James E. Williams Class Nuclear Guided Missile Destroyer
Displacement: 7,500 tons
Length OA: 500'
Beam: 55'
Draft: 24'
Powerplant:
1x D3G nuclear reactor
1x Fairbanks-Morse 16PA6B emergency genset
Propulsion:
Hybrid electrical/mechanical drive
1x shaft with variable pitch propeller
Speed: 30+ knots
Range: Unlimited
Endurance: 45 days
Sensors:
AN/SPY-3 X-band MFR
AN/SQS-53D Low-Frequency sonar
AN/SLQ-32(V) SEWIP Block 2
Kelvin Hughes navigation radars
Armament:
64x Mk 41 VLS (strike length)
2x 155mm VGAS
1x 57mm Mk 110 in LO mount
4x 12.75" LW torpedo tubes
Small Arms
Unfortunately I could not get the text up in time, but I reckon I ought to explain myself. This thing is based on some baseline designs for a "small surface combatant" made as part of a 2007 NAVSEA study on propulsion options. You can find this study, entitled "Alternative Propulsion Methods for Surface Combatants and Amphibious Warfare Ships"
here. The study first examines the likely power requirements for future "small" combatants, "medium" combatants, and large deck amphibs, based on historic data. I put "small" and "medium" in parentheses because the authors envision them being in the neighborhood of 7,500-12,000 metric tons and 34,000-38,000 metric tons, respectively. The study then examines a variety of engineering architectures for each type of combatant, in order to determine which is most efficient for that role. One of the major questions that needed answering was whether or not nuclear power was a cost-effective option for the surface fleet. The conclusion was "probably not." Of all of them, there was only a strong case for the medium combatant, which by far had the highest power requirements. Nonetheless, the break-even analysis was premised on consistently high oil prices. In order to justify nuclear power, one would have to go beyond simple cost calculations.
So while the study found that nuclear power was not suitable for the "small" combatant, I got to thinking that perhaps there is a case for it. If one were to go beyond the cost of fuel itself, and reduce the costs of the fuel infrastructure required to get it out to the fleet, one would be a lot closer to breaking even. At the PoD in the early aughts, the idea is to make a ship suitable for dealing with minor crises that requires minimal replenishment and can thus give the USN a credible forward presence with a small footprint. The ample internal volume can be used for adequate helicopter fuel and dry goods for long stretches. Only a few (vulnerable) auxiliaries would be needed in a region to support a small fleet of these long endurance small combatants. The total size of the auxiliary force, not properly appreciated by the powers that be in the late aughts, could be reduced. Deployments of large gas powered ships, like the Burke class Aegis destroyers and Ticonderoga class cruisers could be reduced by using the small combatants to respond to regional crises. While the ships themselves may not break even compared to a gas powered alternative, it seems plausible that a the Navy's legions of beancounters could make a case that the restructured force deployment model would save money overall. This is music to the ears of the outgoing Bush administration, which wishes to both project an image of American might (nuclear destroyers!) and reduce the cost of the ongoing wars in the middle east. The incoming Obama administration, though deeply skeptical of the up-front costs and atomic-ness of the scheme are eventually convinced by the cost savings argument and minimal footprint concept and allow the program to continue to it's full production run of 18 ships, DGNs 95-112.
These ships would take the place of the retiring Spurances and Perrys and the Littoral Combat Ships, which in this timeline we will assume are not followed through on after someone realizes that they are useless, as well as the Burke restarts. I assume that the Zumwalt program still falls on hard times and gets cut to 3 ships, but with the DGNs being built with the Vertical Gun for Advanced Ships, which uses the same ammunition as their AGS, their main batteries, at least, don't fall into a classic Pentagon Death Spiral. The costs of what are essentially gun launched missiles rather than cannon shells will still be high, but not as high as Tomahawks or other alternatives. To fill the air defense gap left by the aging Ticos and a mere 40 Burkes, a proper large surface combatant, also nuclear powered, is developed in parallel with the DGNs. Thus we have a force structure composed almost entirely of high-end combatants, with the DGNs providing forward presence and Burkes and the CGNs providing support for the carriers. The Zumwalts flap about somewhere in between; with the LCS not being built they become the whipping boys of the people that believe Big Navy can do no right, even though in this timeline they have ammunition for their guns and more development support for SPY-3. As it happens, the Navy can do no right, and everything eventually falls apart. But let's look at the design first.
The nuclear powered small combatants in the study are shown as flush deck with a conventional flared bow, minimal sheer, a long bulbous bow that does not extend below the keel line, and for the nuclear models a minimalist superstructure and what appears to be an integrated deckhouse/mast comparable to Zumwalt's, albeit shaped for a four-face radar. Propulsion for the nuclear models is assumed to be one modified submarine reactor. A specific model is not mentioned. In order to reap the benefits of large production lots and commonality and keep the size down to something a little less silly, I opted to use a modified S9G reactor, the type used in the contemporary Virginia class submarines. With a finely shaped hull to minimize resistance at high speeds, 30 knots should be attainable with only the one reactor. The reactor compartment is located underneath the after superstructure, forward of the hangar. Underneath the hangar is the separated gearbox and electric motor room. IEP propulsion was studied and planned, but the immaturity of the PMMs being designed for Zumwalt and the awkwardness of the alternative electric motors ultimately selected for that class resulted in the design team adopting a hybrid electrical/mechanical propulsion system. To cut the sticker shock of the nuclear powerplant down as much as possible, the designers employed a single shaft, another recommendation of the 2007 study. In low speed operations, the shaft is powered by the electric motor. For high speeds, the mechanical gearing takes over. This point coincides nicely with the point at which the reactor switches from natural circulation to active coolant pumping, essentially giving the crew the options of "quiet" and "fast" running. The large single screw also helps keep radiated noise down. A single large diesel is fitted for backup power in a space forwards of the reactor. This genset can provide power to the electric motor, enabling the ship to "limp home" in the event of a reactor casualty. Additional small generators are provided in the bow and in the stern to provide emergency power to the forward and aft damage control zones. For maneuvering in port or for emergency propulsion there is a The reactor has enough excess power capacity to facilitate the introduction of directed energy weapons or more powerful sensors in the future. It is expected to last for the ship's entire 30 year projected lifespan.
