The U.S. Navy has come up with a novel idea for using offensive mobile naval mines and a robotic submarine to plant them. This approach could even operate as an offensive weapon against Chinese submarines seeking to block access to the South China Sea and Taiwan. China is considered the major submarine threat in the Pacific and the South China Sea is seen as a major future battleground.
Currently China has about 55 diesel-electric subs of recent design in service versus 42 operated by Japan and South Korea, each with 21. Malaysia and Indonesia each have two and Australia has six. The United States has about 30 nuclear attack subs in the Pacific. The anti-China coalition also has a large array of surface and aerial ASW (Anti-submarine warfare) forces.
To even the odds China has built a network of underwater sensors in the South China Sea that is complemented by ASW (anti-submarine warfare) aircraft and surface ships. South Korea and Japan have similar technology monitoring their coastal waters. The only nation capable of blocking Chinese subs from moving out of the South China Sea is the United States, which has underwater sensors and a large fleet of ASW aircraft. The problem is defeating the Chinese diesel-electric submarine force. China has been trying to build effective SSNs for decades and that is still a work-in-progress. Chinese non-nuclear subs are another matter and they have become world-class.
The U.S. Navy believes robotic subs carrying mobile mines would be an effective new ASW asset because the U.S. is already developing some of the new ASW technology needed for this. This includes UUVs (Unmanned Underwater Vessels) and mobile mines. Over a decade ago the navy adopted civilian underwater UUVs used for monitoring the oceans and has been using them to do that as well as collect data useful for wartime submarine operations. With a growing number of civilian and military customers, American UUV developers and manufacturers have been coming up with new ocean research UUVs that also have military applications. The latest example of this is the new class of XLUUVs (extra large UUVs) with the ability to go deeper, carry a cargo bay for other research gear to be stored and deployed from, and operate autonomously for up to six months. The first of these XLUUVs is the Echo Voyager, which Boeing developed from a research project and had the first one ready for testing in 2016. The tests were successful and have involved more complex and completely autonomous operations. In 2019 the navy ordered four militarized “Orca” versions of the Echo Voyager for $11 million each. Both models are diesel-electric powered autonomous subs that are 16 meters (51 feet) long with a payload compartment 9.1 meters long and 2.6 meters (8.5 feet) in diameter and inside the pressure hull. Propulsion is by battery powered electric motors and diesel generators to recharge the batteries when on or near the surface. This XLUUV has no topside sail and can stay underwater for days at a time because there is no crew on board to sustain. While submerged these UUVs can move at 14 kilometers an hour and have sufficient generator fuel to travel 12,000 kilometers. The main difference between Echo Voyager and Orca is that Echo Voyager is built to dive to extreme (3,400 meters/11,000 feet) depths. Orca does without that but adds additional passive sensors and signal processing computers to detect other submarines or surface ships. There is also an underwater communications system for arming the dozen Hammerhead mobile mines Orca is designed to carry and place on the ocean floor in areas like the South China Sea. These Hammerhead bottom mines carry a Mk 54 lightweight torpedo, which is normally carried by ASW helicopters and aircraft. Mk 54 has a range of ten kilometers and a guidance system that is regularly updated. Hammerhead is being used in a similar fashion to a larger version of this used during the Cold War that deployed a larger Mk 48 torpedo. Hammerhead is an encapsulated system equipped with passive sensors to detect and identify submarines and surface ships and attack specific types of targets, like diesel-electric subs larger than Orca.
The first Orca will be delivered in 2022 and if the system works, a big if for the navy these days, the plan is to buy as many as 24 Orcas and use them for a variety of tasks while trying to avoid Chinese efforts to “accidentally” capture one.