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 |
 |
| 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