Here’s a just-for-fun
post. Let’s speculate about LCS shallow
water ASW tactics. I don’t think the
Navy has gamed out an LCS ASW concept of operations so let’s do it for
them! Now, before we go any further,
let’s acknowledge that none of us has the background to discuss this
authoritatively and if we did we probably wouldn’t be able to discuss it
publicly. So, as I said, this discussion
will be just speculative fun.
Let’s start by summarizing
what we think we know about the LCS as it relates to ASW.
- Let’s start by recognizing that we’re focusing
on shallow water ASW because there are better ASW platforms for deep water
operations and the LCS hasn’t got the endurance to conduct sustained deep
water ops.
- The LCS is not built for ASW. It does not have machinery quieting
built in, it lacks a hull mounted sonar, its water jets make it an
acoustic beacon (it’s a better target than hunter), and it has no ship
mounted ASW weapons.
- The only ASW weapon the LCS has is the helo and
it can only operate one helo.
Reports state that the LCS-2 variant can operate two -60 type helos
but I’ve heard that flight deck structural issues limit it to one helo.
- The ASW sensor suite consists of a variable
depth sonar (VDS), SQR-20 multi-function towed array (MFTA), and the MH-60R
helo’s AQS-22 low frequency dipping sonar (ALFS) plus sonobuoys.
- When deployed, the VDS limits the LCS to very
low speeds.
- The MFTA requires a pretty fair water depth in
order to be towed without dragging on the sea bottom. I don’t know what the minimum
operational depth is but I’ve heard the general statement that the MFTA is
not really useful in shallow water.
I’ve also heard that it is possible to only partially stream the
MFTA in order to keep the array from sinking too deeply but then a partial
array is only partially effective.
Now, let’s summarize what we
think we know about the shallow water ASW environment. Due to its nature, shallow water is a very
noisy place. Bottom flow, river
discharge flow, numerous civilian an commercial vessels, surf/shore
interaction, tidal movement, civilian craft, bottom debris including lots of
wrecks and metal structures, and lots of biologics (animal life) all contribute
to making shallow water a very noisy place.
Thus, detection is likely to occur only at much shorter ranges than in
deep water. Passive sonar is going to be
far less effective resulting in an emphasis on active sonar which, again, is
inherently shorter ranged. Further, the
mixing of fresh water from rivers with the salt water and the effects of solar
heating will cause lots of transient thermal and density gradients which will
further complicate acoustic detection and result in shorter range detections.
Finally, let’s summarize
what we think we know about the SSK, the likely shallow water opponent. SSKs are very quiet, slow moving, and quite
deadly with long range, fast torpedoes.
Well, that wasn’t hard to summarize!
So, now we understand the
LCS, the environment, and the enemy (hmm, the Navy has people study ASW for
years and we just became experts in a couple of paragraphs!). With that knowledge, what ASW tactics can we
postulate that would emphasize our strengths, mitigate our weaknesses, and
maximize our chances for success?
The helo is clearly the
strength of the LCS. It allows the ship
to remain at arm’s length and is immune to counterattack (at least from the
sub!). Unfortunately, the helo is also
an inherently weak platform when available in only limited quantities. The old saying is that if you have one helo,
you have none. That’s in recognition of
both the helo’s chronic maintenance issues and the limited endurance
(Lockheed’s product brochure lists mission endurance as 3.3 hours) and small
payload that requires frequent returns to the ship for maintenance, refueling,
and rearming. Remember that ASW is a
very long term operation requiring persistence, patience, and endurance. Even a functioning helo is only available for
several hours out of each 24 hour cycle.
Thus, a ship with only a single helo will only have sporadic ASW helo
coverage. When you subtract the
maintenance, refueling/rearming, and transit times, you quickly realize that the
best a single helo can offer is 4-6 ours of actual ASW coverage per day.
The obvious solution to
limited helo availability is to increase the number of ships, each with a helo,
and pool the helos so as to maximize helo availability. Four helos, and hence four ships, sounds
about right to ensure one helo is always on station. This, then, dictates an LCS ASW tactic of
operating four ships as an ASW squadron.
How, then, do we utilize the
four ship squadron, tactically?
We must first acknowledge
that even four helos operating simultaneously can only provide a very limited
coverage area. Dipping sonars in shallow
water are just not going to provide wide area coverage. More realistically, as we discussed, one or
two helos are going to provide extremely limited coverage. Thus, in order to maximize our chance of
detection, we’ll have to involve the ship’s sensors. A reasonable approach to this is to stake out
a square of interest with a ship at each corner and work in towards the center
with the helos starting at the center and working back out towards the
ships. Hopefully, the constricting box
will herd the submarine towards the center where the helos can locate it or,
eventually, all four ships can combine to locate and prosecute it.
The alternative approach is
for the ships to stand well off and let the helos work the area of interest alone
but their limited coverage is unlikely to succeed.
Having located a target, how
do we attack it? As we noted, the LCS
has no ship mounted ASW weapons so the attack will have to be by helo. There’s nothing wrong with this except for
the helo’s limited availability and limited payload (two torpedoes, max). We may have to make multiple attacks over
several hours due to limited availability.
Maintaining contact on a very quiet target for that length of time will
be a challenge and, again, multiple ships will be useful to track the contact.
Related side comment: If I were the Navy, I’d have designed the LCS
with the ability to share ASW tracks and data in a common tactical
picture. I wonder if they did? I’ve not heard of such a capability.
Lastly, we have to recognize
that asking an unoptimized, acoustically loud ship to play tag with an SSK is
asking for LCSs to be sunk. It’s a fact
of combat. Again, this argues for
operating in multi-ship squadrons. If
one ship is sunk or forced to run, the others can maintain contact and continue
the prosecution.
One of the weaknesses in
this concept is the LCS’ inherent susceptibility to enemy aircraft since the
LCS has only very short range AAW capability.
It would be nice if the group could combine AAW resources for
self-protection but that isn’t possible.
In an area of likely enemy air activity a Burke may be a requirement for
self-defense. If so, the Navy should
also think about incorporating the Burke into an LCS/Burke hunter killer group
– but that’s a topic for another time.
Of course, all of the
preceding discussion presumes that the LCS is operating alone in the ASW
role. It is quite possible that other
air or submarine assets might join in which would necessitate modified tactics. We can’t cover all the permutations in one
blog post so we’ll stick with just the LCS.
This should also provide us with the tactical baseline from which to
modify tactics as other assets enter the equation.
The sharp among you may be
wondering about the value of 4 LCS/4 helos versus a single small helicopter
carrier that could carry, say, 12 helos.
If, as we’ve described, helos are the key to shallow water ASW, then a
helo carrier would be suitable and offer more helos. For probably the same cost as four LCS, a
helo carrier would provide 3X the helos.
Something to think about.
So, what do you think? Anyone have a different idea about how to go
after shallow water subs with the LCS?
This comment has been removed by the author.
ReplyDelete"The Takanami-class DD sure would be a nice substitute for LCS ..."
DeleteThere are so many ships out there that would be nice substitutes for the LCS!
I've seen speculations that a multi-static mode of operation could be developed (it's mainly a software issue) but I have seen no indication that it's actually being done.
DeleteI think you got this but I'll say it just to be clear - the post is about only the LCS in ASW mode. I'm not by any means saying that this would be the optimum way to conduct ASW.
Personally, I wouldn't use the LCS for ASW at all. The combination of active sonar, noisy waterjets, no internal machinery acoustic isolation, lack of hull mounted sonar, and lack of ASW weapons renders the LCS about the least effective and survivable ASW platform I could imagine.
If I were designing a surface ship ASW group, I'd lean towards a small 12-helo carrier and four small, dedicated, purpose built ASW destroyer escorts.
The original invincible concept would make good reading I think.
DeleteHowever they existed to close the giuk gap, not crack open the Baltic sea, an exercise that may simply be impossible, or require carpet bombing the sea.
Some dumb questions before I can even begin to postulate:
DeleteA) Can the LCS use multiple firescouts (say 2/LCS, or a FS and an SH60?) and could the firescouts be modified as a latter day DASH?
B) Kind of a meta question: Given all the issues out there... has there ever been a good surface ship for shallow water ASW?
C) What kind of threat environment are we talking about? Limited conflict ASW? Or full on war in the Persian gulf. I don't think the LCS lasts long at all in the latter situation.
I guess what I'm thinking is that if the LCS is our ship by default, then it would be nice to leverage the VDS as much as possible. FS might help with adding numbers, thought they have issues with range.
Overall my feeling is that this is a really tough job for the LCS crew.
One more thing... would it be technically possible to put SOSUS lines in shallow water areas we might need to cover?If you had some in the PG, for example, you might gain enough knowledge of the signal to noise ratio over time to make all of your sonar's better in that area.
DeleteThis comment has been removed by the author.
Delete" there were a number of distributed fixed/semi-fixed sensor networks that were proposed and/or developed. Unfortunately most died on the vine."
DeleteThat's a shame
If they were feasible it seems like it would be a really powerful tool in time of war.
One ASW asset in any network should be a Virginia class sub. What assets can coordinate the prosecution of ASW with any subs ?
ReplyDeleteI agree that the LCS has a acoustic signature problem with regard to ASW.
Historically, it's been very difficult to communicate with subs on a real time tactical basis. This has somewhat or largely precluded subs from operating with surface ships. Typically, a sub would be assigned an area and all friendly ships and subs would keep out. That's quite a bit different from co-operative sub/surface tactics. Submarine communications have improved but I'm not aware that we can yet communicate on a continuous real time basis.
DeleteTrying to distinguish a friendly sub from an enemy based on occasional "whiffs" of sound is extremely challenging.
This is also why subs don't typically "hunt" together.
How would you envision a sub being part of an ASW team other than by being assigned an area?
. The big "if" in having a sub as part of any ASW prosecution is communications with all assets. If some communication were possible with other assets then the sub could be directed to prosecute the enemy contact.
DeleteSubmarines dont play well with others.
DeleteThey might be modern battleships by name, but they just dont function in a fleet battle.
Assign them a kill box and leave them to kill everything in the box.
They cant do their job if they are tied to a surface flotilla.
Partially agree with your assessment, since you overlooking the utility of helo periscope detection radar (ARPDD). Diesel subs have to expose masts and snorkels fairly often for observation, comms and battery recharge. Not as much of an issue for AIP boats of course.
ReplyDeleteI'd say sending any sort of combatant (LCS, DDG, etc.) into the littorals to fight a modern diesel sub is dumb. You're in his medium, vulnerable to his weapons, and the active sensors you use give away your positon. It's akin to shining a flashlight in a dark room looking for a bad guy with a knife.
The best approach is to use maritime patrol aircraft. Flood the area with periscope detection radar and multi-static active buoys - which if they work as designed should provide good capability in littorals.
You may be overestimating the exposure frequency of a modern diesel-electric sub. Even the classic Russian Kilo is credited with a submerged endurance of 5.5 days cruising at 3 kts.
DeleteASW aircraft would be great to have but in real combat they will be tied up in higher priority areas. The LCS will be assigned to lower priority areas and largely left on their own, I suspect.
I've stated repeatedly that the LCS will make a very poor ASW vessel. However, the premise of the post is that the Navy plans to use them that way so we discussed it that way. Please understand that the discussion does not mean that I believe the LCS is right way to conduct ASW or even a good way. It's not!
When someone develops a FUNCTIONAL multi-static system and tests it in realistic shallow water conditions then I'll factor it in to my thinking. Until then, it falls in the same category with so many other systems that looked good on paper and never panned out. The Navy is trying to make it work but is so far unsuccessfully. That doesn't mean it won't someday work but it hasn't yet.
Here's the DOT&E summation:
"[Offers capability in] select scenarios in some
environments but it does not meet the program’s requirements
in other operational environments or scenarios."
2 LCS mini squadron. One that is a drone that drives around in circles pinging. The other one nearby with its engines off but a Helo aloft. When the first LCS explodes the 2nd can prosecute....
DeleteThis is why the US' western pacific allies have been buying SSKs, small flat tops, and frigates.
ReplyDeleteNot sure why the USN has been buying LCS mind you
I think the conclusion that one must inevitably reach is that the LCS is of limited, if any use in ASW against a competent enemy.
ReplyDeleteThat isn't a conclusion that the USN agrees with, but it's one based on what the evidence suggests.
SSKs, although not invulnerable, and not without their drawbacks seem to have a considerable advantage over what ASW assets exist today. Perhaps that is why AIP SSKs have proliferated.
AIP is a lot less cut and dry than it appears at first.
ReplyDeleteThe T-212 has a 2850kw diesel engine, and a 2x120kw fuel cells.
It can stay under water for up to three weeks, but it is virtually immobile and blind whilst it does so.
Three weeks isnt a long time in a war, its especially not a long time in the build up to a war.
AIPs dont use their AIP normally, they snorkel, and are tracked by enemy ASW assets from the air.
If all of a sudden, all of them suddenly stop showing up, or disappear, its one hell of an obvious sign that war is imminent..
If they dont hide in advance and telegraph that wars coming, they cant run after the fact, 3knots is slow, really slow,
I'm explaining this really badly, there are just massive logistical problems.
New ASW technology...
ReplyDeletehttp://www.janes.com/article/56146/raytheon-delivers-sonar-for-darpa-s-unmanned-asw-vehicle-programme