The F-35B is the world’s first supersonic short takeoff vertical landing (STOVL) aircraft, capable of Mach 1.6 carrying two AIM-120C and two 1,000lb GBU-32 JDAM, as well as being the first stealth plane of its kind. The United States Marine Corps’ (USMC) initial operational experience highlights the fact that a direct comparison between the F-35B and legacy fighters, such as the F/A-18 and AV-8B, is not possible. Lockheed Martin’s F-35 is not simply an improvement over previous generations of aircraft: rather, it rewrites the doctrine and practice of air operations.
The USMC intends to replace both the AV-8B HARRIER and the F/A-18 HORNET fleets with 353 F-35Bs and 67 F-35Cs. The original requirement was for an aircraft with a higher speed when loaded than legacy platforms - one that featured enhanced survivability (especially at low altitudes), advanced avionics and sensors, and autonomous target acquisition capabilities. In addition, autonomy, low observability and sensor fusion have been common features also sought by the US Air Force (USAF) and US Navy (USN).
It is worth noting that the F-35 is the first combat aircraft in which systems are integrated rather than federated. In a plane with federated systems, such as fourth-generation fighters, each new sensor adds to the volume of information the pilot has to analyse in order to take a decision. Fifth-generation aircraft, however, do not require the pilot to analyse masses of data – the system do it for him, providing a synthetic picture offering all possible levels of situational awareness and enabling swift decision-making. This approach speeds up the decision-making process in combat, to the point at which information superiority can overcome any threat.
Professional estimates are that situational awareness is the determining factor in 80% of air combat engagements. In this respect it is important to fully understand that the apparent limitations a STOVL variant imposed on the F-35 design are fairly minor in comparison to the advantages coming from the philosophy the F-35 has been built around.
The STOVL variant is 5,500lbs (2,497kg) heavier than the -A variant because of its peculiar airframe and the presence of additional titanium components. It mounts the Rolls-Royce LiftSystem, built around the F-135 engine, that consists of a shaft-driven LiftFan behind the cockpit, a thrust vectoring nozzle for the engine exhaust (on three Bearing Swivel Modules), and two underwing roll ducts. The F-135 for the -B version is capable of 41,000lbs (182,4kN) thrust, equally split between the main engine and the LiftFan during vertical take-off and/or landing. This elaborate system makes landing operations very swift in comparison to legacy AV-8Bs, as it guarantees the fully automatic command of pitch and roll, thus easing point-to-point approach manoeuvres. The plane even has an automatic programme for landing on amphibious attack ships.
As the F-35B is the most complex variant, and its design has been heavily influenced by the LiftFan, it has a smaller internal weapon bay and less internal fuel capacity than either the -A or -C variants. The weapons loadout is limited to 15,000lbs/6,800kg instead of the other variants’ 18,000lbs/8,160kg – and the same principle applies to fuel load. It can carry 13,500lbs/6,125kg of JP5 fuel internally (against 18,250lbs/8,272kg for the -A variant and 19,750lbs/8,960kg for the -C model) that gives the aircraft a 900nm (1,667km) range of action: it can also be refuelled via the probe-and-drogue method.
Another visible difference is the absence of the internally-mounted GAU-22A 25mm four-barrel Gatling cannon, with 182 rounds. When required, the F-35B and -C can carry the 3,000 rpm GAU-22A in a low-observable pod weighing 445kg and carrying 220 rounds. Estimates credit the gun with 38% greater accuracy than the legacy six-barrelled 20mm M-61 VULCAN.
To Be or Not to Be – the Question is Stealth
The US military has pledged enormous political and financial capital in the deployment of growing numbers and types of stealth hardware. Originally, the F-35 was to have a -30db/sqm radar signature (equivalent to a 10cm2 object), 100 times better than that of the F-22. Today, we know that those expectations have been exceeded: series aircraft have proven much stealthier than prototypes, with a -45db m2 (6mm2) signature, not limited to the frontal arch. This means that the fighter can be the first to attack or to disengage against any target, in the air or on the ground.
For example, an F-35 can detect a semi-stealthy fighter such as a TYPHOON, RAFALE or F-18E at 120km, while they can only detect the F-35 at a 33-38km distance.
There are even rumours that the Sukhoi Su-50, whose RCS is in the 0.1-1m2 range, according to Russian sources, can be detected at 120-150km by the AN/APG-81 active electronically scanned array (AESA) radar. This radar can track 23 targets in nine seconds and engage 19 of them in 2.4 seconds. In addition, and can be coupled with the AN/ASQ-239 EW/ECM suite for false target generation and range-gate stealing using digital RF memory (DRFM) techniques. Key sensors include the AAQ-40 electro-optical targeting system (EOTS), AAQ-37 Distributed Aperture System (DAS), and the Threat Nullification Defensive Resource (ThNDR) DIRCM.
Assessments made during ‘Green Flag’ and ‘Red Flag’ exercises – at least as far as publicly available information is concerned – showed that Russian S-300/400 missiles, deemed capable of downing F-35s by numbers of critics, can engage the plane only at ranges as close as 30km – a shorter range than the F-35’s internal stand-off weapons. To sum up, low observability is seen as the key for boosting survivability in initial hostile air operations. Low observability is not achieved exclusively through the airframe geometry or special materials: doctrine, tactics, and the effect of force multipliers are fundamental as well. For instance, a four-ship F-35 formation has been selected as the optimum guarantee of adequate mutual coverage in terms of sensors, communications, and electronic warfare capabilities.
These allow the formation to maintain a stealth profile, for example, with one aircraft using its radar and the others in passive mode yet able to share the same comprehensive situational awareness in real time through the Communication/Identification/Navigation (CNI) System and/or the Multifunction Advanced Data Link (MADL), thus reducing the electronic footprint of the entire formation. Alternatively, one or more planes might be focussed on EW tasks. As this capacity is common to all F-35s, the -B version can contribute to high-intensity air campaigns from the very beginning.
Such comprehensive capacities will allow the USMC to retire its EA-6B PROWLER fleet without sacrificing the force multiplication effects of its EW suites.
It is no mystery, however, that the primary role of USMC F-35Bs is providing coverage for Marines on the ground, on the beach or in the littorals. The aircraft will thus be focused on close air support (CAS) or battlefield air interdiction (BAI) missions through most of its service life. This has fuelled criticism involving the apparent contradiction between stealth and close fire support. Gen Jon Davis, former Deputy Commandant for Aviation, responded to such criticism by stating, “let them [Lockheed Martin] deliver more, let them do it faster!
” adding that the F-35B’s performance as a fused sensor makes it a primary asset to guarantee the safety of US Marines on the ground. Unlike the AV-8B, the F-35B really is all-weather, can look through clouds, and can deliver its weapons from altitudes and distances at which the lower echelons of air defence cannot intervene. The critical issue for the Corps is integration of the GBU-53/B SDB-II small diameter bomb, eight of which will be mounted internally, that will come with the Block4 release, expected by 2020. The 208lb/127kg ordnance can hit static and moving targets 40 miles away, thus representing a key enabler for the USMC’s new tactics for air-to-ground operations.
The F-35B reached its Initial Operational Capability (IOC) with the USMC in 2015, when the first fighters were deployed at MCAS Iwakuni, Japan, and where 16 aircraft are permanently based and combat ready, today.
The first British and Italian examples have been delivered to USMC Air Station Beaufort, SC, where Marine Fighter Attack Training Squadron 501 (VMFAT-501) is in charge of training. Current plans include another training squadron and two operational squadrons within Marine Aircraft Group 31, thus starting to replace F/A-18C and D. To date, VMFAT-501 has 31 F-35Bs, 19 of which belonging to the USMC, eleven to the Royal Air Force, and one to the Italian Navy, with a second due 2018. The first Italian F-35B, produced at the final assembly and check-out (FACO) facility in Cameri, rolled out in early 2018.
After the first deployment of 6 F-35Bs onboard USS WASP (LHD-1) in March, with Fighter Attack Squadron 121 (VMFA-121), the latest milestone for US F-35Bs was the first combat deployment aboard the amphibious assault ship USS ESSEX as part of the 13th Marine Expeditionary Unit (MEU). Before deployment, some familiarisation activities took place MacDill air force base, FL, to familiarise senior planners with the LIGHTNING II’s capacities and limitations. Afterward, a squadron of F-35Bs from VMFA-211 was deployed to the ESSEX as part of an Amphibious Ready Group (ARG) that included USS ANCHORAGE (LPD-23) and USS RUSHMORE (LSD-47) for a regularly scheduled deployment in the Western Pacific and the Middle East. During the deployment, the ARG participated in the 24th Cooperation Afloat Readiness and Training (CARAT) exercise in Indonesia and the third iteration of the Multilateral Naval Exercise Komodo (MNEK).
At the same time, in July and August, VMFA-21 conducted a new round of carrier and flight deck certifications with USS WASP and ASHLAND (LSD-48). Following deployment, the F-35B is reportedly capable of supporting the full spectrum of combat operations required by the Marine Air-Ground Task Force (MAGTF). In addition, its capability to collect, analyse and share data in real time enhances the whole force’s airborne, surface, and ground-based capabilities in the battlespace.
In comparison to the AV-8B, the F-35B provides an air-dominance asset capable of performing CAS and BAI missions as well. As the USMC put it, it is not a “jack-of-all-trades” but a true “omnirole” fighter – unlike legacy aircraft.
The USMC has activated four squadrons so far (VMFA-121, VMFA-122, VMFA-211, and VMFAT-501) which have logged over 35,000 hours.
The British programme is progressing as well. In July, the first four F-35Bs arrived at RAF Marham, where 617 Squadron has started operating from three 67x67m Vertical Landing Pads (VLP) built on the future British Main Operating Base (MOB) – specifically built to withstand high temperatures. The squadron is expected to reach its IOC by the end of the year, after which 207 Squadron will be activated on the same base and will serve as the Operational Conversion Unit (OCU). Initially, it will deploy five or six aircraft, with a full complement of eight expected in two years. In the meantime, RAF pilots and instructors will keep training at MCAS Beaufort, where more than 150 RAF and Royal Navy (RN) personnel are learning to fly and maintain the F-35B – representing fully one third of the VMFAT-501’s personnel. The RAF and the RN also contribute to the Joint Operational Test Team for the F-35, based at Edwards AFB, with 17 Squadron flying three F-35Bs alongside the USAF’s 461st Flight Test Squadron and 31st Test and Evaluation Squadron flying the F-35A.
Finally, the first flight trials with the aircraft carrier QUEEN ELIZABETH are expected by the end of the year. According to a Lockheed Martin press release, the company has been awarded a $7.8 million contract “for support for first-of-class flying trials and release of the military permit to fly for F-35B LIGHTNING aircraft in support of the government of the United Kingdom,” with an additional $5.78 million yet to be placed.
The RAF and RN will be able to deliver a carrier strike capability by 2020.
Low Availability Issues
Reports indicate at least one matter of grave concern - that the entire F-35 fleet is experiencing low availability due to the lack of the required amount of spare parts: VMFAT-501 has reported rates of availability as low as 38%. Both Air Combat Command (ACC) and the General Accountability Office (GAO) have investigated the issue, concluding that it is not unusual for new aircraft to experience periods of shortage, as the logistic chain has not yet been perfected. Although sophisticated prediction models are used to estimate the volume of parts required, the reality is that these are only estimates until the aircraft actually enters service.
Only after a considerable number of flying hours have been logged can algorithms feeding the aircraft’s Autonomic Logistics Information System (ALIS) learn which parts fail more often than others and tweak the logistic model accordingly. On the industrial side, production of spare parts can be launched in the correct proportions as soon as predictive models start being reliable enough. According to the DoD, this will take a few years, after which no maintenance problems will continue.