Lockheed Martin F-22 Raptor

The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation super maneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack,electronic warfare, and signals intelligence roles. 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. Program partner Boeing Defense, Space & Security provides the wings, aft fuselage, avionics integration, and training systems.

The aircraft was variously designated F-22 and F/A-22 during the years prior to formally entering USAF service in December 2005 as theF-22A. Despite a protracted and costly development period, the United States Air Force considers the F-22 a critical component of U.S. tactical air power, and claims that the aircraft is unmatched by any known or projected fighter. Lockheed Martin claims that the Raptor's combination of stealth, speed, agility, precision and situational awareness, combined with air-to-air and air-to-ground combat capabilities, makes it the best overall fighter in the world today. Air Chief Marshal Angus Houston, former Chief of the Australian Defense 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 combat missions because of delays in the Russian and Chinese fifth-generation fighter programs, a U.S. ban on Raptor exports, and the ongoing development of the planned cheaper and more versatile F-35 resulted in calls to end F-22 production. In April 2009, the U.S. Department of Defense proposed to cease placing new orders, subject to Congressional approval, for a final procurement tally of 187 operational aircraft. The National Defense Authorization Act for Fiscal Year 2010 lacked funding for further F-22 production. The final F-22 rolled off the assembly line on 13 December 2011 during a ceremony at Dobbins Air Reserve Base.

Starting in 2010, the F-22 was plagued by problems with its pilot oxygen systems which contributed to one crash and death of a pilot. In 2011 the fleet was grounded for four months before resuming flight operations, but reports of oxygen systems issues have continued. In July 2012, the Air Force announced that the hypoxia-like symptoms experienced were caused by a faulty valve in the pilots' pressure vest; the valve was replaced and changes to the filtration system were also made.

Design

Characteristics

F-22 Raptor flying with its F119-PW-100engines on full afterburner

The F-22 Raptor is a fifth generation fighter that is considered a fourth-generation stealth aircraft by the USAF. Its dual afterburning Pratt & Whitney F119-PW-100 turbofans incorporate pitch axis thrust vectoring, with a range of ±20 degrees. The maximum thrust is classified, though most sources place it at about 35,000 lbf (156 kN) per engine. Maximum speed, without external weapons, is estimated to be Mach 1.82 in supercruise mode, as demonstrated by General John P. Jumper, former U.S. Air Force Chief of Staff, when his Raptor exceeded Mach 1.7 without afterburners on 13 January 2005. With afterburners, it is "greater than Mach 2.0" (greater than 1,317 mph, 2,120 km/h). Former Lockheed chief test pilot Paul Metz stated that the Raptor has a fixed inlet, as opposed to variable intake ramps, and that the F-22 has a greater climb rate than the F-15, despite the F-15's higher thrust-to-weight ratio of 1.2:1 (the F-22 has a ratio closer to 1:1). The U.S. Air Force claims that the Raptor cannot be matched by any known or projected fighter types, and Lockheed Martin claims: "the F-22 is the only aircraft that blends supercruise speed, super-agility, stealth and sensor fusion into a single air dominance platform.

The F-22 is highly maneuverable, at both supersonic and subsonic speeds. It is extremely departure-resistant, enabling it to remain controllable at extreme pilot inputs. The Raptor'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. The F-22 is also capable of maintaining a constant angle of attack of over 60°, yet still having some control of roll. During June 2006 exercises in Alaska, F-22 pilots demonstrated that cruise altitude has a significant effect on combat performance, and routinely attributed their altitude advantage as a major factor in achieving an unblemished kill ratio against other U.S. fighters and 4th/4.5th generation fighters.

The F-22 has a unique combination of speed, altitude, agility, sensor fusion and stealth that all work together to increase its effectiveness. Altitude plus advanced active and passive electronic warfare systems allow the F-22 to spot targets for its own weapons at considerable ranges. Altitude plus speed increases the reach of the F-22's own weapons. Altitude naturally increases the range from ground based defenses, which increases the effectiveness of stealth, and when combined with speed reduces the time defensive systems have to react to the F-22's attacks.

Avionics

The F-22's avionics include BAE Systems E&IS radar warning receiver (RWR) AN/ALR-94, AN/AAR 56 Infra-Red and Ultra-Violet MAWS (Missile Approach Warning System) and the Northrop Grumman AN/APG-77 Active Electronically Scanned Array (AESA) radar. The AN/ALR-94 is a passive receiver system to detect radar signals; composed of more than 30 antennas blended into the wings and fuselage that provide all around coverage. It was described by Tom Burbage, former F-22 program head at Lockheed Martin, as "the most technically complex piece of equipment on the aircraft." It has a greater range (250+ nmi) than the radar, allowing the F-22 to limit its own radar emissions to maximise stealth. As a target approaches, the receiver can cue the AN/APG-77 radar to track the target with a narrow beam, which can be as focused down to 2° by 2° in azimuth and elevation.

The AN/APG-77 AESA radar

The AN/APG-77 radar, designed for air superiority and strike operations, features a low-observable, active-aperture, electronically-scanned array that can track multiple targets in any weather. The AN/APG-77 changes frequencies more than 1,000 times per second to lower interception probability. Additionally, radar emissions can be focused in an electronic-attack capability to overload enemy sensors.

The radar's information is processed by two Raytheon Common Integrated Processor (CIP)s. Each CIP can process 10.5 billion instructions per second and has 300 megabytes of memory. Information can be gathered from the radar and other onboard and offboard systems, filtered by the CIP, and offered in easy-to-digest ways on several cockpit displays, enabling the pilot to remain on top of complicated situations. The F-22's avionics software has some 1.7 million lines of code, the majority involving processing data from the radar. The radar 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. In 2007, tests by Northrop Grumman, Lockheed Martin, and L-3 Communications enabled the AESA system of a Raptor to act like a WiFi access point, able to transmit data at 548 megabits per second and receive at gigabit speed; this is far faster than the Link 16 system used by U.S. and allied aircraft, which transfers data at just over 1 Mbit/s.

The F-22 has a threat detection and identification capability comparative with the RC-135 Rivet Joint. The F-22's stealth allows it to safely operate far closer to the battlefield, compensating for the reduced capability. The F-22 is capable of functioning as a "mini-AWACS", however the radar is less powerful than dedicated platforms such as the E-3 Sentry. The F-22 allows its pilot to designate targets for cooperating F-15s and F-16s, 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 radar is capable of high-bandwidth data transmission; conventional radio "chatter" can be reduced via these alternative means. The IEEE-1394B data bus developed for the F-22 was derived from the commercial IEEE-1394 "FireWire" bus system. Sensor fusion combines data from all onboard and offboard sensors into a common view to prevent the pilot from being overwhelmed.

In a critical article former Navy Secretary John Lehman wrote "[a]t least [the F-22s] are safe from cyberattack. No one in China knows how to program the '83 vintage IBM software that runs them." Former Secretary of the USAF Michael Wynne blamed the use of the DoD's Ada as a reason for cost overruns and schedule slippages on many major military projects, including the F-22 Raptor. The F-22 uses the INTEGRITY-178B operating system from Green Hills Software, which is also used on the F-35, several commercial airliners and the Orion Crew Exploration Vehicle. However cyberattacks on Lockheed Martin's subcontractors have raised doubts about the security of the F-22's systems and its usefulness in combat as a result.

Herbert J. Carlisle has said that the F-22 can datalink with the Tomahawk (missile).

Cockpit

Cockpit of the F-22, showing instruments, head up display and throttle top (lower left)

The F-22 features a glass cockpit with no analog flight instruments. The primary flight controls are a force-sensitive side-stick controller and a pair of throttles. The monochrome head-up display offers a wide field of view and serves as a primary flight instrument for the pilot; information is also displayed upon six color liquid crystal display (LCD) panels. 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. In August 2006, the Air Force Packaging Technology Engineering Facility (AFPTEF) was tasked with the design of a new shipping and storage container for the fragile F-22 Canopy.

The Raptor has integrated radio functionality for communicating on standard frequencies, the signal processing systems are virtualised rather than a separated hardware module. Radio functions are inactive during the strictest emissions control protocols (EMCON level) to maintain stealth; at lower EMCON levels the pilot may use the radio at will. There has been several media reports on the F-22's inability to communicate with other aircraft and funding cuts on integrating the new datalinking standard, MADL. Voice communication is possible, but not data transfer yet. However, the Joint Tactical Radio System (JTRS), the software-defined radio project, was cancelled in October 2011 (before delivery to the F-22).

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 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. Components include the on-board oxygen generation system (OBOGS), protective pilot garments, and a breathing regulator/anti-g 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 USAF initially wanted the aircraft to use direct voice input (DVI) controls. This was finally judged too technically risky and was abandoned.

Armament

An F-22 fires an AIM-120 AMRAAM

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 compressed-carriage medium range missiles in the center bay and one short range missile in each of the two side bays. Four of the medium range missiles can be replaced with two bomb racks that can each carry one medium-size bomb or four small diameter bombs. Carrying missiles and bombs internally maintains its stealth capability and maintains lower drag resulting in higher top speeds and longer combat ranges. 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. This reduces the Raptor's chance of detection by enemy radar systems due to launched ordnance and also allows the F-22 to launch long range missiles while maintaining supercruise. 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. Air-to-surface ordnance is limited to 2,000 lb (compared to 17,000 lb of F/A-18). The Raptor has an M61A2 Vulcan 20 mm cannon in the right wing root. The M61A2 carries 480 rounds; enough ammunition for approximately five seconds of sustained fire. The opening for the cannon's firing barrel is covered by a door when not in use to maximise stealth. The F-22 has been able to close to gun range in training dogfights while avoiding detection. The cannon fire is tracked by the aircraft's radar and displayed on the pilot's head up display.

For stealth, the F-22 carries weapons in internal bays. The doors for the center bay and smaller side bays are open showing the six LAU-142/A AMRAAM Vertical Ejection Launchers (AVEL).

The Raptor's very high sustained cruise speed and operational altitude add significantly to the effective range of both air-to-air and air-to-surface munitions. This gives it a 40% greater employment range for air to air missiles than the F-35. The USAF plans to procure the AIM-120D AMRAAM, reported to have a 50% increase in range compared to the AIM-120C. While specific figures remain classified, it is expected that JDAMs employed by F-22s will have twice or more the effective range of munitions dropped by legacy platforms. In testing, a Raptor dropped a 1,000 lb (450 kg) unpowered, free-fall JDAM from 50,000 feet (15,000 m), while cruising at Mach 1.5, striking a moving target 24 miles (39 km) away. This reach advantage of the F-22 has been cited by Robert Gottliebsen as sufficient reason for Australia to reject the F-35 in favor of a F-22 that has been updated with F-35 systems.

While the F-22 typically carries its weapons internally, the wings include four hardpoints, each rated to handle 5,000 lb (2,300 kg). Each hardpoint has a pylon that can carry a detachable 600 gallon fuel tank or a launcher holding two air-air missiles. However, the use of external stores has a detrimental effect on the F-22's stealth, maneuverability and speed. The two inner hardpoints are "plumbed" for external fuel tanks; the hardpoints can be jettisoned in flight so the fighter can maximize its stealth after exhausting external stores. A stealth ordnance pod and pylon is being developed to carry additional weapons internally.

Stealth

The stealth of the F-22 is due to a combination of factors, including the overall shape of the aircraft, the use of radar absorbent material (RAM), and attention to detail such as hinges and pilot helmets that could provide a radar return. However, reduced radar cross section is one of five facets of presence reduction addressed in the designing of the F-22. The F-22 was designed to disguise its infrared emissions, reducing the threat of infrared homing ("heat seeking") surface-to-air or air-to-air missiles, including its flat thrust vectoring nozzles. The aircraft was designed to be less visible to the naked eye; radio, heat and noise emissions are equally controlled.

F-22 with external weapons pylons.

The F-22 reportedly relies less on maintenance-intensive radar absorbent coatings than previous stealth designs like the F-117. These materials are 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 has necessitated repair. The exact radar cross section (RCS) remains classified; however, in 2009 Lockheed Martin released information indicating it to have a RCS (from certain angles) of −40 dBsm – the equivalent 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 visibility. Furthermore, stealth contouring and radar absorbent materials are chiefly effective against high-frequency radars, usually found on other aircraft. Low-frequency radars, employed by weather radars and ground warning stations, are alleged to be less affected by stealth technologies and are thus more capable as detection platforms. Rebecca Grant states that while faint or fleeting radar contacts make defenders aware that a stealth aircraft is present, interception cannot be reliably vectored to attack the aircraft.

The F-22 also includes measures designed to minimize its detection by infrared, including special paint and active cooling of leading edges to deal with the heat buildup encountered during supercruise flight.

Specifications

F-22 with drop tanks in transit to Kadena Air Base, Japan, from Langley Air Force Base, Virginia

Data from USAF, F-22 Raptor Team web site, Manufacturers' data, Aviation Week, and Journal of Electronic Defense,

General characteristics

• Crew: 1
• Length: 62 ft 1 in (18.90 m)
• Wingspan: 44 ft 6 in (13.56 m)
• Height: 16 ft 8 in (5.08 m)
• Wing area: 840 ft² (78.04 m²)
• Airfoil: NACA 64A?05.92 root, NACA 64A?04.29 tip
• Empty weight: 43,340 lb (19,700 kg)
• Loaded weight: 64,460 lb (29,300 kg)
• Max. takeoff weight: 83,500 lb (38,000 kg)
• Powerplant: 2 × Pratt & Whitney F119-PW-100 Pitch Thrust vectoring turbofans
  • Dry thrust: 23,500 lb (104 kN) each
  • Thrust with afterburner: 35,000+ lb (156+ kN) each
• Fuel capacity: 18,000 lb (8,200 kg) internally, or 26,000 lb (11,900 kg) with two external fuel tanks. About 3,050 gal or 20,333 lb JP-8 (without additions) internally.
  

Performance

• Maximum speed: **At altitude: Mach 2.25 (1,500 mph, 2,410 km/h) [estimated]
  
  • Supercruise: Mach 1.82 (1,220 mph, 1,963 km/h)
    
• Range: >1,600 nmi (1,840 mi, 2,960 km) with 2 external fuel tanks
• Combat radius: 410 nmi (with 100 nmi in supercruise) (471 mi, 759 km)
• Ferry range: 2,000 mi (1,738 nmi, 3,219 km)
• Service ceiling: 65,000 ft (currently restricted to 44,000 ft, sans vests) (19,812 m)
• Wing loading: 77 lb/ft² (375 kg/m²)
• Thrust/weight: 1.09 (1.26 with loaded weight & 50% fuel)
• Maximum design g-load: -3.0/+9.0 g
  

• Guns: 1× 20 mm (0.787 in) M61A2 Vulcan 6-barreled Gatling cannon in starboard wing root, 480 rounds
• Air to air loadout:
  • 6× AIM-120 AMRAAM
  • 2× AIM-9 Sidewinder
• Air to ground loadout:
  • 2× AIM-120 AMRAAM and
  • 2× AIM-9 Sidewinder for self-protection, and one of the following:
    • 2× 1,000 lb (450 kg) JDAM or
    • 8× 250 lb (110 kg) GBU-39 Small Diameter Bombs
• Hardpoints: 4× under-wing pylon stations can be fitted to carry 600 U.S. gallon drop tanks or weapons, each with a capacity of 5,000 lb (2,268 kg).
  

Avionics

• RWR (Radar warning receiver): 250 nmi (463 km) or more
  
• Radar: 125–150 miles (200–240 km) against 1 m² (11 sq ft) targets (estimated range)
  
• Chemring MJU-39/40 flares for protection against IR missiles.
  

Source

The information contained on this page is unclassified, approved for public dissemination and is released under CC-BY-SA Licensing Agreement.