What little progress there’s been has been almost peripheral in nature. Consider this proud announcement from the Navy proclaiming successful integration testing of the Knifefish Unmanned Underwater Vehicle (UUV) and Textron Unmanned Influence Sweep System (UISS) around the beginning of the year.
During these integration events, both the Knifefish and UISS successfully verified the communications link between Independence and the unmanned systems as well as executed multiple launch and recovery evolutions from the ship. (2)
So, 15 years of effort managed to prove that the communications link worked (at least long enough to complete the test) and that the vehicles could be launched and recovered (at least once). What’s missing from the testing? - How about any semblance of actual performance testing like, can it actually find a mine? I get that you have to start with small, incremental tests of the various subsystems before you can attempt an overall performance test but wouldn’t you think that after 15 years we’d beyond simple comm checks and the basic vehicle launch/recovery stage? But we’re not! I mean, just great – 15 years and we can launch the vehicle and talk to it. Wow. Impressive technological achievement!
As a point of interest, the LCS MCM IOC date has slipped multiple times and is now tentatively scheduled for 2022. (4) By the time IOC is achieved, if it ever is, we’ll be looking at around 20 years of developmental effort !
Okay, I’m mocking the LCS MCM program and rightly so but I actually want to examine one specific aspect of it and that is the influence sweeping.
To begin with, we have to understand that the very concept of the LCS MCM effort was flawed even if everything had worked perfectly. Huh??? How could that be? If everything had worked perfectly the MCM module would have been a success, right? Wrong! The inherent flaw in the concept was, and still is, time. That’s right, time. The MCM module was, and still is, envisioned to laboriously, painfully, sloooooowly look for individual mines and then laboriously, painfully, sloooooowly neutralize them one by one. Given that the speed of the underwater vehicles involved is around 5-7 knots, you can readily imagine how slowly mine clearing operations would proceed. Having examined the various technologies and methodologies, and read the various reports, my best estimate is that each LCS would be fortunate to clear around two mines per hour. Considering that minefields can easily consist of thousands or tens of thousands of mines, I leave it to you to do the math on the total clearance time required.
You don’t believe me about the time and clearance rate, do you? Well, the concept calls for multiple passes through the suspect area. The first pass does a ‘quick’ (quick, meaning 5-7 kts) pass to identify items of interest. The second pass slowly zeroes in on the items of interest and verifies that they are, or are not, actual mines. Systems like the unmanned underwater vehicle Knifefish or the towed AQS-20 sonar are used for the first two passes. The third pass is the actual neutralization pass where an underwater, expendable vehicle self-destructs against the mine. SeaFox, Archerfish, and Barracuda are examples of such vehicles. In the envisioned LCS module, a helo can carry up to four of these neutralization vehicles. Thus, the helo can destroy four mines before it has to return to the host ship to land and reload vehicles. That return to the ship, landing, unloading and reloading, and return to the operational area takes time, time that is added to the effective clearance rate.
By the way, did you realize that search vehicles, such as the Knifefish, have to wait until they return to their host ship to upload their data for analysis? Not until that data is uploaded and the analysis completed can the verification and neutralization of the mine begin. I bet you thought the process was real time and that mines were being neutralized as quickly as they were found! Anyway, that return transit time, vehicle recovery time, upload time, and analysis time all gets added into the effective clearance rate. Now are you beginning to see where the 2 mines per hour clearance rate estimate comes from? And, even that rate may be optimistic!
Each neutralization event requires around 30 minutes. The helo has to position itself, release the neutralization vehicle, the vehicle has to find and positively identify the specific mine, properly position itself relative to the mine, and then detonate. After detonation, the disturbed water has to settle and then the destruction of the mine has to be verified. Doesn’t sound like a speedy process does it (and that’s ignoring the first two passes)? So, at best, the helo can neutralize two mines per hour and, after neutralizing four mines, has to return to the host ship to reload on neutralizers so that 2 mines per hour clearance rate is going to drop to around 1 mine per hour!
Now, if you’re clearing minefields after a conflict is over then, fine, take as much time as you need. However, if you’ve got an assault fleet backed up behind you waiting to hit the beach or a carrier/surface group piled up waiting to transit a chokepoint, clearance speed is of monumental importance and that’s the inherent flaw in the LCS MCM scheme. Even if it worked perfectly, it would be monumentally too slow to be useful in combat. Now you understand what I meant when I said that the concept was flawed even if it had worked perfectly.
This is where sweeping comes in. Sweeping, as opposed to the slow, careful, clearance approach, emphasizes speed by foregoing the location and identification of the individual mines in favor of an area wide attempt to simply trigger the mines into exploding by putting out a signal (acoustic, magnetic, etc.) that mimics a ship’s signature and tricks the mines into exploding. If you can do that, who cares about carefully locating and identifying individual mines? Sweeping is much more efficient. It’s the ‘many’ versus ‘individual’ approach.
However, sweeping has drawbacks. Sweeping is not, and never has been, 100% effective. Thus, the tradeoff is speed for effectiveness. With sweeping, you’re never sure you got all the mines because you never bothered to locate and identify each mine. Thus, you accomplish the sweep very quickly but you accept a degree of risk that you didn’t get all the mines.
In WWII, sweeping was fairly effective because the mines were mostly pretty ‘dumb’ and could be easily triggered. With modern smart mines that can be programmed to ignore initial signals, use multiple aspects of a ship’s signature to decide whether to trigger, and spot sweeping signals, the effectiveness of sweeping has decreased and the associated risk has increased.
The Unmanned Influence Sweeping System (UISS) currently under development consists of the Textron Common Unmanned Surface Vessel (CUSV) tow craft and the signal emitter payload.
The UISS payload includes a specialized magnetic cable that tows a modified Mk-104 acoustic device.
“The Mk-104 generates an acoustic source by cavitation and the specialized cable creates an electromagnetic field. The output of these two emitters generates the appropriate fields that satisfy the mine logic so that the mine detonates,” explained Colleen E. O’Rourke, an official at Naval Sea Systems Command (NAVSEA). (5)
The Mk104 is a legacy sweep unit currently in use by MH-53E MCM helos and has been in service since at least the early 1970s where it was employed in Operation End Sweep, the minesweeping effort that took place at the conclusion of the Vietnam war. The Mk104 can be acoustically adjusted or tuned to mimic specific ship types.
|Mk104 Acoustic Mine Sweep|
The CUSV has towing capacity of 4,000 lbs-force at 20 kts and is claimed to have 20 hours endurance. (3) Will the CUSV actually prove capable of towing the required equipment? Will it prove to be sufficiently reliable (recall that the RMMV failed to meet its reliability requirements and was dropped)? Can we maintain comms with the craft? We’ll see.
|CUSV with what appears to be a Mk104 at the stern.|
What does all this mean? We noted earlier that the inherent flaw in the LCS MCM module concept was the extremely long time required to achieve clearance and that useful clearance rates were simply not achievable using the LCS MCM individual mine approach. The sweep procedure, on the other hand, is much faster but is far less reliable and modern smart mines may well render influence sweeping very ineffective. So, we’re left with a dilemma: clear very slowly which is not useful in combat conditions or sweep quickly but run a significant risk of uncleared mines.
At this point, one might reasonably wonder whether smart mine technology has such an advantage over mine countermeasures as to render the application of countermeasures almost pointless?
Beyond that, the Navy needs to decide what degree of risk it’s willing to accept. Are we willing to conduct rapid combat mine sweeping and accept a significant risk to high value ships? Or, have we reached a point where the risk associated with sweeping is too great to risk high value ships in which case one has to wonder why we would bother with sweeping at all?
Obviously, none of us has the actual performance data on the effectiveness of sweeping against modern, smart mines and without that data we can’t draw any definitive conclusions. My sense is that the LCS MCM individual mine approach is limited to peacetime/non-threat environments and that sweeping can’t produce an acceptable level of risk. That means that the mere presence of mines is sufficient to ban surface ships from operating in the area, swept or not. This has profound operational implications since every potential enemy of ours has mine inventories that number in the thousands to tens of thousands or more. This, alone, almost guarantees we can’t conduct amphibious assaults!
The conclusion is clear – the Navy lacks a credible combat mine clearance capability and influence sweeping is not the solution. As with other non-sexy functions like gun support, logistics, ASW, etc. the Navy has largely ignored mine countermeasures for decades. The fact that we’re using the exact same technology today (although the Navy raves about it for the LCS and would have us believe that it’s some brand new, never before seen capability) as we did in Vietnam tells us all we need to know about the Navy’s misguided priorities.
(1)USNI News website, “Navy’s Remote Minehunting System Officially Canceled, Sonar May Live On”, Megan Eckstein, 24-Mar-2016,https://news.usni.org/2016/03/24/navys-remote-minehunting-system-officially-canceld-sonar-may-live-on
(2)Ocean News and Technology website, “General Dynamics Knifefish UUV and Textron UISS Complete Shipboard Integration Testing”, 28-Jan-2019,https://www.oceannews.com/news/defense/general-dynamics-knifefish-uuv-and-textron-uiss-complete-shipboard-integration-testing
(4)USNI News website, “LCS Mission Package Office Focused On Test, Fielding; IOC Dates Continue to Slip”, Megan Eckstein, 25-Jan-2019,https://news.usni.org/2019/01/25/lcs-mission-package-office-focused-on-test-fielding-ioc-dates-continue-to-slip
(5)Defense Systems website, “Navy approves testing for unmanned minesweeping system”, Katherine Owens, 24-Apr-2017,https://defensesystems.com/articles/2017/04/24/uiss.aspx