The Indian Ministry of Defense (MoD) launched a project to design and develop an Extra Large Unmanned Underwater Vehicle (XLUUV), according to Navy News Network, on April 24. A document released by the Indian Ministry of Defense last month indicated that the Indian Navy plans to procure up to 12 XLUUVs once the prototype is built and passes all tests. 

According to the document, the XLUUV has a maximum payload length of up to 50 meters, a width of up to 5 meters, a height of no more than 10 meters, and a total weight excluding ballast of less than 300 tons.

India’s Defense Research and Development Organization (DRDO)‘s High Endurance Autonomous Underwater Vehicle (HEAUV) model on display at Defense Expo (Defexpo) 2022 in New Delhi, India

That would make it one of the largest submarine drones ever conceived, rivaling Germany’s convertible underwater carrier, the U.S. Navy’s Orca and Russia’s Salma-D, all of which are in the prototype stage. It should be noted that the Indian project is in its initial stages, and specifications may change significantly as the project progresses.

The XLUUV is designed to perform the following roles: surveillance and reconnaissance intelligence, anti-submarine warfare, anti-surface warfare and mine warfare. The autonomous feature is a key requirement whereby the vessel should be able to deploy from the dock, operate in shallow and restricted waters and return to port on its own. And it must be able to be transported on land by a mothership and a trailer. 

External payloads of up to 10 tonnes of weapons are also under consideration, and the MoD is exploring the feasibility of installing two 533mm torpedo tubes and the XLUUV minelaying capability.

The maximum underwater speed is specified as at least 8 knots, and the cruising speed exceeds 4 knots. Propulsion options may include integrated thrusters or propellers using electric motors. 

The XLUUV is specified to have a maximum endurance of more than 45 days using lithium-polymer/lithium-ion batteries or a fuel cell-based air-independent propulsion (AIP) system as a power source. A diesel generator can be used to charge any battery.

India plans to develop a Very Large Military Unmanned Underwater Vehicle (XLUUV)

Sensors installed on the XLUUV will include flank array sonar, towed array sonar, bow sonar, multibeam echosounder bottom profiler, anti-collision sonar, I-band radar, ESM system and cameras with EO/IR periscope mast. It will be able to communicate with other platforms and control stations using satellite communications and underwater communications systems.

The project received Approval-in-Principle (AiP) on January 16, 2023, with prototype development expected by 2025. Other Make-I projects that received AiP on January 16 include 15 shipboard 30kW laser weapon systems, eight 12 MW electric propulsion systems and 55 4MW class gas turbine generators.

Major shipbuilders such as India’s Mazagon Dock Shipbuilders Limited (MDL) and India’s Larsen & Toubro (L&T) are expected to participate in the project. In March 2022, Mazagon Shipyard issued a letter of intent to cooperate with global companies in the design, development and construction of XLUUV. Larsentub has an autonomous underwater vehicle (AUV) portfolio and provides midget submarine designs to the Navy.

The procurement of a dozen XLUUVs will help the Indian Navy bridge the apparent gap in underwater capabilities caused by major delays with the Project-75I submarine. Under the project, Mazagon Shipyard and Larsentub will build six diesel-electric submarines with sea-proven AIP in India and transfer technology.

 Eight smaller High Endurance Autonomous Underwater Vehicles (HEAUVs) are also planned to be selected. These containerized 8-ton submersibles will be capable of conducting anti-submarine warfare and mine countermeasure operations with more than two weeks of endurance.