Although aircraft carriers are a frequent target for critics who emphasise the threat of new weapons, it is striking that the most powerful navy in the world still places great trust in them. Some analysts believe that unmanned aircraft or new precision-attack capabilities will assume the roles of manned combat aircraft. There are also the claims of land-based air enthusiasts who see a role for manned aircraft, but not of the sea-based variety. The future policy of the US Navy is based on the assumption that cruise missiles, future precision-attack systems and UAVs will perform the roles carried out by manned aircraft, and will be used in conjunction with them: complementing manned aircraft but not replacing them.

The aircraft carrier remains the central element in the US Navy force structure and occupies a similarly pivotal role in US national strategy: the most frequent response to a crisis is to send a carrier. Naturally, the carrier is only a part of the contemporary battle group. Attack submarines and surface warships provide protection for the carrier and many complementary capabilities, not least in their ability to deploy land-attack weapons.

Amphibious forces have risen in importance since the cold war and the US Navy includes aircraft-operating ships bigger than carriers of other major navies. The carrier remains the centrepiece of the battle group, its aircraft are crucial for establishing and exploiting control of the battlespace, at sea, over land or where they converge.

The US has an unchallenged lead in many areas of military capability, including strategic intelligence, long-range sealift and airlift and strategic air power. It has a similar advantage in carriers. The UK has three small carriers (one in extended refit), with two new medium-sized carriers promised; France has one medium-sized carrier and a nuclear-powered vessel soon to enter service. The Russian Federation, Spain, Italy, India, Brazil and Thailand each have one medium or small carrier. The US Navy has 12 large carriers (one in reserve), with 10 active and one reserve Carrier Air Wing.

The carrier battle groups needed to meet the warfighting and the present needs of regional commanders-in-chief is 15, but the present lower number is accepted for financial reasons. The force is made up of nine nuclear-powered carriers (CVN), eight of the Nimitz-class plus the venerable USS Enterprise, and three older, conventionally powered vessels (CV) and one in reserve. The most recent is USS Harry S Truman (CVN-75) a 1998 replacement for USS Independence (CV-62). Construction is underway on CVN-76 that enters service next year as the USS Ronald Reagan, replacing the conventionally powered USS Constellation.

The Pentagon's 1993 bottom-up review established a dual-track strategy for future carrier procurement. It advised an evolutionary approach, building on current carrier designs but making greater use of current R&D to introduce innovative technology. It is expected that new systems will confer operational benefits while allowing considerable savings in through-life cost in which the initial purchase is only a small part, annual operating and support costs actually amounting to 80 per cent of the total price tag.

CVN-77

The first element of this approach is the un-named CVN-77 that will begin construction in 2002 and enter service in 2008 to replace USS Kitty Hawk (CV-63). It will represent a gradual evolution of the Nimitz-class, incorporating a number of new technologies with significant benefits that also will act as a technology bridge for the next, more ambitious stage of US carrier development.

CVN-77 will feature a newly designed, integrated combat system; improved island and hangar designs; reduced signature to improve stealth; and reduced manpower compared to the Nimitz class, each of which has a crew of over 6,000 including air wing. The aim is a 15-per-cent reduction in operation and support costs compared to earlier ships in the class. Improvements made in CVN-77 will have wider benefits as some will be retro-fitted to her nine older sister ships. The acquisition cost of CVN-77 will be about $4.5 billion, although this figure has been questioned.

CVNX

The second strand of the dual strategy is the CVNX project. Intended to be a totally new ship, research, development and design costs were prohibitive so it became a further evolution of the Nimitz design. In 1998 it was named CVX or CVX-78: the missing N signified that the ship might not be nuclear-powered. Various options were examined such as oil-fired, diesel and gas turbine with integrated electric drive, although nuclear propulsion remained the favoured option.

Although more expensive, nuclear power offers unlimited endurance and reduced dependence on refuelling ships as well as avoiding reliance on oil, the price of which could increase over the projected 50-year life of future carriers. Studies also examined whether the ship should operate conventional take-off and landing (CTOL) aircraft, as current US carriers, or should adopt short take-off and vertical landing (STOVL) aircraft, such as the joint strike fighter version being planned for the US Marine Corps and the Royal Navy. A STOVL carrier offers advantages in cost and commonality with Marine Corps vessels but potential aircraft performance costs in terms of range, load and stealth. Size-of-ship options considered 80, 60 and 40 aircraft and over 60 ship designs were studied. The conclusion was that the new vessel should be nuclear powered (hence the designation of CVNX) and capable of operating 75 CTOL aircraft.

Future carriers will incorporate the new combat system and other enhancements from CVN-77. It will also feature several new systems including a newly designed nuclear power plant (the Nimitz- class design is 35 years old), drawing on the experience of submarine reactors, as well as a new electric generation and distribution system and a design philosophy that allows easier modernisation and replacement of systems. A big step forward is planned for launching aircraft, the steam catapult is to be replaced with an electro-magnetic aircraft launching system (EMALS). This gives considerable reductions in weight, manning and life-cycle costs, while increasing operational availability and lengthening aircraft life by reducing airframe strain during launch. The ship also will have an electro-magnetic aircraft recovery system.

CVNX-1 is to begin construction in 2006 and enter service in 2013 to replace USS Enterprise (CVN-65), the first of the US nuclear-powered carriers that will have reached the age of 52. Ships of the new class will then begin building at five-yearly intervals. A second ship is planned to start in 2011, to come into service in 2018, a schedule required to meet the 12-carrier force level.

The navy department hopes the CVNX programme will offer life-cycle cost savings of 30 per cent compared to those of the Nimitz class, mainly from a crew reduction of 20 per cent or more. The possibility of greater and more radical changes in future ships of the class is envisaged, especially if these permit savings in life-cycle costs. CVNX-2 could be a modified version of CVNX-1 or a completely new design, trading operational effectiveness against budgetary constraints.

As with other elements of the armed services, there are concerns about overstretch on personnel and equipment. The navy stresses that current build rates will not sustain fleet levels, let alone provide expansion desired by its leadership. The carrier force is subject to criticisms of alleged obsolescence or vulnerability to emerging technological threats. Nevertheless, plans for the programme reflect recent experience that whenever a crisis emerges, the first political response tends to be 'where is the nearest aircraft carrier?'

www.chinfo.navy.mil