Amphibious assault ship
Wasp-class landing helicopter dock (LHD) amphibious assault ships are built by Northrop Grumman Ship Systems (formerly Litton Ingalls Shipbuilding) of Pascagoula, Mississippi, US.
The Wasp-class is the US Navy’s large-deck multipurpose amphibious assault ship. A total of eight Wasp-class ships were built and all eight are active as of June 2020.
LHDs embark, transport, deploy, command and fully support all elements of a marine expeditionary unit (MEU) of 2,000 marines, inserting forces ashore via helicopters, landing craft and amphibious vehicles.
The WASP-class is the first specifically designed to employ air-cushion landing craft (LCACS) and to carry a squadron of Harrier II (AV-8B) STOVL (short take-off vertical landing) jets.
Ingalls delivered USS Wasp (LHD 1) in May 1989 and the ship is operational with the US Navy Atlantic Fleet. The other ships of the class are USS Essex (LHD 2) commissioned in October 1992; USS Kearsage (LHD 3) (October 1993); USS Boxer (LHD 4) (February 1995); USS Batan (LHD 5) (September 1997); USS Bonhomme Richard (LHD 6) (August 1998) and USS Iwo Jima (LHD 7) (June 2001).
In April 2002, the US Navy awarded a contract to Northrop Grumman for the construction of one additional Wasp-class ship, USS Makin Island (LHD 8), which features a new gas turbine propulsion system (instead of the steam propulsion of the other vessels), comprising two GE LM2500+ turbines, rated at 35,000shp and six diesel-electric generators with a controllable pitch propeller.
It marked the first military application for the LM2500+, which is in operation on a number of commercial vessels. Other improvements are to the weapon systems and installation of a new advanced machinery control system. The keel for Makin Island was laid in February 2004. It was launched in September 2006 and began contractor’s sea trials in December 2008. The ship was delivered to the US Navy in April 2009 and commissioned in San Diego in October 2009.
In July 2005, Northrop Grumman was awarded a contract for the development of the USS America (LHA 6) amphibious assault ship, which is a variant of the LHD 8 with the capability to support the F-35B STOVL joint strike fighter and the V-22 Osprey tiltrotor.
In place of a well deck, LHA 6 has an extended hangar deck with two overhead cranes.
The vessel leads an expeditionary strike group and also forms part of the maritime prepositioning force (MPF) – future.
The future MPF will be crucial for the USN’s ‘sea basing’ concept. Seabasing refers to the ability to conduct and support marine landings from ships at sea, rather than from land bases. The vessel was named USS America (LHA 6) in June 2008. The keel was laid in July 2009 and the ship was commissioned in October 2014 to replace the LHA 1 Tarawa class of amphibious assault ships.
America is the lead ship in the America-class of amphibious assault ships. Keel for the second ship in the class, Tripoli (LHA 7), was laid in June 2014 and the ship delivered to the US Navy in February 2020.
Keel-laying ceremony of the third ship, Bougainville (LHA 8), was held in March 2019 and the ship is expected to be delivered to the US Navy in 2024.
In June 2020, Huntington Ingalls received a $145m contract to offer long-lead-time material and procurement activities for the LHA 9 amphibious assault ship.
The Wasp-class carries a mix of assault helicopters, plus six to eight Harriers for close air support. A typical mix of helicopters is 12 CH-46 Sea Knight, four CH-53E Sea Stallion; three UH-1N Huey and four AH-1W Super Cobra helicopters. USS Boxer (LHD 4) became the first ship to deploy the new four-bladed UH-1Y helicopter in October 2008. The vessels are also able to embark the MV-22 Osprey tilt-rotor aircraft.
The ship’s air traffic control system supports simultaneous Harrier and helicopter operations on the ship’s 819ft by 112ft flight deck.
The ship has two deck edge aircraft elevators, each with a lifting capacity of 75,000lbs. The elevators fold for transit through the Panama Canal and are the largest folding elevators in the navy.
The ship is armed with two semi-active radar-guided Nato Sea Sparrow missile systems (NSSMS) for anti-air warfare protection, two rolling airframe missile (RAM) systems and two Phalanx close-in weapon system (CIWS) mounts to counter threats from low-flying aircraft and close-in small craft.
Six super-rapid blooming offboard chaff (SRBOC) decoy system launchers augment LHD 6’s anti-ship missile defences. Three 25mm machine guns and four 12.7mm machine guns are also fitted.
The Wasp is equipped with the following radars: Northrop Grumman Norden AN/SPS-67 G band primary navigation radar; ITT Gilfillan AN/SPS-48E E/F band 3D air search radar; Raytheon (Hughes) mk23 target acquisition system (TAS) for sea-skimming missiles, which can simultaneously track up to 54 targets; Northrop Grumman Norden AN/SPN-43 air search radar; Raytheon AN/SPS-49(V)9 C/D band secondary air search radar; and ITT Gilfillan AN/SPN-35A/B air traffic control radar.
Northrop Grumman AN/UPX-24 interrogator friend or foe (IFF) is also fitted.
The ship’s C4I systems support amphibious operations and secondary mission roles.
Large screen displays and automated C4I systems are located in the combat information centre (CIC), the landing force operations centre (LFOC) and flag plot to monitor and support tactical operations.
A Sperry Marine integrated bridge system (IBS), which provides computerised integrated navigation, steering and control, is to be fitted to Iwo Jima and may be retrofitted to previous vessels of the class.
The ship’s assault support system synchronises the simultaneous horizontal and vertical flow of troops, cargo and vehicles throughout the ship for insertion of forces ashore via helicopters, landing craft and amphibious vehicles.
Six 12,000lb-capacity cargo elevators transport material from cargo holds to staging areas for loading. Cargo to be loaded on board landing craft within the well deck is moved via a monorail system. This system consists of 2,900ft of track in a six-track layout. The five 32ft monorail trains each have a capacity of 6,000lb and a speed of up to 600ft a minute (6.8mph).
The vehicle storage area typically accommodates five M-1 tanks, 25 light armoured vehicles, eight M-198 guns, 68 military trucks (HMMVVVs), ten logistics vehicles, 12 5t trucks, two water trailers, a fuel service truck, four rough terrain forklifts and two generator trailers. These vehicles can be loaded on board landing craft, and the majority can be rigged for transportation to the beach by helicopter.
Off the beach, landing craft is launched and recovered through the very large stern gate, which opens the well deck to the sea. The well deck is 267ft long, 50ft wide and is designed specifically for the fly-in / fly-out capabilities of the air-cushioned landing craft (LCAC).
The LHDs carry three LCACs. The LCAC is a high-speed landing craft capable of carrying a 60t to 75t payload. It can carry payloads such as an M1A1 tank and 5t trucks at a speed of more than 40k (73.6km/h).
The air cushion allows the LCAC to reach more than 70% of the world’s coastline. Conventional landing craft can land at only 15% of coasts.
To launch and recover conventional landing craft, the ship can ballast over 15,000t of seawater to allow these craft to float into and out of the well deck.
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