Japan’s Stealth Fighter Prototype Should Finally Fly in February

But it might not ever become a frontline warplane

Japan’s Stealth Fighter Prototype Should Finally Fly in February Japan’s Stealth Fighter Prototype Should Finally Fly in February
Japan’s Advanced Technology Demonstrator-Experimental, also known as the ATD-X or X-2, will fly from Nagoya Airport to Gifu Air Base at the end of... Japan’s Stealth Fighter Prototype Should Finally Fly in February

Japan’s Advanced Technology Demonstrator-Experimental, also known as the ATD-X or X-2, will fly from Nagoya Airport to Gifu Air Base at the end of February, according to the Japanese defense ministry. This will be the first flight of the high-tech testbed and a major step toward Tokyo’s plans for a domestic stealth fighter.

The Ministry of Defense had planned for the prototype to fly back in 2014, but early last year ministry officials reported that issues with engine restarts had forced a delay to the end of 2015. Reports at the end of last year then suggested a January flight, but articles in the Asahi Shimbun on Jan. 13 and in the Nikkei on Jan. 20 seem to confirm a flight in February.

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The aircraft is currently under the control of the project’s prime contractor, Mitsubishi Heavy Industries, at their Komaki Minami Plant near Nagoya. ATD-X is already undergoing ground-based and taxiing tests. Mitsubishi will turn the prototype over to the Ministry of Defense’s Acquisition, Technology and Logistics Agency in March after the aircraft arrives at Gifu Air Base. From April, testing will begin on the aircraft’s radar systems at the Gifu Test Center, the home of advanced propulsion research in Japan.

The multitude of research programs feeding into ATD-X — technologies such as 3D thrust-vectoring, skin-embedded phased-array antennas and stealth — are due to wrap up by April 2017. There’s a hard deadline. The Mitsubishi F-2 multirole fighter is due to begin retiring in 2028. In 2018, the government plans to decide if ATD-X could form the basis of a wholly domestic fighter production program — or if Tokyo should look abroad for international collaboration or an aircraft to produce under license.


The ATD-X prototype. TRDI photo

History of a future fighter

No one knows yet what that F-2 replacement will look like. ATD-X is not a production fighter. The existing models and Mitsubishi’s prototype are a long way from a finished product. ATD-X is just a test platform to develop and maintain the technologies Japan needs if it wants to be able to build its own future fighters.

Tokyo has always been cautious about losing its technological edge. For a small island nation, technology is a shortcut to military superiority where land, people and industrial capacity cannot hope to match large continental powers. ATD-X is a good example of the Ministry of Defense trying to maintain this lead.

Japan has not made a fighter of its own since the end of the Mitsubishi F-2 production line in 2011. Across Japan’s four major aircraft manufacturers, only Mitsubishi has the skills and capacity to manage the manufacture and assembly of a domestic fighter program, and so the Ministry of Defense does all it can to keep fighters rolling out of the Komaki Minami Plant.

In December, Mitsubishi received the parts for AX-5, the first of 38 F-35s scheduled for assembly in Japan. AX-1 through 4 are under assembly at Lockheed Martin’s plant in Fort Worth, Texas, but Japan hopes to exercise its existing industrial know-how in assembling the remaining aircraft. But the black-box assembly of existing parts is nothing compared to the development and implementation of a working air superiority fighter.

The birth of the ATD-X program owes everything to Tokyo’s fear in the 1990s that the United States would not share its sensitive stealth technology with Japan. The Japanese government lobbied hard during both the F-15J and F-2 programs to convince the U.S. Congress to share the skills and technologies of America’s fourth-generation fighters.

With the impending retirement of the Air Self-Defense Force’s aging F-4EJ Phantoms, Tokyo lobbied even harder for access to the fifth-generation F-22 air superiority fighter. The 1998 Congressional ban on the Raptor’s export in 1998 confirmed Japan’s fears. Tokyo fought to sidestep the ban even as late as 2006, but the 2002 leak of Japanese data from the AEGIS combat system undoubtedly nixed the possibility of Tokyo ever receiving America’s frontline fighter.

The ¥39.4 billion ATD-X program grew out of nine years of research at the Ministry of Defense’s Technical Research and Development Institute — which last year merged with the Acquisition, Technology and Logistics Agency.

From 2000, the institute’s aeronautical engineers developed a highly-maneuverable airframe with decreased radar and infrared visibility. The program also developed paddle-based 3D thrust-vectoring of the IHI XF5-1 low-bypass turbofan engine — which was an earlier product of the organization’s research. Another core feature under development was a self-repairing flight control system that could allow an aircraft to continue flying even after sustaining damage across its airframe.

In 2006, research began on a five-year program testing “smart skin” sensors. By impregnating the fuselage with radar-capable phased-array antennas, a fighter pilot can have 360 degrees of radar awareness and track multiple targets.

Finally, in 2008, a three-year program began integrating these core technologies ahead of the development of a flying prototype from 2009. ATD-X seeks to integrate these stealthiness, maneuverability, survivability and awareness technologies into a flyable airframe that a pilot can operate effectively from an advanced cockpit.

Weapons integration is not yet part of the program. The prototype is 14.2 meters long with a wingspan of 9.1 meters — much smaller than its fifth-generation production counterparts. It is unarmed and has no space for internal weapons bays.

This means that the design is far from fixed. ATD-X is jumble of concepts to help Tokyo hone its fifth-generation industrial and technological know-how without the need for production line. A halfway point on the road toward a sixth-generation production-capable fighter.

Japan's Future Fighter Project will seek to include network-centric warfare concepts such as "cloudshooting" and unmanned standoff platforms. MoD presentation slide
Japan’s Future Fighter Project will seek to include network-centric warfare concepts such as “cloudshooting” and unmanned standoff platforms. Ministry of Defense presentation

What next?

In 2010 the Ministry of Defense made its sixth-generation fighter concept public. The ministry calls it “i³ Fighter,” with the three Is standing for “informed” — able to tap into mobile networked assets — “intelligent” — leveraging leading robotics skills and superior missile technologies — and “instantaneous” — using fly-by-light to improve reaction times and survivability.

The technologies mentioned in the i³ Fighter concept will begin development with the “Future Fighter Project” from April this year. If Japan chooses to pursue a solely domestic sixth-generation fighter, it this new project will likely form the foundation of a production model.

The i³ Fighter concept introduces several new technologies to Japan’s arsenal including network-capable target sharing, the use of unmanned aerial vehicles as stand-off sensor platforms, stealth and counter-stealth capabilities, high-powered gallium nitride radars and directed-energy weapons. Within the next four years, scientists at the Acquisition, Technology and Logistics Agency will wrap-up work on the self-defense capabilities, integrated fire control, full stealth integration and missile systems needed for the Future Fighter Project.

In addition, the ministry has been researching directed-energy weapons for the past five years and plans to continue this long into the future.


TRDI photo

But this quest to develop and maintain the high-tech engineering skills required to make a sixth-generation fighter comes with an hefty price tag. In January last year, the head of the Tohoku Defense Bureau reported that the Future Fighter Project would require a research budget of between ¥500 and ¥800 billion — up to $7 billion. This figure does not include the costs of production and life-cycle maintenance.

If Tokyo chooses to go down the path of domestic production in 2018, the Ministry of Defense and Mitsubishi Heavy Industries will have the enormous task of creating a product that will compete against products from American manufacturers such as Boeing, Northrop Grumman and Lockheed Martin.

Japan’s post-war fighters have all been made under license or using existing airframe designs. For the F-2, for example, Japan used the existing airframe of the F-16 Fighting Falcon and adapted it to their requirements. Continuing down the current path of an almost wholly new platform design will be expensive and unpredictable. This is apparent in the technological difficulties that kept ATD-X on the ground throughout 2015. Its designers are working with an unproven airplane to test unproven technologies.

Mitsubishi and the government could recuperate some of these research and development costs if they could export the final product abroad, but without investment to increase Mitsubishi’s production capacity, this will likely be impossible until the contractor completes delivery to Japan’s Air Self-Defense Force decades from now.

It is too early to predict what the government will decide in 2018 and even harder to predict what the fighter market will look like when the F-2’s successor comes into service. Japan faces a fighter crunch, with plans to mothball its F-4s being postponed until the F-35 can enter service, which even then will fail to recover to the number of fighters in service at the beginning of this decade.

This makes the 2018 decision exceptionally important. Another costly program full of delays could leave Japan handicapped in its constant struggle to insulate its airspace from unfriendly neighbors.

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