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Aviation History
1990
1990 - 2544.PDF
H EADLINES YF-22 ATF prototype set for maiden flight BY JOHN BAILEY IN LOS ANGELES The Lockheed/Boeing/Gen eral Dynamics YF-22 Ad vanced Tactical Fighter (ATF) prototype, publicly unveiled for the first time on 29 August, could be ready to fly by the end of next week. The aircraft, revealed just two days after the first flight of the rival Northrop/McDonnell Douglas YF-23, had already- completed more than 90% of its engine ground runs before the roll out ceremony, and will begin taxi tests this week. Although US Air Force pro gramme director Brig Gen James Fain refuses to speculate on when the first YF-22 will be flight-ready, Lockheed chief test pilot Dave Ferguson says that the aircraft could fly within two weeks of the rollout, barring any unforeseen problems identi fied during taxi trials. The Lockheed team is anx ious to make up time lost to the rival YF-23 contender, and to make use of the time remaining before the December deadline for presentation of final propos als to the Air Force. The YF-23 maiden flight had been expected two weeks ago but the aircraft developed a shimmy in the nose landing gear during high-speed taxi tests, a problem eventually solved with the installation of a mass damper. The two Pratt & Whitney F119 engines were operated at military power setting, without afterburner, throughout the 50- min (light, hut on elunhout Lockheed's YF-22 (above): smaller and more angular than Northrop's YF-23 from Edwards AFB, the F-15 and F-16 chase planes had to apply afterburner to keep up with the aircraft, even with its gear down. The gear was even tually raised and the aircraft reached 290kt (536km/h) and around 25,000ft (7,000m). To demonstrate handling qualities, the YF-23 flew a series of turns in tight formation with the F-16 chase plane. The appearance ol the YF-22. the first GE-powered prototype, was delayed for almost two months by vibration problems with the aircraft's thrust- vectoring system. This has now been cured, and the second, Pratt & Whitney-powered, pro totype is expected to fly about two weeks after the first aircraft. The aircraft revealed at Palmdale, California, last week is substantially different in ap pearance to the rival YF-23, Lockheed YF-22A '- ^wvlfjusrt'X Piclishmiitiroi.a £'.££•£>•' demonstrating an alternative starting point and approach to meeting the same requirement. The aircraft is 19.5m long, 5.4m high, and the large, trape zoidal wing has a span of 13.1m. The wing is fitted with almost full-span leading-edge slats, and two smaller traiiing- edge control surfaces. Two large, fixed trapezoidai tail sur faces are inclined at approxi mately 30° from the vertical, and the forward fuselage has a rhomboidal cross-section. The large, rectangular engine inlets are located outboard of the engines, providing an S- shaped inlet which screens the front compressor blades from forward view. The inlets are sharply inclined at the same angles as the twin tails and there is a narrow, rectangular boundary-layer bleed inlet lo cated between the engine inlets and the fuselage. Low-observable features of the aircraft include the now- familiar blended curves and smooth surface finish, together with some faceting around the edges of the landing-gear doors and maintenance access panels, as well as the rectangular mis sile bay doors located along the side of the engine inlets. Fain reiterates that ATF will be a winner-takes-all pro gramme, despite the risk of one or more of losing team members leaving the military aircraft or engine business. He says that there is no prospect of the US Navy choosing a different team to develop its carrier-based ver sion of the aircraft, and adds: "There is no attempt to have the loser participate in any aspect of the ATF production pro gramme" . Final full-scale development proposals from the two teams will be presented at the end of December and the Air Force, in consultation with the Navy, will announce the winner on April 30 next year. Lockheed chair man Dan Tellep, acknowledging that ATF is "important for our future growth", insists that the loss of the programme "... is not make or break for Lockheed's aircraft activities". • 34 FLIGHT INTERNATIONAL 5-11 September 1990
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