An artist's impression of Japan's sixth-generation F-X fighter. Photo: UK Defense Journal

Japan and the United Kingdom have announced plans to collaborate on engine development for their sixth-generation fighter programs, a joint bid to steal a march in the global fighter jet development race.

Mitsubishi Heavy Industries (MHI) and Ishikawajima Heavy Industries (IHI) will lead Japan’s efforts, while Rolls Royce and BAE Systems will be responsible for the UK’s share. 

Both countries are also working on a “joint air-to-air” missile program and intend to sign a Memorandum of Cooperation to share technologies. Joint engine development efforts are slated to start in April 2022 after a joint feasibility study.

Japan and the UK’s collaboration reflects both parties’ capability requirements for a dedicated air superiority platform. While both countries operate the US-made F-35 fifth-generation jet, that design is optimized for strike missions and not air superiority.

This shows a lack of confidence in the F-35’s air-to-air combat capabilities against Chinese and Russian fifth-generation designs, such as the J-20 and Su-57 respectively. 

There is no agreed-upon definition of what is constitutes a sixth-generation fighter jet, but they may feature technologies such as modular design, optionally-manned capability, drone swarms, directed energy weapons, machine learning, artificial intelligence, virtual reality and augmented reality. 

Japan’s F-X sixth-generation fighter program aims to check China’s air force by fielding a new air superiority fighter that presents an overmatch to China’s existing fifth and fourth-generation fighters. Japan intends to start series production of the F-X in 2031, with entry into service in 2035. 

Japan’s capability requirement for a new dedicated air superiority fighter stems from its need to match China’s aerial swarming tactics in the Senkaku Islands. In 2019, Japan recorded no fewer than 675 Chinese incursions in its air defense identification zone (ADIZ).

F-15 fighter jets sit at Japan’s Air Self Defense Force base at Naha in Okinawa on February 6, 2019. Photo: AFP / Yomiuri Shimbun

Responding to these incursions is the responsibility of Japan’s increasingly overworked 200-strong fourth-generation F-15 fleet. China’s goal may be to wear down Japan’s air force, catch it off-balance, keep it on a reactive posture and inflict material losses from accidents or equipment wear.

While Japan is slated to upgrade the interception capabilities of its F-15 fleet, there are signs that the F-15 design may have reached the limit of its upgradability. Boeing has introduced its F-15 Silent Eagle upgrade, which includes stealth and some features found in fifth-generation fighters but no country has apparently opted for this upgraded model.

Japan also tried to acquire fifth-generation F-22 air superiority fighters from the US, but a US export ban on the F-22 and the closure of the F-22’s production line made this option unfeasible. These factors may have pushed Japan into developing its own sixth-generation fighter. 

The UK’s Tempest program is intended to replace the fourth-generation Eurofighter Typhoon as an air superiority platform and complement the strike capabilities of the UK’s F-35 fleet by 2035.

The program aims to rebuild the UK’s air superiority capabilities, which were de-emphasized due to the previous focus on the War on Terror, wherein there was minimal need for them.

This need is reflected by the UK’s 2021 Defense Command Paper, which stresses the UK’s need for air superiority in a potential great-power conflict against China and Russia. 

The UK has operated the Eurofighter since 2003 and expects the type to remain the backbone of the Royal Air Force until the 2040s, despite having operational costs like the F-35.

An RAF Eurofighter Typhoon armed with a Storm Shadow missile. Credit: Handout.

While the Eurofighter was initially conceived as an air superiority fighter in the 1980s, the design evolved into a multi-role platform, due to the focus on counter-terrorism in the 1990s and 2000s with successive tranche upgrades focusing on strike capabilities over air superiority. 

However, these increasingly expensive upgrades have forced the UK to retire older Eurofighter units 15 years earlier than planned. The UK has fewer than ever planes for air superiority missions, as the Eurofighter fleet has taken on the strike missions that the UK’s recently retired Tornado aircraft used to perform. 

That said, the UK’s requirements for a dedicated air superiority fighter in the context of a future great power conflict may lead to replacing the aging Eurofighter aircraft and rebuilding its air superiority fleet.

The non-optimization of the F-35 for air superiority, plus the need to accelerate development times and share development costs, may have been factors for the UK to start its Tempest program in cooperation with Japan. 

In addition to Japan and the UK’s joint sixth-generation fighter programs, France and Germany are also working on a similar collaboration with their Future Air Combat System (FCAS) program.

The FCAS aims to replace the French Rafales and German Eurofighter Typhoons in the 2040s and is slated to be one of Europe’s largest collaborative defense projects. The FCAS program aims to produce a prototype by 2026, finish development by 2030 and be operational by 2040. 

A Dassault Rafale jet goes through its paces at the Aero India air show in 2017. Photo: Wikipedia

It also aims to boost Europe’s strategic independence by reducing Europe’s dependence on US military technology and security guarantees. As with Japan and the UK, France and Germany’s capability requirement for a dedicated air superiority fighter is driven by the strategic shift from counter-terrorism to a potential great-power conflict, necessitating both countries to rebuild their own dedicated air superiority fighter fleets. 

Meanwhile, the US is also working on its Next Generation Air Dominance (NGAD) program, with a working prototype reportedly flown last year. The NGAD program aims to maintain the US’ lead in air superiority, but little else is known about it as the US has not released much information about the highly classified project. 

Russia and China also have their respective sixth-generation fighter programs, with Russia planning to use its existing Su-57 fighter as a base for its new air superiority platform. China’s possible sixth-generation prototype was spotted by satellite imagery last year, revealing a diamond tailless design similar to proposed US NGAD concepts.