America Class Amphibious Assault Ship, United States of America
The America Class amphibious assault ships are being built by Northrop Grumman Shipbuilding for the US Navy. These ships are intended to replace the Tarawa Class amphibious assault ships. Previously known as LHA (R), the first ship, USS America (LHA-6), is expected to be delivered by 2013. USS America is the fourth ship in the US Navy to bear the name.
In June 2007, the US Navy signed a $2.4bn fixed-price incentive contract with Northrop Grumman for the detail design and construction of the amphibious assault ship, LHA 6. The keel was laid down at Northrop Grumman's Ingalls shipyard in July 2009.
In June 2010, Northrop Grumman was awarded a $175m advance procurement contract for LHA 7 by the US Navy. These funds will be used for the procurement of long-lead time materials and major equipment for the new vessel and to execute initial design and planning. The work will be carried out at the Gulf Coast facilities of the company. LHA-7, named USS Tripoli, will be laid down in April 2013 and her commission is planned in 2018.
USS America (LHA-6) amphibious assault ship design
Based on the hull design of USS Makin Island (LHD-8), USS America (LHA-6) will be equipped with a gas turbine propulsion system. The design incorporates several modifications to complement aviation operations and support activities. The well deck has been converted into an extended hangar deck and includes two wide and high bay areas. An overhead crane will be installed in each bay area for aircraft maintenance.
The design also includes a reconfigurable command and control centre, a hospital, additional aviation fuel storage facilities and aviation support areas. These changes will enable the ship to serve joint, inter-agency and transnational maritime forces.
The ship will have an overall length of 257.2m and a beam of 32.3m. The displacement of the vessel will be 44,854t. The hybrid propulsion system provides a maximum speed of over 22kt. The ship can accommodate 1,204 crew and 1,871 troops.
America Class aircraft capabilities
The vessel will have hangar large enough to accommodate aircraft movement. The ship will also have increased aviation fuel capacity, and storage for aviation parts and support equipment. With its 45,000t displacement and complement of strike fighters, it can serve in the small carrier role.
The America Class can accommodate 12 MV-22B Osprey tilt-rotor aircraft, six STOVL F-35B Lightning II joint strike fighters, four AH-1Z attack helicopters, four CH-53Ks and three UH-1Y utility helicopters. The ship can also support cargo operations, attack helicopters and the AV-8B Harriers. The exact configuration of the ship's aircraft complement will vary based on its mission.
America Class missiles
The America Class amphibious assault ships will be armed with two rolling airframe missile launchers and two evolved Sea Sparrow missile (ESSM) launchers. ESSM launchers are used against incoming missiles, aircraft and other surface threats.
The ship will be fitted with seven twin .50-calibre Browning machine guns. Two 20mm Phalanx close-in weapon systems (CIWS) will also be mounted on the vessel. The phalanx CIWS provides self-defence against anti-ship missiles and close-in air and surface threats.
The America Class ships will be fitted with the ship self-defence system (SSDS) developed by Raytheon. SSDS comprises software and commercial off-the-shelf hardware. It integrates radars with anti-air weapons including hardkill (missiles and rapid fire gun systems) and soft-kill (decoys).
The SSDS receives data from individual radars, the electronic support measures system (radar warning receiver) and the identification-friend or foe system. It forms a composite track from this data which is used to identify, prioritise and track threats.
The system provides final layer of self protection against anti-ship cruise missiles, including subsonic (Mach 0.9) and supersonic (Mach 2+) low-altitude variants.
The ship will be powered with hybrid mechanical-electric propulsion system. The system consists of two LM2500+ gas turbines and two 5,000hp auxiliary propulsion motors. Each gas turbine is rated at 35,290shp and provides speeds in excess of 22kt.
The propellers will be driven either by the gas turbines or by the electric motors. The onboard service electrical system powers the electric motors. The system allows the ship to run in a more fuel efficient mode across its speed range.