The aircraft carriers of tomorrow are beginning to take shape in the minds of US Navy and US industry officials who have been given the job of designing the final Nimitz-class carrier, the CVN-77, and the futuristic CVX - the new class of aircraft carrier destined to serve to the end of the next century.

The USN now operates 12 carriers (11 active and one operational reserve) and its tactical aviation assets, which include ten active-duty air wings and one reserve wing. It is committed to keeping at least a dozen carriers at sea indefinitely, with the Nimitz-class carrier at the heart of the USA's power-projection capabilities for years to come.

The nuclear-powered Nimitz-class warships are in the 90,000t displacement class, with an overall length of almost 335m (1,100ft). Each has four steam catapults to launch aircraft and four arresting wires or cables on the angle deck are used to recover aircraft. Each air wing generally consists of 76 fixed-wing aircraft and six helicopters.


Newport news work

Newport News Shipbuilding, the only US shipyard capable of building nuclear-capable carriers, delivered the John Stennis (CVN-74) to the USN in 1995, and will finish work on the Harry Truman (CVN-75) in 1998. It is under contract to build the $4.5 billion Ronald Reagan (CVN-76), the ninth Nimitz-class nuclear carrier, which will be delivered in 2003.

The USN will need another Nimitz-class carrier, the CVN-77, to replace the conventionally powered Constellation (CV-64) in 2008. Under its current two-track research and development approach, the CVN-77 would act as a transition ship to the new-design large-deck CVX-78 which would replace the nuclear-powered Enterprise (CVN-65) in 2013.

The oil-burning John F. Kennedy (CV-67) reserve-training carrier would be replaced by the CVX-79 in 2018, and the CVX-80 would take the place of the original Nimitz (CVN-68) in the 2023-4 timeframe.

The tenth Nimitz-class carrier will be nuclear-powered and maintain its predecessors' dimensions. It will probably incorporate technology and systems developed for the future CVX carrier, and it would serve as a testbed for some innovations which would be retrofitted into Nimitz-class carriers on watch worldwide.

The continuing future-carrier R&D project includes technical and operational assessments of technology and designs. Areas being explored include affordability, survivability, advanced aircraft launch-and-recovery systems and improved propulsion systems. Meanwhile, ship designers are studying whether a modified island structure and the use of radar-absorbing materials around the carrier's superstructure can reduce its radar signature.

While several US companies have been conducting enabling-research efforts for several years, the USN in June awarded contracts to six of the largest US defence firms to conduct initial CVX engineering development. Although of nominal value, the awards serve to identify the participants which may one day be called upon to build the CVX.

The firms receiving funds are: Avondale Shipbuilding, General Dynamics Electric Boat, Hughes Aircraft, Ingalls Shipbuilding, Lockheed Martin and Newport News Shipbuilding. They will conduct across-the-board studies covering 14 different subject areas, including propulsion, command and control and aviation support. There are options to extend the one-year study contract by four years.


Room for innovation

Newport News Shipbuilding plans to maintain its leadership role in the Ìeld, and it has created the Carrier Innovation Center - a "Skunk Works" for innovative thinking.

For example, it has come up with a more-revolutionary design approach to the CVN-77 which would divide aircraft and ship operations between two islands, incorporate "pit stops" for aircraft refuelling and servicing, which are strategically positioned about the ship, and reposition the elevators.

Manning for today's Nimitz-class carrier includes 3,500 personnel in the ship's company, and an additional 2,200 personnel in an air wing. The USN would like to reduce that by 50% for the CVX.

Newport News Shipbuilding believes that so-called gravity-compensated weapons handling robotics can be used to arm tactical aircraft. Tests conducted by the shipyard show that 225kg weapons can be loaded by one person using a robotically controlled lifting arm. About 8% of the crew handles weapons. Using robotics, one bomb handler will be able to perform the work of five.

Today's carriers use jet-blast deflectors of welded aluminum which circulate sea water to dissipate heat from an aircraft exhaust. Newport News Shipbuilding, borrowing from the aircraft-manufacturing industry, will install deflectors machined from solid sheets of aluminum, thus eliminating the need to shut down flight operations while workers repair weld cracks discovered during launch operations.

The US shipyard also hopes to eliminate the extensive piping system and pumps needed to circulate sea water to the flightdeck. It is determining whether heat-resistant tiles, such as those used on the Space Shuttle, can be a substitute. Aircraft would constantly be rolled over the tiles, and further tests will be conducted to see if they are strong enough for the job. The tiles which would be used on CVN-77 and CVX could be retrofitted to operational Nimitz-class carriers as well.

Some designs generated by Newport News Shipbuilding include a retractable ski jump at the forward end of the flightdeck which would provide aircraft with a more-optimum ßy-away angle. Another concept includes a catapult for launching unmanned air vehicles (UAV).

The next-generation aircraft carrier's size and design will be influenced by the type and number of aircraft it will send to the world's troublespots. Operating today's conventional take-off-and-landing (CTOL) aircraft, such as the Boeing F/A-18E/F Super Hornet strike aircraft, will require catapults and arresting gears. The Joint Strike Fighter project will yield both a CTOL aircraft for the USN and a short take-off and vertical landing (STOVL) aircraft for the US Marine Corps.

Meanwhile, the USN is defining its requirement for a Common Support Aircraft (CSA). Some 250 CSA aircraft are earmarked to replace Lockheed S-3B Vikings, ES-3A Shadows, Northrop Grumman E-2C Hawkeyes and C-2 Greyhounds. It is still unclear whether the CSA will be a CTOL, STOVL or short-take-off-and-landing aircraft.

Whether the CVX will employ today's steam-driven catapult or advanced aircraft launch-and-recovery systems, such as the Electro-Magnetic Aircraft Launch System being developed for the USN by Kaman Electromagnetics, remains to be seen. Significant development would be required before the concept is ready for a new carrier.

Another candidate being evaluated by Newport News Shipbuilding is an internal-combustion aircraft launch system (ICALS) fuelled by JP-5 jet fuel. As part of the concept, JP-5 and a liquid oxidiser are combined and ignited in a combustion module as water is injected, creating steam in a different way. Laboratory tests show that a stable flame which meets the requirements can be sustained.


Simulation efforts

Newport News Shipbuilding hopes to finish modelling and simulation of the EMALS by the end of this year or early 1998. The USN plans to conduct a full-scale ICALS demonstrator for land-based testing beginning in 2000. An evaluation aboard a Nimitz-class carrier may follow.

Innovations may be found beyond the flight deck. Plexiglass boards now found in the air-operations centre may be replaced by large computer screens.

Zonal electrical-distribution systems may be installed to isolate the potential for problems and minimise their impact on the rest of the warship. The USN believes that in addition to greater survivability through uninterrupted power, the system should be easier to install and repair, require less cabling and provide greater flexibility for ship upgrades.

The CVN-77 could also be a testbed for multi-functional, embedded antennas which could replace many of the radar and other antennas which now populate the superstructures of aircraft carriers.

The CVN-77 will be nuclear-powered, but the CVX may not be. Improved powerplants, such as an integrated electric-propulsion system powered by gas turbines, are being evaluated. The USN plans to test an advanced nuclear-power plant against the most promising alternative in 1998, and decide by December 1999 on the best solution.

While much thought has gone into designing the US Navy's next-generation aircraft carrier, Newport News Shipbuilding officials say that a clear picture of what the CVX will look like will not emerge until 1999 or just after the turn of the century.

Source: Flight International