Wasp class amphibious assault ship

The Wasp class is a class of Landing Helicopter Dock (LHD) amphibious assault ships operated by the United States Navy. Based on the Tarawa class, with modifications to operate more advanced aircraft and landing craft, the Wasp class is capable of transporting almost the full strength of a United States Marine Corps Marine Expeditionary Unit (MEU), and landing them in hostile territory via landing craft or helicopters. All Wasp-class ships were built by Ingalls Shipbuilding, at Pascagoula, Mississippi, with lead ship USS Wasp commissioned on 29 July 1989. Eight Wasp-class ships were built, and as of 2011, all eight are active.

Design

The Wasp class is based on the preceding Tarawa-class design. The design was modified to allow for the operation of AV-8B Harrier II aircraft and Landing Craft Air Cushion (LCAC) hovercraft, making the Wasp class the first ships specifically designed to operate these. The main physical changes between the two designs are the lower placement of the ship's bridge aboard the Wasps, the relocation of the command and control facilities to inside the hull, the removal of the 5-inch Mk 45 naval guns and their sponsons on the forward edge of the flight deck, and a lengthening of 24 feet (7.3 m) to carry the LCACs.

Each Wasp class ship has a displacement of 41,150 metric tons (40,500 long tons; 45,360 short tons) at full load, is 253.2 metres (831 ft) long, has a beam of 31.8 metres (104 ft), and a draft of 8.1 metres (27 ft). For propulsion, most of the ships are fitted with two steam boilers connected to geared turbines, which deliver 70,000 shaft horsepower (33,849 kW) to the two propeller shafts. This allows the LHDs to reach speeds of 22 knots (41 km/h; 25 mph), with a range of 9,500 nautical miles (17,600 km; 10,900 mi) at 18 knots (33 km/h; 21 mph). The last ship of the class, USS Makin Island, was instead fitted with two General Electric LM2500 geared gas turbines. The ship's company consists of 1,208 personnel. The ships are the largest amphibious warfare vessels in the world.

Amphibious operations

The LHDs can support amphibious landings in two forms: by landing craft, or by helicopter. In the 81-by-15.2-metre (266 by 49.9 ft) well deck, the LHDs can carry three Landing Craft Air Cushion, twelve Landing Craft Mechanised, or 40 Amphibious Assault Vehicles (AAVs), with another 21 AAVs in the vehicle deck. The flight deck has nine helicopter landing spots, and can operate helicopters as large as the Sikorsky CH-53 Sea Stallion and Boeing Vertol CH-46 Sea Knight.^[5] The size of the air group varies depending on the operation: a standard air group consists of six Harriers and four Bell AH-1W SuperCobras for attack and support, twelve Sea Knights and four Sea Stallions for transport, and three to four Bell UH-1N Iroquois utility helicopters. For a full assault, the air group can be maxed out at 42 Sea Knights, while a Wasp operating in the sea control or 'harrier carrier' configuration carries 20 Harriers (though some ships of the class have operated as many as 24), supported by six Sikorsky SH-60 Seahawk helicopters for anti-submarine warfare. The CH-46 is being replaced by the MV-22 Osprey on a squadron-by-squadron basis, with expected full conversion within all aviation combat elements by 2019. Two aircraft elevators move aircraft between the flight deck and the hangar; in order to transit the Panama Canal, these elevators need to be folded in.
    Each ship is capable of hosting 1,894 personnel of the United States Marine Corps; almost the full strength of a Marine Expeditionary Unit (MEU). A Wasp-class vessel can transport up to 2,860 square metres (30,800 sq ft) of cargo, and another 1,858 square metres (20,000 sq ft) is allocated for the MEU's vehicles, which typically consists of 5 M1 Abrams battle tanks, up to 25 AAVs, eight M198 howitzers, 68 trucks, and up to 12 other support vehicles. An internal monorail is used to shift cargo from the cargo holds to the well deck.
Each Wasp-class ship has a hospital with 600 patient beds and six operating rooms.

Armament and sensors

The armament of the first four Wasp class consists of two Mark 29 octuple launchers for RIM-7 Sea Sparrow missiles, two Mark 49 launchers for RIM-116 Rolling Airframe Missiles, three 20 mm Phalanx CIWS systems, four 25 mm Mark 38 chain guns, and four .50 BMG machine guns. The next three ships, Bataan, Bonhomme Richard, and Iwo Jima, have a slightly reduced weapons outfit to their preceding sister ships, with one Phalanx and one Mark 38 gun removed. Countermeasures fitted to the ships include four to six Mark 36 SRBOC launchers, an AN/SLQ-25 torpedo decoy, AN/SLQ-49 chaff buoys, a Sea Gnat missile decoy, and an AN/SLQ-32 Electronic Warfare Suite.

The sensor suite fitted to each ship is made up of an AN/SPS-48 or AN/SPS-52 air-search radar backed up by an AN/SPS-49 air-search radar, an SPS-67 surface search radar, an AN/URN-25 TACAN system, along with several other radars for navigation and fire control.