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The Lockheed Martin/Boeing F-22 Raptor is an American twin-engine all-weather stealth fighter aircraft developed and produced for the United States Air Force (USAF). As a product of the USAF's Advanced Tactical Fighter (ATF) program the aircraft was designed as an air superiority fighter, but also incorporates ground attack, electronic warfare, and signals intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while program partner Boeing provided the wings, aft fuselage, avionics integration, and training systems. The F-22 descended from the Lockheed YF-22 and first flew in 1997, and was variously designated F-22 and F/A-22 before it formally entered service in December 2005 as the F-22A. Although the USAF had originally planned to buy a total of 750 ATFs and later scaled down to 381, the program was cut to 195 aircraft — 187 of them operational models — in 2009 due to political opposition from high costs, a lack of air-to-air missions at the time of production, and the development of the more affordable and versatile F-35. The last aircraft was delivered in 2012. After a protracted development and initial operational difficulties, the F-22 became a critical component of the USAF's tactical airpower for air-to-air missions against peer adversaries. While designed for counter-air operations, the aircraft has also performed strike and electronic support missions in the Middle East against the Islamic State and Assad-aligned forces. The F-22 will remain a cornerstone of the USAF's fighter fleet until its succession by the crewed Next Generation Air Dominance fighter. Development Origins The F-22 originated from the Advanced Tactical Fighter (ATF) program that the U.S. Air Force initiated in 1981 to replace the F-15 Eagle and F-16 Fighting Falcon. Although the F-15 and F-16 had only recently entered service, intelligence reports indicated that their effectiveness would be quickly eroded by emerging worldwide threats emanating from the Soviet Union, including new developments in surface-to-air missile systems for integrated air defense networks, the introduction of the Beriev A-50 "Mainstay" airborne warning and control system (AWACS), and the proliferation of the Sukhoi Su-27 "Flanker"- and Mikoyan MiG-29 "Fulcrum"-class of fighter aircraft. Initially code-named "Senior Sky", the ATF would become an air superiority fighter program influenced by these reports; in the potential scenario of a Soviet and Warsaw Pact invasion in Central Europe, the ATF was envisaged to spearhead offensive and defensive counter-air operations (OCA/DCA) in this highly contested environment that would then enable following echelons of NATO strike and attack aircraft to hit ground formations; to do so, the ATF would make an ambitious leap in capability and survivability by taking advantage of the new technologies in fighter design on the horizon, including composite materials, lightweight alloys, advanced flight control systems and avionics, more powerful propulsion systems for supersonic cruise (or supercruise) over Mach 1.5, and most importantly, stealth technology for low observability. The USAF initiated an ATF request for information (RFI) to the aerospace industry in May 1981 as well as a subsequent concept development team (CDT) for identifying requirements and managing concept and technology development. In 1983, the CDT became the ATF System Program Office (SPO) and managed the program at Wright-Patterson Air Force Base. Following a period of concept refinement and system requirements definition, the demonstration and validation (Dem/Val) request for proposals (RFP) was issued in September 1985, with requirements placing a strong emphasis on stealth and supercruise. The RFP would see some alterations after its first release; stealth requirements were drastically increased in December 1985, and the requirement for flying technology demonstrator prototypes was added in May 1986 due to recommendations from the Packard Commission. Additionally, the U.S. Navy, under the Navy Advanced Tactical Fighter (NATF) program, eventually announced that it would use an ATF derivative to replace its F-14 Tomcat. Owing to the immense investments required to develop the technology needed to achieve the requirements, teaming between companies was encouraged. Of the seven bidding companies, Lockheed and Northrop were selected on 31 October 1986. Lockheed, through its Skunk Works division, then teamed with Boeing and General Dynamics while Northrop teamed with McDonnell Douglas, and the two contractor teams undertook a 50-month Dem/Val phase, culminating in the flight test of two technology demonstrator prototypes, the YF-22 and the YF-23 respectively; while they represent competing designs, the prototypes were to be "best-effort" vehicles not meant to perform a competitive flyoff or represent a production aircraft, but to demonstrate the viability of its concept and to mitigate risk. Concurrently, Pratt & Whitney and General Electric were contracted to develop the propulsion systems for the ATF engine competition. Dem/Val was focused on system engineering, technology development plans, and risk reduction over point aircraft designs; in fact, after the down-select, the Lockheed team completely redesigned the airframe configuration in the summer of 1987 due to weight analysis during detailed design, with notable changes including the wing planform from swept trapezoidal to diamond-like delta and a reduction in forebody planform area. Contractors made extensive use of analytical and empirical methods, including computational fluid dynamics and computer-aided design software, wind-tunnel testing, and radar cross-section (RCS) calculations and pole testing; the Lockheed team would conduct nearly 18,000 hours of wind-tunnel testing for Dem/Val. Avionics development was marked by extensive testing and prototyping and supported by ground and flying laboratories. During Dem/Val, the SPO used the results of performance and cost trade studies conducted by contractor teams to adjust ATF requirements and delete ones that were significant weight and cost drivers while having marginal value. The short takeoff and landing (STOL) requirement was relaxed to delete thrust-reversers, saving substantial weight. As avionics was a major cost driver, side looking radars were deleted, and the dedicated infrared search and track (IRST) system was downgraded from multicolor to single color and then deleted as well. Space and cooling provisions were retained to allow for the later addition of these components. The ejection seat requirement was downgraded from a fresh design to the existing McDonnell Douglas ACES II. Despite efforts by the contractor teams to rein in weight, the takeoff gross weight estimates grew from 50,000 to 60,000 lb (23,000 to 27,000 kg), resulting in engine thrust requirement increasing from 30,000 to 35,00.... 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