[Chen Shan, special correspondent of Global Times] Japan Aerospace Exploration Agency (JAXA) successfully test-fired a small rocket to verify scramjet technology on 24th, marking an important step in the development of hypersonic weapons in Japan. In recent years, Japan has invested heavily in hypersonic weapons, and its ambitious development plan is directed at China. So what is the current development capability of Japanese hypersonic missiles?
Japan’s technical strength ranks first in the second echelon.
Japan Aerospace Exploration Agency (JAXA) successfully launched a small rocket at Neizhipu Space Observatory in Kagoshima Prefecture on the same day, Kyodo News reported on the 24th. What attracts the attention of the outside world is that the rocket is mainly used for testing hypersonic vehicles with a speed of five or six times the speed of sound. And its successful launch marks another important step forward for Japan’s hypersonic missile program.
Concept map of Japanese hypersonic cruise missile
According to the report, this small rocket called "S-520-RD1" reached a height of 168 kilometers in about 3 minutes and 30 seconds after launch, and then released the test equipment with a length of 9.15 meters. The test equipment then descended at a speed of 5.5 times the speed of sound at high altitude and carried out a combustion test for about 6 seconds.
NHK said that this test is part of a research project commissioned by a subsidiary of Japan’s Defense Ministry, which hopes that related technologies can be used in the defense field in the future. The Japan Times put it more bluntly: "Many countries are developing scramjet engines, and this technology is considered to be of great significance to the development of hypersonic missiles."
Different from the traditional rocket engine, scramjet does not need to carry liquid oxygen, but burns by inhaling oxygen from the air and mixing it with fuel. This design can not only reduce the weight of the rocket, but also greatly improve its payload.
The news that the Japanese Defense Ministry developed domestic hypersonic weapons first appeared at the end of 2018. At that time, Kyodo News broke the news that the Ministry of Defense planned to develop hypersonic cruise missiles, and included funds for researching scramjet engines in the budget for FY 2019, seeking cooperation with JAXA. The successful test of the scramjet independently developed by Japan undoubtedly represents an important step in the development of hypersonic missiles.
In fact, the hypersonic cruise missile represented by scramjet is only one of the two technical routes for Japan to promote hypersonic weapons. According to the plan of Japanese Defense Ministry, hypersonic cruise missile (HCM) and hypersonic gliding bomb (HVGP) will be developed simultaneously in the future. Among them, HCM is propelled by scramjet engine. According to the US Global Security website, "compared with conventional missiles, HCM can maintain a higher cruising speed for a long time, thus reducing the reaction time of opponents, and at the same time, its volume and size are smaller, which can be carried by air platforms such as tactical aircraft". Globally, at present, only the Russian "Zircon" missile is about to enter service, and the United States also conducted a test launch of hypersonic cruise missiles not long ago.
HVGP is more similar to the hypersonic boost-glide weapon developed by Russia, China and the United States, and has many advantages, such as fast flight speed, strong penetration ability and high strike accuracy. First, it was launched by a booster rocket on the ground, and the warhead was separated in the upper layer of the atmosphere with less air resistance, and then glided at hypersonic speed in the atmosphere and maneuvered to avoid interception. The research and development plan is divided into two stages. The first stage is the early equipment type. The warhead adopts a conical pneumatic configuration and is equipped with a small tail to adjust the flight trajectory. It is planned to be in service before 2026. In the second stage, the performance will be upgraded, and the warhead will adopt more advanced waverider design, which will further improve its speed and range, and can also carry out more complicated maneuvering orbit transfer. It is expected to be put into use in the early 1930s.
A model of Japanese hypersonic missile appeared in the inspection photos of Yamamoto Tomoto.
In addition, Japanese hypersonic missiles will use different warheads for maritime and land targets. According to the plan announced by the Ministry of Defense, when attacking maritime targets, armor-piercing warheads will be used, "specially designed to penetrate the flight deck of aircraft carriers". At the first International Exhibition of Defense and Safety Equipment in Japan in 2019, the Japanese side also displayed the prototype of the "hypersonic gliding bomb" and used simulated animation to demonstrate the process of its attack on the aircraft carrier. When it strikes the ground, it will choose the high-explosive warhead for regional suppression. The Ministry of Defense revealed that in the future, these two kinds of hypersonic missiles will be guided by satellite navigation system, with inertial navigation system as backup. It is worth noting that Japan is building a local navigation network consisting of seven satellites to provide continuous positioning for the Self-Defense Forces, which will enable Japan to provide continuous navigation data without relying on foreign satellites.
According to the Swedish Institute for Security and Development Policy, the development of hypersonic missiles is very difficult, and only a few countries are participating in this "competition" at present. Among them, Russia, China and the United States are in the first echelon, while Australia, India, Japan and Europe are in the second echelon. However, in terms of technical strength and actual development progress, Japan ranks first in the second echelon.
Which countries are quietly helping Japan?
Why can Japan rapidly advance the development progress of hypersonic weapons? The US "Defense News" said that Japan has been conducting research and development and technical reserves in various fields related to hypersonic weapons for many years, including satellite navigation technology and solid fuel rockets. However, the report admits that in the fields of hypersonic guidance system, thermal shielding of warheads and missile bodies, and hypersonic propulsion system, Japan still has a long way to go to deploy practical out-of-zone hypersonic weapons.
The "Global Security" website said that to independently develop hypersonic missiles, the first thing you need is test equipment such as hypersonic wind tunnels. These basic scientific research equipment, which need high investment, have become a "roadblock" for many countries to develop hypersonic weapons. The report notes that Japan has complete wind tunnel test facilities, which can meet different needs such as subsonic, transonic, supersonic to hypersonic. Even the National Aeronautics and Space Administration (NASA) took a fancy to Japan’s technical accumulation in the wind tunnel field, and signed an agreement with JAXA in 2020 to conduct independent wind tunnel research on the X-59 supersonic aircraft developed by Boeing.
According to the British "Jane’s" national defense publication, Japan’s hypersonic weapons are mainly developed by Mitsubishi Heavy Industries in cooperation with the Acquisition, Technology and Logistics Bureau of Japan’s Defense Ministry. Mitsubishi Heavy Industries itself is the research institute of various hypersonic wind tunnel systems in Japan. The hypersonic wind tunnel system provided by the company claims to have "the best accuracy in the world", which can provide a test environment with a maximum speed of 10 times, and the continuous working time is more than 30 seconds. JAXA also has several hypersonic wind tunnels, among which the 0.44m Shock Wind Tunnel (HST) can generate high-speed airflow at Mach 10 and Mach 12. Although these wind tunnels can’t be compared with the hypersonic wind tunnels of Mach 20 or even 30 in China, the United States and Russia, they are still unique in the second echelon.
"Hypersonic Gliding Bomb" Planned by Japan
Relying on these advanced wind tunnels and other infrastructure, Japan started very early in the field of hypersonic vehicles. In the 1980s, Japan promoted the "HOPE-X" program, aiming at building a space shuttle that repeatedly shuttles between space and the Earth. In 1996, Japan launched a "hypersonic aircraft testing machine" with a launch vehicle, which reached Mach 10 in the flight test. The plan was eventually cancelled due to technical difficulties and funding cuts, but the relevant technology accumulation was retained.
In 2020, when Japanese Deputy Defense Minister Tomotohiro Yamamoto inspected the Institute of Aviation Equipment of the Self-Defense Force, a model of Japan’s latest hypersonic missile appeared in the background behind him. According to the website of US Naval Intelligence, the model shows the internal structure of Japanese hypersonic missile in detail. It is likely to be powered by a dual-mode scramjet, which can fly at high altitude at a speed of more than five times the speed of sound or higher, and "can pose a threat to China or Russian aircraft carriers".
Japan has also received external technical support in developing hypersonic weapons. India’s Eurasian Times said that in January 2022, the United States and Japan announced plans to sign a new agreement to "strengthen their research and development cooperation in emerging technologies, and strive to seek joint investment to accelerate innovation and ensure the advantages of the alliance in key and emerging fields, including artificial intelligence, machine learning, directional energy and quantum computing". Although in the joint statement issued by the two sides, American and Japanese officials provided little information about the specific content of the R&D sharing agreement, it is widely believed that one of its key points includes cutting-edge space systems and hypersonic missile technology. In addition, the "Ocuss" alliance established by Australia, Britain and the United States has also reached an agreement with Japan to jointly develop hypersonic weapons.
Who is the target of Japanese hypersonic missile?
It is worth noting that the target of Japan’s development of hypersonic missiles is very clear. The schematic diagram released by the Ministry of Defense shows that the "Hypersonic Cruise Missile (HCM)" launched an attack on the "opponent aircraft carrier" under the guidance of satellites and drones. The "opponent aircraft carrier" is very similar to the sliding deck aircraft carrier currently in service in China and Russia. While many Japanese media introduced the "Hypersonic Gliding Bomb (HVGP)", they also specially emphasized that it will be used for "outlying island operations". In recent years, Japan’s enhanced ability to seize the island, the main imaginary enemy is considered to be China.
United press international said that Japan’s hypersonic weapons may be used to attack other countries’ military bases, raising concerns about Japan’s violation of the peaceful constitution. In recent years, the Japanese government has been advocating the development of "ability to attack enemy bases" and taking the opportunity to promote long-range strike equipment including hypersonic weapons.
The Swedish Institute for Security and Development Policy warned that Japan’s hypersonic weapon development plan is very risky and is likely to further disrupt the stability in Northeast Asia. According to the report, HCM and HVGP provide a series of military capabilities that have attracted much attention. In particular, they greatly reduce the time for opponents to warn and respond to incoming missiles or warheads. Compared with traditional ballistic missiles, the maneuverability of hypersonic weapons has improved, so the existing detection and defense systems may not be able to cope with these new technologies. In addition, such mobile weapons can also attack high-value targets more accurately.
According to the report, "since there are almost no bilateral and regional collective stability mechanisms and arms control agreements, the proliferation of hypersonic weapons may mean the retrogression of the regional situation." The report specifically mentioned that it is difficult to distinguish whether hypersonic weapons carry nuclear warheads, and Japan’s related plans may make its neighbors feel uneasy. "If Tokyo decides to implement its own hypersonic weapon, it may pay a heavy price."
