Thinking About Future Sonar Systems

As I have stated many times, I believe the best way to hedge against future peer competitors at sea is not to focus so much on large surface combatants or aircraft carriers, rather maintain and field the most effective, most advanced, most capable submarine fleet possible. I continue to be incredibly impressed by the work done by Electric Boat and Newport News with the Virginia Block III program. This is, without any doubt, the best shipbuilding program the Navy has had since the cold war.

Chris Cavas had an article out back in December on the contract for new Virginia class submarines, previously discussed on the blog here. I'm just now catching up on a lot of reading after a long holiday marked primarily by alcohol and more alcohol, and while reading through this article I noted some details of interest.

The Block III submarines will be the first of the class to be fitted with the Virginia Payload Tubes (VPT), a development of the modified former ballistic missile launch tubes in the Ohio-class converted cruise missile subs. Two VPTs in the bow of each of the new submarines will replace 12 vertical launch tubes used for Tomahawk cruise missiles in previous submarines. The 92-inch-wide VPTs each can hold six cruise missiles.

The new subs also will feature the Large Aperture Bow (LAB) Array of sound-detection gear, replacing the traditional sonar sphere of earlier ships. Hilarides said the LAB Array provides improved passive listening capability over traditional spheres using transducers.

Both technologies are excellent examples of evolutionary designs that not only improve capability, but save money. While I think the Virginia Payload Tubes (VPT) probably gets the most attention, I for one am curious how much the Large Aperture Bow (LAB) Array really improves passive listening capability, and whether this is a technology that could be adapted to be effective on surface ships somehow. Note, I'm speaking directly in regards to the improved passive listening capability, not specifically about adding a LAB to a surface ship.

The Navy is currently mandated by law to develop the CG(X) with nuclear power, even though I think we all agree they will try to get around this law. Lets assume for a moment, the cruisers are nuclear powered. While a lot of systems on a naval vessel require a lot of power, sonars in particular really require a lot of power, indeed the lack of power that could be used to deploy the most advanced sonar systems is something you never hear buyers of some conventional submarines talk about, although it is a problem. Will we see any new technologies for underwater detection enabled by the increase in power nuclear power will give cruisers? Has anyone even considered the potential there? I don't know, I hope so.

My concern is thus. The Navy canceled the Advanced Deployable System (ADS) without replacement, and if you remember the hype, the ADS was supposed to be a huge system advantage the LCS would have in detecting submarines. Well, the ADS is gone, and I'm unaware of any program that has come along to really tackle the issue we need to greatly improve the ASW capability of surface combatants.

There is no question that when the technology is fielded, the unmanned systems deploying listening systems will be very useful in adding to ASW detection networks for fleet forces. However, unmanned systems aren't static arrays, they are deployable systems which have to return to their mothership, which means they can't be deployed too far from the mothership. There is also a problem, the LCS ASW module is, by all accounts I have read, not really intended to support major repairs to broken unmanned systems. There is no tender for the LCS, so this means a return to port. The lack of size for our nations mothership will be an issue, which is why I hope Congress sides with the Navy and does wait until 2010 to see what the Navy learns from both LCS hulls. There is more than a choice between two hulls at stake here, insuring the capability to deploy unmanned systems for operations is sustainable, is at least as important as the other processes involved in the LCS evaluation periods over the course of this year.

Now that Virginia Block III has evolved passive submarine detection technology for our underwater forces, where is a similar evolution in our surface ship forces. Lets be blunt, the ADS was a major part of LCS, and it is gone. Unmanned systems are going to help, but they are going to be tied to the motherships due to the fact all deployable systems have limited endurance capabilities, which combined with the slower speed aspect of ASW detection, is just another aspect of the concept development still to be worked out. Because the LCS isn't a surface combatant, it of coarse does not have a sonar. Unless something changes, looking into the future the DDG-51 can expect to be the major ASW platform for the Navy at sea until after 2030. If we ever build ships smaller than the LCS, does anyone really think we should put much investment in ASW on those platforms? I for one do not think we should, low cost smaller ships means no ASW.

While it is probably not popular to say out loud (shhh), other than ADS, the other real evolution in surface combatant ASW technologies was built into the DDG-1000, but that platform is on the chopping block. When the Navy truncated the DDG-1000 to three (or two, depending upon your level of faith in Navy shipbuilding), ASW capability went out with the bathwater there too.

Retire the S-3s. Yep. The P-3s are old? Very. The P-8s are slow coming online. Affirmative, and likely to slow down more. FFG-7s can do ASW, barely, but thankfully they go away very soon. You know, while they are making modifications to the USCGC Bertholf (WMSL 750) hull to improve fatigue life, maybe we should add a better sonar... you know, so at least one of the 21st century ships our nation is building advances surface sonar capability.