Lockheed Martin F-35 Lightning II
The Lockheed Martin F-35 Lightning II is an American family of single-seat, single-engine, supersonic stealth strike fighters. A multirole combat aircraft designed for both air superiority and strike missions, it also has electronic warfare and intelligence, surveillance, and reconnaissance capabilities. Lockheed Martin is the prime F-35 contractor with principal partners Northrop Grumman and BAE Systems. The aircraft has three main variants: the conventional takeoff and landing F-35A, the short take-off and vertical-landing F-35B, and the carrier variant catapult-assisted take-off but arrested recovery F-35C.
The aircraft descends from the Lockheed Martin X-35, which in 2001 beat the Boeing X-32 to win the Joint Strike Fighter program intended to replace the F-16 Fighting Falcon, F/A-18 Hornet, and the McDonnell Douglas AV-8B Harrier II "jump jet", among others. Its development is primarily funded by the United States, with additional funding from program partner countries from the North Atlantic Treaty Organization and close U.S. allies, including Australia, Canada, Denmark, Italy, the Netherlands, Norway, the United Kingdom, and formerly Turkey. Outside of NATO, Switzerland and Singapore have placed orders for the aircraft, with other countries considering purchases.
The program has drawn criticism for its unprecedented size, complexity, ballooning costs, and delayed deliveries. The decision to start manufacturing the aircraft while it was still in development and testing led to expensive design changes and retrofits., the average unit costs are: US$82.5 million for the F-35A, $109 million for the F-35B, and $102.1 million for the F-35C. The F135 engine costs $20.4 million as of August 2025.
The F-35 first flew in 2006; its variants entered U.S. service in July 2015, August 2016, and February 2019. The aircraft first saw combat in 2018, during Israeli Air Force attacks on Syria. The F-35 has since been used in combat by the U.S. in Afghanistan, Iran, Iraq, Yemen, and Venezuela; by Israel in Gaza, Iran, Iraq, Lebanon, and Yemen; and by the UK in Iraq and Syria. F-35As contribute to US nuclear forward deployment in European NATO countries. The U.S. plans to buy 2,456 F-35s through 2044, which will represent the bulk of its crewed fixed-wing tactical aviation for several decades; the aircraft is to be a cornerstone of NATO and U.S.-allied air power and operate until 2070.
Development
Program origins
The F-35 was the product of the Joint Strike Fighter program, which was the merger of various combat aircraft programs from the 1980s and 1990s. One progenitor program was the Defense Advanced Research Projects Agency Advanced Short Take-Off/Vertical Landing which ran from 1983 to 1994; ASTOVL aimed to develop a Harrier jump jet replacement for the U.S. Marine Corps and the UK Royal Navy. Under one of ASTOVL's classified programs, the Supersonic STOVL Fighter, Lockheed's Skunk Works conducted research for a stealthy supersonic STOVL fighter intended for both U.S. Air Force and USMC; among key STOVL technologies explored was the shaft-driven lift fan system. Lockheed's concept was a single-engine canard delta aircraft weighing about empty. ASTOVL was rechristened as the Common Affordable Lightweight Fighter in 1993 and involved Lockheed, McDonnell Douglas, and Boeing.The end of the Cold War and the collapse of the Soviet Union in 1991 caused considerable reductions in Department of Defense spending and subsequent restructuring. In 1993, the Joint Advanced Strike Technology program emerged following the cancellation of the USAF's Multi-Role Fighter and U.S. Navy's Advanced Attack/Fighter programs. MRF, a program for a relatively affordable F-16 Fighting Falcon replacement, was scaled back and delayed due to post–Cold War defense posture easing F-16 fleet usage and thus extending its service life as well as increasing budget pressure from the Lockheed Martin F-22 Advanced Tactical Fighter program. The A/F-X, initially known as the Advanced-Attack, began in 1991 as the USN's follow-on to the Advanced Tactical Aircraft program for an Grumman A-6 Intruder replacement; the ATA's resulting McDonnell Douglas A-12 Avenger II had been canceled due to technical problems and cost overruns in 1991. In the same year, the termination of the Naval Advanced Tactical Fighter, a naval development of USAF's ATF program to replace the Grumman F-14 Tomcat, resulted in additional fighter capability being added to A-X, which was then renamed A/F-X. Amid increased budget pressure, the DoD's Bottom-Up Review in September 1993 announced MRF's and A/F-X's cancellations, with applicable experience brought to the emerging JAST program. JAST was not meant to develop a new aircraft, but rather to develop requirements, mature technologies, and demonstrate concepts for advanced strike warfare.
As JAST progressed, the need for concept demonstrator aircraft by 1996 emerged, which would coincide with the full-scale flight demonstrator phase of ASTOVL/CALF. Because the ASTOVL/CALF concept appeared to align with the JAST charter, the two programs were eventually merged in 1994 under the JAST name, with the program now serving the USAF, USMC, and USN. JAST was subsequently renamed to Joint Strike Fighter in 1995, with STOVL submissions by McDonnell Douglas, Northrop Grumman, Lockheed Martin, and Boeing. The JSF was expected to eventually replace large numbers of multi-role and strike fighters in the inventories of the US and its allies, including the Harrier, F-16, F/A-18, Fairchild A-10 Thunderbolt II, and Lockheed F-117 Nighthawk.
International participation is a key aspect of the JSF program, starting with United Kingdom participation in the ASTOVL program. Many international partners requiring modernization of their air forces were interested in the JSF. The United Kingdom joined JAST/JSF as a founding member in 1995 and thus became the only Tier 1 partner of the JSF program; Italy, the Netherlands, Denmark, Norway, Canada, Australia, and Turkey joined the program during the Concept Demonstration Phase, with Italy and the Netherlands being Tier 2 partners and the rest Tier 3. Consequently, the aircraft was developed in cooperation with international partners and available for export.
JSF competition
Boeing and Lockheed Martin were selected in early 1997 for CDP, with their concept demonstrator aircraft designated X-32 and X-35 respectively; the McDonnell Douglas team was eliminated and Northrop Grumman and British Aerospace joined the Lockheed Martin team. Each firm would produce two prototype air vehicles to demonstrate conventional takeoff and landing, carrier takeoff and landing, and STOVL. Lockheed Martin's design would make use of the work on the SDLF system conducted under the ASTOVL/CALF program. The key aspect of the X-35 that enabled STOVL operation, the SDLF system consists of the lift fan in the forward center fuselage that could be activated by engaging a clutch that connects the driveshaft to the turbines and thus augmenting the thrust from the engine's swivel nozzle. Research from prior aircraft incorporating similar systems, such as the Convair Model 200, Rockwell XFV-12, and Yakovlev Yak-141, were also taken into consideration. By contrast, Boeing's X-32 employed a direct lift system that the augmented turbofan would be reconfigured to when engaging in STOVL operation.Lockheed Martin's commonality strategy was to replace the STOVL variant's SDLF with a fuel tank and the aft swivel nozzle with a two-dimensional thrust vectoring nozzle for the CTOL variant. STOVL operation is made possible through a patented shaft-driven LiftFan propulsion system. This would enable identical aerodynamic configuration for the STOVL and CTOL variants, while the CV variant would have an enlarged wing to reduce landing speed for carrier recovery. Due to aerodynamic characteristics and carrier recovery requirements from the JAST merger, the design configuration settled on a conventional tail compared to the canard delta design from the ASTOVL/CALF; notably, the conventional tail configuration offers much lower risk for carrier recovery compared to the ASTOVL/CALF canard configuration, which was designed without carrier compatibility in mind. This enabled greater commonality between all three variants, as the commonality goal was important at this design stage. Lockheed Martin's prototypes would consist of the X-35A for demonstrating CTOL before converting it to the X-35B for STOVL demonstration and the larger-winged X-35C for CV compatibility demonstration.
The X-35A first flew on 24 October 2000 and conducted flight tests for subsonic and supersonic flying qualities, handling, range, and maneuver performance. After 28 flights, the aircraft was then converted into the X-35B for STOVL testing, with key changes including the addition of the SDLF, the three-bearing swivel module, and roll-control ducts. The X-35B would successfully demonstrate the SDLF system by performing stable hover, vertical landing, and short takeoff in less than. The X-35C first flew on 16 December 2000 and conducted field landing carrier practice tests.
On 26 October 2001, Lockheed Martin was declared the winner and was awarded the System Development and Demonstration contract; Pratt & Whitney was separately awarded a development contract for the F135 engine for the JSF. The F-35 designation, which was out of sequence with standard DoD numbering, was allegedly determined on the spot by program manager Major General Mike Hough; this came as a surprise even to Lockheed Martin, which had expected the F-24 designation for the JSF.
Design and production
As the JSF program moved into the System Development and Demonstration phase, the X-35 demonstrator design was modified to create the F-35 combat aircraft. The forward fuselage was lengthened by to make room for mission avionics, while the horizontal stabilizers were moved aft to retain balance and control. The diverterless supersonic inlet changed from a four-sided to a three-sided cowl shape and was moved aft. The fuselage section was fuller, the top surface raised by along the centerline and the lower surface bulged to accommodate weapons bays. Following the designation of the X-35 prototypes, the three variants were designated F-35A, F-35B, and F-35C, all with a design service life of 8,000 hours. Prime contractor Lockheed Martin performs overall systems integration and final assembly and checkout at Air Force Plant 4 in Fort Worth, Texas, while Northrop Grumman and BAE Systems supply components for mission systems and airframe.Adding the systems of a fighter aircraft added weight. The F-35B gained the most, largely due to a 2003 decision to enlarge the weapons bays for commonality between variants; the total weight growth was reportedly up to, over 8%, causing all STOVL key performance parameter thresholds to be missed. In December 2003, the STOVL Weight Attack Team was formed to reduce the weight increase; changes included thinned airframe members, smaller weapons bays and vertical stabilizers, less thrust fed to the roll-post outlets, and redesigning the wing-mate joint, electrical elements, and the airframe immediately aft of the cockpit. The inlet was also revised to accommodate more powerful, greater mass flow engines. Many changes from the SWAT effort were applied to all three variants for commonality. By September 2004, these efforts had reduced the F-35B's weight by over, while the F-35A and F-35C were reduced in weight by and respectively. The weight reduction work cost $6.2 billion and caused an 18-month delay.
The first F-35A, designated AA-1, was rolled out at Fort Worth on 19 February 2006 and first flew on 15 December 2006 with chief test pilot Jon S. Beesley at the controls. In 2006, the F-35 was given the name "Lightning II" after the Lockheed P-38 Lightning of World War II. Some USAF pilots have nicknamed the aircraft "Panther" instead, and other nicknames include "Fat Amy" and "Battle Penguin".
The aircraft's software was developed as six releases, or Blocks, for SDD. The first two Blocks, 1A and 1B, readied the F-35 for initial pilot training and multi-level security. Block 2A improved the training capabilities, while 2B was the first combat-ready release planned for the USMC's Initial Operating Capability. Block 3i retains the capabilities of 2B while having new Technology Refresh 2 hardware and was planned for the USAF's IOC. The final release for SDD, Block 3F, would have full flight envelope and all baseline combat capabilities. Alongside software releases, each block also incorporates avionics hardware updates and air vehicle improvements from flight and structural testing. In what is known as "concurrency", some low rate initial production aircraft lots would be delivered in early Block configurations and eventually upgraded to Block 3F once development is complete. After 17,000 flight test hours, the final flight for the SDD phase was completed in April 2018. Like the F-22, the F-35 has been targeted by cyberattacks and technology theft efforts, as well as potential vulnerabilities in the integrity of the supply chain.
Testing found several major problems: early F-35B airframes were vulnerable to premature cracking, the F-35C arrestor hook design was unreliable, fuel tanks were too vulnerable to lightning strikes, the helmet display had problems, and more. Software was repeatedly delayed due to its unprecedented scope and complexity. In 2009, the DoD Joint Estimate Team estimated that the program was 30 months behind the public schedule. In 2011, the program was "re-baselined"; that is, its cost and schedule goals were changed, pushing the IOC from the planned 2010 to July 2015. The decision to simultaneously test, fix defects, and begin production was criticized as inefficient; in 2014, Under Secretary of Defense for Acquisition Frank Kendall called it "acquisition malpractice". The three variants shared just 25% of their parts, far below the anticipated commonality of 70%.
The program received considerable criticism for cost overruns and for the total projected lifetime cost, as well as quality management shortcomings by contractors., the program was 80% over budget and 10 years late.
The JSF program was expected to cost about $200 billion for acquisition in base-year 2002 dollars when SDD was awarded in 2001. As early as 2005, the Government Accountability Office had identified major program risks in cost and schedule. The costly delays strained the relationship between the Pentagon and contractors. By 2017, delays and cost overruns had pushed the F-35 program's expected acquisition costs to $406.5 billion, with total lifetime cost to $1.5 trillion in then-year dollars which also includes operations and maintenance. The F-35A's unit cost for LRIP Lot 13 was $79.2 million in base-year 2012 dollars. Delays in development and operational test and evaluation, including integration into the Joint Simulation Environment, pushed full-rate production decision from the end of 2019 to March 2024, although actual production rate had already approached the full rate by 2020; the combined full rate at the Fort Worth, Italy, and Japan FACO plants is 156 aircraft annually.