Like a spring-loaded toy snake from a tube, the Sea Spear is intended to pop from a mother drone, expand to 50 times its length—and then hang around for months, silently listening for enemy submarines.
The new sonar concept from dronemaker Anduril and Ultra Maritime, a Massachusetts-based company specializing in anti-submarine and electronic warfare, is meant to work with Anduril’s Dive XL or smaller Seabed Sentry underwater drones, drawing power from them and feeding its data to them for on-drone analysis. Sounds that require human notification get passed along via Anduril’s Lattice network.
“You don’t need a ship or submarine that makes noise. This will sit there in an ocean current and be stiff,” Carlo Zaffanella, CEO and president of Ultra Maritime, said at the Navy League’s annual Sea-Air-Space conference in Maryland.
The military has pursued similar concepts in the past, such as DARPA’s 2014 Upward Falling Payload, whose network of subdrones waited on the ocean floor—perhaps for years—before springing to life upon detection of an adversary vessel. But the difficulty of communicating with underwater systesm—and the corrosive effects of seawater—have led to the idea of an intermediary drone between sensors and warships.
“Communication in the water is very complicated,” Zaffanella said. “One of the reasons that towed arrays exist at all is because, generally speaking, all that information comes to the ship or to the submarine, and you use sonar processing on board to determine submarine track. We’re pushing the algorithms right to the tactical edge so that what we are passing through acoustic communications is not high-bandwidth signals, but a low-bandwidth signal.”
Shane Arnott, a senior vice president of program and engineering at Anduril, said the decreasing cost of subdrones also allows operators to deploy the sonar webs over a large enough area to much more effectively monitor portions of the sea that they can’t easily see any other way.
“We’re not just building ones and twos and prototypes—yeah, we’re thinking about our production system, even before the engineering,” Arnott said, adding that he envisions “hundreds” of such drones deployed for a portion of the cost of a conventional submarine.
