Electromagnetic Aircraft Launch System
The Electromagnetic Aircraft Launch System ( EMALS, dt: electromagnetic aircraft launch system ) is an aircraft catapult aircraft carrier, which is currently in development and will come on board ships of Gerald R. Ford class to use for the first time.
Construction
Linear motor
The heart of the catapult is a linear motor, which generates, in contrast to conventional electric motors, not rotational but a straight linear motion to drive the carriage to the acceleration of the aircraft. The linear motor consists of a series of 64 cm long stator coil, which are driven sequentially, and thus move the carriage along the track start. For determining the position of the carriage Hall sensors are used. The movable Start carriage runs laterally by means of rollers and has 160 neodymium magnets.
Energy storage system
The starting process is required for a short time a high electric power ( approximately 50 MW ) than the power supply of the vessel can provide. Therefore, energy is temporarily stored in a flywheel accumulator, which can then be accessed within the shortest possible time. One of four flywheels available with EMALS. They are accelerated to a speed of 6400 min -1 and then each store 121 MJ ( 33.6 kWh). To compensate for the centrifugal forces generated by the rotating masses, two flywheels are always arranged in pairs in opposite directions. Recharging takes 45 seconds. Despite the high efficiency due to the high converted energy is produced a lot of heat which must be dissipated by a liquid cooling.
Energy conversion
An inverter converts the electrical energy from the energy storage system to an AC voltage which is adapted to the position and speed of the carriage start. The frequency thereby increases during startup from 0 to 640 Hz, the voltage from 0 to 1520 V. The maximum current is 6400 A.
Project Status
Benefits
Compared to traditional steam-powered catapults EMALS has a higher efficiency. Due to the elimination of steam generators, hydraulics and pneumatics also simplified the structure and thus reduces the maintenance effort, also the noise level generated is significantly reduced. The precise controllability of the boot process, the catapult can be tailored to the needs of a wide range of aircraft. In addition, the maximum starting frequency increases.
Use
EMALS is being developed for the aircraft carrier of the Gerald R. Ford - class, but also UK plans for its new aircraft carriers of the Queen Elizabeth Class using electromagnetic launch catapults.