Navy’s 85-Foot Orca Unmanned Submarine Will Be A Minelayer First

The Navy could soon have a small fleet of 85-foot unmanned submarines patrolling the ocean depths, ready to dispense undersea mines at a moment’s notice. Testing begins this summer on the Orca extra-large unmanned underwater vehicle, or XLUUV, in its primary role of carrying anti-ship mines in a 34-foot modular payload compartment.

Capt. Scot Searles, the Navy’s program manager for unmanned maritime systems, gave an update on the Orca’s planned capabilities at the recent International Mine Technology Summit, hosted by the Mine Warfare Association in Monterrey, California, as reported by Sea Power Magazine. 

Capt. Scot Searles at the launch of the first of six Orca XLUUVs. NAVSEA
Capt. Scot Searles at the launch of the first of six Orca XLUUVs. NAVSEA

At 80 tons, Orca is too big for a submarine to carry or launch, so it must be put to sea from a pier or larger surface ship. The Navy has not made it clear how it plans to launch and recover such a large UUV operationally.

The base Orca vehicle is modular in construction, with the core vehicle providing guidance and control, navigation, autonomy, situational awareness, core communications, power distribution, propulsion and maneuvering, and mission sensors, according to the Defense Department. It also has a stowable mast designed to be raised when it is at or close to the surface to provide a number of functions, including satellite connectivity.

Sandwiched between that equipment, housed in an aft section with a shrouded propulsor and a nose section studded with sensors, is a space for modular payloads, the first of which is the 34-foot mine-carrying module, Searles said at the Mine Warfare event. 

Orca rendering. Credit: Boeing.

The 34-foot modular mid-section has an eight-ton payload capacity. It’s reconfigurable to carry payloads to suit a range of long-endurance missions, including undersea mines and synthetic aperture sonar for ocean-floor mapping. Navy requirements indicate the UUV will also perform underwater surveillance, electronic warfare, and minesweeping missions. Beyond that, it is planned for Orca to be able to do everything from launching cruise missiles and aerial drones to hunting submarines in the future.

A shrouded propulsor, similar in broad strokes to those used on larger manned Navy submarines, like the Seawolf and Virginia class boats, improves efficiency and dampens noise from the churning prop. Silence is vital for underwater military operations, where enemy forces are alert for acoustic signatures produced by submarines and other craft.

Orca is designed with “well-defined interfaces for the potential of implementing cost-effective upgrades in future increments to leverage advances in technology and respond to threat changes,” the Pentagon said in 2019 when announcing a contract award to Boeing for an initial order of four XLUUVs.

The Orca XLUUV pier-side after its April launching in Huntington Beach, California. NAVSEA

Orca’s hybrid diesel-electric propulsion system will allow it to run silently beneath the waves on batteries recharged by air-breathing diesel generators while running on or very near the surface. The UUV’s combination diesel engine and modern lithium-ion batteries should allow it to stay at sea for months when cruising at about three knots. Incorporating lithium-ion batteries onto diesel-electric submarines is an emerging breakthrough in submarine tech that allows for near air-independent propulsion (AIP) performance without the need of special engines or fuel cell technologies. This also reduces mass and complexity.

Boeing based Orca’s design on its self-funded Echo Voyager, which was also 51 feet long in its basic configuration, but appears to have been extended for further testing. That vehicle has a maximum speed of about nine miles per hour, or 7.8 knots, underwater and could dive to 11,000 feet below the surface. The Echo Voyager could run on batteries alone at 3 miles per hour for about 150 miles. It had the fuel capacity for up to six months of voyaging, giving it a range of around 7,500 miles, or 25 percent farther than the distance from San Francisco, California, to Tokyo, Japan. Orca’s specs should exceed Echo Voyager, potentially greatly, although it isn’t clear how another 34 feet added to its hull will impact its performance.

Echo Voyager seen with a massive hull plug during testing. The modular extension is likely similar to that found on Orca. Credit: Congressional Research Office.

Navy officials have been eager to field the Orca for undersea mining missions, as Vice Adm. James Kilby, deputy chief of naval operations for Warfighting Requirements and Capabilities, told the Seapower and Projection Forces Subcommittee of the House Armed Services Committee last year. Orca will provide valuable data on whether a UUV of its size is capable of laying mines discreetly in hard-to-reach areas that crewed submarines cannot reach, including inside ports.

“We need to get that initial prototype built and start employing it to see if we can achieve the requirements to do that mission set,” Kilby said. “If we can’t meet our milestones, we need to critically look at that and decide if we have to pursue another model or methodology to get after that combatant need. In the case of the XLUUV, we haven’t even had enough run time of that vessel to make that determination yet. Certainly, there [are] challenges with that vehicle.” 

Orca in the water in Huntington Beac. Boeing photo.

The Navy is developing new sea mines that both unmanned and crewed submarines can lay. Orca is a prime candidate for carrying both the Clandestine Delivered Mine — a cylindrical underwater mine for which there is little public information that was supposed to begin delivery in the fiscal year 2020 — and Hammerhead, a torpedo that waits on the seabed listening for enemy submarines to strike. Crewed subs can carry submarine-launched mobile mines (SLMM) like the Mk 67, but the Orca could be even harder for an enemy to detect and could transport the mines closer to a target area for more favorable placement.

With either type aboard, an Orca has the ability to operate across vast swathes of ocean autonomously. Its size and unmanned nature offer a novel method of blocking strategic maritime chokepoints and shutting down enemy ports, shipyards, and seagoing commerce. Though Orca is large for a UUV, it is much smaller and more expendable than crewed submarines and so it could potentially mine rivers, canals, and shallow coastal areas closer to, or even possibly deep within, hostile territory, further distributing mine warfare and disrupting the free movement of hostile naval forces and shipping.

A screenshot from a video animation clip of an Orca placing something on the seafloor. Boeing screencap.

Boeing, and shipbuilding partner Huntington Ingalls Industries, won a $43 million Navy contract in February 2019 to build four operational Orca prototypes based on Boeing’s aforementioned Echo Voyager UUV. The Navy ordered a fifth vehicle in March 2019. The total contract award ended up being $274 million. All five UUVs are scheduled for delivery in 2022. Searles said the Navy plans to add a sixth engineering and development test article to the order to reduce developmental risk and speed the vehicle to service, according to Sea Power Magazine.

That’s an aggressive schedule, considering the first Orca test asset system splashed down in April from a Huntington Beach, California, pier. But the Navy is moving quickly to field a variety of unmanned underwater vehicles in multiple sizes for a laundry list of missions. Systems range from “man-portable” UUVs with a diameter of fewer than 10 inches to surface, or submarine, launched designs with diameters between 10 inches and seven feet, all the way up to XL submersibles like the Orca. Future XLUUVs could come with some form of strike capability, as seen in the UUV “Vision” slide below. 

The Navy’s “UUV Vision,” with Orca at the top, center. NAVSEA

In April, the service published a request for information for a Mining Expendable Delivery Unmanned Submarine Asset (MEDUSA) “to meet future submarine delivery of payloads requirements.” MEDUSA will be a “tactical clandestine mining system,” with an expendable unmanned underwater vehicle (UUV) that can launch from a submarine’s torpedo tube, the Navy’s RFI states. That lands it in the medium-class of UUVs, capable of carrying specialized mission equipment and payloads. The Navy wants four prototype units delivered by the fiscal year 2026. 

Also worth noting is that the Navy is seeking to cancel Snakehead — a large UUV you can read all about here — because it couldn’t be deployed by a nuclear submarine’s dry dock shelter (DDS) as originally envisioned, among other issues. This leaves a large gap between medium and extra-large UUVs. It’s possible something else could take its place, but it could also mean a greater focus on Orca and rapidly developing its more robust capabilities.

A unit established to develop and test UUVS, Unmanned Undersea Vehicle Squadron One (UUVRON 1,) is in its fifth year of operation. With Orca entering in-water testing this summer, the unit will have its hands full. If the tests don’t flounder, the Navy could soon have significant unmanned vessels voyaging the depths at ranges relevant to a fight in the vast Pacific Ocean.

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