The Virginia class submarine is a broad-spectrum US Navy attack submarine, designed to engage enemy naval forces directly. This is in contrast to nuclear missile submarines whose role would be to launch nuclear missiles in the case of a major war. The Virginia class submarine was developed in 2004 as a lower-cost replacement to the Cold War-era Seawolf class submarines, at an acquisition cost of $1.8 billion US Dollars (USD) per unit instead of $2 billion USD per unit.
As of early 2010, six submarines of the series have been built, six have been named and ordered, and more are planned. Though intended to use as many off-the-shelf components as possible, construction costs on the subs has already overrun to about $2.3 billion USD per unit, in part due to a lack of economies of scale.
Like the Los Angeles class submarines they are replacing, the Virginia class submarines will circle the world silently, capable of staying submerged for months at a time thanks to their on-board nuclear reactors, always ready to jump into action in case of a conflict. Unlike conventional vessels, submarines are hard to locate and very difficult to hit using conventional weaponry. Instead, a submarine can only be sunk with depth charges and mines, which have a notoriously poor range and hit rate; torpedoes and other guided missiles, which can be confused by decoys; or rocket-based weapons. Significant submarine warfare has not occurred since World War II.
A Virginia class submarine has a length of 377 feet (115 m), height and width of 34 feet (10 m), and a displacement of 7,800 tons. A standard Virginia class submarine has a crew of 134, with a range unlimited except by food supplies. Two crews usually switch off on 90 day periods.
A Virginia class submarine travels at a speed of about 38 mph using quiet pump-jet propulsors. Instead of conventional periscopes, the Virginia subs use "photonics masts" covered in high-resolution digital and thermal cameras to observe their surroundings. Like other modern military subs, Virginia class subs can travel through the frigid waters of the North Sea and surface in places like the North Pole, where they might be pawed at curiously by polar bears.