[NavalNews] The vast expanse of the Pacific Ocean, over 5,000 nautical miles across, protects the West Coast of the United States against Chinese naval forces in the event of a war. The appearance of new extra-extra-large underwater drones (XXLUUVs) changes this, providing China with low-risk options to directly threaten West Coast ports.
For decades American strategy in East Asia, focused on a potential conflict with China, have viewed the vast expanse of the Pacific Ocean as both a challenge and an advantage. While the distances involved make logistics harder (known as the ‘tyranny of distance‘), the U.S. Navy’s superior conventional power and fact that it would be even harder for Chinese vessels to reach the U.S., insulate the West Coast of America from Chinese aggression. Any war would therefore be fought at arm’s length with U.S. forces only at risk in the immediate theatre of operations. But China may be finding ways to turn this traditional advantage into a disadvantage.
China is building the world’s largest underwater drones, the size of traditional submarines. The first stage of analysis established their existence, and that they are highly likely uncrewed. It is now time to consider why China is building them.
China is testing the two models of extra-extra large underwater drones (XXLUUVs) in the South China Sea. The largest underwater drones in the world by some margin, they rival crewed submarines in terms of size. The designs are likely diesel-electric, per a builders model shown at the defence show, and the same as the U.S. Navy’s much smaller Boeing Orca XLUUV.
EXTREMELY LONG RANGED UNDERWATER DRONES
Making underwater drones so large comes with clear challenges and disadvantages. They are inherently more expensive, more time consuming to build, harder to maintain, and require traditional port facilities. So, one or more of their strengths must outweigh these. Advantages might include a greater weapons load, or more powerful sensors such as towed sonar arrays. But the differentiating strength is likely to be the much greater operational range.
China’s XXLUUVs will have a range of approximately 10,000 nautical miles. This is based primarily on published specifications of a similarly sized conceptual XXLUUV displayed by Chinese shipbuilder at a recent defence show. It also aligns with rough calculations based on the size of the submarine.
The designs are likely diesel-electric, per the builders model shown at the defence show, and the same as the U.S. Navy’s much smaller Boeing Orca XLUUV. The defence show model was armed with torpedoes, mines and could carry smaller underwater drones. It had a diesel generator and unusually large bank of batteries replacing the crew space and taking up most of the hull volume.
10,000+ NAUTICAL MILE RANGE
That design boasted a 7,000 nautical miles on diesels, presumably snorkeling, which is comparable to traditional diesel-electric submarines. But the claimed 3,000 nautical miles submerged is much further; thanks to its massive bank of modern batteries it can sail approximately six times further than the best diesel-electric submarines underwater. This might be used for the final phases of the mission, but it might also prove useful to help the sub slip through anti-submarine defenses between the island chains which separate China from the open ocean.
Range could be further extended by increasing diesel fuel, more batteries, or simply towing them closer to the target before launch. The batteries specified in the defence show model are lithium-iron (LiFe PO4), which are safer than the better-known lithium-ion type (note the one letter difference). While still much more powerful dense than traditional lead-acid batteries, they are less power dense than lithium-ion. The underwater range could thus be doubled simply by swapping the batteries to a lithium-ion type. All these ways could extend the practical range beyond 10,000 nautical miles. And being an uncrewed platform, however expensive, it can be used as an expendable system which doubles the operational radius.
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