In Spring 2020 the RN received its first extra-large uncrewed underwater vehicle (XLUUV). Here we look at how trials and experimentation with Manta are progressing and some of the wider considerations about bringing uncrewed submarines into frontline service.
Since we reported on Manta’s imminent delivery in March 2020 the vessel has been conducting a series of trials and experiments operating from its base in Plymouth. This is a joint effort between manufacturer MSubs, the MoD’s Defence and Security Accelerator (DASA), the Defence Science and Technology Laboratory (DSTL) and the RN’s underwater battlespace and submarine delivery teams.
This £2.4M DASA-funded project will complete the first 2 phases in April 2022. Phase 1 covered delivery and basic seaworthiness and autonomy tests. Phase 2 covers two years of mission testing of gradually increasing complexity. Negotiations have begun for phase 3 which is likely to see the submarine more closely integrated with the navy MARCAP (Maritime Capability) team and conducting trials that relate more directly to the operational environment and de-risk future technologies for SSN(R).
Like most elements of the undersea naval domain, precise details are limited but MSubs say that over the trials period they have gradually ironed out initial bugs and the submarine has now become very reliable with accurate depth control to within 20 cm achieved. Phase 1 trials proved Manta’s ability to dive and maintain a set depth, following waypoints, maintain navigational accuracy and detect then avoid obstacles. The specification also called for the ability to deploy a small 250kg payload such as a mini UUV or a mine (although payload recovery is not part of the specification). MANTA is really more ‘automated’ than ‘autonomous’ at this stage with AI-enabled decision-making capability in development.
As the platform performance has been improving, MANTA has been fitted with sensors including sonars and cameras. Two-way communication is possible while submerged at modest ranges. Inevitable challenges have been encountered during the testing phase, for example, rudders or hydroplanes have been damaged or jammed after hitting debris or weed. This experience has fed back to engineers who have enhanced the design to make it more robust and there are multiple redundancies in the solid-state computing systems on board. The radiated acoustic signature has been measured across its operating envelope and reduced where possible. MSubs retain ownership but MANTA is indemnified against loss allowing increasing risks to being taken to test its capabilities.
There is similar work going on in Southampton especially in the civil sector but Plymouth is developing into the UK centre of excellence for practical maritime autonomy. MSubs has expanded and now employs around 100 staff. Besides their portfolio of UUVs, they have a contract to supply Swimmer Delivery Vehicles to the United States Navy and will be well-positioned to bid for future RN XLUUV procurements. MANTA was assembled in Plymouth with the majority of its content sourced from UK manufacturers.
The RN has been operating small UUVs in various forms for almost two decades in the short-range reconnaissance, survey and mine warfare roles. The XLUUV offers a big step up in terms of potential capability but also presents a series of dilemmas in how they should be deployed operationally.
The First Sea Lord recently placed the undersea domain in the top 3 priorities for the RN. There is little chance of the manned SSN fleet ever exceeding 7 boats so uncrewed systems are clearly the only realistic way to supplement the all-too-thin ORBAT.
Manta is the start of a long developmental road and there are two key technical issues – communications and the fuel source, that are more difficult to overcome for UUVs than for above-water uncrewed systems. At present, there are big limitations on the bandwidth and range of underwater communications. For UUVs this means the amount of real-time intelligence data that can be sent back is restricted unless they surface, potentially compromising their mission. Commands from the mission controller to the UUV may also be limited to short or medium range. This is also a hurdle that must be surmounted if future UUVs are weaponised and a human needs to remain in the decision-making loop for weapon release.
Manta runs on Lithium-ion battery cells and range is dependent on battery life. If future XLUUVs are going to conduct missions that last several days or weeks then there are challenges in developing affordable and practical fuel sources. The highly sophisticated Boeing ORCA XLUUV being developed for the USN uses diesel-electric propulsion, similar to a conventional SSK but this is bulky and expensive. Hydrogen fuel cells are another alternative but dangerous hydrogen and oxygen have to be stored in pressurised bottles and the bi-products disposed of.
Batteries are clearly very attractive for the sake of simplicity and current technology is fine for small or medium size UUVs with a modest endurance. It may be technically possible to build a lithium-ion battery cell to fit in an XLUUV that could provide 5-10 MW hrs of power but such energy-dense cells present a major fire risk. If an XLUUV with such a battery caught fire while being carried on a ship it will be virtually impossible to extinguish and would have to be quickly dispatched overboard before it burned through steel decks. There is clearly a complicated safety case for carrying XLUUVs in the mission bay of a Type 26 frigate for example, before even addressing the challenges of launch and recovery in anything but the calmest sea states.
One of the big decisions that the designers of the SSN(R) which will replace the Astute class will have to make fairly soon is whether the boat will have a ‘mission bay’ to launch and recover future LUUVs or XLUUVs. This would add complexity and size and will present a difficult trade-off between the potential to greatly extend the reach of the SSN while compromising on size, cost and possibly stealth. Sticking to small disposable UUVs that can be launched via or torpedo tube or something marginally larger may be a better option. It is possible small UUVs for reconnaissance and decoy purposes may already be deployed onboard RN submarines.
The 25-metre ORCA is ultimately intended for the long-range independent mission, although this capability has not been fully proven. The RN’s first generation of operational XLUUVs are probably around 5-10 years away from deployment and will likely be considerably smaller than ORCA.
The solution to the power requirements may be available.
Our Technology – Infinite Power (wpengine.com)
Looking forward to more reply’s too your comment.
Interesting idea, never come across it before..!
I’m not an expert, but energy is always conserved so the radio isotope would have to be pretty energy dense- meaning radioactive. You’d have to select one of the “lighter” radioactive types to make sure there was no risk to health.
The question then becomes efficiency, and if the radioisotope can emit enough energy for the task. I think current solar panels are something like 25-30% efficient. I guess it just comes down to how densely they can pack the wafers, and how much energy is required. I’d be interested to see how they develop the tech!
They claim a one metre cube cell can produce 10kW. I’d guess that in the context of LUUVs, a combination with lithium batteries would be used in order to smooth peak demand.
A replacement for a 200 MW reactor in a big sub would be 20,000 cubic metres of Infinite Power battery. Not really scaleable.
The theoretical battery mentioned in the piece with a rating of “5-10 MW hrs of power” doesn’t tell us much even if the battery existed, as MW hrs is not a unit of power but of energy. Without a reasonable idea of power requirements (energy consumed per hour on average) it doesn’t even tell us how often the sub/UUV would need recharging.
Agreed, but we’re talking about XLUUV, not large nuclear subs, so sufficient power to support electronics and keep moving at slow speed is all that is required, not 200mW. The Infinite Power article mentions the lifetime energy of the system because it is aimed at the generation market and needed to give figure for lifetime ROI. Also agree that we can’t guess how useful a couple of 10kW cells would be on an XLUUV without knowing what the power demand is likely to be.
A nuclear sub reactor is in the 200MW range. But thats ‘thermal power’, most of which goes to waste through the cooling system like any rankine cycle system.
It isn’t a new idea.
Radioactive batteries have been around for decades.
By the time you have something radioactive enough, for the energy density, and screen it properly you have a very, very big lump.
I’m afraid I’d class this a ‘bad idea’.
In the article it mentions ‘bi products’ from the fuel cell. Firstly I assume it means byproducts and secondly there are no byproducts other than pure water from a hydrogen oxygen fuel cell? So I’m lost on that one.
Disposing of H2O in the middle of an ocean is hard apparently. 😉
Gamma rays Never get to the surface of the Sun they are blocked and converted to lower energy radiation. Less then 1% of the Sun’s output is X-rays. Some Gamma rays are generated by Solar flares, but are not consistent.
Good job as well, we be fried!!
One huge solar tantrum and we are screwed…
Like a Carrington Event. It is a bit like a major pandemic from infectious disease, long predicted but a surprise when it did happen.
That last solar one was 1859 and not the electronic world we have today
Yep, and it’s not if but when, but I’m told we have satellites monitoring the suns solar activity and if a huge even is predicted we can shut off lots of our vital electrical systems to protect them, is that right? And it would still fry loads of our electronics and cause huge problems, what about satellites orbiting earth too?
Could wreck 90% of cellphone towers electronics, just for starter.
Grid is controlled by digital means now, often they have their own comms system but is it hardened. Same goes for emergency services communications system, they often buy bandwidth from cell phone providers too
US grid is split in 3 and isn’t hardened any where near ours. Depends on strength of the event
I always imagined something similar to this as the “skin” of a spaceship, absorbing cosmic radiation and converting it to power and shielding the occupants.
No idea if it is even possible to design something that will absorb energy at that frequency though.
This would add ……… size
Have you heard how big they say SSN(R) will be?
Interesting progress. Personal opinion on XLUUV idea;
Long-duration isolated operations, with limited com-link. (Ninja-like tasks)
Short-duration linked operations, with limited com-link.
Short-duration linked operations, with high-rate com-link (sat-com buoy deployed?)
Long-duration linked operations, with high-rate com-link (sat-com buoy deployed?)
Some of these tasks do not needed to be an UUV. Actually, most of the ASW tasks can be better done with USV such as iXblue’s Drix USV with TASS, including “with high-rate com-link” tasks.
So, XLUUV will be a Ninja-like asset. (not war-fighting “Holleywood type” Ninja, but sneaking and communication “real Ninja like”).
Great for recon before amphibious assaults.
… such energy-dense cells present a major fire risk
On the propulsion, I am not sure why Li-Ion battery only is a issue with fire? It is surely the same with diesel. In case of fuel cells, it will be even worse. Anyway, it will burn.
On the other hand, there are millions of Li-ion battery based assets operated daily in the world, EV and HV cars. I do not think the battery has higher risk than the fuels? Fuel will burn, those for fuel-cells may even explode, nothing better than batteries, I understand?
My understanding is that Li-Ion batteries can be made particularly energy dense, so when/if they catch fire it can be very intense. Google car fires for Teslas (very energy dence Li-Ion batteries) vs petrol vehicles and you’ll see that the damage to the actual structure of the Tesla is far greater than the petrol cars.
Almost impossible to put out too…
GM advise Chevy Bolt drivers to park their vehicles 50m away from buildings and other vehicles because of the fire risk. It’s not just the risk of fire but the difficulty of putting it out cf fossil fuels that makes operating a large quantity within a mothership problematic. Probably a risk worth taking if the uuv is being operated from shore bases.
Thanks. My point is, “battery safety” is now the top priority in motor car world. And, “safety in car” is by far the most strict safety requirement these days, much strict than military or space, or even aircraft engineering.
In other words, Li-ion battery safety is an engineering world covered with investment of hundreds of millions of dollars every year. So I think it is solvable issue, not critical. It is very different from many “military specific” (and hence cannot enjoy huge investment) technologies.
Motor car technology is a really really giant world.
To which you might add that there are already a number of different Lithium Ion technologies. A XLUUV doesn’t have to use the highest energy density, higher risk technologies, it has the option to use safer solutions and still get the necessary energy storage. For example, at least one Li ion technology has pouch cells that can be cut with scissors or stabbed with a knife, remain stable and don’t start to burn.
Worth noting that Sodium Ion and Solid State batteries are rapidly advancing as well…
The Japanese have working lithium batteries. And the Koreans are nearly there with a technology from Samsung. But really too dangerous mostly.
“They are difficult to fight because you can’t put water on the mega packs … all that does is extend the length of time that the fire burns for.”
“The recommended process is you cool everything around it so the fire can’t spread and you let it burn out,” Beswicke said.
This is not ideal on a sub. Australia rejected Li batteries for the Attack class.
Thanks. But, many of the fuel-cell technology is also very dangerous. I never meant Li-ion battery is safe. No difference to many other “long duration under water technologies”, this is what I wanted to say. For UUVs, we anyway need something to drive them.
Great to see the RN getting involved in this tech, although I wish it was progressing a bit quicker…
Not to criticise, but the US and others are already testing and running long duration autonomous underwater vehicles (AUVs) for survey and search tasks- which have an important contribution to ASW among other missions. Some of those systems are the same size as Manta but can autonomously carry out tasks below the waves over a range of over 1,000 km. It is great that we are developing a domestic capabiltiy- I am all for that. We just need to plug more money into it if we’re serious about it being one of the top 3 focusses for the RN…
“The First Sea Lord recently placed the undersea domain in the top 3 priorities for the RN. There is little chance of the manned SSN fleet ever exceeding 7 boats so uncrewed systems are clearly the only realistic way to supplement the all-too-thin ORBAT.”
If I’d written that Australia needed SSNs, then I would have had people swarming to say how fantasy-fleet that would be. If I’d said the RN might try and get a next-gen anti-ship missile replacement, then the same might have occurred.
Let’s perhaps hold off on such pronouncements. There is always a chance that clever people used well might find a way to increase SSN numbers even by a small amount when we get to the successor to Astute. Maybe not much of a chance, but I think it is there.
Yeah but We is well Woke now like … init…. Long gone is our national focus on real worries.
It’s a bit like watching my fishing float…… I sit there for ages watching the red and white bit bobbing up and down but nothing much really happens. Hopefully a really good news catch will come along soon !
Jesus, what size of fish are you trying to catch?
Well mate…. At My Age, I’m just glad to be able to dangle me tackle truth be known……………………….
Lol, nice to get it out n the Fresh air too ?