The F-22 Raptor is an American fighter aircraft that utilizes stealth technology. It is an air superiority fighter, but is equipped for ground attack, electronic warfare and signals intelligence roles as well. The F-22 is a critical component of the US Global Strike Task Force.
Faced with a protracted development period, the prototype aircraft was variously designated YF-22 and F/A-22 during the three years before formally entering United States Air Force service in December 2005, as the F-22A.
Lockheed Martin Aeronautics is the prime contractor and is responsible for the majority of the airframe, weapon systems and final assembly of the F-22. Along with Lockheed Martin, partner Boeing Integrated Defense Systems provides the wings, aft fuselage, avionics integration, and all of the pilot and maintenance training systems.
In 1981, USAF developed a requirement for a new air superiority fighter intended to replace the capability of the F-15 Eagle.
It was envisaged that the ATF would incorporate emerging technologies including advanced alloys and composite materials, advanced fly-by-wire flight control systems, higher power propulsion systems, and low-observable/stealth technology.
A request for proposal (RFP) was issued in July 1986, and two contractor teams, Lockheed/Boeing/General Dynamics and Northrop/McDonnell Douglas were selected in October 1986 to undertake a 50-month demonstration/validation phase, culminating in the flight test of two prototypes, the YF-22 and the YF-23.
Following a hard-fought fly-off competition, in August 1991 the YF-22 was declared the winner and Lockheed was awarded the contract to develop and build the Advanced Tactical Fighter.
The first production F-22 was delivered to Nellis Air Force Base, Nevada, on 14 January 2003 and "Dedicated Initial Operational Test and Evaluation" commenced on 27 October 2004. As of 2004, 51 Raptors were in service, with 22 more ordered under fiscal year 2004 funding.
The first crash of a production F-22 occurred during takeoff at Nellis Air Force Base on 20 December 2004, in which the pilot ejected safely moments before impact.
The United States Air Force originally planned to order 750 ATFs, with production beginning in 1994; however, the 1990 Major Aircraft Review altered the plan to 648 aircraft beginning in 1996. The goal changed again in 1994, when it became 442 aircraft entering service in 2003 or 2004, but a 1997 Department of Defense report put the purchase at 339.
In 2003, the Air Force said that the existing congressional cost cap limited the purchase to 277.
By 2006, the Pentagon said it will buy 183aircraft, which would save $15 billion but raise the cost of each aircraft, and this plan has been de facto approved by Congress in the form of a multi-year procurement plan, which still holds open the possibility for new orders past that point. The total cost of the program by 2006 was $62 billion. The F-22 is not the most expensive aircraft aloft. That distinction likely belongs to the roughly $2.2 billion-per-unit B-2 Spirit, whose orders went from hundreds to a few dozen when the Cold War ended. Unlike many other tactical fighters, the opportunity for export is currently non-existent because the export sale of the F-22 is barred by federal law. There was a time in the 1970s when the then-new F-16 also had many restrictions.
Most current customers for US fighters are either acquiring earlier designs like the F-15, or F-16 or are waiting to acquire the F-35, which contains much of the F-22's technology but is designed to be cheaper and more flexible.
Several small design changes were made from the YF-22A prototype to the production F-22A. The swept-back angle on the wing's leading edge was decreased from 48 degrees to 42 degrees, while the vertical stabilizer area was decreased 20%.
To improve pilot visibility, the canopy was moved forward 7 inches (178 mm) and the engine intakes were moved rearward 14 inches (356 mm). The shape of the wing and stabilator trailing edges was refined to improve aerodynamics, strength, and stealth characteristics.
The true top-speed of the F-22 is largely unknown to the general public, as engine power is only one factor. The ability of the airframe to withstand the stress and heat from friction is a further, key factor, especially in an aircraft using as many polymers as the F-22.
The F-22's thrust vectoring nozzles allow the aircraft to turn tightly, and perform extremely high alpha (angle of attack) maneuvers such as the Herbst maneuver (or J-turn), Pugachev's Cobra,and the Kulbit, though the J-Turn is more useful in combat.The F-22 is also capable of maintaining a constant angle of attack of over 60°, yet still having some control of roll.
The F-22's avionics include BAE Systems E&IS (formerly Sanders Associates) radar warning receiver (RWR) AN/ALR-94, and the Northrop Grumman AN/APG-77 Active Electronically Scanned Array (AESA) radar.
The AN/APG-77 is possibly the most capable radar in active service, with both long-range target acquisition and low probability of interception of its own signals by enemy aircraft.
With greater range (250+ nmi) than the radar, it enables the F-22 to limit its own radar emission which might otherwise compromise its stealth. As the target approaches, AN/ALR-94 can cue the AN/APG-77 radar to keep track of its motion with a narrow beam, which can be as focused as 2° by 2° in azimuth and elevation.
The F-22 is capable of functioning as a "mini-AWACS." Though reduced in capability compared to dedicated airframes such as the E-3 Sentry, as with its threat identification capability, the F-22's forward presence is often of benefit.
The system allows the F-22 to designate targets for cooperating F-15s and F-16s, and even determine if two friendly aircraft are targeting the same enemy aircraft, thus enabling one of them to choose a different target.
The Raptor is designed to carry air-to-air missiles in internal bays to avoid disrupting its stealth capability. Launching missiles requires opening the weapons bay doors for less than a second, while the missiles are pushed clear of the airframe by hydraulic arms. The aircraft can also carry bombs such as the Joint Direct Attack Munition (JDAM) and the new Small-Diameter Bomb (SDB).
The Raptor carries an M61A2 Vulcan 20 mm rotary cannon, also with a trap door, in the right wing root.
The M61A2 is a last ditch weapon, and carries only 480 rounds; enough ammunition for approximately five seconds of sustained fire.
While in its air-superiority configuration, the F-22 carries its weapons internally, though it is not limited to this option. The wings are capable of supporting four detachable hardpoints.
Each hardpoint is theoretically capable of handling 5,000 lb of ordnance. However, usage of external stores greatly compromises the F-22's stealth, and has a detrimental effect on maneuverability, speed, and range.
Although several recent Western fighter aircraft are less detectable on radar than previous designs using techniques such as radar absorbent material-coated S-shaped intake ducts that shield the compressor fan from reflecting radar waves, the F-22A design placed a much higher degree of importance on low observance throughout the entire spectrum of sensors including radar signature, visual, infrared, acoustic, and radio frequency.
(This text was adapted from http://www.wikipedia.org/ )(GFDL)
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