Eventually, they settled on something towards the larger end, at 7,800 tons submerged displacement. 1 A number of studies were conducted, with displacements ranging from 5,000 tons (too slow and couldn't fit enough missiles) to 8,500 tons (anything bigger would be too close to Seawolf in size and thus not worth it). Quieting would have to meet Seawolf standards, while speed for battle group support would need to be about that of the Los Angeles, which unofficial reports suggest is around 33 kts. The design statement for the new submarine listed seven key missions: covert (Tomahawk) strike, anti-submarine warfare, anti-ship warfare, battle group support, covert intelligence gathering, covert minelyaing and special operations. But in keeping with the program's focus on cost, virtually all of this (except the reactor) was tested at sea before it was installed on the Virginias, mostly on boats of the Los Angeles class.Ī sailor on Colorado uses an XBox controller to operate the photonics mast And the S9G reactor would last for the 30-year life of the submarine, removing the need for an expensive refueling overhaul. To cut weight, the traditional electro-hydraulic ship controls were replaced by electric motors and fiber optic control lines. This was particularly helpful for the sonar, which could use processing power to substitute for array size, matching the performance of the Seawolf suite at a much lower cost. The system was designed to allow the COTS computers to be easily upgraded, taking advantage of the rapid growth in available computing power.

Everything else (tactical picture, sonar, etc) was run by Commercial Off-The-Shelf (COTS) computers. The Virginias broke from this, splitting their combat system so that the military-spec computers talked to the weapons, which required a rigorous certification process to make sure they didn't accidentally start shooting missiles. Previous submarines had relied heavily on military-spec computers for their combat systems and sonar processing, which were both expensive and usually obsolete by the time they entered service. Nor was the photonics mast the only new technology used on the boat. This let the designers of the new submarine move the control room down a deck, giving everyone more space to work, and integrating acoustic and non-acoustic data, with the net result being a Captain with a better picture of what was going on around the boat. Instead of a large structure penetrating the pressure hull, only a small cable penetration is needed, and the control room can be placed anywhere instead of being restricted to just beneath the sail, which could be moved or reduced for better hydrodynamics. The photonics mast also made designing the submarine rather easier. This was larger than a normal periscope head, but most of it could be non-metallic (and thus stealthy) and it was exposed for far less time. The solution came thanks to developments in electro-optics, which allowed the periscope to be replaced with a photonics mast, essentially a set of very nice digital cameras on a telescoping boom, which could record images for analysis at leisure by the crew of the submarine. This is a reasonable procedure for attacking a specific target detected by sonar, but works less well when trying to sort out dozens of possible targets on the fly. But a conventional periscope relies on the Captain to figure out the situation at a brief glance and report back before the periscope comes down again. Sonar's effectiveness was limited in shallow waters, as the beams could only be so narrow, placing a greater emphasis on the periscope. This required changes in the sensor suite. With the Russian submarine fleet largely rusting pierside, the new SSN would need to operate primarily in the littorals. Much of the design of said successor, initially known as Centurion, was driven by a shift in missions. Missouri pierside shows off her two photonics masts

Virginia class submarine control room