fuselage.〔 The aircraft had two, three-bladed rotors, mounted in a side-by-side arrangement on wing-like pylons.〔 The pylons were aerodynamically designed to produce some lift when in forwards flight, slightly unloading the rotors.〔Connor and Lee 2000〕 The construction of the XR-1 was conventional by the standards of the time, with the aircraft's frame consisting of a steel-tube framework, which was covered with fabric.〔 The XR-1 had tail surfaces similar to those of a conventional aircraft, and was equipped with a fixed, taildragger landing gear.〔 The aircraft's wheels freely castered for easier maneuvering on the ground.〔 The cockpit of the XR-1 seated the aircraft's two crew members in a tandem arrangement, the pilot located ahead of the observer, and was extensively glazed to provide good visibility in the aircraft's intended observation and army co-operation role.〔 During the development of the aircraft, Major General Robert M. Danford proposed to the War Department that the XR-1 be evaluated against the Stinson YO-54 and the Kellett YG-1B autogyro.〔Raines 2002, p.42.〕 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「Platt-LePage XR-1」の詳細全文を読む スポンサード リンク
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