Blog 50: 9/2/23: The Most Controversial Aircraft in US History: The F-35 Lightning II, JSF
Lockheed-Martin F-35A over Nellis Test Range, Nevada
Hi all, and Welcome back to Brooke In The Air! This week we’re delving into the history and background of what is arguably the most controversial fighter aircraft in United States and USAF history, not to mention the most well-known at least by name. The Lockheed-Martin F-35 Lightning II, formerly known as the Joint Strike Fighter, of JSF.
Just a reminder, subscribe to my YouTube channel for a a chance to win a luxury trip with me!
Now, Let’s jump right in!
First off, the basics; the Lockheed-Martin F-35 Lightning II was conceived as an American-origin 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 electronic warfare and intelligence, surveillance, and reconnaissance capabilities. Lockheed-Martin is the prime F-35 contractor, with principal partners Northrop Grumman and the UK’s BAE Systems. The aircraft has three main variants: the conventional takeoff and landing (CTOL) F-35A used by the USAF, the short take-off and vertical-landing (STOVL) F-35B used by the US Navy, and the carrier-based (CV) F-35C used by the US Navy.
ORIGINS
Boeing’s infamous and failed X-32 Prototype
The aircraft descends from the Lockheed Martin X-35, which in 2001 beat the Boeing X-32 to win the Joint Strike Fighter (JSF) program. Its development is principally funded by the United States, with additional funding from program partner countries from the North Atlantic Treaty Organization (NATO) and close U.S. allies, including the United Kingdom, Australia, Canada, Italy, Norway, Denmark, and the Netherlands. Several other countries have also ordered, or are considering ordering, the aircraft. The program has drawn so much public scrutiny and criticism for its unprecedented size, complexity, ballooning and taxpayer costs, and much-delayed deliveries.
The acquisition strategy of concurrent production of the aircraft while it was still in development and testing led to expensive design changes and retrofits.
The F-35 first flew in 2006, and entered service with the U.S. Marine Corps F-35B in July 2015, followed by the U.S. Air Force F-35A in August 2016 and the U.S. Navy F-35C in February 2019. The aircraft was first used in combat in 2018 by the Israeli Air Force (IAF). The U.S. plans to buy 2,456 F-35s through 2044, which will represent the bulk of the crewed tactical aviation of the U.S. Air Force, Navy, and Marine Corps for several decades; the aircraft is planned to be a cornerstone of NATO and U.S.-allied air power and to operate until at least 2070.
DESIGN GENESIS
The F-35 was the product of the Joint Strike Fighter (JSF) 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 (DARPA) Advanced Short Take-Off/Vertical Landing (ASTOVL) which ran from 1983 to 1994; ASTOVL aimed to develop a Harrier jump jet replacement for the U.S. Marine Corps (USMC) and the U.K. Royal Navy.
Under one of ASTOVL's classified programs, the Supersonic STOVL Fighter (SSF), Lockheed Skunk Works conducted research for a stealthy supersonic STOVL fighter intended for both U.S. Air Force (USAF) and USMC; a key technology explored was the shaft-driven lift fan (SDLF) system. Lockheed's concept was a single-engine canard delta aircraft weighing about 24,000 lb (11,000 kg) empty. ASTOVL was rechristened as the Common Affordable Lightweight Fighter (CALF) in 1993 and involved Lockheed, McDonnell Douglas, and Boeing. Once Boeing acquired McDonnell-Douglas, the involved parties were reduced to two.
In 1993, the Joint Advanced Strike Technology (JAST) program emerged following the cancellation of the USAF's Multi-Role Fighter (MRF) and U.S. Navy's (USN) Advanced Fighter-Attack (A/F-X) programs. MRF, a program for a relatively affordable F-16 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 F-22 Advanced Tactical Fighter (ATF) program. The A/F-X, initially known as the Advanced-Attack (A-X), began in 1991 as the USN's follow-on to the Advanced Tactical Aircraft (ATA) program for an A-6 replacement; the ATA's resulting A-12 Avenger II had been canceled due to technical problems and cost overruns in 1991 before George H.W. Bush left office the next year.
Lockheed-Martin JSF Enginineer Working on a Mockup
In that same year, the termination of the Naval Advanced Tactical Fighter (NATF), a naval development of USAF's ATF program to replace the aging F-14 Tomcat which by this time was nearing 30 years old, resulted in additional fighter capability being added to A-X, which was then renamed A/F-X.
Amid increased budget pressure, the Department of Defense's (DoD) Bottom-Up Review (or BUR) 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 (JSF) in 1995, with STOVL submissions by McDonnell-Douglas (when they still existed), 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, A-10, and F-117. This obviously has not happened.
DEMONSTRATIONS & IMPROVEMENTS
Lockheed-Martin F-35B STOVL Variant landing on the HMS Queen Elizabeth II
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 (CTOL), carrier takeoff and landing (CV), and Short take off & vertical landing (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 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. 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.
TESTING
Official JSF Testing Badge - Worn by Flight and Ground Crew
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 (3BSM), 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 500 ft (150 m). The X-35C first flew on 16 December 2000 and conducted field landing carrier practice tests.
On 26th of October in 2001, Lockheed-Martin was declared the winner and was awarded the System Development and Demonstration (SD&D) contract; Pratt & Whitney was separately awarded a development contract for the F-135 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 of the USAF; this came as a surprise even to Lockheed-Martin, which had expected the F-24 designation for the JSF.
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 13 cm to make room for mission avionics, while the horizontal stabilizers were moved 5.1 cm aft to retain balance and control. The diverterless supersonic inlet changed from a four-sided to a three-sided cowl shape and was moved 76 cm aft. The fuselage section was fuller, the top surface raised by a mere 2.5 cm along the centerline to accommodate weapons bays. Following the designation of the X-35 prototypes, the three variants were designated F-35A (CTOL), F-35B (STOVL), and F-35C (CV), all with a design service life of 8,000 hours. Prime contractor Lockheed Martin performs overall systems integration and final assembly and checkout (FACO) at 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 2,200 pounds (1,000 kg), over 8%, causing all STOVL key performance parameter (KPP) thresholds to be missed. In December of 2003, the STOVL Weight Attack Team (SWAT) 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 of 2004, these efforts had reduced the F-35B's weight by over 1,400 kg, while the F-35A and F-35C were reduced in weight by 1,100 kg and 860 kg respectively. The weight reduction work cost $6.2 billion USD 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 15th of December in 2006. In late 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.
Testing found several major problems: early F-35B airframes had 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 early 2009, the DoD Joint Estimate Team (JET) 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 third-party contractors.
COST OVERRUNS
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 (GAO) 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 (i.e., to 2070) to $1.5 trillion in 2017 taxpayer dollars which also included operations and, most crucially, maintenance, and proceeded to anger Congress to no end.
The F-35A's unit cost for Lot 13 production was $79.2 million, for example. Delays in development and operational test and evaluation pushed full-rate production to 2023.
SUPPOSED UPGRADES
The first combat-capable Block 2B configuration, which had basic air-to-air and strike capabilities, was declared ready by the USMC in July 2015. The Block 3F configuration began operational test and evaluation (OT&E) in December 2018, the completion of which will conclude SDD. The F-35 program is also conducting sustainment and upgrade development, with early aircraft gradually upgraded to the baseline Block 3F standard by mid-2021.
USAF F-35A, Note the sawtooth pattern of the fuselage.
The F-35 is expected to be continually upgraded over its lifetime. The first upgrade program, called Continuous Capability Development and Delivery (C2D2) began in 2019 and is currently planned to run to 2024.
The near-term development priority of C2D2 is Block 4, which would integrate additional weapons, including those unique to international customers, refresh the avionics, improve ESM capabilities, and add Remotely Operated Video Enhanced Receiver (ROVER) support. C2D2 also places greater emphasis on agile software development to enable quicker releases.
In 2018, the Air Force Life Cycle Management Center (or AFLCMC) awarded contracts to General Electric and Pratt & Whitney to develop more powerful and efficient adaptive cycle engines for potential application in the F-35, leveraging the research done under the Adaptive Engine Transition Program (AETP); in 2022, the F-35 Adaptive Engine Replacement (FAER) program was launched to integrate adaptive cycle engines into the aircraft by 2028.
F-35A over Miami, Florida, USA
Defense contractors have offered upgrades to the F-35 outside of official program contracts. In 2013, Northrop Grumman disclosed its development of a directional infrared countermeasures suite, named Threat Nullification Defensive Resource (ThNDR or simply Thunder). The countermeasure system would share the same space as the Distributed Aperture System (DAS) sensors and acts as a laser missile jammer to protect against infrared-homing missiles.
INTERNATIONAL SALES/EXPORT
In September 2022, the F-35 international delivery was temporarily suspended after determining Chinese-sourced materials were used in Honeywell-branded pumps.
Sales to SCP and non-partner states, including Belgium, Japan, and South Korea, are made through the Pentagon's Foreign Military Sales program. Turkey was removed from the F-35 program in July 2019 over security concerns following its purchase of a Russian S-400 surface-to-air missile system. With the ongoing Russian invasion of Ukraine, this is more than a little controversial; it is bordering on supporting an enemy of the Western world.
DEEPER DESIGN OVERVIEW
The F-35 is a family of single-engine, supersonic, stealth multirole fighters. The second fifth generation fighter to enter US service (the first being the F-22 Raptor) and the first operational supersonic STOVL stealth fighter, the F-35 emphasizes low-observables, advanced avionics, and sensor fusion that enable a high level of situational awareness, and long-range lethality; the USAF considers the aircraft its primary strike fighter for conducting suppression of enemy air defense (SEAD) missions AKA Wild Weasel missions, owing to the advanced sensors, and mission systems.
F-35A with G-Forces being shown as Vortices on the wingtips
The F-35 has a wing-tail configuration with two vertical stabilizers canted for stealth. Flight control surfaces include leading-edge flaps, flaperons, rudders, and all-moving horizontal tails (stabilators); leading edge root extensions or chines also run forwards to the inlets. The relatively short 35-foot wingspan of the F-35A and F-35B is set by the requirement to fit inside USN amphibious assault ship parking areas and elevators; the F-35C's larger wing is more fuel efficient. The fixed diverterless supersonic inlets (DSI) use a bumped compression surface and forward-swept cowl to shed the boundary layer of the forebody away from the inlets, which form a Y-duct for the engine. Structurally, the F-35 drew upon lessons from the F-22; composites comprise 35% of airframe weight, with the majority being composite epoxy materials as well as some carbon nanotube-reinforced epoxy in later production lots. The F-35 is considerably heavier than the lightweight fighters it replaces, with the lightest variant having an empty weight of 13,300 kg; much of the weight can be attributed to the internal weapons bays and the extensive avionics carried.
While lacking the top speed of the larger twin-engine F-22, the F-35 is competitive with fourth generation fighters such as the F-16 and F/A-18, especially when they carry weapons because the F-35's internal weapons bay eliminates drag from external stores. All variants have a top speed of Mach 1.6, attainable with full internal payload. The powerful F135 engine gives good subsonic acceleration and energy, with supersonic dash in afterburner. The large stabilitors, leading edge extensions and flaps, and canted rudders provide excellent high alpha (angle-of-attack) characteristics, with a trimmed alpha of 50°. Relaxed stability and triplex-redundant fly-by-wire controls provide excellent handling qualities and departure resistance. Having over double the F-16's internal fuel, the F-35 has a considerably greater combat radius, while stealth also enables a more efficient mission flight profile.
The F-35's mission systems are among the most complex aspects of the aircraft. The avionics and sensor fusion are designed to enhance the pilot's situational awareness and command and control capabilities and facilitate network-centric warfare. Key sensors include the Northrop Grumman AN/APG-81 active electronically scanned array (AESA) radar, BAE Systems AN/ASQ-239 Barracuda electronic warfare system, Northrop Grumman/Raytheon AN/AAQ-37 Electro-optical Distributed Aperture System (DAS), Lockheed Martin AN/AAQ-40 Electro-Optical Targeting System (EOTS) and Northrop Grumman AN/ASQ-242 Communications, Navigation, and Identification (CNI) suite. The F-35 was designed with sensor intercommunication to provide a cohesive image of the local battlespace and availability for any possible use and combination with one another; for example, the APG-81 radar also acts as a part of the electronic warfare system.
Much of the F-35's software was developed in C and C++ programming languages, while Ada83 code from the F-22 was also used; the Block 3F software has 8.6 million lines of code. The Green Hills Software Integrity DO-178B real-time operating system (RTOS) runs on integrated core processors (ICPs); data networking includes the IEEE 1394b and Fibre Channel buses. To enable fleet software upgrades for the software-defined radio systems and greater upgrade flexibility and affordability, the avionics use commercial off-the-shelf (COTS) components when practical. The mission systems software, particularly for sensor fusion, was one of the program's most difficult parts and responsible for substantial program delays.
INTEGRATED RADAR SYSTEMS
F-35 Helmet Showing Radar Interlink
The APG-81 radar uses electronic scanning for rapid beam agility and incorporates passive and active air-to-air modes, strike modes, and synthetic aperture radar (SAR) capability, with multiple target track-while-scan at ranges in excess of 80 nmi (150 km). The antenna is tilted backwards for stealth.
Complementing the radar is the AAQ-37 DAS, which consists of six infrared sensors that provide all-aspect missile launch warning and target tracking; the DAS acts as a situational awareness infrared search-and-track (SAIRST) and gives the pilot spherical infrared and night-vision imagery on the helmet visor.
The ASQ-239 Barracuda electronic warfare system has ten radio frequency antennas embedded into the edges of the wing and tail for all-aspect radar warning receiver (RWR). It also provides sensor fusion of radio frequency and infrared tracking functions, geolocation threat targeting, and multispectral image countermeasures for self-defense against missiles.
Through sensor fusion, information from radio frequency receivers and infrared sensors are combined to form a single tactical picture for the pilot. The all-aspect target direction and identification can be shared via MADL to other platforms without compromising low observability, while the Link 16 system is present for communication with legacy systems.
APG-81 Radar Antenna Mounted in the F-35s’ Nose
A new radar called the AN/APG-85 is planned for Block 4 F-35s. According to the JPO the new radar will be compatible with all three major F-35 variants. However, it is unclear if older aircraft will be retrofitted with the new radar.
JUDGMENT
The F-35 was designed from the outset to incorporate improved processors, sensors, and software enhancements over its lifespan, i.e. be constantly upgradeable and keep up with evolving technology. Technology Refresh 3, which includes a new core processor and a new cockpit display, is planned for the Lot 15 aircraft. Lockheed-Martin has offered the Advanced EOTS for the Block 4 configuration; the improved sensor fits into the same area as the baseline EOTS with minimal changes.
In June of 2018, Lockheed-Martin picked Raytheon for the improved DAS work. The USAF has studied the potential for the F-35 to orchestrate attacks by unmanned combat aerial vehicles (UCAVs) via its sensors and intelligent communications equipment and the verdict is still out.
STEALTH
Stealth is a key aspect of the F-35's design, and radar cross-section (RCS) is minimized through careful shaping of the airframe and the use of radar-absorbent materials (RAM); visible measures to reduce RCS include alignment of edges, serration of skin panels, and the masking of the engine face and turbine. Additionally, the F-35's diverterless supersonic inlet (DSI) uses a compression bump and forward-swept cowl rather than a splitter gap or bleed system to divert the boundary layer away from the inlet duct, eliminating the diverter cavity and further reducing radar signature. The RCS of the F-35 has been characterized as lower than a metal golf ball at certain frequencies and angles; in some conditions, the F-35 compares favorably to the F-22 in stealth capability and mission optimization.
The F-35's stealth design is primarily focused on high-frequency X-band wavelengths; low-frequency radars can spot stealthy aircraft due to Rayleigh scattering, but such radars are also conspicuous, susceptible to clutter, and lack precision. To disguise its Radar Cross-Section, the aircraft can mount up to four Luneburg lens reflectors.
For added context, a Luneburg lens is a spherically symmetric gradient-index lens. A typical Luneburg lens's refractive index n decreases radially from the center to the outer surface. They can be physically made for use with electromagnetic radiation from visible light to radio waves.
COCKPIT MAKE UP
Imagery from a USAF F-35 Cockpit Simulator
The glass cockpit was designed to give the pilot good situational awareness. The main display is a 50 by 20 cm panoramic touchscreen, which shows flight instruments, stores management, CNI information, and integrated caution and warnings; the pilot can customize the arrangement of the information. Below the main display is a smaller stand-by display. The cockpit has a speech-recognition system developed by the Adacel Corporation. The F-35 does not have a typical head-up display; instead, flight and combat information is displayed on the visor of the pilot's helmet in a helmet-mounted display system (HMDS). The one-piece tinted canopy is hinged at the front and has an internal frame for structural strength.
The Martin-Baker US16E ejection seat is launched by a twin-catapult system housed on side rails. There is a right-hand side stick and throttle hands-on throttle-and-stick system. For life support, an onboard oxygen-generation system (OBOGS) is fitted and powered by the Integrated Power Package (IPP), with an auxiliary oxygen bottle and backup oxygen system for emergencies.
Due to the HMDS's vibration, jitter, night-vision and sensor display problems during development, Lockheed Martin and Elbit issued a draft specification in 2011 for an alternative HMDS based on the AN/AVS-9 night vision goggles as backup, with BAE Systems chosen later that year. A cockpit redesign would be needed to adopt an alternative HMDS. Following progress on the baseline helmet, development on the alternative HMDS was halted in October of 2013. In late 2016, the Gen 3 helmet with an improved night vision camera, new liquid crystal displays, automated alignment and software enhancements was introduced with Lot 7.
ARMAMENT
Now for the good stuff.
To preserve its stealth shaping, the F-35 has two internal weapons bays each with two weapons stations. The two outboard weapon stations each can carry ordnance up to 1,100 kg, or 680 kg for the F-35B, while the two inboard stations carry air-to-air missiles. Air-to-surface weapons for the outboard station include the Joint Direct Attack Munition (JDAM), Paveway series of bombs, Joint Standoff Weapon (JSOW), and cluster munitions (or Wind Corrected Munitions Dispenser). The station can also carry multiple smaller munitions such as the GBU-39 Small Diameter Bombs (SDB), GBU-53/B SDB II, and SPEAR 3 anti-tank missiles; up to four SDBs can be carried per station for the F-35A and F-35C, and three for the F-35B. The inboard station can carry the AIM-120 AMRAAM and eventually the AIM-260 JATM. Two compartments behind the weapons bays contain flares, chaff, and towed decoys.
The aircraft can use six external weapons stations for missions that do not require stealth. The wingtip pylons each can carry an AIM-9X or AIM-132 ASRAAM and are canted outwards to reduce their radar cross-section. Additionally, each wing of the F-35 has a 2,300 kg inboard station and a 1,100 kg middle station, or 680 kg for F-35B. The external wing stations can carry large air-to-surface weapons that would not fit inside the weapons bays such as the AGM-158 Joint Air to Surface Standoff Missile (JASSM) cruise missile. An air-to-air missile load of eight AIM-120s and two AIM-9s is possible using internal and external weapons stations; a configuration of six 910 kg bombs, two AIM-120s AMRAAM (Advanced Medium Range Air-to-Air Missiles), and two AIM-9s Sidewinder Air-to-Air missiles can also be arranged.
F-35A of the US Air Force showcasing the open weapons bays and carrying two (2) B-61 nuclear bombs, each capable of annihilating a city.
The F-35A is armed with a 25 mm GAU-22/A rotary cannon mounted internally near the left wing root with 182 rounds carried; the gun is more effective against ground targets than the 20 mm cannon carried by other USAF fighters. Most crucial to note is that the F-35B and F-35C have no internal gun and instead can use a multi-mission pod (MMP) carrying the GAU-22/A and 220 rounds; the pod is mounted on the centerline of the aircraft and shaped to reduce its radar cross-section. In lieu of the gun, the pod can also be used for different equipment and purposes, such as electronic warfare, aerial reconnaissance, or rear-facing tactical radar.
Lockheed-Martin is developing a weapon rack called Sidekick that would enable the internal outboard station to carry two AIM-120s, thus increasing the internal air-to-air payload to six missiles, currently offered for Block 4.Lockheed Martin is developing a weapon rack called Sidekick that would enable the internal outboard station to carry two AIM-120s, thus increasing the internal air-to-air payload to six missiles, currently offered for Block 4.
The USAF plans for the F-35A to take up the close air support (CAS) mission in contested environments; amid criticism that it is not as well-suited as a dedicated attack platform, such as the beloved A-10 Thunderbolt II. In 2023, USAF chief of staff General Mark Welsh placed a focus on weapons for CAS sorties, including guided rockets, fragmentation rockets that shatter into individual projectiles before impact, and more compact ammunition for higher capacity gun pods. Fragmentary rocket warheads create greater effects than cannon shells as each rocket creates a "thousand-round burst", delivering more projectiles than a strafing run.
However, this is a blog subject all it’s own.
ENGINE SYSTEMS OVERVIEW
The single-engine aircraft is powered by the Pratt & Whitney F135 low-bypass augmented turbofan with rated thrust of 125 kN at military power and 191 kN with afterburner. Derived from the Pratt & Whitney F119 used by the F-22, the F135 has a larger fan and higher bypass ratio to increase subsonic thrust and fuel efficiency, and unlike the F119, is not optimized for supercruise. The engine contributes to the F-35's stealth by having a low-observable augmenter, or afterburner, that incorporates fuel injectors into thick curved vanes; these vanes are covered by ceramic radar-absorbent materials and mask the turbine. The stealthy augmenter had problems with pressure pulsations, or "screech", at low altitude and high speed early in its development. The low-observable axisymmetric nozzle consists of 15 partially overlapping flaps that create a sawtooth pattern at the trailing edge, which reduces radar signature and creates shed vortices that reduce the infrared signature of the exhaust plume. Due to the engine's large dimensions, the U.S. Navy had to modify its underway replenishment system to facilitate at-sea logistics support. The F-35's Integrated Power Package (IPP) performs power and thermal management and integrates environment control, auxiliary power unit, engine starting, and other functions into a single system.
Supercruise Definition
Simply put, Supercruise is sustained supersonic flight of a supersonic aircraft without using active afterburner (also known as "reheat"). Many supersonic military aircraft are not capable of Supercruise and can maintain Mach 1+ flight only in short bursts with afterburners. Aircraft such as the SR-71 Blackbird are designed to cruise at supersonic speed with afterburners enabled. One of the best-known examples of an aircraft capable of Supercruise was the Concorde. Due to its long service (20+ years with Air France and British Airways) as a commercial airliner, the Concorde holds the record for the most time spent supersonic; more than all other aircraft combined. The F-35 is truly the first of its kind.
ENGINE TYPE FOR VARIANTS
The F135-PW-600 variant for the F-35B incorporates the Shaft-Driven Lift Fan (SDLF) to allow STOVL operations. Designed by Lockheed Martin and developed by Rolls-Royce, the SDLF, also known as the Rolls-Royce Lift-System, consists of the lift fan, drive shaft, two roll posts, and a "three-bearing swivel module" (also known as the 3BSM). The thrust vectoring 3BSM nozzle allows the main engine exhaust to be deflected downward at the tail of the aircraft and is moved by a so-called "fueldraulic" actuator that uses pressurized fuel as the working fluid. Unlike the Harrier's “Pegasus” named engine that entirely uses direct engine thrust for lift, the F-35B's system augments the swivel nozzle's thrust with the lift fan; the fan is powered by the low-pressure turbine through a drive shaft when engaged with a clutch and placed near the front of the aircraft to provide a counterbalancing thrust.
In December 2020, GE's XA100 (A100) completed its first successful run. General Electric's detailed design was completed in February 2019, and initial testing at GE's high-altitude test facility in Evendale, Ohio was concluded in May 2021. GE expects that the A100 can enter service with the F-35A and C in 2027 at the earliest.
F-35Cs in formation with 2 F/A-18E/F Super Hornets at “Top Gun” Naval Air Station (NAS) Fallon, Nevada
The F-35 is expected to receive propulsion upgrades over its lifecycle to adapt to emerging threats and enable additional capabilities. In 2016, the Adaptive Engine Transition Program (AETP) was launched to develop and test adaptive cycle engines, with one major potential application being the re-engining of the F-35; in 2018, both GE and P&W were awarded contracts to develop 200 kN thrust class demonstrators, with the designations XA100 and XA101 respectively.
MAINTENANCE
The F-35 is designed to require less maintenance than prior stealth aircraft. Some 95% of all field-replaceable parts are "one deep"—that is, nothing else need be removed to reach the desired part; for instance, the ejection seat can be replaced without removing the canopy. The F-35 has a fibermat radar-absorbent material (RAM) baked into the skin, which is more durable, easier to work with, and faster to cure than older RAM coatings; similar coatings are being considered for application on older stealth aircraft such as the F-22.
The flight control system (FCS) uses electro-hydrostatic actuators rather than traditional hydraulic systems; these controls can be powered by lithium-ion batteries in case of emergency. Commonality between variants led to the USMC's first aircraft maintenance Field Training Detachment, which applied USAF lessons to their F-35 operations.
The F-35 was initially supported by a computerized maintenance management system named Autonomic Logistics Information System (ALIS). In concept, any F-35 can be serviced at any maintenance facility and all parts can be globally tracked and shared as needed. Due to numerous problems, such as unreliable diagnoses, excessive connectivity requirements, and security vulnerabilities, ALIS is being replaced by the cloud-based Operational Data Integrated Network (ODIN). From September 2020, ODIN base kits (OBKs) were running ALIS software, as well as ODIN software, first at Marine Corps Air Station (MCAS) Yuma, Arizona, then at Naval Air Station (NAS) Lemoore, California, in support of Strike Fighter Squadron (VFA) 125 on 16 July 2021, and then Nellis Air Force Base (Nellis AFB), Nevada, in support of the 422nd Test and Evaluation Squadron (TES) on 6th of August of 2021. In 2022, over a dozen more OBK sites will replace the ALIS's Standard Operating Unit unclassified (SOU-U) servers.
OPERATIONAL HISTORY
None, only training and testing has been held and practiced as operations. No actual combat operations are available.
After the redesigned tail hook arrived, the F-35C's carrier-based Development Test I began in November 2014 aboard the supercarrier USS Nimitz and focused on basic day carrier operations and establishing launch and recovery handling procedures. Development Test II, which focused on night operations, weapons loading, and full power launches, took place in October 2015. The final Development Test III was completed in August of 2016, and included tests of asymmetric loads and certifying systems for landing qualifications and interoperability. Operational test of the F-35C began in 2018 by the US Navy.
EVALUATIONS
F-35 pilot mounting the ingress ladder to the cockpit. This ladder is retractable.
The F-35's reliability and availability have fallen short of requirements, especially in the early years of testing. The ALIS maintenance and logistics system was plagued by excessive connectivity requirements and faulty diagnoses. Late in 2017, the Government Accountability Office (GAO) reported the time needed to repair an F-35 part averaged 172 days, which was "twice the program's objective," and that shortage of spare parts was degrading readiness. In 2019, while individual F-35 units have achieved mission-capable rates of over the target of 80% for short periods during deployed operations, fleet-wide rates remained below target. The fleet availability goal of 65% was also not met, although the trend shows improvement. Gun accuracy of the F-35A remains unacceptable per the US Air Force as of early 2023. As of 2020, the number of the program's most serious issues have been decreased by half but no details have been released as of 2023.
The F-35A and F-35B were cleared for basic flight training in early 2012, although there were concerns over safety and performance due to lack of system maturity at the time. During the Low Rate Initial Production (LRIP) phase, the three U.S. military services jointly developed tactics and procedures using flight simulators, testing effectiveness, discovering problems and refining design. On the 10th of September, 2012, the USAF began an operational utility evaluation (OUE) of the F-35A, including logistical support, maintenance, personnel training, and pilot execution.
VARIANTS
As stated, there are three operational variants in US service.
Differentiation of the F-35 Variants A, B, and C for the US Air Force, Marine Corps, and Navy in that order, left to right.
F-35A
The F-35A is the conventional take-off and landing (CTOL) variant intended for the USAF and other air forces. It is the smallest, lightest version and capable of 9 g, the highest of all variants.
Although the F-35A currently conducts aerial refueling via boom and receptacle method, the aircraft can be modified for probe-and-drogue refueling if needed by the customer. A drag chute pod can be installed on the F-35A, with the Royal Norwegian Air Force being the first operator and ally to adopt it.
F-35B
The F-35B is the short take-off and vertical landing (STOVL) variant of the aircraft. Similar in size to the A variant, the B sacrifices about a third of the A variant's fuel volume to accommodate the SDLF. This variant is limited to 7 g. Unlike other variants, the F-35B has no landing hook. The "STOVL/HOOK" control instead engages conversion between normal and vertical flight. The F-35B is capable of Mach 1.6 and can perform vertical and/or short take-off and landing (V/STOL). This variant is commonly utilized by the US Marine Corps.
F-35C
The F-35C is a carrier-based variant designed for catapult-assisted take-off but arrested recovery operations from aircraft carriers. The F-35C is the US Navy’s primary carrier-borne fighter of the 21st century. Compared to the F-35A, the F-35C features larger wings with foldable wingtip sections, larger 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 F-35C is limited to 7.5 g of force.
ALLIED VARIANTS
Only one is known to exist.
ISRAEL
The F-35I Adir (Hebrew: meaning "Awesome", or "Mighty One") is an F-35A with unique Israeli modifications.
The US initially refused to allow such changes before permitting Israel to integrate its own electronic warfare systems, including sensors and countermeasures. The main computer has a plug-and-play function for add-on systems; proposals include an external jamming pod, and new Israeli air-to-air missiles and guided bombs in the internal weapon bays. A senior IAF official said that the F-35's stealth may be partly overcome within 10 years despite a 30 to 40-year service life, thus Israel's insistence on using their own electronic warfare systems. Israel Aerospace Industries (IAI) has considered a two-seat F-35 concept; an IAI executive noted: "There is a known demand for two seats not only from Israel but from other air forces".
PROPOSED VERSION
The Canadian CF-35 was a proposed variant that would differ from the F-35A through the addition of a drogue parachute and the potential inclusion of an F-35B/C-style refueling probe. In 2012, it was revealed that the CF-35 would employ the same boom refueling system as the F-35A.[334] One alternative proposal would have been the adoption of the F-35C for its probe refueling and lower landing speed; however, the Parliamentary Budget Officer's report cited the F-35C's limited performance and payload as being too high a price to pay. Following the 2015 Federal Election, the Liberal Party, whose campaign had included a pledge to cancel the F-35 procurement, formed a new government and commenced an open competition to replace the existing aging CF-18 Hornet fighters. The CF-35 variant was deemed too expensive to develop, and was never considered. The Canadian government decided to not pursue any other modifications in the Future Fighter Capability Project, and instead focused on the potential procurement of the existing F-35A variant. It has been speculated, however, that the Royal Canadian Air Force (RCAF) would still include the drag chute pod as seen on RNoAF F-35As for shortened landing distances.
On the 28th of March in 2022, the Canadian Government began negotiations with Lockheed Martin for 88 F-35As to replace the aging fleet of CF-18 fighters starting in 2025. The aircraft are reported to cost up to CA$19bn total with a life-cycle cost estimated at CA$77bn over the course of the F-35 program. On the 9th of January in 2023, Canada formally confirmed the purchase of 88 aircraft with an initial delivery of 16 aircraft to the RCAF in 2026 and the final batch in 2032. The additional characteristics confirmed for the CF-35 included the drag chute pod for landings at short/icey arctic runways, as well as the 'sidekick' system, which allows the CF-35 to carry up to 6 x AIM-120D missiles internally (instead of the typical internal capacity of 4 x AIM-120 missiles on other variants).
This is all we know so far.
