Why is the technology of the large XLUUV underwater drone strategic for military navies?

After the success of the test phases of its DDO demonstrator, a large underwater drone, or XLUUV, Naval Group was awarded a contract for the design of a new system of the same type, but more imposing, as well as of all the key technologies to equip and implement these naval drones.

In this area, France is not behind, and is even one of the most advanced nations, with the United States. However, it is not the only one to invest significant resources to acquire XLUUV. Indeed, knowing how to design and implement these large military underwater drones will quickly become a strategic issue for many navies. That's why…

If drones have entered the aerial battlefield for several decades, the arrival of these automated systems is much more recent in other spaces of conflict, however often for different reasons. Thus, the main obstacle to the design of a terrestrial drone lies in the management of its mobility on terrain that is by nature chaotic and changing, such as on a battlefield.

In the field of surface drones, it is above all the constraints linked to the duration of missions which concentrate the efforts of researchers. Indeed, where a combat drone will stay in the air for, at best, a few dozen hours, a large surface drone will carry out its mission over several weeks, perhaps even several months, with its share of damages and fortunes at sea.

XLUUV DDO from Naval group
Naval group's DDO large underwater drone demonstrator completed its test program in the summer of 2023.

Underwater drones, for their part, combine the constraints of surface units, with a strong imperative in terms of discretion, especially in the electromagnetic and acoustic domain, while very few countries actually have the skills to design a conventional submarine.

Thus, if, to be operational, a surface drone can rely on a data link with a control center, the essential discretion linked to the military submarine mission requires these electromagnetic exchanges to be reduced as much as possible, and therefore to design a drone with very extensive autonomy in terms of piloting, but also mission control, and even operational decision-making.

A new French program based on Naval Group’s DDO large underwater drone demonstrator

In this area, the French Naval Group has taken the lead in national military programming, by developing, with its own funds, a demonstrator called DDO, for Oceanic Drone Demonstrator.

Its presentation took place, concomitantly with its first launch, in October 2021, on the occasion of Naval Group Innovation Days, an annual industry event intended to promote and present its recent innovations and technological advances.

10 meters long for 10 tonnes of displacement, the DDO has since carried out several test campaigns, both to validate the decisions and developments of Naval Group engineers, and to collect numerous data and experiences linked to its implementation, such as this is the role of a demonstrator.

Navl Group Innovation days 2021 DDO
The DDO was presented during the Naval Group Innovation Days in October 2021.

The industrialist's gamble paid off. Indeed, after funding from the DGA supported Naval Group during the tests of its demonstrator, and as planned by the new LPM 2024-2030, it was notified a research and development contract, from the DGA, for the design, manufacture and testing of a new XLUUV, an acronym for Very Large Unmanned Underwater Vehicle, based on the findings of the DDO program.

The new drone must be larger and heavier than the initial demonstrator, without its dimensions having been specifically defined. During this time, the DDO will serve as a platform for a set of developments in the field of endurance, energy production, sensor integration, and above all automation and socket autonomous decision-making, subjects widely highlighted by the DGA and Naval group in this matter.

The main XLUUV programs around the world

France, Naval Group, and the French Navy are not the only ones to take a close interest in, and invest in, the development of this type of technology. Similar programs, more or less advanced, are, in fact, underway in several countries, in particular those with skills in the design and construction of military submarines.

This is the case of the United States and the US Navy, with the ORCA program, the design of which was entrusted to Boeing and the construction to Lockheed Martin's HHI shipyards. The first prototype was delivered by the manufacturer at the end of last year, and has since been carrying out multiple tests and trials.

Boeing will deliver a total of six XLUUV ORCAs to the US Navy.

26 meters long, but with a displacement of only eight tonnes, the ORCA must be built in six copies, to carry out all the tests and trials, including in terms of operational deployment, in order to be able to begin the design and construction of a class of large (Large) and very large (eXtra Large) autonomous underwater drones coming strengthen and expand the capabilities of the US Navy, starting at the end of the decade.

Several other countries, such as Japan, South Korea, Germany and Israel, have announced in recent months that they are engaged in similar programs. Just like China, however, the state of progress in this area is unknown, with Beijing traditionally being very discreet regarding the development of underwater technologies.

In any case, with a 10-ton demonstrator having already carried out several test campaigns, and an ambitious program to follow, France is at the forefront in the field of XLUUVs, and intends to remain so.

Operational capabilities soon to be essential for all military navies

It must be said that the possibilities promised by the arrival of the XLUUVs in the inventory of large military navies are enough to whet the appetites of naval strategists. Indeed, through their performance, their reduced costs, their mobility and a limited HR footprint, these underwater drones significantly extend the capabilities of traditional submarines, whether conventional or even nuclear powered.

XLUUV DDO Naval group
The DDO is one of the first XLUUVs to have carried out sea trials in 2021.

By their reduced prices, we are talking about €20 million for the surveillance version (10 tonnes) of the DDO, their range of sensors, and their autonomy at sea, the XLUUVs represent, without the slightest doubt, one of the most effective solutions effective for monitoring and securing an extended maritime space, coasts, and even critical naval infrastructure, such as ports and arsenals or submarine cables.

Thus, securing an arsenal, which would require, over time, at least two nuclear submarines passing the baton, or three conventionally powered submarines, could be achieved by 5 or 6 XLUUVs, rotating by flotilla of 2 or 3, and costing only a fraction of the construction and implementation costs of the submarine flotilla immobilized for such a mission, and moreover, very probably, more useful elsewhere.

Large underwater drones can also prove particularly useful in missions too risky to dedicate a submarine to, such as operational naval intelligence near the enemy's coast or its naval device, or target designation.

Thus, an XLUUV can discreetly approach an opposing fleet, identify key ships, and transmit the information to a frigate, another submarine, or a stike of fighter planes, to strike them from a distance. security, while significantly reducing the risk of collateral damage, much more surely than with a conventional submarine.

The dimensions of the American XLUUV ORCA appear in this photo during the naming ceremony of the first prototype.

Finally, XLUUVs have immeasurable mobility, particularly compared to traditional submarines, including nuclear-powered ones. Indeed, due to its dimensions, the DDO can be transported by A400M plane anywhere in the world in 24 hours, while its combat version, 20 meters long, could be transported with a C17. Once delivered, they can reach the sea by truck in just a few hours.

Thus, a large naval drone is capable of being deployed on very short notice, to respond to a crisis situation, much more quickly than an SSN can, even though the fastest naval system, with the aircraft carrier, Today.

All of these capabilities, and those that remain to be imagined and applied, give the XLUUVs a very significant operational potential, acting both as a force multiplier and as a specialized economic alternative, precisely to employ, to the best of their potential, the rare and very expensive attack submarines.

Technological issues on the scale of military issues

However, to achieve this, the technological obstacles to overcome are particularly numerous and difficult. Already, the entry ticket to be able to design effective XLUUVs, capable of exploiting the full potential of this new tool, is particularly high, since it requires knowing how to design and manufacture conventional or nuclear military submarines. .

SSN Suffren
Mastery of the design technologies of a military submarine constitutes the entry point to engage in the design of an XLUUV.

Indeed, the seabed represents one of the environments, along with sidereal space, the most hostile and aggressive that can be addressed by human technology today. If it is obviously possible to cobble together a partially autonomous semi-submarine, potentially capable of carrying out a suicide attack mission, using a satellite link which would negate the benefit of the discussion, the design of a true XLUUV, requires mastering all military underwater skills, and much more.

It's obviously not a mass sport. Indeed, to date, only the five permanent members of the United Nations Security Council, as well as Japan, South Korea, Germany, Sweden, and India, actually have these skills.

The case of Israel, and of Turkey, which will certainly soon reveal a similar program, is special. Although these two countries do not design their submarines, they nevertheless master the majority of the technologies, and have considerable know-how in the field of drones and autonomous systems. Furthermore, neither has any oceanic ambitions strictly speaking.

The second technological challenge, for the design, and especially the effective implementation of XLUUVs, encompasses the issues of discretion, as well as autonomous decision and mission conduct. Indeed, to fully exploit the potential of an XLUUV, it must be at least as discreet, acoustically speaking, as in the electromagnetic spectrum, as a modern military submarine.

MQ-9B Guardian
Modern MALE combat drones remain permanently connected to the flight platform via satellite data link. This is not applicable, or even desirable, for an XLUUV.

Impossible, in these circumstances, to rely on a permanent data link with a land-based piloting and control station, as is the case with aerial combat drones today. This issue is, as such, the priority area of ​​research and development identified by the DGA, in the contract awarded to Naval group a few days ago.

Note: Note, however, that significant efforts are being made, in particular around new generation fighter programs such as FCAS, GCAP or NGAD, to increase decision-making autonomy, and reduce emissions as much as possible, which are as discreet as they are sensitive. to jamming.

However, if an aerial drone is going to operate for a few hours above a sluggish airspace, before returning to its base, the XLUUVs will have to carry out missions lasting several weeks, and therefore demonstrate a capacity for considerable adaptation. more extensive, to respond effectively and in a standardized manner to all the scenarios and situations with which it could be confronted. All, obviously, while retaining, for certain key decisions, human arbitration as an insurmountable barrier.

This mission duration also generates constraints that will need to be addressed. Indeed, a ship at sea, whether or not it is autonomous, is exposed to damage and sea fortunes. The XLUUV must be able to withstand this damage, whether it is linked to the operational context, or simply for its naval use, while continuing its mission with efficiency and reliability, over the required duration.

It will certainly also be appropriate to imagine how major damage could be repaired by support vessels, without a return to port being necessary.

As such, it will be necessary, finally, to have a support capacity adapted to the use of these drones, and above all to ensure that repairs and interventions to compensate for the absence of crew do not saturate the capacities. maintenance, and ultimately, create a traffic jam which would cancel out the benefits expected from the use of these systems.


As we can see, the design and implementation of large underwater drones will probably become, if this is not already the case, one of the major technological and operational challenges linked to naval warfare in the years future.

DDO Naval Group
The biomimetic influence of large cetaceans is evident in the design of Naval Group's DDO.

In this area, France did not miss its start, in particular thanks to the initiative of Naval Group, which developed, with its own funds, even before military planning was interested in the subject, a very promising demonstrator , the DDO, giving it a real technological advance in this area.

Beyond the performance and operational capabilities that these future XLUUVs will bring to submarine fleets, the systems will also have significant commercial potential on the international scene. Their price, in fact, will put them within the reach of many navies that do not have the means to acquire real submarines, or which have a reduced submarine fleet.

The combination of new capabilities, complementary or substitutes for existing systems, and a larger market, makes the XLUUV one of the major future weapon systems, which all navies will have to equip themselves with. They will, moreover, constitute a real pivot of military naval action, whether offensive or defensive. It is therefore important, obviously, not to miss the mark, as was the case in Europe for combat aerial drones.

Article from February 1, 2024 in full version until July 14, 2024

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