【图片】蝗国将来战斗机设计方案【星桌骑士团吧】

Japan’s Ideal Fighter Would Have To Be IndigenousThe Japanese defense ministry is sticking with its idea for a big fighterOct 14, 2016Bradley Perrett | Aviation Week & Space Technology Japan is due to decide in about two years whether to develop an indigenous fighter, modify a foreign type or buy off the shelf. Evidence is pointing strongly to the defense ministry recommending building a Japanese fighter for the 2030s, under the designation F-3.The ministry is sticking to a fighter concept that it worked out in the first half of this decade, one that is not available from a foreign manufacturer and could not be realized by changing a current aircraft. This concept, presented two years ago as 25DMU and largely preserved in a so-far unrevealed updated design, calls for a hefty, stealthy fighter with a big internal load of large air-to-air missiles and long endurance, at the expense of flight performance.Japan’s Future Fighter ChoicesNothing on the market would meet demands for stealth, endurance and weapon loadNo practical modification could achieve it, eitherThe defense ministry is likely to advocate indigenous development, thereforeThe air force, not the ministry, will issue the requirement that should follow the decision on which way to go, due in the fiscal year ending March 2019. But air force thinking has gone into the defense ministry’s studies, and the service will surely be influenced by the views of government fighter technologists who have studied the problem.Above the air arm, however, is the government, which could well balk at the cost of developing a national fighter, especially one as big as the ministry thinks is necessary. Some government officials reportedly favor creating a smaller Japanese fighter, one that would be more exportable.The market for such a fighter may be doubtful. Japan would probably have to strongly differentiate its aircraft from the Lockheed Martin F-35, which by the 2030s should be enjoying the economies of a long production run and could be benefiting from an update.Deemphasis of maneuverability in 25DMU is one of several signs that the ministry’s engineers think Japan’s next fighter should engage its targets from a great distance. Another indication is a study for local adoption of the MBDA Meteor, the Western air-to-air weapon with the longest reach (see page 58). An alternative will be a Japanese missile using the 203-mm (8 in.) diameter of the current AAM-4B, says Hirofumi Doi, manager of the program, called Future Fighter, at the defense ministry’s Acquisition, Technology and Logistics Agency. The Raytheon AIM-120 Amraam is seen as lacking sufficient range.Designers kept the profile of 25DMU shallow to minimize radar reflections. Credit: Colin Throm/AW&STOne more sign of interest in long-range engagement is the ministry’s investigation of the use of air-to-air missiles as big as naval area-defense interceptors (AW&ST May 11-24, 2015, p. 32). And then there is its proposal to send unmanned aircraft ahead of fighters to detect and shoot at targets and to soak up attacks (AW&ST Sept.*26-Oct. 9, p. 20).With its obviously great size and pair of 33,000-lb.-thrust engines, DMU25 reminds many people of the Lockheed Martin F-22, the fighter that Washington refused to sell to Japan a decade ago. But the defense ministry is clearly not interested now in a fighter that, thanks to great power of maneuver as well as stealth, can close to engage with Amraams.In June, the ministry invited potential foreign partners to express interest in its program. Its document, lacking detail, asked for little more than interest, and so it prompted widespread responses, say industry sources.Timing for entry into service by the Future Fighter is not defined more precisely than the 2030s, says Doi. The aircraft is supposed to replace the Mitsubishi Heavy Industries (MHI) F-2, which can be expected to serve for 30 years, perhaps a few years longer. It entered service in 2000.Emphasizing that nothing is ruled out, the project manager tells Aviation Week that extending the F-2’s service life is an option. It does not seem to be a good one, however. The fighter, an enlargement of the Lockheed Martin F-16, is not widely considered to have been a great success. Tellingly, Japan’s F-15 Eagles, built by MHI and Boeing predecessor McDonnell Douglas, are older than the F-2s but will stay in service longer.Another concept design, 26DMU, was worked out a year after 25DMU, which itself descended from the more maneuverable concepts 23DMU and 24DMU. (The numbers in the designation are regnal years of Emperor Akihito, 26 being 2014. “DMU” stands for “digital mockup.”) Design 26DMU preserves the concept of long-endurance and moderate flight performance, says Doi, declining to give more details, such as what it looks like.There is no concept design after 26DMU, he says. Since they completed that one, the ministry’s engineers have been studying trade-offs, such as the effect on cost of an increase in performance. The cessation of concept designs with 26DMU seems to underline the point that the ministry knows what it wants.Clearly, its objective cannot be created from a nonstealthy aircraft in current production. Conceivably, the F-35, which Japan has ordered, could be modified, but the Lockheed Martin fighter would need major surgery, such as wing and weapon bay enlargement. Doi thinks developing a new aircraft would be a better choice, though he points out that the air force could issue a requirement that the F-35 could meet with little or no change.With a wing of high aspect ratio and moderate sweep, the 25DMU design emphasizes range. Credit: Colin Throm/AW&STOne consideration could be whether standoff distance can be preserved in combat. A U.S. industry official, a former fighter pilot, points out that standoff tactics can break down after a few minutes, with at least some fighters getting close to the enemy. Even if others are still at long range, they may be unable to launch standoff attacks for fear of their missiles, arriving in the target area after long flights, locking onto friendlies.The F-2 is tasked with maritime strike and close air support as well as air combat. Those missions are therefore expected of the replacement aircraft, Doi says, though an alternative would be to reassign F-35s to air-to-surface tasks. Japan has ordered 42 F-35s to replace F-4 Phantoms in the air-to-air role.The ministry has been preparing technology for the possible F-3, notably by developing a technology demonstrator, the MHI X-2. That aircraft first flew on April 22 and should be able to fly about 50 more times, accumulating 200 flight hours by the time the program is completed at the end of the Japanese fiscal year to March 2018, says Doi. This, the main flight-testing effort, will begin “in some weeks,” he adds.The X-2 has taken to the air only once more after its first flight. Since MHI delivered it to the government in June, program engineers have, as planned, been using data from its two simple, slow and straight flights to calibrate systems before putting it to work.That work will be mainly to demonstrate stealth, maneuver and propulsion technology. But its development program has accomplished something equally important for the prospective fighter program: It has given engineers who worked on the F-2 a chance to pass on skills before retirement. The fighter engineers whom Japan will rely on in the 2020s and beyond have been working under the F-2 engineers in developing the X-2.Demonstrator programs are valuable for that purpose, says Doi. They are also useful as opportunities in which to make mistakes without severe consequences. He points to a one-year delay late in the X-2 development program that was caused by problems related to stealth, which he does not detail. The consequences of losing a year were not great because the X-2 was only a demonstrator.The aircraft, called ATX-D for most of the time it was under development, has a reported takeoff weight of 13 metric tons (29,000 lb.). Its two engines are IHI Corp. XF5-1s of 11,000*lb. thrust each.