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The Northrop/McDonnell Douglas YF-23 was an American single-seat, twin-engine stealth fighter aircraft technology demonstrator designed for the United States Air Force (USAF). The design was a finalist in the USAF's Advanced Tactical Fighter (ATF) competition, battling the Lockheed YF-22 for a production contract. Two YF-23 prototypes were built with the nicknames "Black Widow II" and "Gray Ghost". In the 1980s, the USAF began looking for a replacement for its fighter aircraft, especially to counter the USSR's advanced Sukhoi Su-27 and Mikoyan MiG-29. Several companies submitted design proposals; the USAF selected proposals from Northrop and Lockheed. Northrop teamed with McDonnell Douglas to develop the YF-23, while Lockheed, Boeing and General Dynamics developed the YF-22. The YF-23 was stealthier and faster, but less agile than its competitor. After a four-year development and evaluation process, the YF-22 was announced the winner in 1991 and entered production as the Lockheed Martin F-22 Raptor. The U.S. Navy considered using the production version of the ATF as the basis for a replacement to the F-14, but these plans were later canceled. The two YF-23 prototypes were museum exhibits as of 2009.〔〔 ==Development== American reconnaissance satellites first spotted the advanced Soviet Su-27 and MiG-29 fighter prototypes in 1978, which caused concern in the U.S. Both Soviet models were expected to reduce the maneuverability advantage of contemporary US fighter aircraft.〔Rich, Michael and William Stanley. (''Improving U.S. Air Force Readiness and Sustainability'' ). Rand Publications, April 1984. p. 7.〕 In 1981, the USAF requested information from several aerospace companies on possible features for an Advanced Tactical Fighter (ATF) to replace the F-15 Eagle. After discussions with aerospace companies, the USAF made air-to-air combat the primary role for the ATF.〔Sweetman 1991, pp. 10–13.〕 The ATF was to take advantage of emerging technologies, including composite materials, lightweight alloys, advanced flight-control systems, more powerful propulsion systems, and stealth technology.〔 In October 1985, the USAF issued a request for proposal (RFP) to several aircraft manufacturers. The RFP was modified in May 1986 to include evaluation of prototype air vehicles from the two finalists. At the same time, the U.S. Navy, under the Navalized Advanced Tactical Fighter (NATF) program, announced that it would use a derivative of the ATF winner to replace its F-14 Tomcat. The NATF program called for procurement of 546 aircraft along with the USAF's planned procurement of 750 aircraft.〔Williams 2002, p. 5.〕 In July 1986, proposals were submitted by Lockheed, Boeing, General Dynamics, McDonnell Douglas, Northrop, Grumman and Rockwell. The latter two dropped out of competition shortly thereafter.〔Miller 2005, pp. 13–14, 19.〕 Following proposal submissions, Lockheed, Boeing, and General Dynamics formed a team to develop whichever of their proposed designs was selected, if any. Northrop and McDonnell Douglas formed a team with a similar agreement.〔Goodall 1992, p. 94.〕 The Lockheed and Northrop proposals were selected as finalists on 31 October 1986. Both teams were given 50 months to build and flight-test their prototypes, and they were successful, producing the Lockheed YF-22 and the Northrop YF-23.〔Jenkins and Landis 2008, pp. 233–34.〕 The YF-23 was designed to meet USAF requirements for survivability, supercruise, stealth, and ease of maintenance.〔("ATF procurement launches new era" ). ''Flight International'', 15 November 1986. p. 10. Retrieved 25 June 2011.〕 Supercruise requirements called for prolonged supersonic flight without the use of afterburners.〔Goodall 1992, p. 91.〕 Northrop drew on its experience with the B-2 Spirit and F/A-18 Hornet to reduce the model's susceptibility to radar and infrared detection.〔Winchester 2005, pp. 198–99.〕 The USAF initially required the aircraft to land and stop within , which meant the use of thrust reversers on their engines. In 1987, the USAF changed the runway length requirement to , so thrust reversers were no longer needed. This allowed the aircraft to have smaller engine nacelle housings. The nacelles were not downsized on the prototypes.〔Miller 2005, p. 23.〕〔Sweetman 1991, pp. 23, 43.〕 The first YF-23 (serial number ''87-0800''), Prototype Air Vehicle 1 (PAV-1), was rolled out on 22 June 1990;〔("YF-23 roll out marks ATF debut." ) ''Flight International'', 27 June – 3 July 1990. p. 5. Retrieved 24 June 2011.〕 PAV-1 took its 50-minute maiden flight on 27 August with Alfred "Paul" Metz at the controls.〔Goodall 1992, p. 99.〕 The second YF-23 (serial number ''87-0801'', PAV-2) made its first flight on 26 October, piloted by Jim Sandberg.〔 The first YF-23 was painted charcoal gray and was nicknamed "Spider"〔 and "Black Widow II", the latter after the Northrop P-61 Black Widow of World War II. It briefly had a red hourglass marking resembling the marking on the underside of the black widow spider before Northrop management had it removed.〔Goodall 1992, p. 120.〕〔Miller 2005, p. 37.〕 The second prototype was painted in two shades of gray and nicknamed "Gray Ghost".〔Pace 1999, p. 50c.〕 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「Northrop YF-23」の詳細全文を読む スポンサード リンク
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