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US Navy Virginia Class Attack Submarines (SSN)


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Summary:

    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 Cold War-era designed Seawolf class attack submarines, and they are slated to replace the aging Los Angeles class submarines, nineteen of which (from a total of 62) have already been decommissioned.

Class Specifications:

  • Overall Length: 377' - 0"
  • Waterline Length: 377' - 0"
  • Extreme Beam: 34' - 0"
  • Waterline Beam: 34' - 0"
  • Max. Navigational Draft: 31' - 0"
  • Light Displacement: Not Available
  • Full Displacement: 7,800 tons
  • Structural Composition: Steel
  • Number of Propellers 1
  • Propulsion Type: 1 General Electric S9G Reactor powering 1 Steam Turbine
  • Total Shaft Horsepower: 25,000 shp
  • Speed: 25+ knots
  • Crew (typ.) Not Available

Innovations:

    The Virginia class incorporates several innovations not previously seen in other submarine classes.

    • Photonics Masts: Instead of a traditional periscope, the class utilizes a pair of 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.
    • Propulsion: The class also makes use of pump-jet propulsors, which significantly reduces the risks of cavitation, allowing for quieter and faster operations.
    • Sonar: 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.
      USS California will be the first Virginia with the advanced electromagnetic signature reduction system built in, but this will be retrofitted into the other submarines of the class

Construction:

    The Virginias were intended, in part, as a cheaper ($1.8 vs $2.8 billion) alternative to the Seawolf class, whose production run was stopped after just three boats. To reduce costs, the Virginia class uses 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 shipbuilding technology improvement.
    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—resulted in high unit costs and (according to some of the witnesses and 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.
    Acoustic stealth comparison (broadband quieting) based on Office of Naval Intelligence data. 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.
    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 underbudget. 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.
    Ross Babbage has called on Australia to buy or lease a dozen Virginia class submarines from the United States.
    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

Boats:

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