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Lockheed Martin X-35 / F-35




The X-35 was the Lockheed Martin Joint Strike Fighter (JSF) demonstrator, competing with the Boeing X-32. In November 1996 Boeing and Lockheed Martin were awarded contracts to build two Concept Demonstrator Aircraft (CDA)—one Conventional Take-Off and Landing (CTOL) version and one Short Take-Off and Vertical Landing (STOVL) version each. The aircraft were not intended to be fighter prototypes, but rather to prove that the selected design concepts would work, hence the use of X-series designations.

Lockheed constructed two prototypes for the evaluation. The initial X-35A reflected the basic Air Force CTOL design, and was used for early flights before being modified into the STOVL version, designated X-35B. While Boeing proposed a direct lift STOVL design based on that used in the Harrier, Lockheed opted for a different approach in meeting the vertical flight requirements. Inspired by the Russian Yak-141, the X-35B incorporated a separate lift-fan that was shaft-driven by the F119 engine, allowing cooler exhaust temperatures during hover. While the Boeing design was more conventional, Lockheed argued that their strategy was better in the long term since it offered more room for growth as the aircraft evolves. The second airframe was the X-35C STOVL demonstrator for the Navy. This model featured an enlarged wing of greater span and area for larger fuel capacity as well as enlarged horizontal tails and flaperons for greater control effectiveness during low-speed carrier approaches.

The X-35 was selected as the winner of the JSF competition on 26 October 2001.

The production aircraft to be designated F-35. The System Development and Demonstration (SDD) phase of the F-35 JSF program started with the signing of the SDD contract in October 2001, and with the delivery of test aircraft scheduled to begin in 2008. During the SDD phase, 22 aircraft (14 flying test aircraft and 8 ground-test aircraft) were to be produced and tested. The JSF program is slated to produce a total of 3,002 aircraft for the United States and United Kingdom armed forces.



Lockheed Martin leads a development team including Northrop Grumman, BAE Systems, and Pratt & Whitney. Lockheed Martin brings in advanced technology experience, stealth technology and other technologies and experience which it has gained during F-22 research and development. Northrop Grumman offers tactical aircraft knowledge, stealth technology and carrier suitability. BAE System provides expertise and experience with short take off and vertical landing (STOVL) technology as well as advanced subcontract management. Pratt & Whitney is the builder of the engine which will power the JSF which is based on the F-119 turbojet from the F-22.

To forfill the demands of the main contractors three different variants are developed. All versions will have a common structure and have the same fuselage and internal weapons bay. They will all three be powered by a F-119 modified engine. All variants will carry the standard designation F-35.

The F-35A is the standard variant with conventional take off and landing developed for the US Air Force, the biggest JSF customer. The F-35A will replace the F-16 and the A-10 aircraft currently operated by the USAF.



The F-35B is the STOVL variant of the JSF. The F-119 is modified using the experience of BAE Systems based on the Rolls-Royce Pegasus engine from the AV-8 Harrier. Unlike the Air Force variant the F-35B carries no internal gun and the air refuelling probe is located on the right side of the forward fuselage instead of receptacle on the top surface of the aircraft. The main customers for the F-35B will be the USMC to replace the F/A-18 Hornet ands the AV-8B Harrier IIs and the United Kingdom to replace the Royal Air Force/Royal Navy combined Harrier force of Sea Harriers and GR.7s.

The F-35C is a modified design which enables the JSF to operate from aircraft carriers using conventional carrier landings and capapult take off. The F-35C internal structure and landing gear have been strengthened to handle the loads associated with catapult launches and arrested carrier landings. It has a larger wing area than other JSF types with larger control surfaces for better low speed handling. Like the F-35B is has a refuelling probe instead of a receptacle. The US Navy will be the biggest customer of this variant. The F-35C will complement the US Navy fleet of F/A-18E/F fighters by replacing the F/A-18 A+ and C Hornet in service.

Lockheed Martin F-35B Lightning II BF-3 - the third example of the short takeoff/ vertical landing version - arrived at NAS Patuxent River, Maryland on February 17, 2010. It made its first flight on February 2 at Fort Worth, Texas  and was taken from there to the naval air station by F-35 Test Pilot Jeff Knowles. Another two F-35Bs are due to join the three aircraft at Patuxent River for the flight test programme.

The F-35B was about to conduct its first vertical landing which would be a major milestone for the short take-off, vertical landing (STOVL) variant and work has started on the first F-35 lightning II for the UK.

The Lockheed Martin X-35C Joint Strike Fighter (JSF) Navy demonstrator completed medium-speed taxi testing Dec. 14 2000 at Palrndale, California, in preparation for first flight as early as Dec. 16. The aircraft, with a larger wing and control surfaces than the X-35A, will undergo about 20 hr. of flight test at Edwards AFB, before being flown to NAS Patuxent River, Md., for the continuation of demonstrations. Meanwhile, Boeing has completed structural mode interaction testing on the X-32B short takeoff and vertical landing demonstrator, expected to fly during the first quarter of 2001. The Boeing X-32A demonstrator completed government-required Navy demonstrations Dec. 2, 2000.

First flown on 24 October 2000, the JSF X-35A demonstrator aircraft completed a highly successful flight-test programme in August 2001, and the fol-lowing October the US Government awarded its development contract to Lockheed Martin over the other contender, Boeing. The lift system uses a counter-rotating lift fan, located behind the cockpit and connected to the engine by a drive shaft, as a primary lifting force. The fan produces more than 18,000 lbs of cool thrust in hover flight, with an additional 18,000 lbs coming from the main engine’s vectored aft nozzle and wing roll-posts. The shaft driven Rolls-Royce lift fan amplifies engine thrust and reduces exhaust temperature and velocity during STOVL operations.



First flown on 24 June 2001, in 2001 the X-35A, reconfigured as the STVOL X-35B, achieved its first vertical take-off, level supersonic flight, and vertical landing.

The X-35C is to evaluate manoeuvering qualities, as a conventional carrier version and first flew on 16 December 2000. This version has larger wing and control surfaces and is stressed for catapult launches and arrested landings. This wing could also be applied to the B or A version.

By March 2010, it appeared that just five F-35s had flown:
F-35A AA-01 on December 25, 2006.
F-35B BF-0 1 on June 11, 2008.
F-35B BF-02 on February 2, 2009
F-35A AF-01 on November 14,2009
F-35B BF-03 on February 2, 2010

The first F-35A has since been retired from flight duty. Two of the three F-35Bs were at Naval Air Station Patuxent River, Maryland, for preliminary STOVL evaluation tests.




F-35 Lightning II
As of 2014, 115 have been built at $106,000,000 each.


Lockheed Martin X 35 JSF Joint Strike Fighter
Length: 50.755 ft / 15.47 m
Wingspan: 32.972 ft / 10.05 m
Wing area: 459.623 sq.ft / 42.7 sq.m
Engine: Pratt & Whitney SE 611, 111834 N
Crew: 1
Armament: 1x MG 27mm Mauser BK27, 7000kg wpn. max.

Engine: one Pratt & Whitney F119-611 turbofan with afterburning
Length: 50 ft 6 in (15.37m)
Wing span: 35 ft 0 in (10.65m)

Engine: P&W F119-611.



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