The EMALS energy-storage system design accommodates this by drawing power from the ship during its 45-second recharge period and storing the energy kinetically using the rotors of four disk alternators the system then releases that energy (up to 484 MJ) in 2–3 seconds. Energy-storage subsystem ĭuring a launch, the induction motor requires a large surge of electric power that exceeds what the ship's own continuous power source can provide. Only the section of the coils surrounding the carriage is energized at any given time, thereby minimizing reactive losses. When energized, the motor accelerates the carriage along the track. The EMALS consists of four main elements: The linear induction motor consists of a row of stator coils with the same function as the circular stator coils in a conventional induction motor. The EMALS uses a linear induction motor (LIM), which uses alternating current (AC) to generate magnetic fields that propel a carriage along a track to launch the aircraft. These control problems allow Nimitz-class aircraft carrier steam-powered catapults to launch heavy aircraft, but not aircraft as light as many unmanned aerial vehicles.Ī system somewhat similar to EMALS, Westinghouse's electropult, was developed in 1946 but not deployed. With no feedback, there often occurs large transients in tow force that can damage or reduce the life of the airframe." The steam system is massive, inefficient (4–6% useful work), and hard to control. One group of Navy engineers wrote: "The foremost deficiency is that the catapult operates without feedback control. However, there are a number of drawbacks. Carriers equipped with four steam catapults have been able to use at least one of them 99.5% of the time. It also reduces the carrier's requirement of fresh water, thus reducing the demand for energy-intensive desalination.ĭeveloped in the 1950s, steam catapults have proven exceptionally reliable. Compared to steam catapults, the EMALS also weighs less, is expected to cost less and require less maintenance, and can launch both heavier and lighter aircraft than a steam piston-driven system. ![]() Its main advantage is that it accelerates aircraft more smoothly, putting less stress on their airframes. ![]() Ford-class aircraft carrier, the USS Gerald R. EMALS was first installed on the lead ship of the Gerald R. The system launches carrier-based aircraft by means of a catapult employing a linear induction motor rather than the conventional steam piston. The Electromagnetic Aircraft Launch System ( EMALS) is a type of aircraft launching system developed by General Atomics for the United States Navy. A drawing of the linear induction motor used in the EMALS
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