In an unveiling ceremony at His Majesty’s Naval Base Devonport on 15 May, the UK Royal Navy marked the culmination of the three-year-long development of its extra-large uncrewed underwater vehicle (XLUUV) under what is known as Project CETUS.
It is now confirmed that the experimental vessel (XV) has been named the XV Excalibur after the Arthurian legend, and an experimental high-speed submarine that the service trialled in the 1950s and 60s.
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The capability has a length of 12 metres (m), a width of 2m, and a displacement of 19 tonnes.
UUVs make up 42% of the global military uncrewed maritime vehicles market, which is projected to grow at a compound annual growth rate of 8.9% over the next decade, according to GlobalData intelligence.
Since the Plymouth-based manufacturer, MSubs, delivered the autonomous platform to the Royal Navy earlier this year, the XLUUV has undertaken harbour and sea acceptance trials at Devonport.
Now, Excalibur will join the Fleet Experimentation Squadron, a unit that was recently formed under the Disruptive Capabilities and Technologies Office, where it will join surface ship XV Patrick Blackett.
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What will Excalibur do now?
As a demonstrator, the platform will not perform operational duties but will shape future concepts.
“The lessons learnt from this… programme will build on our experience from existing programmes, such as the Mine Hunting Capability programme, to inform more extensive use of these technologies in a mixed force of crewed and uncrewed systems,” said Commodore Marcus Rose, deputy director underwater battlespace capability.
It will serve as the testbed for emerging maritime technology, both exploiting the natural intelligence surveillance, reconnaissance and stealth aspects of the XLUUV, alongside its ability to carry bespoke payloads.
To some extent, the integration of emerging sensing capabilities with the platform has already occurred. In 2022, during Nato exercise REPMUS, another British naval supplier SEA tested its sonar solution from another XLUUV – the S201 – built by MSubs in 2005, a precursor that the company recently described as the “spiritual predecessor” to Excalibur.
Excalibur development: internals
During the Undersea Defence Technology conference at Oslo in March, MSubs naval architect Callum McCullough dubbed the autonomous submarine as “a pick-up truck of the sea.”
For that reason, the payload bay is the particular focus to the design. It “breaks massively from convention,” he said, as the large bay uses a strong carbon fibre chassis, which can hold five tonnes of potential total mass, as well as nine cubic metres of volume.
The modular design consists of ten sections, which reduces downtime. “When, inevitably, there is a fault – we all know that that will happen, and we’ve got to lift the vehicle out – we can quickly access everything that you need to access,” McCullough said.
MSubs designed the battery system in-house. The main motor was designed by their engineers with other parts manufactured by suppliers across the country.
Both the Royal Navy and MSubs have a few specified payloads they each plan to test on Excalibur in the coming months and years.
