Virginia class submarine

The Virginia class (or SSN-774 class) is a class of nuclear-powered fast attack submarines (SSN) in service with the United States Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions. They were conceived as a less expensive alternative to the Seawolf class attack submarines, designed during the Cold War era, and they are planned to replace the older of the Los Angeles-class submarines, nineteen of which have already been decommissioned (from a total of 62 built).

Innovations

The Virginia class incorporates several innovations not previously incorporated into other submarine classes.

Photonics Masts

Instead of a traditional periscope, the class utilizes a pair of AN/BVS-1 telescoping photonics masts located outside the pressure hull. Each mast contains high-resolution cameras, along with light-intensification and infrared sensors, an infrared laser rangefinder, and an integrated Electronic Support Measures (ESM) array. Signals from the masts' sensors are transmitted through fiber optic data lines through signal processors to the control center. Visual feeds from the masts are displayed on LCD interfaces in the command center.

Propulsor

The class also makes use of pump-jet propulsors, which significantly reduces the risks of cavitation, allowing for quieter operations.

Improved sonar systems

The Virginia class submarines are equipped with a bow-mounted spherical active/passive sonar array, a wide aperture lightweight fiber optic sonar array (three flat panels mounted low along either side of the hull), as well as two high frequency active sonars mounted in the sail and keel (under the bow). The submarines are also equipped with a low frequency towed sonar array and a high frequency towed sonar array.
The USS California will be the first Virginia-class submarine with the advanced electromagnetic signature reduction system built into it, but this system will be retrofitted into the other submarines of the class.

Other Improved Equipment

• The high speed, turbocharged Caterpillar 3512B V-12 replaced the venerable medium speed Fairbanks-Morse 38D81/8 Opposed Piston engines used since the pre-World War II Tambor class submarine in the Virginia class diesel generator.

• Fiber-optic fly-by-wire Ship Control System replaces electro-hydraulic systems for control surface actuation.

Construction and controversy

The Virginias were intended, in part, as a cheaper ($1.8 billion vs, $2.8 billion) alternative to the Seawolf class submarines, whose production run was stopped after just three boats had been completed. To reduce costs, the Virginia-class submarines use many "commercial off-the-shelf" (or COTS) components, especially in their computers and data networks. In practice, they actually cost less than $1.8 billion (in fiscal year 2009 dollars) each, due to improvements in shipbuilding technology.
In hearings before both House of Representatives and Senate committees, the Congressional Research Service and expert witnesses testified that the current procurement plans of the Virginia class — one per year at present, accelerating to two per year beginning in 2012 — would result in high unit costs and (according to some of the witnesses and to some of the committee chairmen) an insufficient number of attack submarines. In a March 10, 2005 statement to the House Armed Services Committee, Ronald O'Rourke of the CRS testified that, assuming the production rate remains as planned, "production economies of scale for submarines would continue to remain limited or poor."
The Virginia class is built through an industrial arrangement designed to keep both GD Electric Boat and Newport News Shipbuilding and Drydock Company (the only two U.S. shipyards capable of building nuclear-powered vessels) in the submarine-building business. Under the present arrangement, the Newport News facility builds the stern, habitability and machinery spaces, torpedo room, sail and bow, while Electric Boat builds the engine room and control room. The facilities alternate work on the reactor plant as well as the final assembly, test, outfit and delivery.
O’Rourke wrote in 2004 that, "Compared to a one-yard strategy, approaches involving two yards may be more expensive but offer potential offsetting benefits." Among the claims of "offsetting benefits" that O'Rourke attributes to supporters of a two-facility construction arrangement is that it "would permit the United States to continue building submarines at one yard even if the other yard is rendered incapable of building submarines permanently or for a sustained period of time by a catastrophic event of some kind", including an enemy attack.
In order to get the submarine's price down to $2 billion per submarine in FY-05 dollars, the Navy instituted a cost-reduction program to shave off approximately $400 million in costs off each submarine's price tag. The project was dubbed "2 for 4 in 12," referring to the Navy's desire to buy two boats for $4 billion in FY-12. Under pressure from Congress, the Navy opted to start buying two boats a year earlier, in FY-11, meaning that officials would not be able to get the $2 billion price tag before the service started buying two submarines per year. However, program manager Dave Johnson said at a conference on March 19, 2008, that the program was only $30 million away from achieving the $2 billion price goal, and would reach that target on schedule.
In December 2008, the Navy signed a $14 billion contract with General Dynamics and Northrop Grumman to supply eight submarines. The contractors will deliver one submarine in each of fiscal 2009 and 2010, and two submarines on each of fiscal 2011, 2012 and 2013. This contract will bring the Navy's Virginia-class fleet to 18 submarines. And in December 2010, the United States Congress passed a defense authorization bill that expanded production to two subs per year. Two submarine-per-year production resumed on September 2, 2011 with commencement of SSN-787 construction.
On 21 June 2008, the Navy christened the New Hampshire (SSN-778), the first Block II submarine. This boat was delivered eight months ahead of schedule and $54 million under budget. Block II boats are built in four sections, compared to the ten sections of the Block I boats. This enables a cost saving of about $300 million per boat, reducing the overall cost to $2 billion per boat and the construction of two new boats per year. Beginning in 2010, new submarines of this class will include a software system that can monitor and reduce their electromagnetic signatures when needed.
In September 2010, it was found that urethane tiles, applied to the hull to dampen internal sound and absorb rather than reflect sonar pulses, were falling off while the subs were at sea.
Professor Ross Babbage of the Australian National University has called on Australia to buy or lease a dozen Virginia class submarines from the United States.

 Tango Bravo

Because of the slow rate of Virginia production, the Navy entered into a program with DARPA to overcome Technology Barriers (TB or Tango Bravo) to lower the cost of attack submarines so that more could be built to keep up the size of the fleet.
These include:

• Propulsion concepts not constrained by a centerline shaft.
• Externally stowed and launched weapons (especially torpedoes).
• Conformal alternatives to the existing spherical sonar array.
• Technologies that eliminate or substantially simplify existing submarine hull, mechanical and electrical systems.
• Automation to reduce crew workload for standard tasks

Specifications

• Builders: GD Electric Boat and Northrop Grumman Newport News
• Length: 377 ft (114.91 m)
• Beam: 34 ft (10.36 m)
• Displacement: 7,800 long tons (7,900 t)
• Payload: 40 weapons, special operations forces, unmanned undersea vehicles, Advanced SEAL Delivery System (ASDS)
• Propulsion: The S9G nuclear reactor
• Maximum diving depth: greater than 800 ft (240 m)
• Speed: 25+ knots
• Planned cost: about US$1.65 billion each (based on FY95 dollars, 30-ship class and two ship/year build-rate)
• Actual cost: about $1.8 billion each (as of 2009)
• Crew: 120 enlisted and 14 officers
• Armament: 12 VLS & four torpedo tubes, capable of launching Mark 48 torpedoes, UGM-109 Tactical Tomahawks, Harpoon missiles and the new advanced mobile mine when it comes available.

Boats

 

Block I

• USS Virginia (SSN-774), commissioned and in service.
• USS Texas (SSN-775), commissioned and in service.
• USS Hawaii (SSN-776), commissioned and in service.
• USS North Carolina (SSN-777), commissioned and in service.

Block II

Block II boats are built in four sections rather than ten sections, saving about $300 million per boat.

• USS New Hampshire (SSN-778), commissioned and in service.
• USS New Mexico (SSN-779) commissioned and in service.
• USS Missouri (SSN-780), commissioned and in service.
• USS California (SSN-781), commissioned and in service.
• Mississippi (SSN-782), keel laid down June 9, 2010, and expected to be delivered in April 2012.
• Minnesota (SSN-783), named July 15, 2008, keel laid down May 20, 2011 and expected to be delivered in April 2013.

Block III

 

SSN-784 through approximately SSN-791 are planned to make up the Third Block or "Flight" and began construction in 2009. Block III subs will feature a revised bow, including some technology from Ohio class SSGNs.

• North Dakota (SSN-784), named July 15, 2008 and is contracted for delivery in August 2014.
• John Warner (SSN-785), named January 8, 2009 and is contracted for delivery in August 2015.

• SSN-786, construction begun March 2011.
• SSN-787, construction begun Sep 2, 2011.
• SSN-788
• SSN-789
• SSN-790
• SSN-791

Block IV

No block IV submarines are yet under contract. The first block IV submarine is not scheduled to be procured until FY14. Based on the planned split between block IV and block V boats, the following hull numbers will comprise block IV procurement.

• SSN-792
• SSN-793
• SSN-794
• SSN-795
• SSN-796