After China, Russia, and the Franco-German couple, it is Japan's turn to communicate on its Rail Gun program, or electric cannon. The ATLA, the Japanese equivalent of the DGA, released a video showing a Rail Gun prototype and explaining the objectives of this programof Defense.
In the purely defensive logic of the Japanese self-defense force, the Rail Gun is designed above all to reinforce the anti-aircraft and anti-missile defense system of its AEGIS heavy destroyers, with a strike capacity against opposing buildings. And in fact, with a muzzle exit speed of Mach7, a Rail Gun can reach a target 200 km away in ballistic fire, several tens of kilometers in direct fire against aerial threats, and at a rate of fire of 10 minutes shots.
However, the system suffers from a very significant need for electrical energy, requiring a production of 12 MWh to support such an excess of power, and therefore ships designed specifically for this need. In addition, it releases significant heat, requiring a very efficient and energy-intensive cooling system, which significantly affects the discretion of the supporting building.
Thus presented, the Rail Gun appears to be a promising system, but in no way revolutionary for the field of naval combat. However, this is to ignore several specific aspects of this technology capable, in fact, of generating significant upheavals at this level.
First of all, the technology as presented today is only in its infancy. If the maximum range is 200 km (120 nm) for an initial speed of Mach 7, it increases to 350/400 km upon reaching Mach9. Likewise, the rate of fire of 10 rounds per minute could increase to 60 rounds per minute according to the engineers working on the subject. This rate will be made possible thanks, among other things, to the absence of powder and the space savings (and risks) that this generates.
Secondly, the guidance and nature of the projectiles have great room for improvement. According to American studies, it would already be possible to guide the projectile by GPS, but other types of terminal guidance are possible, such as laser, infrared or radar. Indeed, in the terminal phase, the projectile is no longer subject to the effects of hypersonic solids, such as high temperatures and the creation of plasma. It will be essential, however, to develop technologies capable of handling the phenomenal acceleration of the projectile during firing, of the order of 20.000 G for firing at Mach7, as well as suitable control systems.
The projectile itself may be specialized, depending on whether it is used against a ship, an aircraft, a hardened land target or not. But the ability to precisely regulate the power of the shot and the nature of the projectile while maintaining a very high rate of fire obviously opens up new employment prospects.
In fact, from a defensive and access denial weapon, the Rail Gun can quickly evolve into an offensive and support weapon, and thus return surface ships to a role that was theirs for centuries, the domination of the seas and support of landed and land forces. In addition, the potential of the Rail Gun, and its specific needs in terms of electrical production, tends to favor the return of large combat surface units, such as cruisers, capable of producing sufficient energy for several electric cannons, by carrying a significant range of missiles allowing the building's strike capabilities to be extended. Thus, the cruiser would resume its role as a first strike, or first entry, vessel, with the mission of eliminating threats to aircraft and drones deployed at a safe distance by aircraft carriers.
This logic is not far from that which prevailed in the design of the Zumwalt heavy destroyers, in this case around ten years too early for the technology actually available.