Japan has outlined its R&D Roadmap for its homegrown, stand-off, hypersonic weapons, confirming that it is seeking an incremental increase in capacity and providing more details on the types of threats it is targeting with this new class of weapons.
Hypersonic weapons, which can achieve a speed five times faster
than Mach 5, are the latest version of precision guided munitions (PGM) that are part of the larger family of long-range strike weapons systems.
Japan hypersonic weapons
In a Japanese-language document published on the website of the Acquisition, Technology and Logistics Agency, (ATLA) the Government stated that two classes of stand-off hypersonic systems would be deployed— the Hypersonic Cruise Missile (HCM) and the Hyper Velocity Gliding Projectile (HVGP).
The former will be powered by a scramjet engine and appears to be similar to a typical missile, albeit one that cruises at a much higher speed while being able to travel at long distances.
On the other hand, the HVGP will feature a solid-fuel rocket engine that will boost its warhead payload to a high altitude prior to separation, where it will then slide to its target using its altitude to maintain high velocity until impact.
The Agency also provided more details on payloads of warheads, with different warheads planned for both seaborne and land targets. The former will be an armor-piercing warhead designed specifically to penetrate the’ deck of the [aircraft] carrier,’ while the ground-attack version will use a high-density, explosively formed projectile, or EFP, for area suppression.
Area suppression effects for the latter will be achieved through the use of multiple EFPs, which are more commonly known as the shaped charge. The EFP consists of a concave metal hemispheric or cone-shaped liner supported by a high explosive, all in a steel or aluminum housing. When the high explosive is detonated, the metal liner is compressed and pressed forward, forming a jet whose tip can travel as fast as 6 miles per second.
Japan is developing two advanced anti-surface warheads that will be fitted onto two hypersonic weapons that are currently also under development. ATLA plans to arm these weapons, namely HVGP and HCM, with the ‘Sea Buster’ tandem-charge warhead and a multiple explosively formed penetrator (MEFP) warhead.
The ‘Sea Buster’ warhead is developed to specifically target surface vessels, most likely larger warships. It is reportedly composed of a main warhead, which carries armour-piercing high-explosive shells and a nose fuze, and a precursor warhead that uses shaped charges.
Japan’s road map also revealed that the country is taking an incremental approach to designing warhead shapes and developing solid-fuel engine technology, with plans to launch early versions of both in the 2024 to 2028 timeframe. They are expected to enter service in the early 2030’s.
The Agency expects both systems to navigate through satellite navigation with an inertial navigation system as a backup. Japan seeks to establish a seven-satellite network to enable its self-defense forces to position continuously, enabling it to provide continuous navigation data without relying on foreign satellites.
Warhead guidance is achieved either by radio-frequency imagery converted from doppler shift data— which the government agency said will be able to identify stealthy naval targets under all weather conditions— or by an infrared searcher capable of discriminating against specific targets.
Japan has been conducting R&D in various areas related to hypersonic weapons for a number of years, although most of it has benefited other areas such as satellite navigation and solid-fuel rockets.
More work remains to be done, however, in areas such as hypersonic guidance systems, warhead and missile-body thermal shielding, and hypersonic propulsion systems, in order to enable Japan to develop a viable standoff capability for hypersonic weapons.