America-class Amphibious Assault Ship - Design

Design

The design of the USS America is based on the USS Makin Island (LHD-8), herself an improved version of the Wasp class amphibious assault ships with gas turbine power. About 45 percent of the "Flight 0" design of this class is based on that of the Makin Island, but with her well deck omitted to allow more room for aircraft, their spare parts and weapons, and their fuel. Note that the gas turbines of the Makin Island, the America, and her possible successors burn the same kind of fuel (JP-4) that is burned in the gas turbines of their helicopters, the jet engines of their AV-8B Harrier fixed-wing attack planes, the engines of the MV-22 Osprey aircraft that they can carry, and (in future ships), the gas turbines of the Landing Craft Air Cushions (LCACs) that they could carry in their well decks. All of this greatly simplifies the storage, distribution, and use of the fuels for these craft.

The typical aircraft complement for the first two vessels is expected to be 12 MV-22B Osprey transports, six STOVL F-35B Lightning II attack aircraft, four CH-53K heavy transport helicopters, seven AH-1Z/UH-1Y attack helicopters, and two Navy MH-60S "Knighthawks" for air-sea rescue. The exact make-up of the ship's aircraft complements will vary according to her mission. She can carry about 20 AV-8Bs or F-35Bs, and two MH-60Ses to serve as a small aircraft carrier as demonstrated by Landing Helicopter Dock (LHD) operations in Operation Iraqi Freedom.

Any further warships in this class will also have a well deck for amphibious warfare in their sterns to contain landing craft (such as the Landing Craft Air Cushion (LCAC) exactly as in the Tarawa class amphibious assault ships (LHA)s and the Wasp class amphibious assault ships.

The addition of a well deck will leave less space for aircraft on board the ships, but the "Early Operational Assessment" of 2005 criticized the "Flight 0" design because the expanded aviation facilities gave no space for a well deck. Also, the USS America has reduced stowage space for military vehicles, and the size of her hospital was reduced by two-thirds with respect to the Wasp-class ships.

Before he became the Under Secretary of the Navy, Robert O. Work, also brought into question the usefulness of an amphibious warfare ship without a well deck. The concept of the Landing Platform Helicopter (LPH) had failed when their helicopters met antiaircraft systems off the coast of Lebanon during the late 1970s. In that case, Marines had to be moved first onto the warships that had well decks.

The U.S. Marine Corps is now more concerned about attacks by antiship missile, hence the Commandant of the Marine Corps wants to keep the amphibious ships farther offshore. In that case Marines would be sent ashore in long-ranged MV-22 V/STOL aircraft. The MV-22 is significantly larger than the largest helicopters used by the Marine Corps and the Navy in the past. Hence, the America has twice the displacement of the much older Iwo Jima class amphibious assault ships (all of which are now decommissioned).

Setting the beam of the America at 106 feet is dictated by the need for these ships to pass through the Panama Canal. The Congressional Budget Office found that LH(X) class ships would be more cost-effective if they were built with nuclear power—if the price of oil reached and stayed above $140 per barrel by 2040.

A modified version of the design of the USS America, designated the MPF(F), LHA(R), or T-LHA(R), was proposed for two ships of the Maritime Prepositioning Force (Future). The MPF(F) is the Navy's concept for a "sea base" to support operations ashore starting in about 2025.

These two ships would hypothetically be manned by a civilian crew from the Military Sealift Command, and hence not armed with weapons. Funding for the MPF(F) and the LHA(R) was tabled by the Senate Armed Services Committee in the fiscal year 2008 budget. The U.S. Navy now intends to buy more ships of the America class for its fleet of amphibious warfare ships.

The so-called "LHX" was a warship that was proposed in the late 1990s to replace the Tarawa-class ships, but with a dry deck for hovercraft rather than a floodable "well deck". After the year 2000, the LHX, the so-called "Amphibious Assault Ship Future Replacement", was put forward to replace all of the LHDs.

The new LHX could be a Flight 2 design of the America-class built with a well deck and a smaller island superstructure, which would give it 20 percent more capacity on the flight deck. This would remove the current restriction on MV-22s to land on spots 5 and 6, and also giving room for four MV-22B, three F-35B Lightning IIs, or three CH-53Ks to use the flight deck. In 2008, the procurement of Flight 2 ships was tentatively planned for 2024, but that might not be practical or affordable by then.