Lockheed Martin F-22 Raptor

 Lockheed Martin F-22 Raptor

The Lockheed Martin/Boeing F-22 Raptor is an American twin-engine, all-weather, supersonic stealth fighter aircraft. As a product of the United States Air Force'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 airframe and weapons systems and conducted final assembly, while program partner Boeing provided the wings, aft fuselage, avionics integration, and training systems

First flown in 1997, the F-22 descended from the Lockheed YF-22 and was variously designated F-22 and F/A-22 before it formally entered service in December 2005 as the F-22A. Although the U.S. Air Force (USAF) had originally planned to buy a total of 750 ATFs to replace its F-15 Eagles, it later scaled down to 381, and the program was ultimately 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.^{[N 2]} The last aircraft was delivered in 2012

The F-22 is a critical component of the USAF's current high-end tactical airpower. While it had a protracted development and initial operational difficulties, the aircraft became the service's leading platform for air-to-air missions against peer adversaries. Although designed for counter-air operations, the F-22 has also performed strike and electronic surveillance, including missions in the Middle East against the Islamic State and Assad-aligned forces. The F-22 is planned to remain a cornerstone of the USAF's fighter fleet until its succession by the crewed Next Generation Air Dominance fighter.

The F-22 originated from the Advanced Tactical Fighter (ATF) program that the U.S. Air Force (USAF) initiated in 1981 to replace the F-15 Eagle and F-16 Fighting Falcon. Intelligence reports indicated that their effectiveness would be 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.^[3] Code-named "Senior Sky", the ATF would become an air superiority fighter program influenced by these threats; in the potential scenario of a Soviet and Warsaw Pact invasion in Central Europe, the ATF was envisaged to support the air-land battle by spearheading 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 perform air interdiction against 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) around Mach 1.5, and stealth technology for low observability

The USAF published an ATF request for information (RFI) to the aerospace industry in May 1981, and following a period of concept and specification development, the ATF System Program Office (SPO) issued the demonstration and validation (Dem/Val) request for proposals (RFP) in September 1985, with requirements placing strong emphasis on stealth, supersonic cruise and maneuver. The RFP saw some alterations after its initial release, including more stringent signature reduction requirements in December 1985 and adding the requirement for flying technology demonstrator prototypes in May 1986.^{[N 3][8]} Owing to the immense investments required to develop the advanced technologies, teaming between companies was encouraged. Of the seven bidding companies,^{[N 4]} Lockheed and Northrop were selected on 31 October 1986.^{[N 5]} Lockheed, through its Skunk Works division at Burbank, California, teamed with Boeing and General Dynamics while Northrop teamed with McDonnell Douglas. These two contractor teams undertook a 50-month Dem/Val phase, culminating in the flight test of two technology demonstrator prototypes, the Lockheed YF-22 and Northrop YF-23; while they represented competing designs, the prototypes were meant for demonstrating concept viability and risk mitigation rather than a competitive flyoff.^{[N 6]} Concurrently, Pratt & Whitney and General Electric competed for the ATF engines.^[12][13]

Dem/Val was focused on system engineering, technology development plans, and risk reduction over point aircraft designs; in fact, after down-select, the Lockheed team completely redesigned the airframe in the summer of 1987 due to weight analysis, with notable changes including the wing planform from swept trapezoidal to diamond-like delta and a reduction in forebody planform area.^[14][15] The team extensively used analytical and empirical methods including computational fluid dynamics and computer-aided design software, wind tunnel testing (18,000 hours for Dem/Val), and radar cross-section (RCS) calculations and pole testing. Avionics systems were tested in ground prototypes and flying laboratories.^[16] During Dem/Val, the SPO used trade studies from both teams to review ATF requirements and adjust 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. Side looking radars and the dedicated infrared search and track (IRST) system were eventually removed as well, although space and cooling provisions were retained to allow for their later addition. The ejection seat was downgraded from a fresh design to the existing 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 (22,700 to 27,200 kg), resulting in engine thrust requirement increasing from 30,000 to 35,000 lbf (133 to 156 kN) class.^[17]