Warfare is going drone: cheap to produce, fast to make in quantity, and disposable
Northrop Grumman’s answer was to build something that spends most of its working life parked on the ocean floor with nearly everything switched off. It is called Manta Ray. It can be transported anywhere in the world in five shipping containers, gets bolted together on a dock in two days, swims out by pumping seawater through itself instead of turning a propeller, then anchors to the ocean floor and sleeps there until someone wakes it.
The big problem with drones almost always comes down to the battery – especially underwater where it is nearly freezing. Instead of spinning a propeller, this drone acts like an underwater glider. It pumps seawater in to get heavy and sinks. It then pumps water back out to get light and rise. To move forward, it uses it’s wings convert all that vertical rising and falling into forward motion.
Additionally, to extend mission time, they have also been experimenting with ways to attach to the sea floor and passively collect energy to recharge batteries and extend total mission time.
It’s uncertain how well all the trials went, there’s been no further information since May 2024. The drone the Navy actually keeps ordering in volume is a 10-foot tube called Lionfish.