Manufacturer to develop electromagnetic launcher in a five-year deal worth over $145m
General Atomics (GA) is to develop the electromagnetic catapult for future US Navy aircraft carriers, after beating Northrop Grumman to the service's five-year electromagnetic aircraft launch system (EMALS) development contract, worth over $145 million.
The electrically powered EMALS will replace steam-driven catapults on carriers, beginning with CVN 21, which is scheduled to enter construction in 2007 and service in 2014. The system will provide a smoother launch, reducing stress on the aircraft, says GA programme manager Tony Kopacz.
Under four-year, $80 million risk-reduction contracts awarded to both competitors, GA built a full-scale, half-length launcher for testing at the Naval Air Warfare Center in Lakehurst, New Jersey. Land-based testing of a full-length launcher is to begin three years into development, and a year ahead of a production decision, says Kopacz.
Each CVN 21-class carrier will be equipped with four EMALS. The GA design is made up of four elements: energy storage; power conversion; linear motor; and control system. Electrical power from the ship is stored as potential energy in spinning generators. On activation, the stored energy is converted to an electrical waveform that is applied to the linear induction motor, starting at one end and moving down the launcher.
The aircraft to be launched is hitched to an armature, or vane, lying between the left and right stators of the linear motor, says Kopacz. As the travelling wave moves down the series of stators, the induced electromagnetic force locks up the vane and pulls it, and the aircraft, along. Power is regulated to achieve a controlled, gentler application of force. When the aircraft is at launch speed, the vane is stopped and returned electrically.
A 30% reduction in crewing is the major benefit, says Kopacz. The system is designed for launch speeds of 55-200kt (100-370km/h) and will launch a broader spectrum of aircraft than steam catapults, he says. GA and Northrop Grumman are still competing to supply the companion turboelectric arresting gear for future carriers.
GRAHAM WARWICK / WASHINGTON DC
Source: Flight International