8 February 2015

Lockheed Martin F-22 Raptor

The Lockheed Martin F-22 Raptor is a single-seat, twin-engine, all weather stealth tactical fighter aircraft developed for theUnited States Air Force (USAF). The result of the USAF's Advanced Tactical Fighter program, the aircraft was designed primarily as an air superiority fighter, but has additional capabilities including ground attack, electronic warfare, and signals intelligence roles. Lockheed Martin is the prime contractor and is responsible for the majority of the airframe, weapon systems, and final assembly of the F-22, while program partner Boeing provides the wings, aft fuselage, avionics integration, and training systems.

The aircraft was variously designated F-22 and F/A-22 prior to formally entering service in December 2005 as the F-22A. Despite a protracted development as well as operational issues, the USAF considers the F-22 a critical component of its tactical air power, and states that the aircraft is unmatched by any known or projected fighter. The Raptor's combination of stealth, aerodynamic performance, and situational awareness gives the aircraft unprecedented air combat capabilities. Air Chief Marshal Angus Houston, former Chief of the Australian Defence Force, said in 2004 that the "F-22 will be the most outstanding fighter plane ever built."
The high cost of the aircraft, a lack of clear air-to-air missions due to delays in Russian and Chinese fighter programs, a ban on exports, and development of the more versatile and lower cost F-35 led to the end of F-22 production. A final procurement tally of 187 operational production aircraft was established in 2009 and the last F-22 was delivered to the USAF in 2012.

In 1981 the U.S. Air Force developed a requirement for an Advanced Tactical Fighter (ATF) as a new air superiority fighter to replace the F-15 Eagle and F-16 Fighting Falcon. Code named "Senior Sky", this program was influenced by the emerging worldwide threats, including development and proliferation of Soviet Su-27 "Flanker"- and MiG-29 "Fulcrum"-class fighter aircraft. It would take advantage of the new technologies in fighter design on the horizon, including composite materials, lightweight alloys, advanced flight-control systems, more powerful propulsion systems, and stealth technology. The request for proposals (RFP) was issued in July 1986 and two contractor teams, Lockheed/Boeing/General Dynamics and Northrop/McDonnell Douglas, were selected on 31 October 1986 to undertake a 50-month demonstration phase, culminating in the flight test of two technology demonstrator prototypes, the YF-22 and the YF-23.
Each design team produced two prototype air vehicles, one for each of the two engine options. The Lockheed-led team employed thrust vectoring nozzles on YF-22 for enhanced maneuverability in dogfights. The ATF's increasing weight and cost drove out some features during development. A dedicated infra-red search and track (IRST) system was downgraded from multi-color to single color and then deleted; the side-looking radars were also deleted, but space and cooling provisions were retained to allow for their future addition. The ejection seat requirement was downgraded from a fresh design to the existing McDonnell Douglas ACES II.
After the flight test demonstration and validation of the prototypes, on 23 April 1991, Secretary of the USAF Donald Rice announced the YF-22 as the winner of the ATF competition. The YF-23 design was considered stealthier and faster while the YF-22 was more maneuverable. The aviation press speculated that the YF-22 was also more adaptable to the U.S. Navy's Navalized Advanced Tactical Fighter (NATF), but by 1992, the Navy had abandoned NATF. In 1991, the USAF planned to buy 648 aircraft.

Production and Procurement
Prime contractor Lockheed Martin Aeronautics manufactured the majority of the airframe and performed final assembly at Dobbins Air Reserve Base in Marietta, Georgia; program partner Boeing Defense, Space & Security provided additional airframe components as well as avionics integration and training systems. F-22 production was split up over many subcontractors across 46 states to increase Congressional support, though this production split may have contributed to increased costs and delays. Many capabilities were deferred to post-service upgrades, reducing the initial cost but increasing total program cost. Production supported over 1,000 subcontractors and suppliers and up to 95,000 jobs.
The F-22 had several design changes from the YF-22. The swept-back angle on the wing's leading edge was decreased from 48° to 42°, while the vertical stabilizers were shifted rearward and their area decreased by 20%. To improve pilot visibility, the canopy was moved forward 7 inches (18 cm), and the engine intakes moved rearward 14 inches (36 cm). The shapes of the wing and stabilator trailing edges were refined to improve aerodynamics, strength, and stealth characteristics. Due to increasing weight during development, range and aerodynamic performance were slightly reduced.

The first F-22, an engineering and manufacturing development (EMD) aircraft named Raptor 4001, was unveiled at Marietta, Georgia on 9 April 1997, and first flew on 7 September 1997. In 2006, the Raptor's development team, composed of over 1,000 contractors and the USAF, won the Collier Trophy, American aviation's most prestigious award. The F-22 was in production for 15 years, at a rate of roughly two per month during peak production.
The USAF had originally envisioned ordering 750 ATFs at a cost of $26.2 billion, with production beginning in 1994. The 1990 Major Aircraft Review led by Secretary of Defense Dick Cheney reduced the number to 648 aircraft beginning in 1996. By 1997, funding instability had further cut the number to 339. By 2003, existing funding limited procurement to 277 fighters; in 2004, the Department of Defense (DoD) further reduced the number to 183 operational aircraft, despite the USAF's preference for 381. In 2006, a multi-year procurement plan was implemented to save $15 billion but raise the cost of each aircraft. That year the program's total cost was projected to be $62 billion for 183 F-22s distributed to seven combat squadrons. In 2007, Lockheed Martin received a $7.3 billion contract that increased the order to 183 production F-22s and extended manufacturing through 2011.
In April 2006, the Government Accountability Office (GAO) assessed the F-22's cost to be $361 million per aircraft, with $28 billion invested in development and testing; the Unit Procurement Cost was estimated at $178 million in 2006, based on a production run of 181 aircraft. It was estimated by the end of production, $34 billion will have been spent on procurement, resulting in a total program cost of $62 billion, around $339 million per aircraft. The incremental cost for an additional F-22 was estimated at about $138 million in 2009. In March 2012, the GAO increased the estimated cost to $412 million per aircraft.

Ban on Exports
The F-22 cannot be exported under American federal law. Customers for U.S. fighters are acquiring earlier designs such as the F-15 Eagle and F-16 Fighting Falcon or the newer F-35 Lightning II Joint Strike Fighter, which contains technology from the F-22 but is designed to be cheaper, more flexible, and available for export. In September 2006, Congress upheld the ban on foreign F-22 sales. Despite the ban, the 2010 defense authorization bill included provisions requiring the DoD to prepare a report on the costs and feasibility for an F-22 export variant, and another report on the impact of F-22 export sales on U.S. aerospace industry.
Some Australian politicians and defense commentators proposed that Australia should attempt to purchase F-22s instead of the planned F-35s, citing the F-22's known capabilities and F-35's delays and developmental uncertainties. However, the RAAF determined that the F-22 was unable to perform the F-35's strike and close air support roles. The Japanese government also showed interest in the F-22 for its Replacement-Fighter program. The Japan Air Self-Defense Force (JASDF) would reportedly require fewer fighters for its mission if it obtained the F-22, thus reducing engineering and staffing costs. However, in 2009 it was reported that acquiring the F-22 would require increases to the defense budget beyond the historical 1 percent of GDP. With the ending of F-22 production, Japan chose the F-35 in December 2011. Israel also expressed interest, but eventually chose the F-35 because of the F-22's price and unavailability.

Production Termination
Throughout the 2000s, the need for F-22s was debated due to rising costs and the lack of relevant adversaries. In 2006, Comptroller General of the United States David Walker found that "the DoD has not demonstrated the need" for more investment in the F-22, and further opposition to the program was expressed by Secretary of Defense Donald Rumsfeld, Deputy Secretary of Defense Gordon R. England, Senator John McCain, and Chairman of U.S. Senate Committee on Armed Services Senator John Warner. The F-22 program lost influential supporters in 2008 after resignation of Secretary of the USAF Michael Wynne and General T. Michael Moseley. Nevertheless, in 2008, Congress passed a defense spending bill funding the F-22's continued production and the Pentagon released $50 million of the $140 million for four additional aircraft, raising the total orders for production aircraft to 187 and leaving the program in the hands of the next administration.
In November 2008, Secretary of Defense Robert Gates stated that the Raptor was not relevant in post-Cold War conflicts such as in Iraq and Afghanistan, and in April 2009, under the new Obama Administration, he called for ending F-22 production in fiscal year (FY) 2011, leaving the USAF with 187 production aircraft. In July, General James Cartwright, Vice Chairman of the Joint Chiefs of Staff, stated to the Senate Committee on Armed Services his reasons for supporting termination of F-22 production, including shifting resources to the multirole F-35 to allow proliferation of fifth-generation fighters for three service branches and preserving the F/A-18 production line to maintain the military's electronic warfare (EW) capabilities in the EA-18G Growler. Issues with the F-22's reliability and availability also raised concerns. After President Obama threatened to veto further production, the Senate voted in July 2009 in favor of ending production and the House subsequently agreed to abide by the 187 production aircraft cap. Gates stated that the decision was taken in light of the F-35's capabilities, and in 2010, he set the F-22 requirement to 187 aircraft by lowering the number of major regional conflict preparations from two to one.

In 2010, USAF initiated a study to determine the costs of retaining F-22 tooling for a future Service Life Extension Program (SLEP). ARAND paper from this study estimated that restarting production and building an additional 75 F-22s would cost $17 billion, resulting in $227 million per aircraft or 54 million higher than the flyaway cost. Lockheed Martin stated that restarting the production line itself would cost about $200 million. Production tooling will be documented in illustrated electronic manuals stored at the Sierra Army Depot. Retained tooling will produce additional components; due to the limited production run there are no reserve aircraft, leading to considerable care during maintenance.
Russian and Chinese fighter developments have fueled concern; in 2009, General John Corley, head of Air Combat Command, stated that a fleet of 187 F-22s would be inadequate, but Secretary Gates dismissed this concern. In 2011, Gates explained that Chinese fifth-generation fighter developments had been accounted for when the number of F-22s was set, and that the U.S. would have a considerable advantage in stealth aircraft in 2025, even with F-35 delays. In December 2011, the 195th and final F-22 was completed out of 8 test and 187 operational aircraft produced, the aircraft was delivered to the USAF on 2 May 2012.

The first combat-capable Block 3.0 aircraft first flew in 2001. Increment 2, the first F-22 upgrade program, was implemented in 2005 and enables the aircraft to employ Joint Direct Attack Munitions (JDAM). Increment 3.1 provides improved ground-attack capability through synthetic-aperture radar mapping and radio emitter direction finding,electronic attack and the GBU-39 Small Diameter Bomb (SDB); testing began in 2009 and the first upgraded aircraft was delivered in 2012. Increment 3.2 is a two-part upgrade process; 3.2A focuses on electronic warfare, communications and identification, while 3.2B will allow the F-22 to better employ the AIM-9X and AIM-120D missiles. The subsequent Increment 3.3 may include the adoption of an open avionics platform and air traffic control updates.
To enable two-way communication with other platforms, the F-22 can use the Battlefield Airborne Communications Node (BACN) as a gateway. Lockheed Martin and Northrop Grumman are currently competing to connect the F-22 with other platforms while maintaining stealth. Other upgrades being developed include IRST functionality for the AN/AAR-56 Missile Launch Detector (MLD) and integration of the Visionix Scorpion helmet-mounted cueing system (HMCS) to enable off-boresight missile launches. In March 2010, the USAF accelerated software portions of 3.2 to be completed in FY 2013.

In January 2011, the USAF opened the Raptor enhancement, development and integration (REDI) contract to bidders, with a $16 billion budget. In November 2011, Lockheed Martin's upgrade contract ceiling was raised to $7.4 billion. Nearly $2 billion was allocated for structural repairs and to increase fleet availability rate from 55.5% to 70.6% by 2015. Some F-35 technology, such as more durable stealth coatings, have been applied to the F-22. Elements such as MADL are delayed until the F-35 is in service. By 2012, the update schedule had slipped seven years due to instability in requirements and funding. In 2014 the USAF moved to cut upgrade funding. Upgrades due in 2015 will allow the F-22 to employ the AIM-9X and have full Link 16 reception and transmission capability. An upgrade scheduled in 2018 will integrate the AIM-120D into the weapons suite. The F-22 fleet is planned to have 36 Block 20 training and 149 Block 30/35 combat aircraft in 2016.
The F-22 is currently being upgraded with a backup oxygen system, software upgrades and oxygen sensors to address the frequent oxygen deprivation issues and normalize operations. In 2013, the faulty flight vest valves were replaced and altitude restrictions lifted; distance restrictions will be lifted once a backup oxygen system is installed. In April 2014 the USAF stated in Congressional testimony that installation of automatic backup oxygen systems on the F-22 fleet would be completed within twelve months.
The F-22 was designed for a lifespan of 30 years and 8,000 flight hours, with a $100 million "structures retrofit program". Investigations are being made for upgrades to extend their useful lives further. In the long term, the F-22 is expected to eventually be replaced by the Next Generation TACAIR.

The F-22 Raptor is a fifth generation fighter that is considered fourth generation in stealth aircraft technology by the USAF. It is the first operational aircraft to combine supercruise, supermaneuverability, stealth, and sensor fusion in a single platform. The Raptor has large shoulder-mounted diamond wings, four empennage surfaces, and a retractable tricycle landing gear. Flight control surfaces include leading and trailing-edge flaps, ailerons, rudders on the canted vertical stabilizers, and all-moving horizontal tails; these surfaces also serve as speed brakes.
The aircraft's dual afterburning Pratt & Whitney F119-PW-100 turbofan engines are closely spaced and incorporate pitch-axis thrust vectoring nozzles with a range of ±20 degrees; each engine has maximum thrust in the 35,000 lbf (156 kN) class. The F-22's thrust to weight ratio in typical combat configuration is nearly at unity in maximum military power and 1.25 in full afterburner. Maximum speed without external stores is estimated to be Mach 1.82 during supercruise and greater than Mach 2 with afterburners.
The F-22 is among only a few aircraft that can supercruise, or sustain supersonic flight without using fuel-inefficient afterburners; targets can be intercepted which subsonic aircraft would lack the speed to pursue and an afterburner-dependent aircraft would lack the fuel to reach. The Raptor's high operating altitude is also a significant tactical advantage over prior fighters. The use of internal weapons bays permits the aircraft to maintain comparatively higher performance over most other combat-configured fighters due to a lack of drag from external stores. The F-22's structure contains extensive amounts of high-strength materials to withstand stress and heat of sustained supersonic flight. Respectively, titanium alloys and composites comprise 39% and 24% of the aircraft's structural weight.

The F-22 is highly maneuverable at both supersonic and subsonic speeds. Computerized fly-by-wire control system and full authority digital engine control (FADEC) make the aircraft highly departure resistant and controllable at aggressive pilot inputs. The Raptor'srelaxed stability and powerful thrust vectoring powerplants enable the aircraft to turn tightly and perform very high alpha (angle of attack) maneuvers such as the Herbst maneuver (J-turn) and Pugachev's Cobra. The aircraft is also capable of maintaining over 60° alpha while having some roll control.
The Raptor's aerodynamic performance, sensor fusion, and stealth work together for increased effectiveness. Altitude, speed, and advanced active and passive sensors allow the aircraft to spot targets at considerable ranges and increase weapons range; altitude and speed also complement stealth's ability to increase the aircraft's survivability against ground defenses such as surface-to-air missiles.

Key avionics include BAE Systems EI&S AN/ALR-94 radar warning receiver (RWR), Lockheed Martin AN/AAR-56 Infra-Red and Ultra-Violet Missile Launch Detector (MLD) and Northrop Grumman AN/APG-77 Active Electronically Scanned Array (AESA) radar. The MLD features six sensors to provide full spherical infrared coverage. The RWR is apassive radar detector with more than 30 antennas are blended into the wings and fuselage for all-round coverage. Tom Burbage, former F-22 program head at Lockheed Martin, described it as "the most technically complex piece of equipment on the aircraft." The range of the RWR (250+ nmi) exceeds the radar's, and can cue radar emissions to be confined to a narrow beam (down to 2° by 2° in azimuth and elevation) to increase stealth. Depending on the detected threat, the defensive systems can prompt the pilot to release countermeasures such as flares or chaff.
The AN/APG-77 radar features a low-observable, active-aperture, electronically scanned array that can track multiple targets under any weather conditions. Radar emissions can also be focused to overload enemy sensors as an electronic-attack capability. The radar changes frequencies more than 1,000 times per second to lower interception probability and has an estimated range of 125–150 miles, though planned upgrades will allow a range of 250 miles (400 km) or more in narrow beams. Radar information is processed by two Raytheon Common Integrated Processor (CIP)s, each capable of processing up to 10.5 billion instructions per second. In a process known as sensor fusion, data from the radar, other sensors, and external systems is filtered and combined by the CIP into a common view, reducing pilot workload.

The F-22's ability to operate close to the battlefield gives the aircraft threat detection and identification capability comparative with the RC-135 Rivet Joint, and the ability to function as a "mini-AWACS", though the radar is less powerful than those of dedicated platforms. The F-22 can designate targets for allies, and determine whether two friendly aircraft are targeting the same aircraft. This radar system can sometimes identify targets "many times quicker than the AWACS". The IEEE-1394B data bus developed for the F-22 was derived from the commercial IEEE-1394 "FireWire" bus system. In 2007, the F-22's radar was used as a wireless data transceiver during tests, transmitting data at 548 megabits per second and receiving at gigabit speed, far faster than the Link 16 system.
The F-22's software has some 1.7 million lines of code, the majority involving processing radar data. Former Secretary of the USAF Michael Wynne blamed the use of the DoD's Ada for cost overruns and delays on many military projects, including the F-22. Cyberattacks on subcontractors have reportedly raised doubts about the security of the F-22's systems and combat-effectiveness. In 2009, former Navy Secretary John Lehman considered the F-22 to be safe from cyberattack, citing the age of its IBM software.

The F-22 has a glass cockpit with all-digital flight instruments. The monochrome head-up display offers a wide field of view and serves as a primary flight instrument; information is also displayed upon six color liquid crystal display (LCD) panels. The primary flight controls are a force-sensitive side-stick controller and a pair of throttles. The USAF initially wanted to implement direct voice input (DVI) controls, but this was judged to be too technically risky and was abandoned. The canopy's dimensions are approximately 140 inches long, 45 inches wide, and 27 inches tall (355 cm x 115 cm x 69 cm) and weighs 360 pounds.
The F-22 has integrated radio functionality, the signal processing systems are virtualized rather than as a separate hardware module. There has been several reports on the F-22's inability to communicate with other aircraft, and funding cuts have affected the development of the MADL data link. Voice communication is possible, but not data transfer.
The integrated control panel (ICP) is a keypad system for entering communications, navigation, and autopilot data. Two 3 in × 4 in (7.6 cm × 10.2 cm) up-front displays located around the ICP are used to display integrated caution advisory/warning data, communications, navigation and identification (CNI) data and also serve as the stand-by flight instrumentation group and fuel quantity indicator. The stand-by flight group displays an artificial horizon, for basic instrument meteorological conditions. The 8 in × 8 in (20 cm × 20 cm) primary multi-function display (PMFD) is located under the ICP, and is used for navigation and situation assessment. Three 6.25 in × 6.25 in (15.9 cm × 15.9 cm) secondary multi-function displays are located around the PMFD for tactical information and stores management.

The ejection seat is a version of the ACES II (Advanced Concept Ejection Seat) commonly used in USAF aircraft, with a center-mounted ejection control. The F-22 has a complex life support system, which includes the on-board oxygen generation system (OBOGS), protective pilot garments, and a breathing regulator/anti-g (BRAG) valve controlling flow and pressure to the pilot's mask and garments. The protective garments are designed to protect against chemical/biological hazards and cold-water immersion, to counter g-forces and low pressure at high altitudes, and to provide thermal relief. It was developed under the Advanced Technology Anti-G Suit (ATAGS) project. Suspicions regarding the performance of the OBOGS and life support equipment have been raised by several mishaps, including a fatal crash.

The Raptor has three internal weapons bays: a large bay on the bottom of the fuselage, and two smaller bays on the sides of the fuselage, aft of the engine intakes. It can carry six medium range missiles in the center bay and one short–range missile in each side bay; Four of the medium range missiles can be replaced with two bomb racks that can each carry one medium-size or four smaller bombs. Carrying armaments internally maintains the aircraft's stealth and minimizes additional drag. Missile launches require the bay doors to be open for less than a second, during which hydraulic arms push missiles clear of the aircraft; this is to reduce vulnerability to detection and to deploy missiles during high speed flight.
The F-22 can also carry air-to-surface weapons such as bombs with Joint Direct Attack Munition (JDAM) guidance and the Small-Diameter Bomb, but cannot self-designate for laser-guided weapons. Internal air-to-surface ordnance is limited to 2,000 lb. An internally mounted M61A2 Vulcan 20 mm cannon is embedded in the right wing root with the muzzle covered by a door to maintain stealth. The radar projection of the cannon fire's path is displayed on the pilot's head-up display.
The F-22's high cruise speed and altitude increase the effective ranges of its munitions, it has 50% greater employment range for the AIM-120 AMRAAM than prior platforms, and range will be further extended with the introduction of the AIM-120D. While specifics are classified, it is expected that JDAMs employed by F-22s will have twice or more the effective range of legacy platforms. In testing, an F-22 dropped a 1,000 lb (450 kg) JDAM from 50,000 feet (15,000 m) while cruising at Mach 1.5, striking a moving target 24 miles (39 km) away.

While the F-22 typically carries weapons internally, the wings include four hardpoints, each rated to handle 5,000 lb (2,300 kg). Each hardpoint can accommodate a pylon that can carry a detachable 600 gallon fuel tank or a launcher holding two air-to-air missiles; the two inboard hardpoints are "plumbed" for external fuel tanks. The use of external stores degrades the aircraft's stealth and kinematic performance, so the external attachments can be jettisoned in flight to restore those characteristics after releasing external stores. A stealthy ordnance pod and pylon was being developed to carry additional weapons in the mid-2000s.
The F-22 was designed to be highly difficult to detect and track by radar. Measures to reduce its radar cross section include airframe shaping such as planform alignment of edges, fixed-geometry serpentine (see S-duct) inlets that prevent line-of-sight of the engine faces from any exterior view, use of radar absorbent material (RAM), and attention to detail such as hinges and pilot helmets that could provide a radar return. The F-22 was also designed to have decreased radio, infrared signature and acoustic signature as well as reduced visibility to the naked eye. The aircraft's flat thrust vectoring nozzle reduces infrared emissions to mitigate the threat of infrared homing ("heat seeking") surface-to-air or air-to-air missiles. Additional measures to reduce the infrared signature include special paint and active cooling of leading edges to manage the heat buildup from supersonic flight.
Compared to previous stealth designs like the F-117, the F-22 is less reliant on RAM, which are maintenance-intensive and susceptible to adverse weather conditions. Unlike the B-2, which requires climate-controlled hangars, the F-22 can undergo repairs on the flight line or in a normal hangar. The F-22 features a Signature Assessment System which delivers warnings when the radar signature is degraded and necessitates repair. The F-22's exact radar cross-section (RCS) is classified; however, in 2009 Lockheed Martin released information indicating it has an RCS (from certain angles) of −40 dBsm – equivalent to the radar reflection of a "steel marble". Effectively maintaining the stealth features can decrease the F-22's mission capable rate to 62–70%.

The effectiveness of the stealth characteristics is difficult to gauge. The RCS value is a restrictive measurement of the aircraft's frontal or side area from the perspective of a static radar. When an aircraft maneuvers it exposes a completely different set of angles and surface area, potentially increasing radar observability. Furthermore, the F-22's stealth contouring and radar absorbent materials are chiefly effective against high-frequency radars, usually found on other aircraft. The effects of Rayleigh scattering and resonance mean that low-frequency radars, employed by weather radars and early warning radars, are more likely to detect the F-22 due to its physical size. However, such radars are also conspicuous, susceptible to Clutter (radar), and have low precision. Additionally, while faint or fleeting radar contacts make defenders aware that a stealth aircraft is present, reliably vectoring interception to attack the aircraft is much more challenging. According to the USAF an F-22 surprised an Iranian F-4 Phantom II that was attempting to intercept an American UAV, despite Iran's claim of having military VHF radar coverage over the Persian Gulf.

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