Two Platforms for Two Missions: Rethinking the LUSV

By Ben DiDonato

The Navy’s current Large Unmanned Surface Vehicle (LUSV) concept has received heavy criticism on many fronts. To name but a few, Congress has raised concerns about concepts of operation and technology readiness, the Congressional Research Service has flagged the personnel implications and analytical basis of the design, and legal experts have raised alarm over the lack of an established framework for handling at-sea incidents involving unmanned vessels. An extensive discussion of these concerns and their implications would take too long, but in any case, criticism is certainly extensive, and the Navy must comply with Congress’s legal directives.

That said, the core issues with the current LUSV concept arise from one fundamental problem. It’s trying to perform two separate roles – a small surface combatant and an adjunct missile magazine – which have sharply conflicting requirements and require radically different hulls. A small surface combatant needs to minimize its profile, especially its freeboard, to better evade detection, needs a shallow draft for littoral operations, and must have not only a crew, but the necessary facilities for them to perform low-end security and partnership missions to provide presence. The adjunct missile magazine, on the other hand, must accommodate the height of the Mk 41 VLS which substantially increases the draft and/or freeboard, should not have a crew, and should avoid detection in peacetime to increase strategic ambiguity. Not only do these conflicts make it irrational to design one vessel to fulfill both missions, but they point to two entirely separate types of vessels since the adjunct missile magazine role should not be filled by a surface ship at all.

The Adjunct Missile Magazine

The adjunct missile magazine role is best filled by a Missile Magazine Unmanned Undersea Vessel (MMUUV). Sending this capability underwater immediately resolves many of the issues associated with a surface platform since it cannot be boarded, hacked, detected by most long-range sensors, or hit by anti-ship missiles, and so obviates most crew, security, and legal questions. The size required to carry a full-sized VLS also makes it highly resistant to capture since it should have a displacement on the order of 1,000 tons, far more than most nets can bring in, and it could also be designed with a self-destruct capability to detonate its magazine.

The cost should be similar to the current LUSV concept since it can dispense with surface ship survivability features like electronic warfare equipment and point defense weapons to offset the extra structural costs. Because it has no need to fight other submarines and would use standoff distance to mitigate ASW risks, it has no need for advanced quieting or sonar and could accept an extremely shallow dive depth. Even a 150-foot test depth would likely be sufficient for the threshold requirement of safe navigation, and anything past 200 feet would be a waste of money. These are World War One submarine depths. Furthermore, since it only needs to fire weapons and keep up with surface combatants while surfaced, a conventional Mk 41 VLS under a watertight hatch could be used instead of a more complex unit capable of firing while submerged. For additional savings, the MMUUV could be designed to be taken under tow for high-speed transits rather than propel itself to 30+ knots. A speed on the order of 5 knots would likely be sufficient for self-propelled transit, and it would only need long range, perhaps 15,000 nautical miles, to reach its loiter zone from a safe port without tying up underway replenishment assets. Since visualization is helpful for explaining novel concepts, the Naval Postgraduate School (NPS) design team produced a quick concept model to show what this platform might look like. In the spirit of minimizing cost at the expense of performance, and projecting that tugs could handle all port operations, all control surfaces are out of the water while surfaced to reduce maintenance costs.

Rendering of the MMUUV. (Author graphic)

On the command-and-control front, the situation is greatly simplified by the fact that the MMUUV would spend most of its time underwater. In its normal operating mode, it would be dispatched to a pre-planned rendezvous point where it would wait for a one-time-use coded sonar ping from a traditional surface combatant commanding it to surface. It would then be taken under tow and fired under local control using a secure and reliable line-of-sight datalink to eliminate most of the concerns associated with an armed autonomous platform. A variation of this operating mode could also be used as a temporary band-aid for the looming SSGN retirement, since MMUUVs could be loaded with Tomahawks, prepositioned in likely conflict zones, and activated by any submarine or surface ship when needed to provide a similar, if less flexible and capable, concealed strike capability to provide strategic ambiguity. Finally, these platforms could be used as independent land attack platforms by pre-programming targets in port and dispatching them like submersible missiles with a flight time measured in weeks, instead of minutes or hours. Under this strike paradigm, a human would still have control and authorize weapon release, even if that decision and weapon release happens in port instead of at sea. This focus on local control also mitigates cybersecurity risks since the MMUUV would not rely on more vulnerable long-range datalinks for most operations and could perform the independent strike missions with absolutely zero at-sea communications, making cyberattack impossible.

As a novel concept, this interpretation of the adjunct missile magazine concept obviously has its share of limitations and unanswered questions, particularly in terms of reliability and control. Even so, these risks and concerns are much more manageable than the problems with the current LUSV concept, and so give the best possible chance of success. More comprehensive analysis may still find that this approach is inferior to simply building larger surface combatants to carry more missiles, but at least this more robust concept represents a proper due-diligence effort to more fully explore the design space.

The Small Surface Combatant

The other role LUSV is trying to fill is that of a small surface combatant. These ships take a variety of forms depending on the needs and means of their nation, but their role is always a balance of presence and deterrence to safeguard national interests at minimal cost. The US Navy has generally not operated large numbers of these types of ships in recent decades, but the current Cyclone class and retired Pegasus class fit into this category.

While limited information makes it difficult to fully assess the ability of the current LUSV concept to fill this role, what has been released does not paint a promising picture. The height of the VLS drives a very tall hull for a ship of this type which makes it easy to detect, and therefore vulnerable, a problem that is further compounded by limited stealth shaping and defensive systems. There also does not seem to be any real consideration given to other missions besides being an adjunct missile magazine, with virtually no launch capabilities or additional weapons discussed or shown. This inflexibility is further compounded by the Navy’s muddled manning concept, which involves shuffling crew around to kludge the manned surface combatant and unmanned missile magazine concepts together in a manner reminiscent of the failed LCS mission module swap-out plan. Finally, the published threshold range of 4,500 nautical miles, while likely not final, is far too short for Pacific operations without persistent oiler support.

The result is a vulnerable, inflexible ship unsuited to war in the Pacific, and thus incapable of deterring Chinese aggression. This may indicate the current LUSV concept is intended more as a technology demonstrator than an actual warship. However, because the U.S. Navy urgently needs new capabilities to deter what many experts see as a window of vulnerability to Chinese aggression, the current plan is unacceptable.

Fortunately, there is an alternative ready today. The Naval Postgraduate School has spent decades studying these small surface combatants and refining their design, and is ready to build relevant warships today. The latest iteration of small surface combatant design, the Lightly Manned Autonomous Combat Capability (LMACC), achieves the Navy’s autonomy goals while providing a far superior platform at a lower cost and shorter turnaround time. Where the LUSV design is large, unstealthy, and poorly defended, the LMACC has a very low profile, aggressive stealth shaping, SeaRAM, and a full-sized AN/SLQ-32 electronic warfare suite designed to defend destroyers, making it extremely difficult to identify, target, and hit. While the LUSV concept is armed with VLS cells, LMACC would carry the most lethal anti-ship missile in the world, LRASM, as well as a wide range of other weapons to let it fulfill diverse roles like anti-swarm and surface fire support, something that cannot be done with LUSV’s less diverse arsenal. To maximize its utility in the gray zone, the LMACC design boasts some of the best launch facilities in the world for a ship of its size.

On the manning front, LMACC has a clearly defined and legally unambiguous plan with a permanent crew of 15, who would partner with the ship’s USV-based autonomous capabilities and team with a variety of other unmanned platforms. This planned 15-person crew is complemented by 16 spare beds for detachments, command staff, special forces, or EABO Marines to maximize flexibility, and also hedges against the unexpected complications with automated systems which caused highly publicized problems for LCS.

LMACC was designed with the vast distances of the Pacific in mind, so it has the range needed for effective sorties from safe ports and provisions to carry additional fuel bladders when even more range is needed. Unlike the LUSV concept which Congress has rightly pushed back on, LMACC is a lethal, survivable, flexible, and conceptually sound design ready to meet our needs today.

The full details of the LMACC design were published last year and can be found in a prior piece, and since that time the engineering design work has been nearly completed. A rendering of the updated model, which shows all exterior details and reflects the floorplan, is below. Our more detailed estimating work, which has been published in the Naval Engineer’s Journal and further detailed in an internal report to our sponsor, Director, Surface Warfare (OPNAV N96), shows we only need $250-$300 million (the variation is primarily due to economic uncertainty) and two years to deliver the first ship with subsequent units costing a bit under $100 million each. The only remaining high-level engineering task is to finalize the hullform. This work could be performed by another Navy organization such as Naval Surface Warfare Center Carderock, a traditional warship design firm, one of the 30 alternative shipyards we have identified, an independent naval architecture firm, or a qualified volunteer, so we can jump immediately into a production contract or take a more measured approach based on need and funding.

Rendering of the LMACC. (Author graphic)

LMACC has also been the subject of extensive studies and wargaming, including the Warfare Innovation Continuum and several Joint Campaign Analysis courses at NPS. Not only have these studies repeatedly shown the value of LMACC when employed in its intended role teamed with MUSVs and EABO Marines, especially in gray zone operations where its flexibility is vital, but they have also revealed its advantage in a shooting war with China is so decisive that not even deliberately bad tactics stop it from outperforming our current platforms in a surface engagement. Finally, while our detailed studies have focused on China as the most pressing threat, LMACC’s flexibility also makes it ideally suited to pushing back on smaller aggressors like Iran and conducting peacetime operations, such as counterpiracy, to guarantee its continued utility in our ever-changing world.

Conclusion

While there are still some questions about the MMUUV concept which could justify taking a more measured approach with a few prototypes to work out capabilities, tactics, and design changes before committing to full-rate production, there is an extensive body of study, wargaming, and engineering behind LMACC which conclusively prove its value, establish its tactics, and position it for immediate procurement at any rate desired. If the Navy is serious about growing to meet the challenge of China in a timely manner, it should begin redirecting funding immediately to pivot away from the deeply flawed LUSV concept and ask Congress to authorize serial LMACC production as soon as possible. Splitting the LUSV program into two more coherent platforms as described in this article will allow the Navy to fully comply with Congress’s guidance on armed autonomy, aggressively advance the state of autonomous technology, and deliver useful combat capability by 2025.

Mr. DiDonato is a volunteer member of the NRP-funded LMACC team lead by Dr. Shelley Gallup. He originally created what would become the armament for LMACC’s baseline Shrike variant in collaboration with the Naval Postgraduate School in a prior role as a contract engineer for Lockheed Martin Missiles and Fire Control. He has provided systems and mechanical engineering support to organizations across the defense industry from the U.S. Army Communications-Electronics Research, Development and Engineering Center (CERDEC) to Spirit Aerosystems, working on projects for all branches of the armed forces. Feel free to contact him at Benjamin.didonato@nps.edu or 443-442-4254.

Additional points of contact:

The LMACC program is led by Shelley Gallup, Ph.D. Associate Professor of Research, Information Sciences Department, Naval Postgraduate School. Dr. Gallup is a retired surface warfare officer and is deeply involved in human-machine partnership research. Feel free to contact him at Spgallup@nps.edu or 831-392-6964.

Johnathan Mun, Ph.D. Research Professor, Information Sciences Department, Naval Postgraduate School. Dr. Mun is a leading expert and author of nearly a dozen books on total cost simulation and real-options analysis. Feel free to contact him at Jcmun@nps.edu or 925-998-5101.

Feature Image: Austal’s Large Unmanned Surface Vessel (LUSV) showing an optionally-manned bridge, VLS cells and engine funnels amidships, and plenty of free deck space with a tethered UAS at the rear. The LUSV is meant to be the U.S. Navy’s adjunct missile magazine. (Austal picture.)

13 thoughts on “Two Platforms for Two Missions: Rethinking the LUSV”

  1. This is the best non-classified attempt at breaking out the missions of small combatants and pairing those needs with distributed platforms. This is well thought out and introduces an alternative approach to the assumed plan. I hope this gains some mainstream attention.

    I’ll start with the MMUUV. Going with a cheap UUV is a valid discussion, but based on securing the basket of eggs it would carry, not cost. XLUUV at 50+ tons looks to be costing between 80-120 million each. The Advanced Seal Delivery System had a best case estimate for mass production of $125M in 2001 dollars. It was also about the size of XLUUV. Both are shallow diving and slow. A 4 tube SSBN section costs about $80 million and that’s without the VLS launcher that would go in them like an SSBN. I think a very low ball estimate of what is envisioned here would be $350 million vs max of $230 million for LUSV. I could see that price spiral as the risk here is high and our own national technical base for conventional subs is weak. It solves some problems, but introduces new ones. You may tow it into the area, but then everyone knows it is there and it can only get somewhere else slowly. One aspect I like of LUSV is the potential to quickly reload in the rear and bring missiles back up to the fight. That is lost with a UUV. Maybe figure out how to do this with a submersible barge launched off ships like the Cape May.

    I’ll post separately on the LMACC later.

    1. Thanks!

      As for the MMUUV, I agree that there are a lot of questions to be answered, especially in terms of cost and manufacturing. That said, I strongly caution against any kind of proportional cost estimate since anything modern you could compare it against is spending money on stealth which wouldn’t apply here. Technologically, MMUUV would be closer to a WWI or WWII sub than anything modern, but I’m also not willing to trust simple inflation scaling because that indicates a Gato-class sub would cost under $50 million today which seems far too low. Ultimately, this is why I’m guessing the cost will be in the same ballpark as LUSV, but it’s so different from anything modern that you’d probably need to pay a shipyard to fully design it before you got a trustworthy number, and even that would probably still change during production.

      Also, you have the towing backwards. It would drive itself into the area and then be taken under tow once it got there, not be towed into the area. That preserves stealth and ambiguity until it’s weapons are needed, although the slow transit speed is an issue as you noted. Of course, there’s nothing preventing you from towing it home or between theaters if you want to speed things up, and a Cape May-style lift is another interesting option, but it’s intended to perform long-range submerged transit under its own power so none of these tricks are necessary.

      Thanks again, and I look forward to hearing your thoughts on LMACC.

      1. I’m going to try and cover things not mentioned in comments from the original post regarding the LMACC.

        – On your current design. I think you will want to raise the bridge by a deck, just for basic seakeeping and for visibility should you choose anything large or manually operated on the bow.

        – I think the back end of the vessel will be heavy with both an 11m RHIB and Searam. Plus, when that RHIB offloads it may need some ballast to compensate. Ever seen a Reliance cutter with 1 RHIB launched? It gives the ship a very real list. This issue is more fore and aft in your design rather than port and starboard. I know M80 Stilletto could launch an 11M RHIB, but the weight stayed in the center of an extremely stable hull.

        – The space alotted for LRASM is way too small. Looks like the schematic for a Harpoon Mk 141 launcher isn’t easy to get to on line any more, but eyeballing missiles that would be shorter than LRASM with a booster you are going to need to clear at least 15 feet high and long for each quad launcher. Their exhaust can’t back into one another unless you vent them like ADL. You will need to stagger them and they would also need to be a deck higher. to have access from the bow to stern of the ship via at least one deck below. Also, no need for the complication of doors. Just keep them below bulwarks like other ships. (example Ambassador III)

        – I know there is some yada yada yada in the hull selection, but hybrid and water jet is still very new and IPS and waterjet doesn’t exist. Why introduce that risk? That is literally what has slaughtered LCS the most. Waterjets are good for shallow water work, but cost more to maintain and still have the noise. If using them, the range needs to think about a high economic speed relative to traditional hulls. This is another big miss on LCS.

        I still like the MUSV hull adapted to your purpose. You likely need the longer, 206 foot version. I might even say a 225′ x 36′ hull like Miss Netty might be more appropriate although I’d rather scale up the MUSV hull type. Really Ambassador III might be adapted/grown also, but that would really need a significant redesign as the engines are out of production and the MTU replacement is a larger engine for the same power. You’ll notice Ukraine started out buying Barzans from the UK. Those and Roussen are what Ambassador III is based on. Their plan has changed now to a new, smaller Babcock design.

        1. Thanks, there are a lot of great points in this, as well as a few places where scale and this more true to life model threw you off. For clarity, I’ll go through your points in order.

          1. We share your concerns about the bridge windows being washed out, especially since LMACC is intended to make regular trans-oceanic voyages. Unfortunately, the AN/SLQ-32 is absolutely enormous and must have 360 degree visibility to effectively protect the ship, so if we raised the bridge a deck we’d have to raise that beast a deck as well which will almost certainly kill our stability. The only way around that is to give up most of our side visibility with a small pilot house between the array clusters, and while I’m not sure that’s worthwhile, I will look into it further. The other side of this is that the DAS will be located as high up as possible, ideally at the top of the mast, and the plan is for the computer to use that for navigation most of the time (along with the COTS radar and AIS), so that should help mitigate the issue.

          2. We have this covered already. It’s hard to see in this overview picture since I thought it was more important to show the inside of the launch bay, but there’s a protrusion between the jets which is subdivided with port and starboard ballast tanks to compensate for the weight changes when launching and recovering the RHIB and UUV. Also, from an overall balance perspective, the engines are a lot further forward than usual thanks to the integrated electric propulsion system so the weight at the stern isn’t an issue.

          3. The more realistic model is tricking you, and you’re actually significantly underestimating the size of LRASM. What you see is just the muzzle. LRASM is so big that the rear of the launch tube is actually down near the keel and the exhaust routs clear across the ship to the hatch next to the muzzle. The missiles are naturally staggered and cross in the middle of the ship with just a single central hallway between them on the upper deck. The lower deck is even worse with awkward port/starboard missile maintenance spaces and no cross-connection due to the bulk of the missiles in the center of the ship down there. This problem was a major design driver and you can see how I went out of my way to show exactly how it fits together in the earlier model. As for the doors, they’re better for stealth than bulwarks, can help it look less threatening during port visits, and protect the missiles from severe weather which is especially important in the arctic.

          4. While electric propulsion is actually more than a century old (first used on USS Jupiter/USS Langley), you are correct that it hasn’t been combined with a waterjet like this. There are a lot of reasons I took that risk, but I’ll hit the big ones for you quickly. First, I think the cleaner rotation (i.e. no engine vibration) provided by electric motors should be good for the jets because it reduces the energy transmitted into the seals and bearings, so I think we’re more likely to see benefits than problems. Second, shallow-water operation and agility is absolutely vital to let the ship blend into littoral clutter. Third, power demands are skyrocketing as technologies like laser weapons mature, so IPS is essential for meeting future needs, especially since I intend to use a block development model for future upgrades like the Virginias. Fourth, I’m very interested in acoustic quieting to avoid detection by hostile submarines, and both IPS and waterjets help keep the ship quiet. Fifth, an IPS reduces maintenance needs by eliminating the gearbox which is vital with such a small crew.

          5. LMACC is a bit bigger than MUSV. The dimensions and displacement are obviously subject to change since we haven’t finalized our hullform yet, but the current numbers are 214′ long, 29′ waterline beam (the taper means the maximum beam is a bit wider), 6.5′ draft, and 600 tons. While we could use a parent design like the ones you mention, my general feeling is that it’s a false economy due to the compromises you have to make to fit into an existing hull and the fact that the steel hull is cheap in comparison to the stuff you put into it. As for the engines, we obviously can’t make a final selection without a finalized hullform to give us our actual power requirements, but I’m definitely not picking an engine going out of production because that’s just asking for trouble.

          I’m looking forward to hearing more of your thoughts and will see what the rest of the team thinks about a small pilot house for open-ocean transits.

          1. I think you can probably bump the SEWIP out a bit behind a raised bridge similar to both NSC and and OPC. I think you may have some benefit to build a bit of breathing room with a 225′ x 36, 900 ton’ hull like Ms. Netty. Obviously, everything aside from hull and machinery would be rearranged.

            Their is infinite export and, therefore, diplomatic potential with a ship this size.

          2. While that position isn’t terrible, it still leaves a blind spot forward. That’s acceptable on a cutter that probably won’t get shot at, and if it does probably won’t be on the receiving end of the latest and greatest missiles, but LMACC is very much intended to go into harms way and needs every advantage it can get to survive complex multi-axis attacks by large numbers of cutting edge weapons. Considering the EW suite is LMACC’s most important defensive system, any blind spots in coverage are critical vulnerabilities we can ill-afford. This is especially true of a blind spot forward since that’s also a blind spot for SeaRAM and likely also MHTK, so the ship would be completely defenseless there if we made your suggested change.

            On a related note, we discussed the idea of a small upper pilot house and decided not to go with it. Many tug boats have them, and the limitations and design complications just aren’t worth it here, especially given our stability concerns. For LMACC, it’s better to rely on the cameras further up the mast and have the spare parts onboard to fix anything that goes wrong. Also, there’s always the option of sticking a lookout on the upper deck or on the mast as a last resort.

            As for a larger hull, my calculations indicate what we have now meets our needs including breathing room, but if the naval architect we get says we need to go bigger then so be it. That said, it looks to me like Ms. Netty has a significantly deeper draft and a totally different propulsion arrangement so it isn’t a particularly useful reference point.

            Finally, I agree that there’s a ton of export potential for LMACC. I’ve already put together a floorplan for a 10′ coast guard hull segment which adds medical facilities, a brig, and extra hygiene capacity to meet the demand for a dual-use warship, and I also see a lot of value in donating older ships once their systems get too old for our own use.

  2. Please please please, spell out acronyms on first use people.
    I assume LUSV means L___(something, maybe light?), unmanned surface vehicle (although the picture does not conform to my idea of “light”). The audience is not just a few program geeks in Crystal City, is it? then don’t go all “inside baseball” jargony at us readers.
    John T. Kuehn, CDR, USN (retired)

    1. Sorry, I’m not sure how we missed that in editing. LUSV stands for Large Unmanned Surface Vessel and is the Navy’s current program for procuring a mostly unmanned ship armed with VLS cells.

      1. Thanks you so much and I will ensure it is diffused to the great unwashed on my daily Acronym of the Day (AOD) on Twitter.
        vr, John

  3. A private consortium of small companies recently developed an unmanned 52′ X 16′ catamaran hull, water jet propelled high speed craft with a bow ramp. It is called the Littoral Connector Unmanned Resupply (LCUR). LCUR can be operated in full autonomous mode, remote control or manned. Payload is 10000 lbs. The vessel is low-observable, and travels at speeds exceeding 35 KTS. It can operate in high sea states in an A2/AD environment. Cost is $2.5M per unit.

  4. Great article. Giving thought to the post-commissioning time before the first operational deployment, the limited number of yards to perform maintenance/repair, and the 2+ years to return the Fitzgerald and the McCain to the fleet. Each of the above are addressed in some meaningful fashion If 30+ shipyards could potentially contribute to building hulls for the two designs discussed above. Certainly sounds like a potentially very resilient answer to the challenges faced now and a tangible option that Congress can properly vet in the present and not years down the road.

  5. Wouldn’t making the the adjunct magazine into an uuv limit its usefulness?

    It was my impression the magazine ship was to tag along with ddg and ffg. If successful the adjunct usv would allow a ddg to off load some or all of the tomahawk thus making it equal or better than the cg. Basically a money saving scheme that also could lend flexibility to the reloading process(ddg or ffg continue on with the mission while the usv leaves to reload.

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