Electromagnetic Aircraft Launch System The Electromagnetic Aircraft Launch System ( EMALS ) is a system under development by the United States Navy to launch carrier - based aircraft from catapults using a linear motor drive instead of conventional steam piston s . This technology reduces stress on airframes because they can be accelerated more gradually to takeoff speed than with steam - powered catapults . Other advantages includes lower system weight , cost , and maintenance ; the ability to launch both heavier and lighter aircraft than conventional systems ; and lower requirements for fresh water , reducing the need for energy - intensive desalination . Design and development . The EMALS is being developed by General Atomics for the U . S . Navy ' s newest " Gerald R . Ford " - class aircraft carriers . In June 2010 , the land - based prototype of the system passed initial tests , with the first aircraft launch from the system taking place at the end of 2010 . Linear induction motor . The EMALS uses a linear induction motor ( LIM ) , which uses electric currents to generate magnetic fields that propel a carriage down a track to launch the aircraft . The EMALS consists of four main elements : The linear induction motor consists of a row of stator coils that have the function of a conventional motor ’ s armature . When energized , the motor accelerates the carriage down the track . Only the section of the coils surrounding the carriage is energized at any given time , thereby minimizing reactive losses . The EMALS ' LIM will accelerate a aircraft to . Energy storage subsystem . The induction motor requires a large amount of electric energy in just a few seconds — more than the ship ' s own power source can provide . The EMALS energy - storage subsystem draws power from the ship and stores it kinetically on rotors of four disk alternators . Each rotor can store more than 100 megajoules , and can be recharged within 45 seconds of a launch , faster than steam catapults . Power conversion subsystem . During launch , the power conversion subsystem releases the stored energy from the disk alternators using a cycloconverter . The cycloconverter provides a controlled rising frequency and voltage to the LIM , energizing only the small portion of stator coils that affect the launch carriage at any given moment . Control consoles . Operators control the power through a closed loop system . Hall effect sensors on the track monitor its operation , allowing the system to ensure that it provides the desired acceleration . The closed loop system allows the EMALS to maintain a constant tow force , which helps reduce the launch stresses on the plane ’ s airframe . Advantages . Compared to steam catapults , EMALS weighs less , occupies less space , requires less maintenance and manpower , is more reliable , and uses less energy . Steam catapults , which use about 614 kilograms of steam per launch , have extensive mechanical , pneumatic , and hydraulic subsystems . EMALS uses no steam , which makes it suitable for the Navy ' s planned all - electric ships . The EMALS could be more easily incorporated into a ramp . Compared to steam catapults , EMALS can control the launch performance with greater precision , allowing it to launch more kinds of aircraft , from heavy fighter jets to light unmanned aircraft . EMALS can also deliver 29 percent more energy than steam ' s approximately 95 megajoules , increasing the output to 122 megajoules . The EMALS will also be more efficient than the 5 - percent efficiency of steam catapults . Systems to use EMALS . EMALS is a design feature of the " Ford " - class carrier . Converteam UK were working on an electro - magnetic catapult ( EMCAT ) system for the " Queen Elizabeth " - class aircraft carrier . In August 2009 , speculation mounted that the UK may drop the STOVL F - 35B for the CTOL F - 35C model , which would have meant the carriers being built to operate conventional ( CV ) take off and landing aircraft utilizing the UK - designed non - steam EMCAT catapults . In October 2010 , the UK Government announced it had opted to buy the F - 35C , using a then - undecided CATOBAR system . A contract was signed in December 2011 with the General Atomics Company of San Diego to develop EMALS for the " Queen Elizabeth " - class carriers . However , in May 2012 , the UK Government reversed its decision after the projected costs rose to double the original estimate and delivery moved back to 2023 , cancelling the F - 35C option and reverting to its original decision to buy the STOVL F - 35B . Rear Admiral Yin Zhuo of the People ' s Liberation Army Navy has said that China ' s next aircraft carrier will also have an electromagnetic aircraft launch system .