The Lockheed Martin X-35 is a concept demonstrator aircraft (CDA) developed by
Lockheed Martin
The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...
for the
Joint Strike Fighter program
Joint Strike Fighter (JSF) is a development and acquisition program intended to replace a wide range of existing fighter, strike, and ground attack aircraft for the United States, the United Kingdom, Italy, Canada, Australia, the Netherlands ...
. The X-35 was declared the winner over the competing
Boeing X-32
The Boeing X-32 is a concept demonstrator aircraft that was designed for the Joint Strike Fighter competition. It lost to the Lockheed Martin X-35 demonstrator, which was further developed into the Lockheed Martin F-35 Lightning II.
Developm ...
and a developed,
armed
Armed (May, 1941–1964) was an American Thoroughbred gelding race horse who was the American Horse of the Year in 1947 and Champion Older Male Horse in both 1946 and 1947. He was inducted into the National Museum of Racing and Hall of Fame in ...
version went on to enter production in the early 21st century as the
F-35 Lightning II
The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, all-weather stealth multirole combat aircraft that is intended to perform both air superiority and strike missions. It is also able to provide ele ...
.
Development
![Lockheed F-35 Joint Strike Fighter](https://upload.wikimedia.org/wikipedia/commons/1/1b/Lockheed_F-35_Joint_Strike_Fighter.jpg)
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 JSF program was created to replace various aircraft while keeping development, production, and operating costs down. This was pursued by building three variants of one aircraft, with the initial goal of the variants sharing over 70% of their parts.
The first is the F-35A, a
conventional takeoff and landing (CTOL) variant. It is the smallest and lightest version, and is intended primarily to replace the U.S. Air Force's aging
F-16 Fighting Falcon
The General Dynamics F-16 Fighting Falcon is a single-engine multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it evolved into a successful ...
s and
A-10 Thunderbolt II
The Fairchild Republic A-10 Thunderbolt II is a single-seat, twin-turbofan, straight-wing, subsonic attack aircraft developed by Fairchild Republic for the United States Air Force (USAF). In service since 1976, it is named for the Republic ...
s. This is the only version with an internal gun, the
GAU-22. The F-35B is the
short-takeoff and vertical-landing (STOVL) variant due to replace the
U.S. Marine Corps AV-8 Harrier II
The McDonnell Douglas (now Boeing) AV-8B Harrier II is a single-engine ground-attack aircraft that constitutes the second generation of the Harrier family, capable of vertical or short takeoff and landing (V/STOL). The aircraft is primari ...
s and
F/A-18 Hornet
The McDonnell Douglas F/A-18 Hornet is an all-weather, twinjet, twin-engine, supersonic aircraft, supersonic, carrier-based aircraft, carrier-capable, Multirole combat aircraft, multirole combat aircraft, designed as both a Fighter aircraft, ...
s, and
Royal Air Force
The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...
/
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
Harrier GR7/GR9s beginning in 2015.
The Royal Navy will use this to replace its Harrier GR7s and the RAF replace its Harrier GR9s. The U.S. Marine Corps will use the F-35B to replace both its AV-8B Harrier IIs and F/A-18 Hornets with a design similar in size to the Air Force F-35A, trading fuel volume for vertical flight systems. Like the Harrier, guns will be carried in a pod. Vertical flight is by far the riskiest, and in the end, a decisive factor in design. Lastly, the F-35C, a
carrier
Carrier may refer to:
Entertainment
* ''Carrier'' (album), a 2013 album by The Dodos
* ''Carrier'' (board game), a South Pacific World War II board game
* ''Carrier'' (TV series), a ten-part documentary miniseries that aired on PBS in April 20 ...
-based (CV) variant, will replace the "legacy"
F/A-18 Hornet
The McDonnell Douglas F/A-18 Hornet is an all-weather, twinjet, twin-engine, supersonic aircraft, supersonic, carrier-based aircraft, carrier-capable, Multirole combat aircraft, multirole combat aircraft, designed as both a Fighter aircraft, ...
s and serve as a stealthy complement to the
F/A-18E/F Super Hornet
The Boeing F/A-18E and F/A-18F Super Hornet are twin-engine, carrier-capable, multirole fighter aircraft variants based on the McDonnell Douglas F/A-18 Hornet. The F/A-18E single-seat and F/A-18F tandem-seat variants are larger and more ad ...
.
It will have a larger, folding wing and larger control surfaces for improved low-speed control, and stronger landing gear for the stresses of carrier landings. The larger wing area provides increased range and payload, achieving much the same goal as the much heavier Super Hornet. The U.S. Navy initially planned to purchase 480 JSF; this number was eventually revised to 260 aircraft, with an additional 80 for the U.S. Marine Corps.
The primary customers and financial backers are the United States and the United Kingdom. Eight other nations are also funding the aircraft's development. Total program development costs, less procurement, are estimated at over
US$
The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
40 billion, of which the bulk has been underwritten by the United States. Production costs are estimated at
US$
The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
102 million per unit for 2,400 units.
There are three levels of international participation. The United Kingdom is the sole 'Level 1' partner, contributing slightly over US$2 billion, about 10% of the development costs. Level 2 partners are
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
, which is contributing US$1 billion, and the
Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
, US$800 million. At Level 3 are
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, US$440 million;
Turkey
Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
, US$175 million;
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, US$144 million;
Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
, US$122 million; and
Denmark
)
, song = ( en, "King Christian stood by the lofty mast")
, song_type = National and royal anthem
, image_map = EU-Denmark.svg
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Danish Realm, Kingdom of Denmark
...
, US$110 million. The levels generally reflect the financial stake in the program, the amount of technology transfer and subcontracts open for bid by national companies, and the priority order in which countries can obtain production aircraft.
Israel
Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
and
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
have also joined as Security Cooperative Participants. Due to delays in development and testing, the introduction date of the F-35 was gradually pushed from 2010 to 2015.
Design
Elements of the X-35 design were pioneered by the
F-22 Raptor
The Lockheed Martin F-22 Raptor is an American single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). As the result of the USAF's Advanced Tactical Fighter (ATF) program, th ...
, and portions of the VTOL
exhaust duct design were previously used by the
Convair Model 200
The Convair Model 200 was a design for a supersonic vertical takeoff and landing (VTOL) fighter requirement for the United States Navy Sea Control Ship. Further versions were planned for conventional catapult launches and landing using the arre ...
, a 1972 supersonic VTOL fighter requirement for the
Sea Control Ship
The Sea Control Ship (SCS) was a small aircraft carrier developed and conceptualized by the United States Navy under Chief of Naval Operations Elmo Zumwalt during the 1970s. Currently the term refers to naval vessels that can perform similar du ...
; in particular, the three-bearing swivel nozzle used in the X-35B was pioneered by the Convair design.
Additionally, Lockheed purchased technical data from the canceled
Yakovlev Yak-141
The Yakovlev Yak-141 (russian: Яковлев Як-141; NATO reporting name "Freestyle"), also known as the Yak-41, is a Soviet supersonic vertical takeoff/landing (VTOL) fighter aircraft designed by Yakovlev. It was used for testing.
Design ...
in 1991 for examination and analysis of its swivel nozzle.
Although
helmet-mounted display
A helmet-mounted display (HMD) is a device used in aircraft to project information to the pilot's eyes. Its scope is similar to that of head-up displays (HUD) on an aircrew's visor or reticle. An HMD provides the pilot with situation awareness, ...
systems have already been integrated into some
fourth-generation fighters such as the
JAS 39 Gripen
The Saab JAS 39 Gripen (; English: ''griffin'') is a light single-engine multirole fighter aircraft manufactured by the Swedish aerospace and defense company Saab AB. The Gripen has a delta wing and canard configuration with relaxed stabilit ...
, the F-35 will be the first modern combat aircraft in which helmet-mounted displays will replace a
head-up display
A head-up display, or heads-up display, also known as a HUD (), is any transparent display that presents data without requiring users to look away from their usual viewpoints. The origin of the name stems from a pilot being able to view informa ...
altogether.
[Jenkins, Jim]
"Chief test pilot gives brief on F-35."
''DC military'', 2001. Retrieved 6 July 2008.
During concept definition, two demonstrator airframes for each contractor team would be flight-tested. Lockheed Martin's demonstrator aircraft consisted of the X-35A (which was later converted into the X-35B), and the larger-winged X-35C. Both the
X-32 and X-35 power plants were derived from Pratt & Whitney's
F119, with the STOVL variant of the latter incorporating a Rolls-Royce Lift Fan module. Because these were proof of concept demonstrators for STOVL risk reduction, the demonstrator aircraft did not need to have the internal structure or most subsystems of the final aircraft as a weapon system.
Shaft-driven lift fan
Instead of lift engines or using a direct lift engine like the
Rolls-Royce Pegasus
The Rolls-Royce Pegasus, formerly the Bristol Siddeley Pegasus, is a British turbofan engine originally designed by Bristol Siddeley. It was manufactured by Rolls-Royce plc. The engine is not only able to power a jet aircraft forward, but also ...
in the
Harrier jump jet
The Harrier, informally referred to as the Harrier jump jet, is a family of jet-powered attack aircraft capable of vertical/short takeoff and landing operations (V/STOL). Named after a bird of prey, it was originally developed by British ma ...
, the X-35B was powered by the F119-PW-611 which used the new shaft-driven
lift fan
Lift fan is an aircraft configuration in which lifting fans are located in large holes in an otherwise conventional fixed wing or fuselage. It is used for V/STOL operation.
The aircraft takes off using the fans to provide lift, then transitions ...
system, patented by Lockheed Martin engineer
Paul Bevilaqua
Paul Bevilaqua is an aeronautics engineer at Lockheed Martin in California. In 1990, he invented the lift fan for the Joint Strike Fighter F-35B along with fellow Skunk Works engineer Paul Shumpert.
In 2005, Bevilaqua was elected as a member o ...
, and developed by Rolls-Royce.
[.] In normal wing-borne flight, the F119-PW-611 was configured as a normal medium-bypass
reheated
''Reheated'' is the twelfth album by Canned Heat, released in 1988. It features two members of the band's classic lineup, Fito de la Parra and Larry Taylor. Among the titles, "Bullfrog Blues" was originally on the B-side of the first single record ...
turbofan. The turbofan acted somewhat like a
turboshaft engine
A turboshaft engine is a form of gas turbine that is optimized to produce shaftpower rather than jet thrust. In concept, turboshaft engines are very similar to turbojets, with additional turbine expansion to extract heat energy from the exhaust ...
embedded into the fuselage (but with a much smaller percentage of total heat energy being extracted by the turbine stage).
A portion of engine power was extracted via a turbine, and used to drive a shaft running forward via a clutch-and-bevel gearbox to a vertically mounted,
contra-rotating
Contra-rotating, also referred to as coaxial contra-rotating, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of torque. Examples include some aircraft propellers, res ...
lift fan. This was located forward of the main engine in the center of the aircraft (this can also be viewed the same as a
high-bypass turbofan
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
but with the low-pressure fan stages mounted remotely from the engine core on an extended, clutched shaft, and creating thrust downwards rather than back around the engine core as in a conventional turbofan).
Bypass air from the cruise engine medium-bypass turbofan compressor stages exhausted through a pair of roll-post nozzles in the wings on either side of the fuselage, while the thrust from the lift fan balanced the thrust of the hot core stream exhausting through vectored cruise nozzle at the tail. The X-35B powerplant effectively acted as a flow multiplier, much as a
turbofan
The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...
achieves efficiencies by moving unburned air at a lower velocity, and getting the same effect as the Harrier's huge, but supersonically impractical main fan.
Like lift engines, this added machinery was dead weight during flight, but the increased lift thrust enhanced take-off payload by even more. The cool fan also reduced the harmful effects of hot, high-velocity air which could harm runway pavement or an aircraft carrier deck. Though risky and complicated, it was made to work to the satisfaction of DoD officials, and flight testing of the X-35 demonstrators reduced risk to
Technology Readiness Level
Technology readiness levels (TRLs) are a method for estimating the maturity of technologies during the acquisition phase of a program. TRLs enable consistent and uniform discussions of technical maturity across different types of technology. TR ...
6.
Operational history
Flight test evaluation
The X-35A first flew on 24 October 2000 and tested air vehicle performance and handling characteristics. After 28 test flights, the aircraft was converted to the X-35B, which added the shaft-drive lift fan, aft swivel nozzle, and roll posts. On 20 July 2001, to demonstrate the X-35's STOVL capability, the X-35B took off in less than , went supersonic, and landed vertically.
["Propulsion system in Lockheed Martin Joint Strike Fighter wins Collier Trophy."](_blank)
''Lockheed Martin'', 28 February 2003. Retrieved 9 January 2010. The X-35C first flew on 16 December 2000 and tested simulated carrier recovery and power approach.
In the fly-off between the X-32 and the X-35, the latter was judged to be the winner. As a result, a contract for System Development and Demonstration (SDD) of the F-35 was awarded on 26 October 2001 to Lockheed Martin.
[Bolkcom, Christopher]
"JSF: Background, Status, and Issues," p. CRS-4.
''DTIC'', 16 June 2003. Retrieved 18 September 2010.
F-35 production
There are a number of differences between the X-35 and F-35, which was designed to be an operational weapon system. The forward fuselage was lengthened by to make room for mission avionics, while the horizontal stabilizers were correspondingly moved aft to retain balance and control. The diverterless supersonic inlet cowl shape changed from a four-sided to a three-sided shape and was moved aft. To accommodate weapons bays, the fuselage section was fuller with the top surface raised by along the centerline. Following the designation of the X-35 prototypes, the three variants were designated F-35A (CTOL), F-35B (STOVL), and F-35C (CV).
Aircraft on display
![20180328 X-35B Udvar-Hazy 2](https://upload.wikimedia.org/wikipedia/commons/c/c0/20180328_X-35B_Udvar-Hazy_2.jpg)
The X-35A was converted into the X-35B for the STOVL part of the competition. It now resides at the
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution, also called the Air and Space Museum, is a museum in Washington, D.C., in the United States.
Established in 1946 as the National Air Museum, it opened its main building on the Nat ...
Steven F. Udvar-Hazy Center
The Steven F. Udvar-Hazy Center, also called the Udvar-Hazy Center, is the Smithsonian National Air and Space Museum (NASM)'s annex at Washington Dulles International Airport in the Chantilly area of Fairfax County, Virginia. It holds numerous ...
, near
Washington Dulles International Airport
Washington Dulles International Airport , typically referred to as Dulles International Airport, Dulles Airport, Washington Dulles, or simply Dulles ( ), is an international airport in the Mid-Atlantic (United States), Eastern United States, loc ...
in Virginia.
Following the end of the competition, the X-35C was transferred to the
Patuxent River Naval Air Museum
The Patuxent River Naval Air Museum is a museum at Lexington Park, Maryland, first opened in 1978, which preserves and interprets the Naval Air Station Patuxent River history and heritage of advancing US naval aviation technology with artifacts, ...
in
St. Mary's County St. Mary's County may refer to:
* St. Mary's County, Maryland
*St. Mary's County, Utah Territory
There are 29 counties in the U.S. state of Utah. There were originally seven counties established under the provisional State of Deseret in 1849: ...
,
Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
.
Specifications (X-35A)
Differences between variants
See also
Notes
References
Bibliography
*
*
*
* .
* .
* .
* .
External links
* .
* .
* .
* .
* .
{{Stealth aircraft
Edwards Air Force Base
X-035
2000s United States experimental aircraft
Single-engined jet aircraft
Mid-wing aircraft
Lift fan
Lockheed Martin F-35 Lightning II
Articles containing video clips
Aircraft first flown in 2000
Stealth aircraft