We’ve Spotted Japan’s New Stealth Fighter

ATD-X makes its first appearance as Tokyo’s warplane plans advance

War Is Boring
Jun 30, 2014 · 6 min read


Japan is working on a homegrown stealth fighter. It’s called the ATD-X. And we apparently just got our first glimpse of the prototype.

In mid-June, a blurry photo appeared on a Chinese Internet forum, purporting to depict the first ATD-X demonstrator aircraft outside a hangar in Tokyo.

The Japanese government hopes to develop the ATD-X into the frontline F-3 fighter to replace its Boeing F-15Js. Tokyo is also procuring the American-made F-35A Lightning II stealth fighter as a replacement for older F-4EJ Phantom IIs.

Tokyo plans to build 38 of the 42 Lockheed Martin F-35s itself and acquire the other four from the American factory. The total cost to Japan is $8 billion. Manufacturing the jets on the home islands should help sustain the domestic aerospace industry—specifically, fighter-maker Mitsubishi.

The ATD-X offers similar industrial benefits. But there’s a clear military rationale, as well.

As tensions with China escalate, the Japan Air Self-Defense Force sees a need for a warplane that is more than a stealthy “bomb truck”—as critics have portrayed the F-35. The Lightning II could prove useful, but no one pretends it’s a highly maneuverable air-to-air fighter.

And that’s exactly what Japan needs to defeat China’s own fighters.

Previously, Japan had hoped to acquire the American F-22 Raptor as its high-end fighter, but lawmakers in Washington banned export of the sophisticated warplane—and production has now ended.

To be clear, Mitsubishi’s ATD-X demonstrator is not itself a fighter. It’s too small and it certainly lacks weapon systems. But it could lead to the F-3 fighter.

The photo, similar to the blurry snapshots that often precede the public unveilings of new Chinese warplane designs, looks like it may well be the real thing.

The garish red-and-white color scheme is typical of aircraft belonging to Japan’s Technical Research and Development Institute, which develops new air systems on behalf of Tokyo’s Ministry of Defense. TRDI’s i3 Fighter project is researching advanced technologies that could be applicable to a future combat jet.

In terms of outward appearance, the plane in the photo bears some resemblance to a previously published ATD-X configuration known as 23DMU, which the Defense Ministry first revealed at a Japanese defense symposium in late 2013. 23DMU is one of a series of three-dimensional digital mockups that Tokyo has used to study next-generation fighters.

Like the 23DMU, the aircraft in the photo combines twin tail fins that cant outboard, closely coupled twin engines and a cropped delta wing with prominent leading-edge extensions.

Tokyo’s official fighter timeline also suggests the red-and-white aircraft is the ATD-X. According to the original plan, Mitsubishi was going to roll out the ATD-X in May 2014, but for some reason the company delayed. In September 2013, TRDI announced that static strength testing of the ATD-X airframe had begun.

According to Kyle Mizokami, War is Boring’s resident expert on Japanese aerospace technology, the photo was taken outside Nagoya Aerospace System Works, part of Mitsubishi Heavy Industries. The cameraman was a Japanese amateur, Mizokami surmised. The serial number of the aircraft reportedly is 51001.

TRDI revealed a full-scale mockup of the ATD-X back in 2007. The research agency tested the model at a radar range in France in order to determine its ability to avoid detection. The mockup possessed an overall external appearance apparently influenced by the F-22, including thrust-vectoring paddles on its twin engines.

But in its latest 23DMU guise, the ATD-X looks more like the F-35 than the F-22, perhaps reflecting Japan’s intention to learn from co-production of the Lightning II.

But while 23DMU relates to the ATD-X demonstrator, TRDI is also studying more advanced 24DMU and 25DMU fighter concepts. Thus, while the ATD-X may be a test bed for technology-development, the F-3 could also incorporate design elements from more cutting-edge concepts.

The 24DMU, for instance, seems to draw on the Northrop YF-23, the aircraft that lost out to the F-22 in the U.S. Air Force’s fighter competition back in the early 1990s. In the 24DMU, the engines are now more widely spaced, the engine intakes are narrower and trapezoidal in cross section and an all-moving V-tail replaces the twin fins and stabilizers.

Having a “tunnel” between the engines allows for tandem weapons bays, rather than the single bay in the 23DMU. Additional bays for short-range air-to-air missiles are in the wing roots. The 24DMU reportedly will be able to carry anti-ship missiles and an aft-looking radar on its tail.

The exact configuration of 25DMU is still under development, but we assume it will be even more ambitious than the 24DMU. The one available study indicates an unorthodox combination of a highly-swept wing plus tail surfaces reduced to a pair of small, downward-canted fins.

Whichever airframe concept Japan adopts, the indigenous fighter should be powered by a new turbofan engine currently under development by Ishikawajima-Harima Heavy Industries.

The XF5-1 engine is interesting for a number of reasons. First, it incorporates a complex array of inlet vanes designed to mask it from hostile radars. That should infer a high degree of stealth in the frontal sector.

Second, its advertised power rating seems surprisingly low, at just 5,000 kilograms with afterburning. Even in a twin-engine installation, that seems at odds with the idea of the F-3 as a heavyweight fighter—a genuine successor to the F-15 or F-22 and a challenger to China’s J-20.

According to the government’s plan, full-scale development of the F-3 should begin in 2016 or 2017, and a first prototype could take to the air in 2024 or ’25. Should Tokyo appropriate adequate funding, the F-3 could enter production sometime around 2027.

Whatever the F-3 ends up looking like, Japan’s continued commitment to the program shows just how seriously it takes air superiority and manned fighters. While it’s unclear exactly how many F-3s the island nation might procure, the new fighter will likely supplant the Mitsubishi F-2 strike fighter in the first half of the 2030s before replacing the F-15 in the air superiority role.

The fact that Washington wouldn’t permit Japan a license to import the F-22 might just give Tokyo a useful head-start when it comes to designing the next line of fighters, the successors to the F-22 and F-35. Some analysts have even recommended that the U.S. join Japan in developing a common sixth-generation fighter, to enter service around 2030.

War Is Boring

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