Japan expanding cooperation with Britain on development of new ASDF fighter jet

Final arrangements are being made for Britain to join in the development of airframe parts for a successor to the Air Self-Defense Force’s F-2 fighter jet, according to Japanese government sources.

Japan had already decided to co-develop the aircraft’s engine with a British manufacturer. It now aims to reduce development costs — which are expected to reach several trillion yen — by also co-developing airframe parts around the engine.

The government hopes to finalize the framework for the envisaged cooperation with Britain by March. It plans to start building prototypes in fiscal 2026, with the goal of beginning flight tests in the 2030s, the sources said.

Britain will be involved in developing the parts near the jet engine’s air intake and exhaust ports. As these parts directly affect the thrust and other aspects of the fighter’s performance, the Defense Ministry concluded that “it would be more logical to develop them with the engines,” according to a senior ministry official.

These parts are also important because they are closely related to the stealth capability and overall configuration of the airframe.

The government aims to deploy the successor aircraft in around 2035 when the retirement of F-2 fighters begins. Britain is currently working on the research and development of the next-generation Tempest fighter jet with the aim of introducing it around the same time. There are expectations, therefore, that efficiency can be boosted in common areas of development.

Britain is also willing to disclose information to Japan, a boon because there will be less confidential information and restrictions on aircraft upgrades after the deployment.

To foster domestic industry and ensure freedom of modification, the government will advocate that development of the new fighter jet be overall led by Japan, and proceed with joint development among eight domestic companies.

The government also plans to receive technical support from a U.S. company for the aircraft systems and other parts because Japan and the United States jointly respond to contingencies. The aircraft’s operation therefore must be highly compatible with the U.S. military.