The three prototype extra-large autonomous undersea vehicles (XL-AUV) which Anduril Australia is contracted to build for Defence will be the size of a school bus and their hulls will not be waterproof – far from it.

Instead, each prototype will feature a wet hull – a design where water flows freely inside the skin of the XL-UAV.

This makes the submersible easy and fast to manufacture since no heavy welding is required to turn the hull into a pressure vessel to accommodate a human crew.

And, as Anduril chief executive David Goodrich points out, thanks to the simple and cost-effective manufacturing system the design can be varied in terms of size and payload capacity to suit specific missions.

“Each prototype will be iterative; we’re not just building three of the same vehicle.,” he explains.

“They’ll be delivered over the three-year life of the program at a fraction of the cost of existing undersea capabilities.

“They’ll have a framework of aluminium covered with a lightweight skin, that has gaps in it, and they will travel completely flooded. They’ll have a common battery-powered propulsion system at the stern, a common navigation and control system in the nose cone, and everything in between is for the payload.

“The midsection modules can be of varying lengths to meet specific requirements.

“The batteries are pressure-resistant, and all the navigation and control subsystems are inside pressure vessels the size of propane gas tanks that are located in various parts of the vehicle, leaving the maximum amount of space for payloads that will be accessed via payload doors and covers.”

Goodrich declines to speculate on payloads, but says they’re likely to facilitate a range of mine, counter-mine and intelligence, surveillance and reconnaissance tasks.

The XL-AUV’s range and endurance will depend on what payload modules are carried.

However, as a starting point Anduril will be using technology derived from its recently acquired US AUV manufacturer Dive Technologies, whose 3-tonne AUV is able to autonomously conduct missions for up to 10 days with an architecture that scales for multi-week missions.

It is also capable of conducting missions along the sea floor at depths of up to 6000m.

“The XL-UAV will be integrated with Anduril’s artificial intelligence-powered Lattice operating system and operate itself. Where the submarines are likely to go there’s not a great deal of connectivity, so they’ve got to be super-smart,” Goodrich states.

“Our autonomous systems mean that you can have really sophisticated sensor processing on the vehicle so it can do things, like analyse the signature of the propulsion system, sonar reflections and so on to identify a vessel of interest and exactly what it’s doing. There are various ways that the XL-AUV can communicate through the Lattice system.”

Getting the submersible in and out of the water is part of the overall production system. A solution has been reached but has not yet been announced.