US Navy receives LPD 22 from HII*

The landing platform dock 17, San Antonio Class, is the latest class of amphibious force ship for the United States Navy. The mission of the San Antonio class is to transport the US Marine Corps "mobility triad" – that is, advanced amphibious assault vehicles (AAAVs), air-cushioned landing craft (LCAC) and the MV-22 Osprey tiltrotor aircraft – to trouble spots around the world. 

Construction of the first ship of 12, the San Antonio (LPD 17), began in June 2000. The ship's keel was laid in December 2000. It was launched in July 2003 and commissioned in January 2006. The San Antonio is homeported at Norfolk naval base, Virginia. The vessel achieved initial operating capability (IOC) in May 2008 and made its first deployment in August 2008 as part of the Iwo Jima expeditionary strike group.

The keel of the second ship, New Orleans (LPD 18), was laid in October 2002. It was launched in November 2004, delivered in December 2006 and commissioned in March 2007. The keel of the third, Mesa Verde (LPD 19), was laid in February 2003, launched in January 2005 and commissioned in December 2007.

The keel for the fourth, USS Green Bay (LPD 20), was laid in August 2003, launched in August 2006 and delivered in August 2008. It was commissioned in January 2009. New Orleans and Green Bay are homeported at San Diego.

The keel for USS New York (LPD 21) was laid in September 2004. It was launched in December 2007 and commissioned in November 2009. Construction of USS New York included 24t of steel salvaged from the wreckage of the World Trade Center, as a memorial to those who lost their lives in New York on 11 September 2001.

Other contracted vessels are the San Diego (LPD 22), Anchorage (LPD 23), Arlington (LPD 24), Somerset (LPD 25) and Murtha (LPD 26). The keel of San Diego was laid in May 2007 and launched in May 2010 for commissioning in 2011. Arlington's keel was laid in May 2008 and launched in November 2010. The Keel of Anchorage was laid in September 2007 and launched in February 2011.

The last ship is scheduled for delivery by 2012. The ships are to replace the functions of the LPD 4, LSD 36, LKA 113 and LST 1179 classes of amphibious ships.

In December 1996 the US Navy awarded a contract to an industrial alliance led by Northrop Grumman Ship Systems (formerly Litton Avondale), with General Dynamics Bath Iron Works, Raytheon Electronic Systems and Intergraph Corporation, to design and construct the first of an anticipated 12 ships under the navy's LPD 17 programme. It was planned that Avondale would build eight and Bath Iron Works four ships.

However, in June 2002, the US Navy signed an MoU with Northrop Grumman and Bath Iron Works, making Northrop Grumman responsible for the construction of all San Antonio Class vessels, while Bath is the builder of four Arleigh Burke destroyers, previously assigned to Northrop Grumman.

Design

The ship is constructed from steel and designed to minimise radar cross section. Enhanced survivability features include improved fragmentation and nuclear blast protection and shock-hardened structure. Automation and integration of systems has enabled a significant reduction in crew, projected to be 361.

The ship provides three vehicle decks of 25,402ft² and two cargo holds with 25,548ft³ for bulk cargo and ammunition magazines in addition to 1,234m³ for cargo fuel. 

Accommodation is provided for two LCAC (landing craft air cushioned), 700 troops and 14 new AAAVs. Each LCAC is capable of carrying 60t of cargo and vehicles, including the M1A2 Abrams tank, at speeds of up to 40kt. 

The ship's advanced enclosed mast / sensor (AEM/S) system consists of two large eight-sided structures, which house the radar and communications antennae with a hybrid frequency-selective surface. As well as reducing the ship's radar cross section, the AEM/S system also protects the equipment from exposure to the elements.

Aircraft

At the stern of the ship the landing deck is able to accommodate two Sikorsky CH-53E Sea Stallion helicopters, six Bell AH-1W Super Cobra helicopters, four Boeing CH-46 Sea Knight helicopters or two Boeing Bell MV-22 Osprey tiltrotor aircraft.

The hangar deck provides aviation maintenance facilities and is sufficiently large to accommodate one Sea Stallion, two Sea Knight, three Super Cobra helicopters or one MV-22 Osprey tiltrotor aircraft. The hangar doors are constructed by Indal Technologies. Each blast-resistant door weighs 18,000kg and has three horizontal folding panels.

USS San Antonio began flight operations testing with the V-22 Osprey tiltrotor and CH-46 Sea Knight helicopter in June 2006.

Weapon systems

Two mk31 mod 0 launchers are capable of launching the fire-and-forget Raytheon rolling airframe missile (RAM). The RAM (RIM 116) surface-to-air missile has dual-mode radio frequency / infrared guidance and is designed to engage anti-ship missiles. It has a range of 8km. Space and weight provision has been made for the future fitting of a vertical launcher for the evolved Seasparrow missile (ESSM) if required.

The ship is equipped with two mk46 mod 1 30mm guns for close-in surface self-defence. The mk46 is a dual-axis stabilised chain gun with a firing rate of up to 250 rounds a minute. The fire director includes a thermal imager, low-light TV camera and laser rangefinder, with a closed-loop tracking system.

The gun can be operated locally at the gun turret or remotely in the combat information centre. Additional armament includes two mk26 mod 18 50-calibre machine guns.

SSDS (ship self-defence system)

San Antonio is one of the classes of vessels planned to receive the SSDS (ship self-defence system) mk2 being developed by Raytheon for the US Navy. SSDS will be an integration of all the ship's self-defence systems and will include multi-function radar, advanced integrated electronic warfare system and infrared search and track system (IRST).

LPD 22, the sixth of the class, is scheduled to be the first ship to receive the complete system, which will be retrofitted to the rest of the class. SSDS is also to be fitted to the US Navy projected new carriers (CVN 76) and destroyers (DD-X).

The ship is equipped with a fibre-optic shipboard wide area network (SWAN) from Raytheon, which connects ship systems, sensors and combat systems to the ship’s command consoles.

In February 2004, Harris Corporation was awarded a contract to provide high-frequency (HF) radio broadband communications systems for the San Antonio Class.

Countermeasures

The ship is equipped with the AN/SLQ-25A Nixie towed decoy system, from Argon ST of Fairfax, Virginia, and the mk53 Nulka decoy launching system, developed by the Australian Defence Science and Technology Organisation in Canberra and Lockheed Martin Sippican in Massachusetts.

Nulka is a hovering rocket system, which seduces incoming missiles away from the ship.

The Raytheon AN/SLQ-32A (V) 2 ESM (electronic support measures) system is a detection and jamming system which provides surveillance, warning and electronic countermeasures against missile attack.

LPD 22 and later vessels will be fitted with the advanced integrated electronic warfare system (AIEWS).

Sensors

The ship's radars include: ITT AN/SPS-48E three-dimensional air search radar operating at C/D band, Lockheed Martin AN/APQ-9B surface surveillance and tracking radar operating at I band, Raytheon AN/SPS-64(V)9 navigation radar operating at I band and two Northrop Grumman Norden Systems AN/SPS-73 surface search radar operating at I-band.

Propulsion

The ship is powered by four Colt-Pielstick 2.5 STC diesel engines developing 10,400hp each. The main reduction gears from Philadelphia Gear Corp turn two shafts with Bird Johnson controllable pitch propellers. A new high-power "low-drag" propeller hub design provides improved propeller efficiency.

The ship's electrical power is provided by five 2,500kW Caterpillar ship service diesel generators (SSDG), with self-cleaning strainers and filters and electric pumps. Seven 200t York air-conditioning units are fitted for cooling of systems and habitation. The ship auxiliary systems are all electric, including electric heating, electric water heaters and a 72,000gpd reverse osmosis water-generating plant.

* En motiu de l'entrega de la setena unitat de la classe San Antonio (LPD 17), us oferim la fitxa tècnica publicada a Naval Tecnology.