US and Royal Navy fire Mk 48 torpedo from uncrewed Excalibur submersible
A Sept. 13 test off Scotland proved a US heavyweight torpedo can launch from a British autonomous underwater vehicle, a milestone for AUKUS Pillar 2.
What to know
- A U.S. Mk 48 Heavyweight Torpedo was launched from the Royal Navy's uncrewed Excalibur submersible on Sept. 13 at a Scottish test facility, a proof of concept rather than an operational deployment.
- The test is framed as an early operational win for AUKUS Pillar 2, the U.S.-U.K.-Australia agreement enabling shared uncrewed undersea vehicle payload systems.
- Follow-on work under Project CUTLASS will extend integration to Anduril's Dive-XL platform, covering payload data, command-and-control architecture, and tactical employment.
- Technical reporting notes Excalibur's payload bay cannot fit the Mk 48 internally, so the torpedo was mounted externally in a cradle, underscoring the engineering work still needed for full interchangeability.
“Excalibur has no torpedo tubes, but a large central payload bay with doors at the top and bottom. However, the Mk 48 torpedo… is too long to fit in the standard central payload bay.”
Navy Lookout, UK naval affairs outlet · Defense News ↗ · Sep 21
Daryl Caudle U.S. Chief of Naval Operations
Royal Navy Operator of the Excalibur UUVU.S. Navy Provider of the Mk 48 torpedo and test partnerAnduril Maker of the Dive-XL UUV platform
How it unfolded 2 developments, newest first · click a bar or a number to jump articlesposts
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Navies outline follow-on work under Project CUTLASS
The Navy release describes 'follow-on acceleration with Project CUTLASS,' which will use the Anduril Dive-XL platform to mature payload integration, command and control architectures, and tactical employment for uncrewed undersea vehicles.
“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. By integrating weapons, payloads, and mission architectures across allied platforms, we are increasing the flexibility, scale, and combat power of our combined forces and ensuring they are ready to meet the strategic demands of tomorrow.”
— Adm. Daryl Caudle, Chief of Naval Operations · source -
first by Defense News, 1d ago
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Navy leadership publicizes the test as an interchangeability milestone
The U.S. Navy announces the successful proof-of-concept launch via press release and social media, with CNO Adm. Daryl Caudle calling it a historic first for allied undersea warfare; Defense News reports on the test the same week.
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📰 U.S. NAVY UPDATE: U.S. Navy and Royal Navy Successfully Test Fire Torpedo from Unmanned Undersea Vehicle 📍WASHINGTON – On September 13, 2026, the U.S. Navy and the Royal Navy successfully conducted the proof-of-concept launch of an exercise U.S. Mk 48 Heavyweight Torpedo
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background
Royal Navy launches US Mk 48 torpedo from Excalibur UUV — At the British Underwater Test & Evaluation Centre in Scotland, an exercise Mk 48 Heavyweight Torpedo is launched from a cradle attached to the hull of the nearly 40-foot Excalibur, validating mechanical, electrical and software integration of a US weapon on an allied autonomous vessel.
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background
US, UK and Australia sign AUKUS Pillar 2 UUV payload agreement — The three nations agree to enable Uncrewed Undersea Vehicle payload systems usable across each country's UUVs, setting the stage for weapon interchangeability trials.
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Royal Navy unveils Excalibur uncrewed submarine — The Excalibur uncrewed underwater vehicle, the Royal Navy's first uncrewed submarine, is unveiled, later serving as the platform for the Mk 48 torpedo launch.