Electromagnetic catapult

For the system under development by the United States, see Electromagnetic Aircraft Launch System.

An electromagnetic catapult, also known as the electromagnetic aircraft launch system (EMALS) when specifically referring to the system used by the United States Navy, is a type of aircraft catapult that uses a linear induction motor system, rather than the single-acting pneumatic cylinder (piston) system in conventional steam catapults. The system is used on aircraft carriers to launch fixed-wing carrier-based aircraft, employing the principles of electromagnetism and Laplace force to accelerate and assist their takeoff from the shorter flight deck runways. Currently, only the United States and China have successfully developed electromagnetic catapults, which are installed on the Gerald R. Ford-class aircraft carriers (currently only the lead ship CVN-78 being operational), the Type 003 aircraft carrier Fujian and the upcoming Type 076 amphibious assault ship Sichuan (51).

Electromagnetic catapults have several advantages over their older, superheated steam-based counterparts. Electromagnetic operation recharges via electric energy and thus much faster than the pressurization process of steam systems, and does not suffer power loss with distance (where volume expansion within the steam catapult cylinder proportionally reduces pressure), temperature changes (which directly affects pressure according to ideal gas law) and leakages (which matters in pressure vessels but is irrelevant in electromagnet systems). The electromagnetic acceleration is also more uniform (unlike steam acceleration, whose accelerative force is always highest at the very initial phase, thus creating a distinct "jolt"), therefore reducing the stress upon the airframe considerably, resulting in increased safety and endurance as well as lower maintenance costs for the aircraft. Electromagnetic catapults are configurable and can assigned varying power outputs to different sections, thus allowing them to tailor optimal acceleration to individual aircraft according to different payload weights and takeoff behaviours. Electromagnetic systems are more compact and also weigh less, have fewer linkage components and thus are expected to cost less and require less maintenance, and also require no fresh water boiling for their operation, thus reducing the need for energy-intensive desalination and sophisticated piping systems used in steam catapults, which take up significantly more space below the flight deck.

History

Developed in the 1950s, steam catapults have a proven history of reliability due to it being a maturity technology. Carriers equipped with four steam catapults have been able to use at least one of them at 99.5% of the time.^[1] These have, however, several drawbacks. One group of Navy engineers wrote: "The foremost deficiency is that the catapult operates without feedback control. With no feedback, there often occurs large transients in tow forces that can damage or reduce the life of the airframe."^[2] The steam system is massive, inefficient (4–6%),^[3] and hard to control. 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.

General Atomics Electromagnetic Systems (GA-EMS) developed the first operational modern electromagnetic catapult,^[4] named Electromagnetic Aircraft Launch System (EMALS), for the United States Navy. The system was installed on USS Gerald R. Ford aircraft carrier, replacing traditional steam catapults. This innovation eliminates the traditional requirement to generate and store steam, freeing up considerable area below deck. With the EMALS, Gerald R. Ford can accomplish 25% more aircraft launches per day than the Nimitz class and requires 25% fewer crew members.^[5] 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.^[6][7] A system somewhat similar to EMALS, Westinghouse's electropult, was developed in 1946 but not deployed.^[8]

China developed an electromagnetic catapult system in the 2000s for aircraft carriers, but with a different technical approach. Chinese adopted a medium-voltage, direct current (DC) power transmission system,^[9] instead of the alternating current catapult system that United States developed.^[6][10] The system first installed on the Chinese aircraft carrier Fujian. The ship is the first aircraft carrier in the world to successfully launch a fifth-generation fighter using the electromagnetic catapult system.^[11]

Systems under development

The concept of a ground carriage is intended for civilian use and takes the idea of an electromagnetic aircraft launch system one step further, with the entire landing gear remaining on the runway for both takeoff and landing.^[12]

China

Rear Admiral Yin Zhuo of the Chinese Navy said in 2013 that China's Type 003 next aircraft carrier would also have an electromagnetic aircraft launch system.^[13] Multiple prototypes were spotted by the media in 2012, and aircraft capable of electromagnetic launching were undergoing testing at a Chinese Navy research facility.^[14]

According to a report in July 2017, construction of Type 003 was rescheduled in order to choose between a steam or electromagnetic catapult, and the latest competition results showed electromagnetic launchers would be used on Type 003.^[15][16]

China's electromagnetic catapult was installed on its third aircraft carrier Fujian in 2021, becoming the only carrier besides the U.S. Navy's Gerald R. Ford-class to deploy this technology.^[17][18] The electromagnetic catapult is also installed on the upcoming Type 076 amphibious assault ship, enabling the ship to unmanned combat aerial vehicles (UCAV) and possibly manned carrier-based aircraft.^[19]

Fujian began sea trials in May 2024.^[20] By May 2025, she had completed eight sea trials, including takeoff and landing tests with J-15T heavy multirole fighters, J-35 stealth fighters and KJ-600 AEW&C aircraft.^[21] In August 2025, Chinese media released a video teasing the launch of the Shenyang J-15T variant on the Fujian with electromagnetic catapults. Though no complete sequence of the take-off and recovery was shown,^[22] analysts believed the carrier and its air wing were reaching an important milestone.^[23]

On 22 September 2025, the Chinese state broadcaster released multiple videos and photos — suspected to be from a sea trial earlier in the year — showing the complete catapult launch and arrestor recovery (CATOBAR) sequence for J-15T, J-35 and KJ-600 aircraft on the Fujian.^[22] PLA Navy also announced that Fujian had achieved "initial full-deck operational capability", laying the foundation for the subsequent integration with the carrier aviation wing and the carrier battle group.^[24] The EMALS of Fujiyan is powered by a Medium-Voltage Direct Current (MVDC) integrated power system—the first of its kind in the world, which is more reliable compared to the AC-based EMLAS of the Gerald R. Ford-class.^[25]

The planned Type 004 aircraft carrier, a suspected nuclear-powered supercarrier^[26][27] currently in construction at the Dalian Shipyard since 2024,^[28] will almost certainly be also equipped with electromagnetic catapults due to the success of the system on Fujian.^[29]

Russia

Russia's United Shipbuilding Corporation (USC) is developing new launch systems for warplanes based on aircraft carriers, USC President Alexei Rakhmanov told TASS on 4 July 2018.^[30]

United States

General Atomics EMALS was designed for and into the Gerald R. Ford-class aircraft carrier.^[31] A proposal to retrofit it into Nimitz-class carriers was rejected. John Schank said: "The biggest problems facing the Nimitz class are the limited electrical power generation capability and the upgrade-driven increase in ship weight and erosion of the center-of-gravity margin needed to maintain ship stability."^[32]

India

In 2013, the Indian Navy reportedly sought to equip the aircraft carrier with electromagnetic catapult, which could enable the launching of larger aircraft as well as unmanned combat aerial vehicles.^[33] Though, it was initially planned to be imported from foreign firms for INS Vishal, reports as of 2024 suggests, it is being developed indigenously by Bharat Electronics with assistance from private sector companies. The system concept has been demonstrated to senior Indian Navy officials and Minister of Defence. The Navy plans to gain clearance for construction of ground-based full scale model to initiate development.^[34]

In August 2024, Research & Development Establishment (Engineers) has developed a scaled-down prototype capable of launching payloads up to 400 kg over a short span of 16 to 18 meters. Two technologies successfully developed for the electromagnetic catapult were Pulse Power, which controls the electromagnetic catapult's power requirements and ensures precise and dependable launches, and Linear Electric Machine, which produces the electromagnetic force required to launch aircraft.^{[35][36][37][38]}

Ships with electromagnetic catapult

United States

• Gerald R. Ford-class aircraft carrier (in service)^[39]

China

• Chinese aircraft carrier Fujian^[39] (undergoing sea trials)
• Type 076 landing helicopter dock^[40] (launched)
• Type 004 aircraft carrier (under construction)

France

• Future French aircraft carrier (planned)

Russia

• Project 23000 (proposed)

India

• INS Vishal (proposed)

See also

• Coilgun
• Railgun
• Mass driver
• Modern United States Navy carrier air operations
• Naval aviation