Discussions between Japan and the United Kingdom concerning the development of Japan’s next-generation F-X fighter have been ongoing for five years. During that period, Japan has moved away from early plans to procure a derivative of an existing foreign-designed aircraft or to simply join an existing fighter program, and instead has opted to develop an indigenous fighter from scratch, albeit with input from allied nations. It arrived at the decision following successful trials of the indigenously-developed X-2 technology demonstrator.
F-X is receiving support from a number of partner companies. On December 18, 2020, Japan declared Lockheed Martin the “primary partner for technical assistance” for the F-X program, specifically providing integration support to prime contractor Mitsubishi Heavy Industries (MHI). Lockheed Martin's participation centers on datalink connectivity with U.S. equipment, which will be crucial in securing bilateral interoperability. Some reports suggest that Lockheed will also assist in developing an integrated radar and missile system, a more maneuverable airframe design, low-observable features, and radar-absorbent materials.
In parallel, the Japanese MoD (JMOD) has continued to drive collaboration with the UK at the F-X sub-system level, with the aim of reducing development cost and mitigating technical risk and a number of joint programs with the British have already started. Many share technologies with the ongoing Tempest sixth-generation fighter effort in Europe.
An Anglo-Italian “Team Tempest” partnership lies at the heart of the industrial group now developing the future combat air system (FCAS), planned to gradually replace the Eurofighter Typhoon in RAF service from 2035, and almost certainly those in Italian service. On December 21, 2020, the defense ministers of Italy, Sweden, and the UK signed a trilateral MoU on the development of the Tempest future fighter, though Sweden’s primary interest lies in the so-called “adjuncts” being developed to operate alongside the manned fighter, including unmanned assets such as the Mosquito loyal wingman, and the various attritable and expendable drones under development. BAE Systems reportedly briefed the Indian Ministry of Defence on FCAS and Tempest at Aero India 2019, hoping to explore the potential for collaboration on Tempest, and then gave a detailed commercial and financial presentation in 2021.
Japan’s F-X and the Tempest program run on almost parallel timelines, aiming for an in-service date in the mid-2030s. “They have an F-X program that has a very similar timeframe to us, 2035," said Royal Air Force Air Commodore Johnny Moreton. "The threat is very similar to the one that we are anticipating, and in terms of an industrial nation, clearly, they sit at the top table, as do we.”
At one time there were even hopes that Japan might become a full member of Team Tempest, and, while that didn't happen, the JMOD has outlined a commitment to applying “Tempest-like” digital engineering techniques and technologies in the development of the F-X, and there is already significant co-operation between the UK and Japan. “Joint development opportunities with Japan bring benefits in terms of shared technology and program development costs, and helps us build a stronger strategic relationship with Japan,” a senior British Tempest insider explained. Some of the co-operation efforts have been ongoing for some time.
The two countries launched a joint research project studying beyond-visual-range air-to-air missile technology in 2014, for example. The UK provided some missile technologies from MBDA’s Meteor long-range missile, while Japan integrated advanced radio-frequency (RF) seeker technologies developed for the AAM-4B missile by the Mitsubishi Electric Corporation. The Joint New Air-to-Air Missile (JNAAM) program transitioned into a technology demonstrator project in Fiscal Year 2018, and trial production of a prototype began. The partners expect to complete the project during FY 2022, after which they will evaluate the performance of the missile and decide whether it should be put into mass production.
As part of its fiscal year 2021 budget request, the JMOD asked the Ministry of Finance for JPY1.2 billion ($11.4 million) to fund the co-development of the JNAAM with the United Kingdom, including the production of a trial batch of missiles. As well as equipping the F-X, a production JNAAM could arm Tempest, and the Japanese and UK F-35 Lightning II fighter fleets.
In February 2021, the ambitious “Jaguar” (Japan and Great Britain Universal Advanced RF) project was briefly outlined. Jaguar is a prospective, co-operative universal radio-frequency (RF) system understood to combine the functions of radar, passive radio-frequency detection, jamming, and communications. It is not known how Jaguar could fit in with the gallium nitride-based active electronically scanned array radar under development for F-X by Toshiba and Fujitsu. This radar reportedly is to be fused with an infrared and electromagnetic sensor. Jaguar technology might form part of the sensing solution for the Leonardo Integrated Sensing And Non-Kinetic Effects (ISANKE) system being developed for Tempest.
In late December, Japan and the UK confirmed their intention to proceed with a joint engine demonstrator program, which was due to begin in January 2022. Intended to produce an all-new, full-scale power and propulsion demonstrator, the program would use complementary technologies developed by Rolls-Royce and IHI Corporation. The engine will be an advanced turbofan at the heart of the F-X aircraft’s propulsion, power, and thermal management systems.
Subsequently, the Japanese government announced that it had arranged for UK participation not only in the engine but also in the design of “relatable parts of the aircraft.” The cost-ineffectiveness to use a Japanese-designed center fuselage containing intakes and jetpipes with Tempest's engine meant it would be “more rational to develop it together with the engine." Therefore, both aircraft could share the same engine and similar fuselage sections, reducing development costs.
At the same time, the two nations agreed a memorandum of cooperation that will allow them to pursue further joint technologies, and they agreed to explore the feasibility of further collaboration throughout 2022. The UK and Japan hope to extend the partnership beyond engine technologies to the development of new electronic warfare and radar equipment while designing both the program and the aircraft in a way that each participating country will have full “freedom of modification,” thereby ensuring that any resulting aircraft can be customized to meet national requirements.
