Electromagnetic Aircraft Launch System (EMALS)

Electromagnetic Aircraft Launch System (EMALS)

EMALS is a complete launch system designed to replace the existing steam catapult currently being used on aircraft carriers. The USS Gerald R. Ford, the first ship of the CVN-21 Future Aircraft Carrier Class, will use electromagnetic launch systems.

EMALS provides:

Reduced Manning Workload
Reduced Thermal Signature
Increased Launch Availability
Reduced Topside Weight
Reduced Installed Volume
Launch capability for unmanned aerial vehicles

In 2000, GA was awarded the prime contract for a 4 year Program Definition and Risk Reduction (PDRR) by Naval Air Systems Command (NAVAIR) for the design and manufacture of a prototype EMALS. In 2004 GA was awarded the follow on System Development and Demonstration (SDD) contract. In late 2007, The GA team completed the Critical Design Reviews for the EMALS system and began manufacturing hardware and software for component and integrated system testing.

The next step is to install the full size, ship representative EMALS equipment in the recently completed EMALS land-based test facility at Naval Air Engineering Station (NAES) Lakehurst, N.J. The EMALS equipment installation began in mid 2008, with integrated system testing to begin in 2009. EMALS equipment will be installed in CVN 78.

The EMALS system is a multimegawatt electric power system involving generators, energy storage, power conversion, a 100,000 hp electric motor, and an advanced technology closed loop control system with diagnostic health monitoring. In addition to building the power conversion and motor equipment, GA provides the power system integration and logistics support for this state-of-the-art power electronic system. During the current SDD phase, GA will design, build, and operate a fully integrated EMALS system at the SDD test site in Lakehurst, N.J.

EMALS linear motors under construction at GA’s plant in Tupelo, Miss.
EMALS SDD test site at the Naval Air Engineering Center in Lakehurst, N.J.	EMALS dead-load testing

The EMALS consists of six major subsystems:

	Prime Power Interface This system provides the interconnect with the ship's electrical distribution system and delivers power to drive the energy storage generators.
	Launch Motor Developed in a linear induction motor configuration, the launch motor is a compact, modular, integrated flight-deck structure that converts electrical current into the electromagnetic forces to accelerate the aircraft along the launch stroke. The motor design will tolerate the range of conditions experienced in the flight-deck environment and operating scenarios. A simple moving shuttle will interface with the aircraft in the same manner as the existing catapults. After the aircraft launches, the electric current in the motor will reverse to brake the shuttle to a complete halt without the use of a water brake.
	Power Conversion Electronics The power conversion electronics derive power from the energy store and convert this power to traveling wave of energy of the appropriate voltage and current to drive the shuttle along the launch stroke. Based on solid-state technology GA uses in its line of commercial power equipment, the power electronics are packaged as compact modules in cabinets that are located below deck.
	Launch Control The EMALS uses a state-of-the-art system to control the current into the launch motor in real time. More precise endspeeds are achievable over a wider range of aircraft types and weights over those of steam catapults. The smoother acceleration may extend the lifetime of the aircraft. High reliability and a system architecture with inherent redundancy is achieved by use of commercial off-the-shelf components where possible. Modularity is emphasized to ease installation and maintenance — important factors in life cycle planning.
	Energy Storage The required energy for a launch is drawn from the energy storage devices during each two- to three-second launch. The energy storage devices are recharged from ship’s power between launches. In March 2008, the program celebrated a milestone with the successful completion of factory acceptance testing of the motor generator component of the EMALS energy storage subsystem (ESS). Four additional ESS systems will be built to support development testing at the NAES Lakehurst, N.J., culminating in aircraft launches at the test site.
	Energy Distribution System This system delivers the energy from the power conversion system to the launch motor and comprises cables, disconnects, and terminations.

GA EMALS TEAM MEMBERS
Team Member		Expertise
General Atomics Electromagnetic Systems Division		Electromagnetic System Design and Fabrication, System Integration, Power Electronics and Controls, Software, and Logistics
Alion Science and Technology		Specialty Engineering
Foster Miller, Inc.		Control Systems, System Health Monitoring
University of Texas at Austin – Center for Electromechanics		Energy Storage Systems Design and Analysis
L3 Communications – Applied Technologies Pulse Sciences		Power Electronics
Kato Engineering		Energy Storage Systems Manufacture
STV, Inc.		Test Site Design/Integration, Naval System Logistics

For more information contact:
Susan Wojtowicz
Director, Launch and Recovery Programs
Sue.Wojtowicz@gat.com