The Lockheed Martin F-35 Lightning II is a family of single-seat, single-engine, fifth generation multirole fighters under development to perform ground attack, reconnaissance, and air defense missions with stealth capability. The F-35 has three main models; the F-35A is a conventional takeoff and landing variant, the F-35B is a short take off and vertical-landing variant, and the F-35C is a carrier-based variant.

The F-35 is descended from the X-35, the product of the Joint Strike Fighter (JSF) program. JSF development is being principally funded by the United States, with the United Kingdom and other partner governments providing additional funding. The partner nations are either NATO members or close U.S. allies. It is being designed and built by an aerospace industry team led by Lockheed Martin. The F-35 carried out its first flight on 15 December 2006.

The United States plans to buy a total of 2,443 aircraft to provide the bulk of its tactical airpower for the U.S. Air Force, Marine Corps and Navy over the coming decades. The United Kingdom, Italy, Netherlands, Australia, Canada, Norway, Denmark, Turkey, Israel and Japan are part of the development program and may equip their air services with the F-35.

The JSF program was designed to replace the United States military F-16, A-10, F/A-18 (excluding newer E/F "Super Hornet" variants) and AV-8B tactical fighter aircraft. The F-35 is being built in three different main versions to suit various combat missions. A fourth variant, the F-35I is an export version for Israel.

F-35A

The F-35A is the conventional takeoff and landing (CTOL) variant intended for the U.S. Air Force and other air forces. It is the smallest, lightest F-35 version and is the only variant equipped with an internal cannon, the GAU-22/A. This 25 mm cannon is a development of the GAU-12 carried by the USMC's AV-8B Harrier II. It is designed for increased effectiveness against ground targets compared to the 20 mm M61 Vulcan cannon carried by other USAF fighters.

The F-35A is expected to match the F-16 in maneuverability and instantaneous and sustained high-g performance, and outperform it in stealth, payload, range on internal fuel, avionics, operational effectiveness, supportability, and survivability.  It is expected to match an F-16 that is carrying the usual external fuel tank in acceleration performance.  It also has an internal laser designator and infrared sensors, equivalent to the Sniper XR pod carried by the F-16, but built in to reduce radar cross section.

The A variant is primarily intended to replace the USAF's F-16 Fighting Falcon. It was also to replace the A-10 Thunderbolt II starting in 2028.

The F-35A can be outfitted with either of the two main air to air refueling types, which was a consideration in the Canadian purchase, and a deciding factor in the cost for the Japanese purchase.

F-35B

The F-35B is the short takeoff and vertical landing (STOVL) variant of the aircraft. Similar in size to the A variant, the B sacrifices about a third of the other version's fuel volume to make room for the vertical flight system. Takeoffs and landing with vertical flight systems are by far the riskiest, and in the end, a decisive factor in design. Like the AV-8B Harrier II, the B’s guns will be carried in a ventral pod. Whereas the F-35A is stressed to 9 g, the F-35B is stressed to 7 g.  The F-35B was unveiled at Lockheed Martin's Fort Worth plant on 18 December 2007, and the first test flight was on 11 June 2008.

Unlike the other variants, because it can land vertically the F-35B has no landing hook. The "STOVL/HOOK" button in the cockpit initiates conversion instead of dropping the hook.  The F-35B sends jet thrust directly downwards during vertical takeoffs and landing and the nozzle is being redesigned to spread the output out in an oval rather than a small circle so as to limit damage to asphalt and ship decks.  The variant's three-bearing swivel nozzle that directs the full thrust of the afterburning jet engine is moved by a “fueldraulic” actuator, using pressurized jet fuel.

The United States Marine Corps plans to purchase 340 F-35Bs, to replace all current inventories of the F/A-18 Hornet (A, B, C and D-models), and AV-8B Harrier II in the fighter, and attack roles. The Marines are planning to use the F-35B from "unimproved surfaces at austere bases" and are preparing landing spots with "special, high-temperature concrete designed to handle the heat from the JSF".

The Royal Air Force and Royal Navy plans to use the F-35B to replace their Harrier GR9s, which were retired in 2010. One of the Royal Navy requirements for the F-35B design was a Shipborne Rolling and Vertical Landing (SRVL) mode to increase the maximum landing weights for carried weapons via wing lift.  In October 2010, the UK announced plans to order to the CATOBAR F-35C variant instead, but in May 2012 the UK reverted back to purchasing the F-35B, citing the cost of equipping the UK's new aircraft carriers for the F-35C.  On 19 July 2012 the Defence Secretary Philip Hammond, in a speech in the USA, indicated that the UK would initially receive 48 F-35B and would announce at a later date what the final numbers will be.

The Italian Navy is preparing Grottaglie Air Station for future operations with the F-35B. The Italian Navy is to receive 22 aircraft between 2014 and 2021, with its Cavour aircraft carrier set to be modified to operate them by 2016.

Commandant of the Marine Corps, General James Amos has said that, in spite of its increasing costs and schedule delays, there is no plan B to substitute for the F-35B.  The F-35B is larger than the aircraft it replaces, which required the USS America (LHA-6) to be designed without needed well deck capabilities.  In 2011, the USMC and USN signed an agreement that the USMC will purchase 340 F-35B and 80 F-35C while the USN will purchase 260 F-35C. The five squadrons of marine corps F-35Cs will be assigned to the Navy carriers while the Marine Corps F-35Bs will be used on amphibious ships and ashore.

On 6 January 2011, Gates said that the 2012 budget would call for a two-year pause in F-35B production during which the aircraft may be redesigned, or canceled if unsuccessful. Gates stated, "If we cannot fix this variant during this time frame, and get it back on track in terms of performance, cost and schedule, then I believe it should be canceled."  The probation was ended by Defense Secretary Leon Panetta on 20 January 2012 because of progress made over the past year.

Lockheed Martin executive vice president Tom Burbage and former Pentagon director of operational testing Tom Christie have said that most of the delays in the total program have been due to issues with the F-35B, which forced massive redesigns on the other versions.

The USMC intends to declare Initial Operational Capability with about 50 F-35s running interim Block 2B software in the 2014 to 2015 timeframe.

Lockheed Martin Vice President Steve O’Bryan has said that most F-35B landings will be purely conventional in order to reduce stress on the vertical lift components. Conventional operations also reduce the risk of self-induced foreign object damage.

On 3 October 2011, the F-35B began its initial sea-trials by performing a vertical landing on the deck of the amphibious assault ship USS Wasp.

The USAF will not be replacing the A-10 with the F-35B, because the F-35B will not be able to generate sufficient sorties.

F-35C

Compared to the F-35A, the F-35C carrier variant features larger wings with foldable wingtip sections, larger wing and tail control surfaces for improved low-speed control, stronger landing gear for the stresses of carrier arrested landings, a twin-wheel nose gear, and a stronger tailhook for use with carrier arrestor cables. The larger wing area allows for decreased landing speed while increasing both range and payload.

The United States Navy will use the F-35C carrier variant. It intends to buy 480 F-35Cs to replace the F/A-18A, B, C, and D Hornets. The F-35C will also serve as a low-observable complement to the Super Hornet.  On 27 June 2007, the carrier variant completed its Air System Critical Design Review (CDR). This allows the first two functional prototype F-35C units to be produced.  The C variant is expected to be available beginning in 2014.  The first F-35C was rolled out on 29 July 2009.  The United States Marine Corps will also purchase 80 F-35Cs, enough for five marine fighter-attack squadrons, for use with navy carrier air wings in a joint service agreement signed on 14 March 2011.

On 6 November 2010, the first F-35C arrived at Naval Air Station Patuxent River. At the time, it was determined that the replacement engines for at-sea repair are too large to be transported by current underway replenishment systems.  In 2011, the F-35Cs were grounded for six days because of a software error in the code that was intended to keep the wings from folding in mid-flight.  On 27 July 2011, the F-35C test aircraft CF-3 completed its first steam catapult launch during a test flight in Naval Air Engineering Station Lakehurst. The TC-13 Mod 2 test steam catapult, representative of current fleet technology, was used. In addition to the catapult launches at varying power levels, the integrated test team is to execute a test plan over three weeks to include dual-aircraft jet blast deflector testing and catapult launches using a degraded catapult configuration to measure the effects of steam ingestion on the aircraft.

On 13 August 2011, the F-35 integrated test force completed jet blast deflector (JBD) testing at the Lakehurst facility, with a round of two-aircraft testing. F-35C test aircraft CF-1 along with an F/A-18E tested a combined JBD cooling panel configuration to assess the integration of F-35s in aircraft carrier launch operations. “We completed all of our JBD test points efficiently,” said Andrew Maack, government chief test engineer. “It was a great collaborative effort by all parties.” The government and industry team completed tests that measured temperatures, pressures, sound levels, velocities, and other environmental data. The combined JBD model is to enable carrier deck crews to operate all air wing aircraft, now including the F-35C, as operational tempo requires. Future carrier suitability testing is scheduled throughout 2011, including ongoing catapult testing and the start of arrestment testing in preparation for initial ship trials in 2013.  On 18 November 2011, the U.S. Navy used its new Electromagnetic Aircraft Launch System (EMALS) to catapult an F-35C into the air for the first time.

The USN is dealing with the following issues in adapting their carriers to operate the F-35C.

• The F135 jet engine exceeds the weight capacity of traditional replenishment systems and generates more heat than previous engines.
• The F-35C's stealthy skin will require new repair techniques and extensive damage will require returning the aircraft to the factory for repairs.
• The F-35C uses volatile lithium-ion batteries and higher voltage systems than traditional fighters.
• The F-35C carries new weapons not previously used on carrier aircraft.
• And the F-35C generates so much classified data that mission briefing rooms will require extra security

Other versions

F-35I

The F-35I is an F-35A with Israeli modifications. A senior Israel Air Force official stated "the aircraft will be designated F-35I, as there will be unique Israeli features installed in them". Despite an initial refusal to allow such modifications, the U.S. has agreed to let Israel integrate its own electronic warfare systems into the aircraft’s built-in electronic suite. That would let Israel gradually add indigenously produced EW sensors and countermeasures once it receives its first squadron. In addition, a plug-and-play feature added to the main computer will allow for the use of Israeli electronics in an add-on fashion. Israel will be able to fit its own external jamming pod and plans to install its own air-to-air missiles and guided bombs in the F-35’s internal weapon bays.   A contract was issued for this in 2012.  Israeli pilots are scheduled to start training in F-35s in December 2016 with the first squadron activated about a year later.

Israel Aerospace Industries has considered playing a role in the development of a proposed two-seat F-35. An IAI executive stated, "There is a known demand for two seats not only from Israel but from other air forces. Advanced aircraft are usually two seats rather than single seats."   IAI also plans to produce conformal fuel tanks to extend the range.

A senior IAF official has said that elements of the stealth on the F-35 may be overcome in 5 to 10 years, while the aircraft will be in service for 30 to 40 years, which is why Israel has insisted on the ability to install their own electronic warfare systems. “The basic F-35 design is OK. We can make do with adding integrated software.”

CF-35

The Canadian CF-35 is a proposed variant that would differ from the F-35A through the addition of a drag chute and an F-35B/C style refueling probe.  Norway may also use the drag chute option, as they also have icy runways.  The Norwegians have reported good results with using drag chutes on their current F-16 fleet and expect similar results with the F-35.

The alternative would be to adopt the F-35C for its probe refueling and lower landing speed, but the Parliamentary Budget Officer's report cited the F-35C's limited performance and payload as too high a price to pay.  Although the heavier F-35C airframe does reduce the maximum G-level as compared to the F-35A, the F-35C will have both the largest internal fuel capacity and longest range out of the three F-35 variants, though it will be more expensive than the F-35A.

In 2012 it was revealed that the CF-35, if purchased, would use the same refueling system as the F-35A.

Source: Wikipedia