Losing steam: US Navy carriers go electric

Half a century after the introduction of steam-driven catapults, the US Navy (USN) aircraft carrier community is entering an era that trades steam and hydraulics for advanced electronic circuitry.

Construction of the first in a new line of carriers, Gerald R Ford (CVN 78), is due to begin in 2008 and the USD10.5 billion ship will use electricity instead of steam for launching combat aircraft, cooking meals and heating sailors' living quarters. Its nuclear reactors will produce more electricity than any other warship, powering a maintenance revolution as well as one of the navy's 'floating cities'.

The CVN 78-class carriers - the fruit of the CVN 21 design and development programme - will have powerful new radar, upgraded landing systems and larger flight decks than their Nimitz-class predecessors. The ship's company plus air wing will number a relatively meagre 4,660 personnel, between 1,000 and 1,200 fewer than the total required in the older carriers.

Many technological advances contribute to the manpower efficiency gain. For example, radars in the new ship will not need to rotate, dramatically reducing wear and tear; and the USN says its new electromagnetic launch system can be operated by about 90 sailors, compared to the 120 needed for steam-driven catapults. Pilots on take-off may reap the most noticeable benefits as the new catapult will push them smoothly aloft, in contrast to the steam-driven jolt of the existing carriers.

"Going through a catapult launch is akin to getting launched on a roller coaster," says Louis Uffer, manager of the USN's Electromagnetic Aircraft Launch System (EMALS) programme. "You wouldn't want to be jerked right out of your seat. You want to get nice and gently thrown on your roller-coaster ride. EMALS is going to do the same thing for the naval aviators who get to launch off aircraft carriers. This is going to be the start of whatever their thrill ride is, whatever mission they go on."

Thrill rides are an everyday occurrence for the carrier fleet, the centrepiece of the USN's fighting force. Each flat-top can accommodate more than 75 aircraft, with a lineup that typically includes four F/A-18 strike interdictor squadrons, a squadron of S-3B reconnaissance aircraft, a squadron of E-2C command-and-control aircraft and a helicopter squadron. Future plans will see the embarkation of unmanned aerial vehicles; in August 2007 it was announced that Northrop Grumman had won a USD635.9 million Unmanned Combat Air System-Demonstrator (UCAS-D) contract from US Naval Air Systems Command, after the company's X-47B drone was selected (ahead of Boeing's X-45) as the developmental testbed for the navy's first carrier-launched unmanned strike aircraft.

Also, the F/A-18s will be joined by a carrier version of the F-35 Lightning II Joint Strike Fighter (JSF), which will bring stealth and state-of-the-art electronics to maritime aviators. The USN plans a mix of the two supersonic combat aircraft, so that it can take advantage of the F-35's new capabilities without replacing its entire inventory and sucking funds from other programmes.

All these aircraft give the carriers their enormous combat power, including the potential to deliver nuclear weapons if needed. They also represent a shift in the navy's use of carriers and sea-based aircraft since their introduction in the early 20th century.

"At the end of World War II we had 99 carriers," says Vice Admiral David Architzel, one of the USN's senior acquisition officials. "Today's carriers are tremendously more capable. We measure things today not by number of aircraft per target but number of targets per aircraft."

Image: An E-2C Hawkeye of Carrier Airborne Early Warning Squadron 116 makes an arrested landing aboard the Nimitz-class carrier USS Abraham Lincoln (CVN 72) during a joint taskforce exercise off southern California. (US Navy) 582 of 3,927 words