Uncrewed

A British Excalibur uncrewed underwater vehicle (UUV) has fired a U.S. Mk 48 heavyweight torpedo in what is said to be a first-of-its-kind test for both countries. Though just a proof-of-concept so far, this is a significant new step for the United States and the United Kingdom toward future operational fleets of armed UUVs.

The U.S. Navy and the Royal Navy conducted the armed UUV test at the British Underwater Test & Evaluation Center (BUTEC), a maritime test range in Scotland, on September 13. Personnel from the Pentagon’s Defense Innovation Unit (DIU) and the Naval Undersea Warfare Center Keyport Division (NUWC Keyport), as well as unspecified industry partners, also took part, per a U.S. Navy press release.

The test was also carried out under the umbrella of Pillar 2 of the trilateral Australia-United Kingdom-United States (AUKUS) defense cooperation agreement, which was first announced in 2021. AUKUS’ Pillar 2 covers a wide range of advanced technology cooperation, with particular focus on uncrewed platforms and autonomy. Pillar 1 of the agreement centers on support for Australia’s establishment of a nuclear submarine force.

For the September 13 test, the Mk 48 torpedo was slung under the Excalibur UUV. The nearly 40-foot (12-meter) long, 19-metric-ton submersible drone has a large internal payload bay, but it is reportedly not large enough to accommodate the Mk 48, which is the standard heavyweight torpedo in U.S. Navy service today. The 19-foot-long, 21-inch-diameter weapon has been successively upgraded over the years to expand its capabilities and improve its resistance to enemy countermeasures.

The Royal Navy officially unveiled Excalibur, which was developed by U.K.-based MSubs under Project Cetus, last year. The external torpedo launch capability was the result of two additional efforts, called Project Broadsword and Trial Iron, according to the U.S. Navy release.

The September 13 test “successfully validated the mechanical, electrical, and software integration of a U.S. kinetic payload onto an allied autonomous vessel, proving that allied forces can rapidly achieve weapon interchangeability,” the Navy’s release adds. “Approved in February 2026 by the Department of the Navy Rapid Capabilities Office (DONRCO), the project was executed in less than seven months.”

How the Excalibur UUV was controlled during the test and whether the torpedo was launched at a test target of some kind are unknown. TWZ has reached out for more information.

“BROADSWORD is a great example of how AUKUS Pillar II drives interoperability in across the alliance. Demonstrating the launch of a US torpedo from a UK extra-large unmanned underwater vehicle (XLUUV) is an important early step in developing lethality in our undersea autonomous systems,” U.S. Navy Vice Adm. Robert Gaucher, Director of Submarine Programs, did say in a statement. “We look forward to continuing to leverage the AUKUS partnership to keep pushing the potential warfighting advantages of unmanned undersea systems.”

“This successful test marks a historic first for allied undersea warfare,” U.S. Navy Adm. Daryl Caudle, Chief of Naval Operations, also said in a statement. “Proving that we can seamlessly launch a U.S. heavyweight torpedo from a Royal Navy autonomous underwater vehicle validates our shared vision for true interchangeability.

“This is a really important moment in our journey towards building a hybrid navy, which is where the Royal Navy will sail with crewed ships and submarines alongside uncrewed and autonomous vessels,” Luke Pollard, U.K. Minister of State for Defence Readiness and Industry, separately said in an interview with LBC radio. “It is a substantial increase in our lethality, to show that torpedoes can be fired not just by the Astute class hunter-killer submarines that we have in the Royal Navy, but also now by our uncrewed systems.”

The U.S. Navy and the Royal Navy employ various tiers of UUVs operationally today, but primarily for mine-sweeping and reconnaissance and surveillance missions. Future fleets of submersible drones capable of carrying out attacks on other vessels will create entirely new operational possibilities. Operated closely together with crewed surface warships and submarines, torpedo-toting UUVs could be sent ahead into riskier environments and offer an immediate option for engaging any threats they might find. Even a bigger UUV like Excalibur would also be more challenging for opponents to spot and track than a traditional attack submarine.

Excalibur is also in a category of larger and more capable submersible drones that offer significant endurance and higher degrees of autonomy. Adding in the ability to launch torpedoes, in turn, then opens the door to new concepts for employing these UUVs in groups more independently of crewed companions. In the future, for instance, armed Excaliburs or similar UUVs might be deployed to a particular maritime choke point to not just monitor for enemy movements, but actively hold them at risk.

The Royal Navy’s Xtra Large Underwater Autonomous Vehicle – project CETUS

In addition, in general, UUVs offer a way to expand total undersea warfare capacity in a more cost-effective manner compared to acquiring and fielding more traditional submarines. The ability to have more presence below the waves at a lower price point also translates to more persistence across large areas, something that could be especially valuable across the broad expanses of the Pacific, as well as other bodies of water globally. This presents additional targeting challenges and uncertainty for opponents.

“In securing the North Atlantic, especially against those nations that wish to do us harm, like Russia, the ability for us to now say it’s not just where our submarines are that you need to worry about – it is about how we create greater deterrence and question marks in the eyes of our adversary, with uncrewed systems there as well,” U.K. Minister Pollard said in speaking with LBC.

Pollard’s remarks here speak to particular considerations the British government is faced with just in its backyard. This includes the so-called Greenland-Iceland-United Kingdom (GIUK) Gap, which is the main path through which Russian Navy submarines transit to and from bases in the northwestern end of that country and the Atlantic proper. There is also the English Channel and the nearby Baltic Sea. The Royal Navy has limited capacity with its crewed submarines to monitor this and other critical regional chokepoints. UUVs could then help take pressure off its fleet of just five (of a planned seven) Astute class submarines, helping free those boats up for the myriad other missions they are tasked with, including carrier escort and special operations support.

“By converting commercial and allied uncrewed undersea hulls into high-end strike assets, the partnership drastically alters the cost-exchange ratio in contested maritime environments,” the U.S. Navy’s press release today notes, as well.

There are still many questions still to be answered about future larger UUV operations, including just how they will be deployed and recovered. Video the U.S. Navy released today shows that the torpedo-armed Excalibur was launched into the water in Scotland using a commercial truck-mounted crane. U.S. shipbuilders Huntington Ingalls Industries (HII) and General Dynamics National Steel and Shipbuilding Company (NASSCO), among others, have been working on new options for launching and retrieving larger drone submersibles from surface warships. External carriage on the hulls of ships and/or submarines might also be an option in the future.

Additional torpedo and other munition options for UUVs beyond the full-size Mk 48 could also be on the horizon. The U.S. Navy has invested heavily in compact and lightweight torpedo designs that could be well suited for employment from underwater drones like Excalibur.

The U.S. Navy says it is working with its international partners on another similar UUV capability demonstration, but this time involving an Anduril Dive-XL, under what is dubbed Project Cutlass. This effort “will tackle advanced payload integration data, command and control architectures, and tactical employment scenarios to further mature uncrewed undersea capabilities,” according to the U.S. Navy’s release.

The Royal Australian Navy is already in the process of acquiring and fielding a militarized version of the Dive-XL, called Ghost Shark. It’s also worth noting that the Dive-XL evolved from the earlier Dive-LD design. The Dive-LD is in at least limited operational U.S. Navy service now, a fact that was revealed by Iran’s capture of one of these submersible drones earlier this month, as you can read more about here.

Introducing: Dive-XL

The U.S. Navy is also continuing to push ahead with plans to field a force of Orca XLUUVs from Boeing. In August, the service announced that an Orca had conducted a 1,000-nautical-mile transit in the Pacific the preceding month as part of the ongoing development of that design.

Other countries are pursuing larger UUVs, as well. China has been making strides in this regard and is in some ways ahead of other competitors globally.

Excalibur’s ability to launch a standard Mk 48 heavyweight torpedo is already an important show of progress now toward a shared goal of a future underwater ecosystem that includes submersible drones that are able to attack other vessels.

Contact the author: joe@twz.com

A new drone collaboration by Cessna owner Textron and autonomy provider Merlin Labs aims to offer the U.S. military a hot production line and a familiar platform for uncrewed aerial logistics, including in contested environments.

The product is SkyCourier UX, a drone version of the Cessna 408 SkyCourier that has flown for FedEx, foreign special operations forces and small remote commercial airlines during its six years of active service. TWZ previously covered how the SkyCourier would likely end up taking on military applications when it was first announced, which you can read here.

Introducing SkyCourier UX

A partial full-size model on the show floor at the Air & Space Forces Association’s Air, Space & Cyber Conference in Washington, D.C., this week showed a nose that opened with hydraulics to a cargo bay in lieu of a cockpit. We have seen this same front door conversion concept for uncrewed cargo-carrying helicopters as of late. This allows for easy loading of outsized cargoes without specialized equipment, according to the company, though it does not increase the payload. Like the original SkyCourier, it’s good for about 6,000 pounds, or three standard containers.

The form factor of the uncrewed SkyCourier variant is otherwise identical to its crewed counterpart, with twin turboprops, a high-wing configuration and an aluminum body. 

As with the base SkyCourier, a major advantage of the aircraft is its optimization for loading and carrying standard pallets. This means that cargoes don’t necessarily have to be downloaded, broken up and repackaged for movement to forward positions. This is a big logistical advantage and can speed the flow of critical supplies to where they are needed most. 

The aircraft’s range is about 900 nautical miles, which the makers say suits it well for Pacific island-hopping, allowing for refueling stops on austere runways. It can take off on runways as short as 3,300 feet and land in just 2,500 feet, according to a spec sheet.

The Textron/Merlin collaboration aims to differentiate itself with proven capability in the missions it intends to fulfill, along with the ability to roll out a new drone variant fast and one it can sustain consistently. Bob Gibbs, Textron’s vice president of special missions sales, told reporters in a Monday briefing that the conventional SkyCourier was now fulfilling new orders, not previously announced, to deliver modified aircraft to foreign nations for medical evacuation, casualty evacuation and environmental protection.

“The aircraft’s being operated literally from the Arctic to the Amazon,” Gibbs said. “There are three different island nations in the Pacific that have airline fleets of them. We support our aircraft in 170 countries around the world. So, just like a Cessna Caravan or a Beechcraft King Air, they’re ubiquitous. You find them anywhere, and we support them anywhere in the world.”

The $7 Million Flying Box: Inside the Cessna SkyCourier

While the 900-mile range can’t take the loaded-up aircraft the nearly 2,000-mile stretch between the first and second island chains, Merlin and Textron executives said they don’t need to accomplish that to make it effective.

“This is the ability to disperse the forces among the second island chain … to do the island-hopping to be able to get to, whether it’s Palau, Tinian, Saipan, pick your various islands there,” Kyle Kremer, a retired Air Force major general who now advises Merlin, said. “With the range that it has, it has the ability to agilely move through there” and connect logistics pipelines.

The autonomy package, Merlin Pilot, is already in use under a $105 million U.S. Special Operations Command contract to develop autonomy for the C-130J Super Hercules transport aircraft. It’s been flown aboard four different single and multi-engine airframes, the company says. A promotional web page for Merlin Pilot shows tanker-class and commercial cargo applications with developing and future capabilities.

Merlin has also teamed with the Air Force to develop an AI copilot for KC-135 tankers that can decrease crew workload and even possibly fly the aircraft on its own in the future. TWZ reported on planned tests for these autonomy-enabled tankers in 2024, with the flights set to begin the following year.

However, the Air Force has not confirmed the completion of any flight tests for the effort since. And on Wednesday, Lt. Gen. Daniel Tulley, commander of Air Force Mobility Command, appeared to confirm that the tests had never taken place.

“There’s some companies out there who have offered to develop things where they can bring a carry-on kit onto old KC-135s and other aircraft, but we haven’t seen them test those successfully,” he said. 

He added that autonomy technology may lack the maturity needed for tanker missions.

“An optionally manned or an unmanned tanker at range, [at] the ranges we needed to operate at. It’s a very large aircraft, and we’re not yet to where we’re employing fully autonomous large aircraft. But the technology, I would say, is there and rapidly getting there,” he said.

Tulley did stress that the Air Force saw a need for unmanned aircraft in the last-tactical-leg delivery.

“I’m wrestling with that as we develop an AMC strategy,” he said. “There is absolutely room for some sort of autonomous or other small light lift capability, and that’s just one domain in the air, right? This could be by sea, could be by land, but there is absolutely some requirement for distribution from those major points of debarkation.”

In addition to autonomous takeoff, landing and navigation, and protection of the flight envelope, Merlin Pilot, the company says, has digital copilot human-machine teaming characteristics that include pilot health monitoring, gaze tracking and fatigue detection; pilot incapacitation and contingency response; and flight monitoring and assistance.

Some of Textron’s new features are making light steps toward autonomy already. Gibbs pointed out that the company’s Cessna Citation Gen3 business jets now include standard Garmin auto-land technology.

“Obviously, it’s a different scale than what Merlin’s doing as far as automation,” he said. “But … as we develop new products, we try to future-proof them, and so that’s where you get this nice transition between us.”

The SkyCourier can cost up to $8.5 million, depending on modifications, and while the SkyCourier UX sports GPS-denied navigation and the ability to seek different flight paths to avoid danger, it doesn’t have other built-in defenses. For contested logistics missions, it’s not clear how much risk the services are willing to tolerate for a relatively small logistics payload capability. Kremer maintained, though, that a drone of this size could be a mission-saving capability when dispatched to austere locations. And, in a Pacific conflict, it may reduce demand on already-stretched C-130 transports, now the smallest platform capable of carrying standard containers and long overtasked.

“If you can’t get the spare tire, if you can’t get the component, that small thing where you need it in these dispersed operations, they don’t keep the big logistic supply chain built up in these locations,” Kremer said. “You have to be able to get it where you need it, when you need it, and that’s what this provides.”

Nonetheless, the Air Force has a clear appetite for a capability like this. Last year, it signed a $17.5 million contract to put a Reliable Robotics autonomy package on a Cessna 208B Caravan. 

On Monday, Air Force Chief of Staff Gen. Ken Wilsbach reiterated the Air Force’s interest in unmanned aerial logistics platforms.

“We’re doing testing on them,” he said in response to an audience question. “We believe that there’s some value in that as well. It certainly could be valuable in the Pacific with the ranges that we’re talking about, and so we’re looking at several different options and evaluating them. But I would say nothing, no program of records just yet, but [we’re] certainly taking a look at some demonstrators and the like to see what’s available to us.”

Notably, China has made significant advancements in developing logistic drone capabilities, with reported successful flight tests of massive heavy-lift uncrewed aircraft, including a 7-ton cargo plane that’s currently the world’s largest uncrewed freighter to take flight. Among them is China’s CH-YH1000, a medium-altitude cargo drone developed by the China Academy of Aerospace Aerodynamics that boasts, like SkyCourier UX, a hatch in lieu of a cockpit for ease of flat-pallet loading up to a weight of 1.2 tons. These are just some of an increasing number of similar systems being developed in China that aim to take the crew out of lower-end logistical missions over short, medium and long distances.

Though Textron and Merlin have yet to build a SkyCourier UX prototype, Merlin CEO Matt George emphasized that the company had chosen to partner with Textron because they could start delivering aircraft fast.

“You’ll see over the course of the show a lot of concept aircraft. You’ll see a lot of renders. You’ll see a lot of people who have big empty factories all around the country,” he said. “But I also want to be very clear about the fact that none of this matters without production … There’s 14,000 Americans working in Wichita, Kansas, on a production line where these aircraft, at least in the crewed configuration, are coming off the production line. So when we talk about capability, we’re talking about that capability and bringing that capability to bear soon, rather than in the future.”

Next in the development process, executives say, will be an optionally piloted version of SkyCourier that will allow users to develop comfort with the platform and open the door to further iteration. 

The Textron/Merlin team is also leaving its options open in terms of which U.S. military customer might find its platform most useful.

“I hope [the Army and Air Force] fight over it,” Gibbs said.

Contact the editor: Tyler@twz.com