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World’s Largest Submarine Drone Being Built In Germany

The MUM (Modifiable Underwater Mothership) will be the latest uncrewed underwater vehicle (UUV) when it hits the water. A unique concept, it is longer and twice as wide as any publicly known designs. Image TKMS

As the last Typhoon class submarine is retired, another underwater giant is starting construction. The German MUM (Modifiable Underwater Mothership) will be the largest autonomous underwater vehicle in the world.

Uncrewed underwater vehicles (UUVs) are getting bigger. The latest designs, being introduced in the United States, Britain, China and elsewhere, are several times bigger than most mainstream models already in service. With size, comes greater capability and flexibility. But it also adds complexity. So much more that the evolution of UUVs can be said to be slower so far than their cousins in the air. Yet the seas are changing.

Now German shipbuilder TKMS (Thyssenkrupp Marine Systems) is preparing to start construction of their MUM underwater drone. This drone is much larger than any known type.

Assembly of the prototype MUM (Modifiable Underwater Mothership) is expected to start in the summer. Overall length of the prototype will be around 25 Meters (82 feet).

Size Matters: The Typhoon Of UUVs

At face value this length is arounds the same as the U.S. Navy’s Orca XLUUV (extra-large uncrewed underwater vehicle) with that design’s extended payload section included. But in the same way that the famous Russian Typhoon Class submarine was much larger than the similar-length U.S. Navy’s Ohio class submarine, the MUM is twice as wide. TKMS term this a ‘flat fish’ type design.

One advantage of the wide layout is increased stability when surfaced. In its civilian role it is not intended to spend time at periscope depth, instead being either deep and fully submerged, or on the surface. The width also allows the sail, which is itself modular, to be mounted on one side. Other XLUUVs do not have sails, but the MUM is of course, in a different league in terms of scale.

The inner hull is constructed out of sections which are sized off 10 foot or 20 foot shipping containers. Other XLUUVs, notably British and Australian designs, are also designed around the size of shipping containers. But those are sized to fit inside them, whereas MUM is built around them. This is a unique concept in the submarine world which also makes it easier to transport when broken into sections.

Potential Roles

TKMS have conceived this as a civilian design. In essence it is a large flexible “work horse” UUV able to incorporate user-defined payloads. Because of its size and power system it excels with comparably heavy, power-hungry, payloads which cannot be carried by smaller craft. Potential roles include offshore services such as inspection, maintenance and repair. It can also aid exploration offshore oil and gas fields, or marine minerals. In these roles it could take core samples via a drill, or support seismic surveying. Roles could also include law enforcement such as inspection of strategic national infrastructure.

Although civilian in nature, no doubt Navy’s will be watching its development closely.

MUM in its military variants: Mine-laying, hunter killer and scout/intelligence. First unveiled at NEDS 2019.

The payload space is larger than other designs. It is approximately 10 tons in-water weight and the size of a 20 foot shipping container. This allows multiple smaller UUVs, remote operated vehicles (ROVs) or objects which can be placed on the sea floor.

The prototype will be powered by hydrogen fuel cell AIP (air independent power) propulsion. This will generate around 80 kW nominal power and will be supplemented by lithium-ion batteries for peak loads. The power is enough for sensors and mechanical payloads as well as the two counter-rotating screws (propellers).

The MUM is an interesting design which has been talked about for some time. But as it nears prototype phase it will become a prominent project worthy of attention.

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