[Popular Science of Chinese Military Technology] How powerful is the electromagnetic catapult technology on aircraft carriers?

As we all know, the combat effectiveness of an aircraft carrier depends on various carrier-based aircraft, and the take-off capability and efficiency of carrier-based aircraft largely determine the combat capability of the aircraft carrier formation.

The "standard configuration" of future aircraft carriers

There are three main ways for carrier-based aircraft to take off, such as the rolling takeoff method, which directly accelerates on the raised deck at the end to gain lift to take off; the direct takeoff method, which uses the downward high-temperature and high-speed airflow to obtain the upward reaction force; and the catapult takeoff method, which uses the catapult to boost the aircraft to obtain a higher acceleration. Among them, catapult takeoff has the highest comprehensive performance and is currently widely used by various countries. In recent years, the electromagnetic catapult launch system (EMALS) has begun to emerge and is regarded as the "standard configuration" of future aircraft carriers.

The electromagnetic catapult system is a system that uses electrical energy to convert into magnetic energy and then into the kinetic energy required by the load to propel an object to a certain speed quickly. The linear motor is used as the power device of the electromagnetic catapult. The system inputs a strong current to make the coil generate a magnetic field, thereby giving energy to the "reciprocating vehicle" connected to the magnetic module to accelerate it and propel the fighter to take off.

The electromagnetic catapult system mainly includes linear motors, energy storage systems, control systems and power electronics systems. Among them, the energy storage system obtains and stores enough energy from the aircraft carrier's power distribution system within a certain period of time, and then releases it in a very short time. The power electronics system is used to control pulse discharge and thus control the linear motor. The control system comprehensively processes various information to ensure the normal operation of each device. These device systems work together to achieve the best catapult effect.

Electromagnetic catapult can greatly improve the combat effectiveness of aircraft carriers

The US military is a pioneer in the field of electromagnetic catapults. In the 1940s, the US Navy designed, manufactured and tested an electromagnetic aircraft catapult system using electromagnetic induction motor technology. However, due to the end of World War II and the high cost of the system, the project was cancelled. Later, in order to further verify the feasibility of electromagnetic catapult carrier-based aircraft, the US Navy restarted such research projects in 1982, and conducted electromagnetic catapult, braking and recovery, as well as system performance and electromagnetic radiation tests in 1988. In the 1990s, the US Navy proposed the concept of all-electric warships when designing the next generation of aircraft carriers (CVN-21). The most important technological innovation was the replacement of steam catapults with electromagnetic catapults. In the process of demonstrating the CVN-21 plan, it was officially determined to develop an electromagnetic aircraft catapult system for aircraft carriers.

Because the technical threshold of the electromagnetic catapult system is very high, currently, apart from the United States, only China has complete R&D and manufacturing capabilities. For example, China's second self-developed aircraft carrier, the Fujian, uses an electromagnetic catapult system.

Unique advantages of electromagnetic catapult

Compared with steam catapult, the advantages of electromagnetic catapult are more prominent.

First, the electromagnetic catapult has a wider energy range. The maximum energy range of the electromagnetic catapult is 20% higher than that of the steam catapult, which can take off heavy aircraft at a faster speed. Its fine and precise control enables it to simultaneously launch smaller and lighter aircraft (such as drones). There is no need to worry about excessive elastic force causing damage to the aircraft or too little elastic force preventing the aircraft from taking off, as when using a steam catapult. This allows aircraft carriers to carry more different aircraft models, greatly expanding the combat capabilities of active aircraft carriers. In addition, appropriate ejection force can also reduce the probability of pilots being injured during takeoff, which is very beneficial to maintaining the pilots' own health.

Currently, only China and the United States have mastered electromagnetic catapult technology.

Secondly, electromagnetic catapults improve the efficiency of carrier-based aircraft deployment. According to US statistics, if a large aircraft carrier is equipped with four steam catapults, it can usually launch up to 200 times a day, and if electromagnetic catapults are used, it can reach about 270 times a day.
At the same time, compared with steam catapults, the performance of electromagnetic catapults is more stable. Electromagnetic catapults have advanced feedback and closed-loop control systems, which can make the peak-to-average acceleration ratio of any catapult more constant and the aircraft's departure speed change range smaller. Moreover, if steam catapults are used, seawater must be converted into fresh water first, and then fresh water into steam, which has high operating costs, while the cost of using electricity for electromagnetic catapults is much lower.
In addition, compared with the steam catapult system, the electromagnetic catapult system is significantly lighter and smaller in size, reducing the need for a large amount of auxiliary equipment on the ship, such as hydraulic oil, fresh water and steam. The layout of each component is more flexible, which can maximize the optimization of the internal layout of the aircraft carrier, increase the flexibility of the aircraft carrier design, and potentially enhance the survivability of the aircraft carrier.

About the author: Lan Shunzheng specializes in research and theoretical writing on space strategy, military strategy, and international relations. While serving in the army, he edited and published his first military theory book, "Random Thoughts on National Defense by an Army Sergeant - Soldiers Going Out of the Frontier". While studying for a master's degree at the School of International Relations, he focused on space strategy. Now he often publishes related articles on online media and military magazines. In addition, his second monograph, "Zhenxing Dinghai - Building China's Future Space Military Strategy", has also been published.

Produced by: Science Popularization China

Producer: Guangming Online Science Department

Author: Lan Shunzheng (military science writer)

Scientific review: Fei Boyu (senior military content editor)

Planning: Jin He