US Navy Los Angeles Class Attack Submarines (SSN)
The Los Angeles class, sometimes called the LA class or the 688 class, is a class of nuclear-powered fast attack submarines (SSN) that forms the backbone of the United States submarine fleet. With 43 submarines on active duty and 19 retired, the Los Angeles class is the most numerous nuclear powered submarine class in the world. The class was preceded by the Sturgeon class and followed by the Seawolf and Virginia classes. Except for USS Hyman G. Rickover (SSN-709), submarines of this class are named after U.S. cities, breaking a long-standing Navy tradition of naming attack submarines after sea creatures.
The final 23 boats in the series, referred to as "688i" boats, are quieter than their predecessors and incorporate a more advanced combat system. These 688i boats are also designed for under-ice operations: their diving planes are on the bow rather than on the sail, and they have reinforced sails.
- Overall Length: 362' - 0"
- Waterline Length: 362' - 0"
- Extreme Beam: 33' - 0"
- Waterline Beam: 33' - 0"
- Max. Navigational Draft: 31' - 0"
- Light Displacement: 5,700 tons
- Full Displacement: 6,072 tons
- Structural Composition: Steel
- Number of Propellers 1
- Propulsion Type: 1 General Electric S6G Reactor powering 2 Steam Turbines
- Total Shaft Horsepower: 30,000 shp
- Speed: 28+ knots
- Crew (typ.): Officers: 12; Enlisted: 98
According to the U.S. government, the top speed of Los Angeles-class submarines is over 25 knots (46 km/h, 29 mph), although the precise maximum is classified. Some estimates put the top speed at 30–33 knots. Tom Clancy, in his book Submarine: A Guided Tour Inside a Nuclear Warship, puts the top speed of a Los Angeles class submarine at 37 knots.
Government sources give the maximum operating depth as 650 feet (200 m), while Patrick Tyler, in his book Running Critical, suggests a maximum operating depth of 950 feet (290 m). Although Tyler cites the 688-class design committee for this figure, the government has not commented on it. The maximum diving depth is 1,475 feet (450 m) according to Jane's Fighting Ships, 2004-2005 Edition, edited by Commodore Stephen Saunders of Royal Navy.
Weapons and fire control systems:
Los Angeles class submarines carry about 25 torpedo-tube-launched weapons and all boats of the class are capable of launching Tomahawk cruise missiles horizontally (from the torpedo tubes). The last 31 boats of this class also have 12 dedicated vertical launching system (VLS) tubes for launching Tomahawks.
Engineering and auxiliary systems:
There are two watertight compartments in the Los Angeles class of submarines. The forward compartment contains crew living spaces, weapons handling spaces and control spaces not critical to recovering propulsion. The aft compartment contains the bulk of the submarine's engineering systems, power generation turbines and water making equipment. Some submarines in the class are capable of delivering SEALs through either the Dry Deck Shelter (DDS) system or the Advanced SEAL Delivery System (ASDS). A variety of atmospheric control devices are used to remain submerged for long periods of time without ventilating, including an Electrolytic Oxygen Generator (EOG) nicknamed "the bomb".
USS Greeneville with Advanced SEAL Delivery System (ASDS) attached.
While on the surface or at snorkel depth the submarine may use the submarine's auxiliary or emergency diesel generator for power or ventilation (e.g., following a fire). The diesel engine in a 688 class can be quickly started by compressed air during emergencies or to evacuate noxious (non-volatile) gases from the boat, although 'ventilation' requires raising of a snorkel mast. During non-emergency situations, design constraints require operators to allow the engine to reach normal operating temperatures before it is capable of producing full power, a process that may take from 20 to 30 minutes. However, the diesel generator can be immediately loaded to 100% power output, despite design criteria cautions, at the discretion of the submarine commander via the recommendation of the submarine's Engineer, if necessity dictates such actions to a) restore electrical power to the submarine, b) prevent a reactor incident from occurring or escalating, or c) to protect the lives of the crew or others as determined necessary by the commanding officer.
Normally, steam power is generated by the submarine's nuclear reactor delivering pressurized hot water to the steam generator, which generates steam to drive the steam driven turbines and generators. While the emergency diesel generator is starting up, power can be provided from the submarine's battery through the Ship Service Motor Generators (SSMGs). Likewise, propulsion is normally delivered through the submarine's steam driven main turbines that drive the submarine's propeller through a reduction gear system. The submarine has no main shaft conventional engines.