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Supportive Bloke

An interesting take.

If the sonar buoy electronics are so good then why isn’t there…….? They are probably good enough for active but not for passive.

But I agree that these kind of systems are significant force multipliers and do have a space in the overall panoply of sensors.


Agree, interesting, but still hurdles to overcome.

Sonar buoys are effective bits of kit, but have several constraints. The biggest of which is detection range, which is purely down to the size of the kit (nominally 5″ diameter x 36″ length which everything has to fit into).

As a broad brush range analogy, if a TA sonar 2076/87 detection range against a SM was equivalent to the size of a football pitch, then a slim line array(Krait) might be equivalent to the penalty area, a dipping helo sonar to half of the centre circle, and a buoy equivalent to perhaps the D on the penalty area. The lack of detection range is one of the reasons that MPAs drop at least 4+ buoys in any string, not including the ‘bathy’ buoy.

Prior to dropping buoys, the receiver depth needs setting, something you can’t alter once it’s ejected. Not can they reposition themselves, once gone. The buoy has a squib/explosive charge which goes of to activate the inflation collar which keeps the antenna above the water, the sound of which travels further then the detection range of the buoy on any given day. It is reasonably easy for a SM to avoid a string of buoys if the squib is detected, rendering them somewhat redundant as they drift away on the current. Depending on the prevailing sea conditions, active buoys can have a range advantage over their passive counterparts.

An issue with using a dipping sonar on a UAV is that the wire also contains the power and data cable. So said UAV would need some form of data transmission unit to send the info to the control aircraft, adding both weight and power requirements.

Using UAVs isn’t an easy fix, but is probably the way forward to supplement crewed systems in the future given the costs of manned air assets.


From reading some accounts of ASW work during the cold war, I understand that another limitation for sonobuoys is the distance that they can transmit their data to a receiver for processing- whether that’s a helo or fixed wing aircraft. Given the large ranges that ASW can cover, even if they have a contact on their sonar, a sonobuoy could be “unheard” and therefore useless in the hunt.
As the article says, having the UAVs as relays for these sonobuoys builds the real-time picture of the total area.

Nick Brough

Autonomous systems may help, but in addition to data processing electronics and multiple systems each Drone would need employ, you need to find space on the Helicopter platform to control the entire operation, which is likely (and in facts needs to be) over the horizon from the warship/battle group/convoy.

There is then the issue of weather (especially in the Atlantic or Artic winter), seven before you consider the question of failure rates, redundancy, minimum number needed to cover a specified area etc etc. Then is there enough space in the warship (storage, repairs, additional crew, fuel, weapons etc ) ?

I have often wondered just how effective the protection of a Carrier group with just two ASW frigates plus helicopters from the carrier) would actually be in a real war time environment with air, sea and submarine submarine threat spheres operating at once.

I also wonder about electronic noise as a possible method of detection let alone the question of submarine and airborne ECM/EW issues.


Very true, one of the benefits of Merlin is its size for equipment and people for managing the data throughput. That’s one of the reasons also why I was seeing the UAVs first used as data relays rather than processors- much easier to manage as a staged development of capability.
Size and space is always a tricky one, and your question about sufficient resource to protect a CSG is a valid one. I suppose, given the reduced size of the Russian sub fleet, it’d be OK (as long as we keep developing stuff like the UAVs). But with China’s fleet, I’m not so sure. Yes, they’re not as good, but there’s an awful lot of them…


and outside of Medium Rotary-Wing there is MQ-9B.

Last edited 1 month ago by fvf
John Clark

Sea Guardian would certainly be a huge force multiplier for our small Posiden force.

If you increased the Posiden force to 12 and added another 10 airframes to our Protector fleet of 16, (with 8/10 Sea Guardian kits), then you would have a really capable and sustainable Maritime patrol force.

Bloke down the pub

It seems we are looking at three possible rotary classes: 200kg MTOW, 700kg MTOW and 3 ton MTOW.

The 200kg class, exemplified by the RN Peregrine is just too small to be useful for ASW. I had thought perhaps at least as a relay carrier, until I saw the relay size in the photo. To dismantle a useful (and expensive) ISR to let it carry a few sonobuoys or a relay is a waste of effort and money.

The 700kg class (such as the Schiebel S-300) seems far more promising. With 5 times the payload of the S-100 on which Peregrine is based, it could already carry the weight of a lightweight dipping sonar such as the L3 Harris Firefly (<220kg) for 4 hours, long enough to be useful. Whether it has the space to carry this inside or underslung is unknown, and power may also be an issue, but we may be close to a working system. Furthermore the S-300 fits in a 20ft container or a Navy POD and could be worked on alongside a Merlin in a T26 hangar. The larger VSR-700, for all its heavier payload and longer duration, might be a less easy fit.

3 ton Proteus (payload >1ton) should be able do it all, if not necessarily at once: sonobuoys, dipping sonar, multistatic sensor fusion, lightweight torpedo. It should have the power, the range and the useful duration, although we’ll have to wait until 2025 for flight testing to be sure. It won’t be able to fit in a hangar alongside a Merlin and would have to be kept in the T26 mission bay, although no problem to put it alongside a Wildcat in a T31 or a T45 hangar.

With P8s and MQ-9Bs the UK local airspace out to a few hundred miles should have good coverage, but efforts further afield will need to be ship based. The right combination of ASW drones would need to be figured out as information comes in and may ultimately depend on cost: perhaps something like Proteus for dipping sonar and overall coordination, a couple of S-300s for sonobuoy distribution, with Wildcat for the torpedoes. Working towards getting a 700kg class rotary seems worthwhile, but I wonder if USVs or UUVs with a tail would be the better complement to Proteus for second-tier sub hunting from a T31.

The Whale Island Zoo Keeper

As T31 and T45 don’t have onboard ASW capabilities why would you carry an ASW drone?


So that you have some way to detect Submarines/UUV’s at a lower cost than fitting the whole ship with ASW sensors and quietened hull form + insulation etc

Supportive Bloke

We don’t really know the current state of play.

My *suspicion* of PiP was also to quieten the T45 machinery. It is an EP system so is fundamentally suited to ASW – OK wrong hull form etc.

As for T31 it is know that an upgrade package was agreed with Babcock – what is in it is unannounced. Its parent IH is an acceptable ASW asset.

So I’d be surprised if nothing was the answer to capability.

The thought process appears to be ATM – how can capability be added fast and relatively cheaply into existing programs without stalling them…..


I’m wondering if the addition of ASW features to the T31 might not be to deal with traditional submarine threats, but rather UUVs? We’ve seen, both in Ukraine and the Red Sea, the havoc that UAVs can cause. The development of UAVs is more advanced currently, but UUVs have the potential to carry larger warheads and hit ships below the waterline.
Imagine a swarm attack, not of UAVs but UUVs, and any current warship would be in trouble. Outrunning the UUVs at full speed would be one option, but in doing so, would expose any ships they were escorting.

Last edited 1 month ago by Sean
Supportive Bloke

That also assumes that the drones cannot be retargeted onto the ships being escorted?

Shame there is a war on: information is therefore somewhat limited.

Last edited 1 month ago by Supportive Bloke

I’d assume they can be retargeted which is why the escorted ships would be exposed if the warships did a high-speed runner.

As for war, one thing is known. HMG has drastically ramped up spending in industry on research and development projects since the start of the war.


HMG has drastically ramped up spending in industry on research and development projects since the start of the war

Do you have any sources that you could quote? Where does the finance come from?


The instigation of PIP on the T45s addresses many issues that the T45 propulsion system had, but turning the T45 into a stealthy ASW capable unit isnt one of them.
Yes is does address some of the noise issues the T45 has\had. Newer DE will run quieter then those they replaced thereby decreasing your radiated noise signature (which they needed as they were always v noisy ships), which is always a bonus.
Don’t believe that the first two T32s will have an active sonar fit yet, as the hull doesn’t have the cut outs to incorporate one. It is possible to do that further down the line at their first major docking period should the RN so desire. FFBNW for a TA system, different ball game entirely. I can see all the plumbing going into that effort more readily then a hull mounted active set up. That just leaves the issue of finding enough sonar operators to man the system…….

Supportive Bloke

Thing was that T45 had to have a GT running in order to be under way under the old setup. The two DGs were not man enough.

Now a T45 can run at lower speeds solely on the three new DG sets. As they are bound to be in acoustic enclosures and the published specs were for rafted I think we can assume a big noise reduction.

I agree that it doesn’t make T45 an ASW optimised hull but it does mean that it isn’t a CSG’s prime noisemaker!


To supplement the manned ASW helicopter

Greta Thunderpants



You don’t say and I thought that it was for pizza delivery. lol


“As T31 and T45 don’t have onboard ASW capabilities why would you carry an ASW drone”

Often the main feature of this story escapes some

Last edited 1 month ago by Duker

You could add the BAE Strix….

That has sonobuoy dropping AND dipping sonar configurations….plus light attack with Brimstone, Razer, Sea Venom etc…plus the usual ISTAR stuff…


Just wonder at the cost of expendable sonobuoys, how you deny the enemy obtaining a buoy or maybe the tech is not valuable.

Supportive Bloke

That is built into the calculus of using them.

We have been using them for years……

The secret sauce is really in the signal aggregation and processing which isn’t done in the buoy itself.


Thank you


Nowadays state-of-the-art signal processing is done by software and the buoys are just essential underwater microphones array collecting data and forwarding them to somewhere else for processing. After the battery runs out on the buoy then it normally sinks to the bottom.

Back in the 70s, there was an incident where the US managed to get hold of a Soviet buoy and discovered that inside it was some Texas Instrument chips from the US. Most probably more buoys were retrieved by other countries, friend and foe.

Remember the incident of the USN EP-3E being forced to land in Chinese territory in 2001?
During the journey to landing, the crews onboard were busy destroying the hardware with fire axes, pouring coffee inside the PC/laptop, and throwing paper documentation overboard.

What was critically important was to destroy the hard disks with the software stored on them. The hard disks contained the collected data, signal processing algorithms, documentation, and encryption keys that can give away what the USN was interested in and its capability.
Throwing the hard disks overboard and hoping sea water could damage the magnetic medium enough so that not much data could be retrieved should they ever be recovered is a quick way.
There are better methods to destroy hard disk data but takes a long time.

How much sensitivity information the Chinese managed to recover from the EP-3A is unknown.

Last edited 1 month ago by Harken

Diversity of options for ASW is there.

What is clear is, all idea needs thorough evaluation. So, why not try and verify? Just “thinking” of “super good idea”, waiting for some “final good option” is not the way to go.

History says,

reality is much more important than assumption. Many “brilliant idea” dies after just a short trial. Then just do it.Simple and robust wins.New technology rapidly evolves = increase its weights and powerAs such, “cheap and numerous” is attractive but I cannot believe it is easy. In ASW, “cheap and numerous” example is only sonobuoys to date. Helicopter carried dipping sonar has evolved so large to keep it effective, that even Wildcat faces big endurance cut when equipped with. For any RWUAS, “good dipping sonar” will be deadly heavy.

With this simple thinking, “UAV deployed and relayed sonobuoy” shall be the first choice, and “re-usable sonobuoy type technology” will be the second promising.

Just one opinion.

Last edited 1 month ago by donald_of_tokyo

“good dipping sonar” -may be or may not be deadly heavy. It depends of RW UAV payload and requirement for actually “good enough” dipping sonar. Currently manufactured active sonobuoys (considered as basis) offer couple options for weight and performance

The Whale Island Zoo Keeper

I think the trend will be more towards optionally manned aircraft.

Bloke down the pub

I was expecting some mention of LUSVs, such as an autonomous XV Patrick Blackett, carrying a containerised towed array as here, TRAPS – Towed Reelable Active/Passive Sonar – GeoSpectrum Technologies Inc . This adds persistence beyond anything UAVs can provide and there is still the prospect of adding UAVs to them. Maybe this will be a topic for a later edition of your eminent organ.


I think, the topic is focused on unmanned aerial assets so why would we expect mention of USV? No argument about TRAPS, its performance elipse anything what UAV may have be equipped today, but one does not exclude another. Surface-borne sonar systems are more porwerful -nothing new here. But even having such beast like S2087 LFAS on frigate, aerial assets provide advantage in manouver and short reaction (beyond USVs capabilities). I agree with prospect about USV with towed array in group with UAVs