The Japanese “Daily News” reported in 2022 that Japan would collaborate with the United States in developing railgun technology. The results came quickly. However, it’s puzzling that the U.S. railgun technology was already shelved in 2021. Did Japan merely copy U.S. technology and succeed? Has Japan truly made breakthroughs in railgun technology?
Japan’s Railgun seems legit
ATLA officially released a test video on platform X. A square device connected to many wires was seen, with a tubular gun muzzle at its front. When tested, a flash of light was observed from the muzzle, and a moment later, an accelerated projectile was fired into the distant sea. The projectile is not visible due to its extreme speed. Below is an edited GIF image (without dropped frames):
On platform X, many netizens doubted the authenticity of the launch. Firstly, the flash at the muzzle raised eyebrows, followed by concerns about the number and thickness of the wires on the gun barrel. The third issue was the absence of any frame showing the projectile, leading some to accuse Japan of falsification.
Is Japan’s Railgun a hoax?
Was gunpowder used to produce the muzzle flash? Traditional cannons rely on the explosion of gunpowder to propel projectiles, resulting in flames and smoke as the projectile exits the muzzle. Unburnt, hot, combustible gases might reignite when exposed to fresh air, leading to the muzzle flame.
Thus, the question is whether railguns produce such flames. The answer: they might or might not. Electromagnetic guns have three firing modes. While coil guns and homopolar guns don’t produce flames, railguns do. This is because the projectile in railguns “short circuits” between two conductors, generating an incredibly strong electric arc. This causes extremely high temperatures inside the “barrel,” and when the projectile exits, it might leave behind a flame.
Based on ATLA’s video, a blue smoke and sparks were observed. The sparks are consistent with the characteristics of metal fragments burning after an electric arc short circuit. The blue smoke is puzzling, but it could possibly be due to the combustion of protective material used on the rails or the high-temperature gasification of the projectile’s support. It’s unlikely related to gunpowder combustion.
Another issue is the inability to see the projectile from the muzzle. In most traditional cannons, if filmed with a regular camera, frame-by-frame playback would typically show the projectile’s trajectory. However, no frame in ATLA’s video shows the projectile, raising doubts.
The answer remains uncertain. According to the data released by Japan, the speed is 2230 m/s. Based on the released photos, the distance the projectile travels within the visible area is likely less than a dozen meters, taking only 0.004 seconds. A camera with a frame rate of 223fps would be needed to capture the projectile, while typical smartphones only reach 60fps.
Another question is the small size of the cables on Japan’s railgun, while the U.S. railgun has notably thicker cables. Those familiar with railguns might find this suspicious. However, I believe the thin wires might be for sensors rather than power, and as long as they can transmit data, their size isn’t an issue.
Based solely on this video, it’s hard to confirm if Japan’s test was genuine. If it is real, does it pose a threat to China? What’s the level of Japan’s railgun technology? Why did the U.S. fail, while Japan succeeded?
Japan’s Railgun Technology: Where does it stand?
U.S. media “TheDrive” provided detailed data. The prototype of ATLA’s medium-caliber electromagnetic railgun has a caliber of 40mm and can fire a 320g (0.7 lb) steel projectile at a speed of up to 2230 m/s (Mach 6.5), with a muzzle kinetic energy of 5MJ. ATLA’s goal is to achieve muzzle kinetic energy of over 20MJ.
In the future, these weapons will be installed on 27DD or 27DDG warships (Atago-class missile destroyers). They are intended for air defense, sea and land strikes, and even for defense against hypersonic missiles and Ballistic Missile Defense (BMD) using railgun technology.
Would you believe if I told you that Japan’s globally recognized “sea trial” super railgun is just a large toy? Let’s look at some data to understand: China tested a railgun in 2018 that fired a 25 kg projectile at Mach 7.3 (2.48 km/s, with another source saying 2.575 km/s), hitting a target 250 km away.
Thus, Japan isn’t the so-called global leader. China had already conducted tests but hadn’t reported them publicly. Consequently, Japan took the title. So, where does Japan’s railgun rank?
Measured in grams and with a caliber of only 40mm, Japan’s railgun seems like a toy due to its limited practical value. The muzzle kinetic energy of Japan’s recent test is estimated at 7.9MJ, while China’s publicly tested railgun reached 77MJ, approximately ten times that of Japan’s toy. This level has reached practical application.
How tough is railgun technology, and why did the U.S. military fail?
The article had mentioned that there are three types of railgun technologies: railguns, coil guns, and homopolar guns, each with different applications. Railguns are currently the leading tech for high-speed electromagnetic projectile launch. The working principle of railguns is quite simple, as illustrated by a diagram in the article.
However, you must understand that this method doesn’t work well under low current. But, with mega-ampere currents, the surrounding magnetic field of the current is intense, providing substantial power, resulting in very high acceleration.
To launch such a projectile, how much power is needed?
For example, China’s railgun requires about 77MJ of energy for a 25 kg projectile moving at 2,480 m/s, equivalent to 21.4 kWh. If this energy is used within an hour, the power is 21.4KW. If used in 0.1 seconds, the power becomes 756MW. However, railgun efficiency can only reach 50%, so the actual power is more like 1512MW, comparable to ten aircraft carriers’ power. Sounds terrifying, doesn’t it?
Therefore, for railguns, aside from the launch principle, an extreme power source is required. This source should consist of a generator, an energy storage facility, a momentary discharge energy facility, and a control system.
Why both energy storage facilities and momentary discharge components? It’s simple: lithium batteries have high capacity but can’t discharge quickly, while supercapacitors discharge fast but have limited storage. Combine both, and you get the best of both worlds. Charging a 42 kWh battery pack shouldn’t be an issue since modern electric cars have 100 kWh battery packs. However, the discharge rate of these batteries might not be sufficient. Charging will also take time. If charging takes 3 minutes for 42 kWh, a power of 840KW is required. Considering conversion efficiency, 1000KW might be more accurate. Therefore, a 1MW generator would suffice.
However, if the railgun operates using a lithium battery + supercapacitor combination, it could directly draw power from the ship’s all-electric propulsion system. The system would charge the batteries during peacetime and use them directly during wartime. This would avoid the hassle of starting gas turbines, which, though quick, would be too slow for the railgun. Thus, the combination of lithium batteries and supercapacitors is ideal.
Power might not be the toughest challenge: rail erosion is.
Japan has good electric vehicle technology, and its power technology should be competent. Whether it can achieve the necessary power level remains unknown, as this tech exceeds civilian scopes. But this isn’t the most challenging part; railguns have a nearly insurmountable problem: rail erosion.
Imagine the environment of electric welding. A conventional welding current is just over 100A, with larger ones reaching 600A. 1000A is for the extreme end. Now, what level is mega-amperes? It’s 1000A multiplied by 1000. With such monstrous currents, the most pressing problem is erosion. After a few shots, the rails need replacing. Both the BAE Systems and General Atomics railguns developed in the U.S. couldn’t pass this hurdle. As per public reports, after several dozen shots, the rails need replacement. This was a primary reason the U.S. military abandoned its railgun project in 2021.
Japan-U.S. Collaboration: Japan’s Railgun, Just a Big Toy
On January 5, 2022, the Japanese “Daily News” reported that Japan would develop railguns to counter neighboring countries’ growing hypersonic weapons. In the government’s 2022 preliminary budget, 6.5 billion yen (about 56 million USD) was allocated for the railgun project, a joint venture between the U.S. and Japan, leveraging each other’s strengths. The Japanese side stated that U.S. railgun power technology was ahead of Japan’s.
In the supplementary budget of the 2016 fiscal year, the Ministry of Defense allocated 1 billion yen (equivalent to 8.64 million USD) for electromagnetic launch technology and even produced a prototype that year. This prototype could fire a 16mm diameter projectile at a speed of 2,297 m/s. Such a small railgun is just a large toy. This time, the caliber was increased to 40mm, but it still remains a toy.
By current standards, Japan’s railgun technology doesn’t seem intimidating, and there doesn’t appear to be any leakage of classified information. The muzzle kinetic energy is only 10% of China’s 2018 tech. We should still remain vigilant, however, as Japan’s determined development of railgun technology isn’t driven by goodwill.
China’s Railgun Tech Spills Over: It’s Now Mainstream
China was a latecomer in the field of electromagnetic launch but made rapid breakthroughs. Now, China has produced military-grade railguns and electromagnetic catapults. However, electromagnetic launch applications extend beyond just military use. Currently, China’s electromagnetic launch technology has been integrated into civilian applications, such as electromagnetic launched fire extinguishing bombs, electromagnetic catapult microgravity testing equipment, electromagnetic sleds, and large coil guns.
Among them, electromagnetic sleds and large coil guns have the most potential for electromagnetic launch applications. Here, the focus is not on launching projectiles but satellites and manned spacecraft. A track or vacuum coil tunnel several tens of kilometers long, or a circular tunnel, can accelerate satellites or manned spacecraft to 4~5 km/s. Once ejected, rockets can be activated to enter space, saving a significant amount on launch costs.
For example, with a constant acceleration of 6G, reaching 4.5 km/s requires a track about 82 km long for manned launches. For satellite launches, the distance can be reduced to several kilometers. After all, satellites, unlike astronauts, cannot withstand high overloads. Considering the cost of track construction, satellites can be launched at their overload limit.
If launching satellites or spacecraft using electromagnetic technology becomes feasible, it will revolutionize space travel and significantly reduce costs.
Source: Xingchen