Tech Insights

Are Electric Launches the Future of Navy Aircraft?

May 14, 2024 by Kevin Clemens

Electromagnetic launching systems are compact, efficient, and adaptable to aircraft size and weight. However, the system design may still need perfecting.

Hurtling a fully loaded jet fighter from the deck of an aircraft carrier requires tremendous power. Traditionally, steam catapults, developed in the 1950s, have been used to launch carrier aircraft, and the U.S. Navy has four such devices available on its ships to ensure reliability and redundancy.

Steam catapults have several drawbacks. They are an all-or-nothing system, providing the same towing forces regardless of the size and weight of the aircraft they are launching. This can result in damage or a reduced life of an aircraft's airframe. This lack of control makes it difficult to launch light unmanned aerial drones using the same catapult used for heavy fighter aircraft. 

 

Electromagnetic Aircraft Launch System on Navy ship.

Electromagnetic Aircraft Launch System on Navy ship. Image used courtesy of U.S. Naval Air Systems Command 

 

An alternative is the Electromagnetic Aircraft Launch System (EMALS). Instead of steam, an electrically powered linear induction motor propels the aircraft off the flight deck. The technology is featured on the U.S. nuclear aircraft carrier Gerald R. Ford, which entered service in 2017.

 

Electrifying Aircraft Launches

EMALS uses AC to create magnetic fields along stator coils that, when energized section by section, can accelerate a carriage attached to the aircraft along a track. The energy required is momentarily greater than that provided by the ship’s nuclear reactors, so a kinetic energy storage system spins four rotors using the ship's energy during a 45-second recharge period. During launch, this kinetic energy converts to electrical energy with four disc alternators, and the energy is released over the 2 to 3 seconds it takes to launch the aircraft. Each rotor can deliver about 34 kW. An EMALS can accelerate a 100,000-pound aircraft to about 150 mph over the 300-foot-long launching track. 

 

EMALS demonstration. Video used courtesy of U.S. Navy

 

The big advantage EMALS has over a traditional steam catapult is its feedback control system, which uses Hall-effect sensors along the track. The closed-loop system moderates the tow force depending on the aircraft's weight, reducing launch stresses on the airframe and helping enhance safety and aircraft longevity. 

EMALS also occupy less space below the deck (more room for aircraft and munitions storage) and require fewer people to operate.

 

Not So Simple: Do Launch Problems Persist?

Although the EMALS catapult seems straightforward, the process has not gone as smoothly as hoped. A June 2023 United States Government Accountability Office report highlighted EMALS’ lack of reliability on the Gerald R. Ford and suggested the system’s failure rate has been much higher than expected than the steam catapult system it was designed to replace. 

 

Chinese EMALS Developments

Undeterred by the problems the U.S. Navy experienced with its EMALS, the Chinese Navy is developing its electromagnetic launch system for its latest aircraft carriers. 

Unlike the U.S. system, which uses AC to develop a linear electromagnetic force accelerating a carriage, the Chinese system uses a powerful DC)motor to drive a heavy flywheel. When an aircraft is ready to launch, the flywheel passes its kinetic energy through an eddy current clutch to a winding wheel that pulls a shuttle with a steel cable, accelerating the aircraft to takeoff speed. The eddy current clutch means the flywheel and winding wheel are not in physical contact. 

The system, deployed on China’s newest aircraft carrier, Fujian, reportedly can launch large 30-ton fixed-wing aircraft from the carrier deck in 2.1 seconds, in just 100 meters.