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The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner. Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was the company's first high-bypass-ratio turbofan.〔Gunston 1989, p.126.〕 ==Design and development== The JT9D was developed as part of the design phase of the C-5 Galaxy. A contract was awarded to Pratt & Whitney to study the type of large engine needed, but the production contract was eventually awarded to General Electric and their TF39 turbofan. The JT9D was, however, chosen by Boeing to power the 747, with that aircraft's first flight taking place on 9 February 1969. Flight testing of the engine had begun in June 1968, using a Boeing B-52E as a testbed. The JT9D-3, which entered service in 1970, was constructed using titanium and nickel alloys. The engine featured a single-stage fan, a three-stage low-pressure compressor and an eleven-stage high-pressure compressor coupled to a two-stage high-pressure turbine and four-stage low-pressure turbine. This version of the JT9D weighed and produced thrust. Production ceased in 1990. JT9D engines powering USAF E-4A airborne command posts were designated Pratt & Whitney F105. Pratt & Whitney's designated successor to the JT9D family is the PW4000, which features fewer parts, greater reliability, and lower base selling price. 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「Pratt & Whitney JT9D」の詳細全文を読む スポンサード リンク
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