The Lockheed Martin F-35 Lightning II is a fifth-generation, single-seat, single-engine, stealth multirole fighter, that can perform close air support, tactical bombing, and air defense missions. The F-35 has three different models; one is the conventional takeoff and landing variant, the second is short takeoff and vertical-landing variant, and the third is a carrier-based variant.
The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. Its development is being principally funded by the United States, with the United Kingdom and other partner governments providing additional funding. It is being designed and built by an aerospace industry team led by Lockheed Martin with Northrop Grumman and BAE Systems as major partners. Demonstrator aircraft flew in 2000, with the first flight on 15 December 2006.
The Joint Strike Fighter evolved out of several requirements for a common fighter to replace existing types. The actual JSF development contract was signed on 16 November 1996.
The contract for System Development and Demonstration (SDD) was awarded on 26 October 2001 to Lockheed Martin, whose X-35 beat the Boeing X-32. According to Department of Defense officials and British Minister of Defence Procurement Lord Bach, the X-35 consistently outperformed the X-32, although both met or exceeded requirements. The designation of the fighter as "F-35" came as a surprise to Lockheed, which had been referring to the aircraft in-house by the designation "F-24".
The F-35 appears to be a smaller, slightly more conventional, single-engine sibling of the sleeker, twin-engine F-22 Raptor, and indeed drew elements from it. The exhaust duct design was inspired by the General Dynamics Model 200 design, which was proposed for a 1972 supersonic VTOL fighter requirement for the Sea Control Ship. For specialized development of the F-35B STOVL variant, Lockheed consulted with the Yakovlev Design Bureau, purchasing design data from their development of the Yakovlev Yak-141 "Freestyle". Although several experimental designs have been built and tested since the 1960s including the Navy's unsuccessful Rockwell XFV-12, the F-35B is to be the first operational supersonic STOVL fighter.
The F-35 is designed to be America's "premier surface-to-air missile killer and is uniquely equipped for this mission with cutting edge processing power, synthetic aperture radar integration techniques, and advanced target recognition."
Some improvements over current-generation fighter aircraft are:
* Durable, low-maintenance stealth technology;
* Integrated avionics and sensor fusion that combine information from off- and onboard sensors to increase the pilot's situational awareness and improve target identification and weapon delivery, and to relay information quickly to other command and control (C2) nodes;
* High speed data networking including IEEE 1394b and Fibre Channel.
* The Autonomic Logistics Global Sustainment (ALGS), Autonomic Logistics Information System (ALIS) and Computerized Maintenance Management System (CMMS) help ensure aircraft uptime with minimal maintenance manpower.
The Teen Series of fighters (F-15, F-16, F/A-18) were notable for always carrying large external fuel tanks, but as a stealth aircraft the F-35 must fly most missions on internal fuel. Unlike the F-16 and F/A-18, the F-35 lacks leading edge extensions (LEX) and instead uses stealth-friendly chines for vortex lift in the same fashion as the SR-71 Blackbird. The small bumps just forward of the engine air intakes form part of the diverterless supersonic inlet (DSI) which is a simpler, lighter and stealthier means to ensure high-quality airflow to the engine over a wide range of conditions.
The F-35's main engine is the Pratt & Whitney F135. The General Electric/Rolls-Royce F136 is being developed as an alternate engine. The STOVL versions of both powerplants use the Rolls-Royce LiftSystem, patented by Lockheed Martin and built by Rolls-Royce. This system is more like the Russian Yak-141 and German VJ 101D/E than the preceding generation of STOVL designs, such as the Harrier Jump Jet in which all of the lifting air went through the main fan of the Rolls-Royce Pegasus engine.
The LiftSystem is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM). The 3BSM is a thrust vectoring nozzle which allows the main engine exhaust to be deflected downward at the tail of the aircraft. The lift fan near the front of the aircraft provides a counter-balancing thrust. Somewhat like a vertically mounted turboprop within the forward fuselage, the lift fan is powered by the engine's low-pressure (LP) turbine via a drive shaft and gearbox. Roll control during slow flight is achieved by diverting pressurized air from the LP turbine through wing mounted thrust nozzles called Roll Posts.
The F-35B lift fan achieves the same 'flow multiplier' effect as the Harrier's huge, but supersonically impractical, main fan. Like lift engines, this added machinery is just deadweight during horizontal flight but provides a net increase in payload capacity during vertical flight. The cool exhaust of the fan also reduces the amount of hot, high-velocity air that is projected downward during vertical takeoff (which can damage runways and aircraft carrier decks). Though complicated and risky, the lift system has been made to work to the satisfaction of DOD officials.
To date, F-136 funding has come at the expense of other parts of the program, reducing the number of aircraft built and increasing their costs. However, the F-136 team has claimed that their engine has a greater temperature margin which may prove critical for VTOL operations in hot, high altitude conditions.
The F-35 includes a GAU-22/A four-barrel 25mm cannon. The cannon will be mounted internally with 180 rounds in the F-35A and fitted as an external pod with 220 rounds in the F-35B and F-35C. The gun pod for the B and C variants will have stealth features. This pod could be used for different equipment in the future, such as EW, reconnaissance equipment, or possibly a rearward facing radar.
Internally (current planned weapons for integration), up to two air-to-air missiles and two air-to-air or air-to-ground weapons (up to two 2,000 lb bombs in A and C models (BRU-68); two 1,000 lb bombs in the B model (BRU-67)) can be carried in the bomb bays. These could be AIM-120 AMRAAM, AIM-132 ASRAAM, the Joint Direct Attack Munition (JDAM) – up to 2,000 lb (910 kg), the Joint Standoff Weapon (JSOW), Small Diameter Bombs (SDB) – a maximum of four in each bay (Three per bay in F-35B), the Brimstone anti-armor missiles, and Cluster Munitions (WCMD). The MBDA Meteor air-to-air missile is currently being adapted to fit internally in the missile spots and may be integrated into the F-35. The UK had originally planned to put up to four AIM-132 ASRAAM internally but this has been changed to carry 2 internal and 2 external ASRAAMs. It has also been stated by a Lockheed executive that the internal bay will eventually be modified to accept up to 6 AMRAAMs.
At the expense of being more detectable by radar, many more missiles, bombs and fuel tanks can be attached on four wing pylons and two near wingtip positions. The two wingtip locations can only carry AIM-9X Sidewinder. The other pylons can carry the AIM-120 AMRAAM, Storm Shadow, AGM-158 Joint Air to Surface Stand-off Missile (JASSM) cruise missiles, guided bombs, 480-gallon and 600-gallon fuel tanks. An air-to-air load of eight AIM-120s and two AIM-9s is conceivable using internal and external weapons stations, as well as a configuration of six 2,000 lb bombs, two AIM-120s and two AIM-9s. With its payload capability, the F-35 can carry more air-to-air and air-to-ground weapons than legacy fighters it is to replace as well as the F-22 Raptor. Solid-state lasers were being developed as optional weapons for the F-35 as of 2002.
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