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Aviation History
1997
1997 - 0929.PDF
mm/mm Work on this carrier-capable F~22 (above) ended when the US Navy lost interest in the Naval ATE Lockheed's earliest ATF concepts fright) owed much to its then-secret ¥-111 stealth fighter inance. Crucially, the team was able to use these laboratories to validate its software algorithms for sensor fusion, the key to its concept for the F- 22 "pilot-vehicle interface". Development bids were submitted in December 1990, after both teams had flown pro totypes powered by the rival Pratt & Whitney YF119 and General Electric YF120 engines. All four engine/airframe combinations met the ATF requirement, but in April 1991 the Air Force selected the Fl 19-powered F-22, saying that it offered better capability at lower cost and with lesser risk. The Lockheed/Boeing/GD team was award ed a $9.55 billion contract for F-22 engineering and manufacturing development (EMD) in August 1991, while P&W received a separate, $ 1.4 billion contract to develop the F119. At that time, 11 flight-test aircraft were planned, includ ing two F-2 2 B two-seaters. Today, nine develop ment aircraft are being built, all single-seat F-22 As, while the Air Force production require ment has been cut from 648 F-22 A/Bs to 438 air craft, all single seaters. CHANGING REQUIREMENT The original ATF requirement was for 750 air craft, and die US Navy at one time was interest ed in 550 Naval ATF variants. The Navy dropped its interest before EMD award, to con centrate on the General Dynamics/McDonnell Douglas A-12 Avenger II Advanced Tactical Aircraft. After cancellation of the troubled A-12 programme, a derivative of the F-22 was pro posed to meet the Navy's A/F-X requirement, but this was ultimately cancelled. Flight testing of the YF119-powered YF-22 was resumed in October 1991, to gather addi tional loads and environment data for use in design of the F-22. Flight testing continued until April 1992, when the aircraft was damaged in an accident. The YF-22 had been flown for just over lOOh when it crashed. Although no longer flightworthy, the damaged prototype was modi fied to represent the production F-22, and the aircraft is being used as a pole model to test antenna performance. The first of a series of schedule changes came in January 1993, when budget cuts forced the programme to be rephased. This reduced the number of development aircraft from 11 to nine, still including two F-22B tandem-seat trainers, and the number of Fl 19 flight-test engines from 33 to27. Development of die two-seater was for mally deferred by the Air Force in July 1996, to save money, but the number of development and production aircraft remained unchanged. In January 1997, the programme was again restructured, leading to the cancellation of four pre-production verification (PPV) F-22s, which had been intended to bridge the gap between development and low-rate initial production (LRIP) aircraft. This reduced the number of planned production F-22s to 438. At the same The Northrop/McDonnell Douglas YF-23 was dramatically different - and ultimately unsuccessful time, LRIP was stretched from four to five years and the number of aircraft to be produced during this phase reduced to 70. The PPV aircraft were to have been used for initial operational test and evaluation. Instead the last two EMD and first two LRIP aircraft will be used. CONFIGURATION CHANGES There have been several design changes since award of the EMD contract, principally to reduce weight and radar cross-section (RCS). In March 1994 it was announced that the F-22's RCS was not meeting die specification, largely as a result of fitting doors and panels on the under side of the aircraft to provide maintenance access. The problem was uncovered by using new computer-modelling tools and was overcome by combining access panels and reducing the num ber of drain holes on the bottom of the aircraft. Lockheed Martin began testing a full-scale pole model of the F-22 at its Helendale, California, RCS test-range in November 1996. Programme general-manager Tom Burbage says that results show that the aircraft is meeting or exceeding its radar-signature specification. In April 1995, the Lockheed Martin/Boeing team was awarded a 24-month Air Force con tract to explore derivatives of the F-22. The study was later curtailed, after the team had looked at missions such as precision strike, electronic reconnaissance and suppression of enemy air- defences. Burbage still anticipatess F-22 deriva tives will emerge once production is under way. He believes die F-22, with its stealth and preci sion, is the only aircraft that can perform the deep-targeting mission for long-range missiles, such as those to be carried by the Navy's planned Arsenal Ship. There is also the potential for development of export derivatives on the F-2 2. Several countries have been briefed on the aircraft, but no licence to sell the aircraft has yet been granted. Israel and South Korea are thought to be among the coun tries most interested in the F-22. Lockheed Martin/Boeing believes that export sales of 12 F- 22s annually, in addition to the 48 aircraft a year now planned for the L"S Air Force, could sub stantially reduce production costs. J A FLIGHT INTERNATIONAL SUPPLEMENT
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