submarine

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

Recent satellite imagery of a shipyard in northeastern China offers interesting new insights into the country’s next-generation submarine developments. The images notably show a pumpjet propulsor and other features worth examining on an example of what is generally described as a new class of nuclear-powered attack submarine, or SSN.

TWZ has obtained a new image taken on September 18 of the submarine in question, which is being built at the Bohai Shipyard in Huludao, from Vantor. Janes reported on this submarine earlier today, based on a separate Vantor image from September 1. The outlet also described the boat as a Type 095, a commonly used, but still unofficial designation. This is something we will come back to later on.

As mentioned, the pumpjet propulsor immediately stands out in both images. This is also understood to be a feature on the Type 093B nuclear-powered attack submarine, a significantly improved variation on that earlier design, which first emerged in the early 2020s. Compared to traditional exposed propellers and more basic shrouded types, pumpjets offer benefits for quieter operation and efficiencies, especially at higher submerged speeds.

The recent imagery also highlights the submarine’s X-shaped stern plane arrangement. This is not found on the Type 093B, which is considered to be something of a bridge between that class and the next-generation design. Broadly speaking, an X-shaped configuration offers advantages when it comes to enhanced maneuverability, efficiency, and safety, which can be particularly useful in littoral environments. It can also provide benefits when it comes to acoustic signature reductions across significant parts of the submarine’s operating envelope compared to the cruciform stern planes.

Another Chinese submarine design that emerged in 2024, currently referred to as the Type 041 or Zhou class, and that is understood to feature a hybrid nuclear/conventional propulsion system, also has an X-shaped stern configuration. The first known example of the Type 041 came to light after it appeared to have sunk in a shipyard.

An X-shaped stern arrangement also looks to be a feature on yet another new class of submarine that appeared at the JN (Jiangnan) Shipyard in Shanghai earlier this year. Initial reports also suggested that the design lacked a traditional sail. However, it has been confirmed that it has a sail, but that is very small proportionally to the overall size of the boat. Truncated sails can offer performance and other advantages, but there are trade-offs.

The image of the submarine that Janes obtained also notably shows an open rectangular-shaped section aft of the sail. The September 18 image that we received from Vantor shows a structure placed over that section of that submarine, obscuring ongoing work on that part of the boat. The Type 095 is widely expected to feature some type of vertical launch system (VLS) array able to accommodate a variety of anti-ship and land-attack cruise missiles, as well as potentially hypersonic types. The Type 095 is also sometimes referred to as a guided missile submarine, or SSGN, as a result. The open area seen in the September 1 shot could be where the VLS array is set to be fitted. It might also provide access to the reactor compartment or another area of the submarine.

Interestingly, the September 18 image also shows what look to be at least two relatively large circular openings, side-by-side, at the bow end of the submarine in front of the sail, the purpose of which is not immediately clear. There is a possibility these could also be for vertically launching munitions or other payloads. As a point of comparison, U.S. Virginia class nuclear attack submarines, starting with the Block III version, have two large-diameter Virginia Payload Tubes (VPT), one in front of the other, in the bow in front of their sails. At the same time, the openings on the submarine in Huludao also appear to be in a position that is very close to where the submarine’s main sonar array would be installed, and they could be tied to that aspect of the design, too.

“I think it’s too early to be sure about the VLS configuration from publicly available imagery. I realize people assume the large rectangular space halfway behind the sail is the VLS, but I am not sure this is the case and I’d caution to jump to conclusions. The space could also be related to work on the reactor compartment,” Alex Luck, a naval analyst who closely tracks submarine and Chinese navy developments, told TWZ. “With Type 093B, the VLS after launch was initially covered with a tarp, and then the installed launchers were readily visible quite quickly during the fitting-out process. The work process may change with these newer boats, but the different appearance during launch and fitting out needs to be considered in that regard.”

“I do expect Type 095 to have a VLS of some sort, but I am not sure as of yet what the configuration would look like, or where exactly it is located,” he added.

The bigger outstanding question may be exactly what type of submarine is currently being built now at the Bohai Shipyard. Based on a review of additional imagery from Planet Labs’ archive, the boat appears to be around 394 feet (120 meters) long. When the first example of what was assessed to be a Type 095 emerged in Huludao in February, it was estimated to have a length of roughly 361 feet (110 meters). The ‘small sail’ design that broke cover earlier this year in Shanghai is also estimated to be some 394 feet/120 meters long based on available imagery, but also looks to be narrower than the boat presumed to be a Type 095 in February.

“One significant question is the nature and difference between the boat launched by Bohai in February, and the two newer hulls launched in late May/early June both by Bohai and at Jiangnan in Shanghai,” Luck, the naval analyst, also told TWZ. “Specifically, we do not quite know whether they are for different operational roles, or rather a two step development for one final configuration of a new SSN. I think the latter is at least plausible.”

“A related question then is what boat we are looking at now with the new imagery, i.e. the February boat or the newer hull Bohai had launched,” he continued. “Without exact and reliable measurements that question for now is unresolved in the public discourse. For now we need more, and more detailed imagery, including of the different boats together, to clarify these aspects.”

“This [September 1] image reinforces my impression that the boat launched in February may have been a one off not including the full spec featured on the notional 095A launched by Bohai and Jiangnan in late May. We’ve already seen both versions side by side in Bohai,” Luck also wrote on X after Janes‘ published its report.

Regardless, the emergence in recent years of so many new, more modern submarines, and across what appear to be several distinct classes, is significant. It is no secret that China’s People’s Liberation Army Navy (PLAN) is working to significantly expand the size and capabilities of its submarine force with a clear eye toward extending operations further and further out in the Pacific, at least. In the past, U.S. officials have publicly said the overall quality of newer Chinese submarines has been getting closer in parity to American designs.

“The PLA Navy is executing a significant strategic shift from diesel-electric to all-nuclear construction, representing a fundamental departure from historical construction patterns,” U.S. Navy Rear Adm. Mike Brookes, head of the Office of Naval Intelligence, wrote in prepared remarks ahead of a hearing before members of the U.S.-China Economic and Security Review Commission in March.

In particular, the Type 095, as well as the new Type 096 nuclear-powered ballistic missile submarine, “represent next-generation platforms expected to enter service during the late 2020s through 2030s,” Brookes also wrote at that time. “These submarines will incorporate substantial advancements in nuclear reactor design, sensor performance, weapons integration, and noise quieting technologies.”

Submarine modernization efforts are just one aspect of a larger effort by the PLAN to expand its capabilities above and below the waves. Chinese shipyards have also been producing ever-more capable aircraft carriers, amphibious assault ships, destroyers, frigates, and more in recent years, as well. The pace of China’s construction of new surface ships and submarines has also been growing, creating a particularly significant and still-widening disparity in this regard with the U.S. Navy. This is something that has become increasingly concerning, as TWZ routinely highlights.

Work in Huludao, as well as shipyards elsewhere in China, is certainly already revealing interesting new insights into China’s next-generation submarine efforts.

Contact the author: joe@twz.com