美国F22猛禽战斗机介绍

美国F22猛禽战斗机介绍 F22 Design The Lockheed Martin F-22 Raptor is a single-seat, twin-engine, all weather stealth tactical fighter aircraft developed for the United 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.[6] 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.[8] 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.[N 1] 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. Overview 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, maneuverability, stealth, and sensor fusion into 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 control surfaces also serve as the speed brake. The aircraft's dual afterburning Pratt & Whitney F119-PW-100 turbofan engines are placed close together and incorporate pitch axis thrust vectoring nozzles with a range of ?20 degrees; each engine has a 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 sustained 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.[109] The use of internal weapons bays allows the aircraft to maintain comparatively higher performance over most other aircraft 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 enable it to remain controllable at aggressive pilot inputs. The Raptor's relaxed stability and thrust vectoring allow 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 F-22 is also capable of maintaining over 60? alpha while having some roll control. The F-22's aerodynamic performance, sensor fusion, and stealth work together for increased effectiveness. Altitude, speed, and advanced active and passive sensors allow targets to be spotted at considerable ranges and increase weapons range. Altitude and speed also complement stealth's effectiveness by increasing distance between the aircraft and ground defenses and giving defensive systems less time to react. Avionics Key avionics include BAE Systems EI&S AN/ALR-94 radar warning receiver (RWR),[116] 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.[84] The RWR is a passive 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. 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. Cockpit Cockpit of the F-22, showing instruments, head up display and throttle top 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.[135] 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.[136] Suspicions regarding the performance of the OBOGS and life support equipment have been raised by several mishaps, including a fatal crash. Armament AIM-120 AMRAAM (right) fitted in a weapons bay of an F-22 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.[141] Internal air-to-surface ordnance is limited to 2,000 lb.[142] 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.[143] The radar projection of the cannon fire's path is displayed on the pilot's head-up display. F-22 with external weapons pylons 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 eventual 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 has a pylon that can carry a detachable 600 gallon fuel tank or a launcher holding two air-air missiles. The use of external stores degrades 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 to maximize the aircraft's stealth after exhausting external stores. A stealth ordnance pod and pylon is being developed to carry additional weapons internally. Stealth For stealth, the F-22 carries weapons in internal bays. The doors for the center and side bays are open; note the six LAU-142/A AMRAAM Vertical Ejection Launchers The F-22 was designed to be highly difficult to detect and track by radar. Measures to reduce its radar signature include airframe shaping such as planform alignment of edges, fixed-geometry serpentine 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, heat and noise emissions 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.[150] 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.[109] 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".[152] 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 ground warning stations, are more likely to detect the F-22 due to its physical size. However, such radars are also large, conspicuous, and less precise. 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.[155] 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. Specifications (F-22A) Orthographically projected diagram of the F-22A F-22 Raptor tail feathers USAF poster of key F-22 features and armament 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 (18.92 m) Wingspan: 44 ft 6 in (13.56 m) Height: 16 ft 8 in (5.08 m) Wing area: 840 ft? (78.04 m?) Airfoil: NACA 64A?05.92 root, NACA 64A?04.29 tip Empty weight: 43,340 lb (19,700 kg) Loaded weight: 64,840 lb (29,410 kg) Max. takeoff weight: 83,500 lb (38,000 kg) Powerplant: 2 × Pratt & Whitney F119-PW-100 pitch thrust vectoring turbofans Dry thrust: 26,000 lb (116 kN) each Thrust with afterburner: 35,000+ lb (156+ kN) each Fuel capacity: 18,000 lb (8,200 kg) internally, or 26,000 lb (12,000 kg) with two external fuel tanks Performance Maximum speed: At altitude: Mach 2.25 (1,500 mph, 2,410 km/h) Supercruise: Mach 1.82 (1,220 mph, 1,960 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) (470 mi, 760 km) Ferry range: 2,000 mi (1,740 nmi, 3,220 km) Service ceiling: >65,000 ft (20,000 m) Wing loading: 77.2 lb/ft? (377 kg/m?) Thrust/weight: 1.08 Maximum design g-load: ?3.0/+9.0 g Armament Guns: 1× 20 mm (0.787 in) M61A2 Vulcan 6-barrel Gatling cannon in right wing root, 480 rounds Air to air loadout: 6× AIM-120 AMRAAM 2× AIM-9 Sidewinder Air to ground loadout: 2× 1,000 lb (450 kg) JDAM or 8× 250 lb (110 kg) GBU-39 Small Diameter Bombs 2× AIM-120 AMRAAM 2× AIM-9 Sidewinder 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 (2,270 kg). Avionics AN/APG-77 radar: 125–150 miles (200–240 km) against 1 m2 (11 sq ft) targets (estimated range) AN/AAR-56 Missile Launch Detector (MLD) AN/ALR-94 radar warning receiver (RWR): 250 nmi (463 km) or more detection range MJU-39/40 flares for protection against IR missiles