A lightweight towed array sonar developed by SEA has been successfully integrated and trialled with the Manta XLUUV. This combination of technologies has significant implications for anti-submarine warfare, seabed warfare and underwater surveillance capabilities.
The 9-metre Manta uncrewed submersible built by MSubs in 2020 has been conducting a series of trials and experiments off Plymouth, run as part of the MoD’s Defence and Security Accelerator (DASA) programme. SEA worked with MSubs to add their Krait passive towed array to Manta and designed a low-risk launch and recovery process. During the trial, it was confirmed Manta could be operated with a functional 150m thin-line towed KraitArray attached. The sonar was integrated with the existing communications and sensor systems which provide position, time, speed and depth data to create a detailed acoustic profile of the underwater environment. A support vessel was used to simulate the noise of submerged targets for the KraitArray to track.
The Krait Defence System is a compact Anti-Submarine Warfare (ASW) concept developed by SEA primarily for small vessels. There are four elements comprising the passive towed array (KraitArray), an active sonar (KraitSense), an acoustic torpedo decoy system (KraitShield) and a lightweight ASW torpedo launcher (KraitStrike). Some or all of the elements of this modular system can be fitted to existing platforms such as OPVs. This is not comparable with the sophisticated high-end Thales Sonar 2087 and ASW systems fitted to the Type 23/26 frigates but perhaps should be considered as a low cost, bolt-on option that could give the Type 31s and OPVs a basic ASW capability in extremis.
The KraitArray is made from three 50m modules, giving a total length of 150m with a bend radius of 100m. The array can be lowered to depths of 300m and is equipped with up to 128 acoustic channels and 32 non-acoustic sensors. SEA say that KraitArray is already in production for undisclosed overseas customers.
It is likely that the array was just attached to the stern of the Manta XLUUV for the trials and not streamed from an internal reel. The Astute class submarines have a towed array over 120m in length on a towing cable that is at least 600m long and can quietly deploy and retract the array from an internal reel as required. (A backup ‘clip on’ array is also carried on the upper casing). The TA is part of the highly sophisticated sonar Type 2076 which includes active and passive arrays, powerful signal processing software and skilled human operators. The KraitArray is obviously a lot simpler but towed arrays are especially useful as they distance the sensor from the noise radiated into the water by the submarine’s machinery and water flowing over the hull. They can also place the sensor lower in the water column, closer to the source of the noise or into the thermal or salinity layers that channel sounds over long distances.
Although passive sonars do not require large power supplies, developing the towed array equipped XLUUV to a point where it can serve as an operational asset will involve overcoming several hurdles. Manta uses lithium batteries that can only be recharged from an external power source which constrains its range. The Boeing Orca XLUUV, the first of which was recently launched by the US Navy, has conventional diesel-electric propulsion, periodically surfacing to recharge its batteries using a diesel generator. This allows ORCA to be deployed on patrols for weeks and it may also carry active sonar needed to obtain fire control solutions. Later iterations could eventually be weaponised with torpedoes to prosecute targets independently.
Autonomous weaponised submersibles present particularly difficult command and control problems and for the foreseeable future at least, their value will be primarily for deployment on ISR missions. When a contact of interest is detected, to be of tactical use the XLUUV needs to pass the data on as soon as possible. This is likely to involve either relatively short-range underwater communication with another ‘data node’ UUV or submarine or the vessel must come close to the surface and pass data to satellites or maritime patrol aircraft.
There is a long list of potential missions for the towed array-equipped XLUUV that would help supplement the work of the RN’s overstretched SSN force. These range from simple patrols of UK waters to sanitise the approaches to ports looking for intruding adversary submarines to more long-range deployments in the North Atlantic to supplement ongoing ASW work. In future, XLUUVs could be deployed from the Type 26 frigates to sanitise waters ahead of the carrier strike group or carried by the MROSS for use in monitoring undersea infrastructure. Let us hope that the DASA initiative succeeds in accelerating this capability into service as soon as possible.
Good news that things are progressing fast in this department. The urgency to deploy systems of this ilk underscored by Russia’s threats and actual aggression.
The Royal Canadian Navy use the Geospectrum TRAPS towed reelable sonar system as an add on containerised sonar on their Kingston class opvs. Something similar for the Rivers would seem to be a sensible way to go.
Are we? I know that we put in an order for some, but have yet to hear of them being used, let alone delivered.
Thats what the UK’s Krait Defence system is as well…
https://www.sea.co.uk/maritime/products/krait-defence-system/
Interesting achievement, but not convincing.
I understand ASW is more and more multi-static. Without data transfer, XLUUV’s TAS cannot join the multi-static game as a node. However, if it is coupled with towed floating buoy with satcom or com-link to MALE UAV (such as SkyGuardian), it can join the multi-static ASW game.
I know it’s a daft question but what weapons does the RN use if they locate a submarine? Is it still a stingray lightweight torpedo from a wildcat? I’m guessing we moved on from depth charges.
Heavy torpedo from a Merlin.
Wildcat is not the ASW platform.
Stingray torpedo from Merlin, AND Wildcat, both. In recent trials onboard HMS Trent, Wildcat almost always carried two Stingray, for certification, I guess.
Wildcat in ASW roles has always been a “torpedo deployer”. And, yes, it primary roles are always utility and anti-surface. ASW is just a secondary role.
Depth charges are still in stock…they were trialled from Merlin. Not sure if Wildcat has ever carried out trials for them though.
They still have a place….in fact for destroying easy targets like UUV’s they’re far prefereable,,,
MK75 Sting Ray from Merlin, Wildcat and MTLS. Merlin can prosecute and attack using MK75. Wildcat can only drop on a location using MATCH/Vectac. T23 can launch from its 4 tubes.
DC MK 11 is still in service and carried by the aircraft. Useful for use in V shallow water or against surfaced targets. Its can also be used as a “shot across the bows” for things like a VLCC who probably won’t see a 30mm hitting the water.
This seems to be excellent technology. The Manta is a good size to fit in a frigate boat bay, so I don’t see why it needs to have long independent endurance. If a Type 31 can operate two of them alternately, and have a Merlin on standby, isn’t that the basis of a continous ASW system?
It doesn’t have to be Captas standard. The Type 31 is a second tier frigate and if it has a second tier ASW capability, that’s okay because it will only improve over time as the battery powered XLUUV gets even quieter and the thin-line array becomes more sensitive.
But in order for the combination to improve, the navy has to keep ordering new versions, not just evaluating them. Having an initially operational system ready for the 2026 work up of HMS Venturer seems like a reasonable target.
See the SEADrix for an even better solution…uses the same Krait Array from SEA and the iXBlue unmanned surface vessel for 8 days duration.
Autonomous off board sensors are the way to go. But these aren’t replacements for boats.
And our escorts still need to be quiet.
They will need endurance to keep up with fleet speeds. What enters service will have to be much bigger.
And probably for choke points such as GUIK a ship with a large towed VDS that could accommodate a helicopter and or missiles would be better. Especially if a good sized air search radar is fitted too.
“They will need endurance to keep up with fleet speeds. What enters service will have to be much bigger.”
How does this work ATM?
At cruise speed sonar is pretty much blinded?
I should imagine they will sprint and drift. But they will need to big enough to keep up with or even a head of the fleet. I can’t see these being much smaller than say a few thousand tonnes. About the size of an O boat.
I would suppose in theory you could use it very much like a very large self locomotive sonar buoy. With an escort ship moving into a forward position of say a carrier group movement dropping it off. Then it could slowly move looking for contacts as the carrier groups overtakes and it could be picked up by a tailing ship, then rinse and repeat, with the mission bays in the RN escorts it gives them an option to do do this sort of evolution. It would allow the sensor platform to operate at the slow speed needed for ASW work. I do think there is going to be a lot of operational work around autonomous vessels as they develop as will as how the escorts based around mainly autonomous capability opportune in a task group. To could see a future where T31 and T32 do not operate in the same way as a traditional escort screen but spend their time moving around and deploying/redeploying assets.
I think navel warfare is heading to a paradigm shift to the same level as the move from wind power and wood to coal and iron or of the dominance of air and sub sea power. What I think is holding it back is fixed view on limitations on range and or speed. But these will be managed by a change in paradigm, as subs with limited underwater range and speed or aircraft with tiny ranges changes navel warfare for ever when people learnt how to operate them effectively so will autonomous vessels, but like navel aviation they will need the navel to adept the shape. Operations and role of some warships to maximise the use of the new asset.
The only thing I like about these system’s is if ever a space mission was to go the Jupiter Europa moon.
So can see a lot of money is on the cards to invest for these systems.
Krait Arrays come in 50 metre sections which can be configured to run 150 metres as this test. They can also be custom made in shorter versions as required by the customer for various applications.
Let’s hope we can use this in the North Atlantic, maybe controlled by Faslane? It would free up our scarce Nuclear subs…
Obviously this UUV enhanced STASS should be deployed to, and operated from, areas to which OPFOR submarines operate. Primarily that would be Norway adjacent to the the RU Northern Fleet operating submarines. Such deployments would correspond to our practice of USN USNS T-AGOS ships such as ABLE, LOYAL, INVINCIBLE etc. operating concept since the mid – 1980ies, as well as routine US|UK|FR SSN deployments to the Barents Sea supported by port infrastructure at Bergen & Tromsø. That’s were the most relevant submarines currently operate. There is an immense potential to establish new concepts, also in conjunction with LR MPAs such as UK|US|NOR P-8A Poseidons that operate in the Norwegian & Barents Sea.
Its interesting tech but how do we stop it being hijacked by unfriendly powers? And what’s to stop someone cutting the towed array (and even making off with it – didn’t a Russian sub do this recently to one of our Type 23’s arrays)??
Conquerer did to a Russian in 82……. that was just after its work down south.
Assuming the Russia-Ukraine war runs on well into 2023, it might be possible on that timescale to deploy this combination from the Ukrainian coast. Light enough to airfreight into Ukraine, hence getting round the problems the Treaty of Montreux causes.
Americans seem to be focusing on their MANTA XLUUV being a covert minelayer. Though under the 1908 Hague convention untethered mines which are active for more than an hour are illegal.
Would this be able to track and hit Putin’s Tsunami Bomb?