According to the South China Morning Post, China’s military industry has developed a new type of electromagnetic catapult equipment. The entire system has a simple structure, much smaller in size compared to conventional electromagnetic catapults. Moreover, a single set of equipment can simultaneously perform electromagnetic launching and electromagnetic arresting, with average fault-free operation time far exceeding that of the electromagnetic launching and arresting equipment on the Ford-class carriers. It’s simply genius design!
China has developed a new electric bullet technology! It’s massive and violent.
The South China Morning Post states that this electromagnetic catapult can accelerate a 30-ton aircraft from zero to 70 meters in just 2.1 seconds, which is shorter than the current conventional electromagnetic catapults that take 3 seconds to achieve the same speed with a 30-ton fighter jet. This indicates that this catapult has greater power, or it can easily launch heavier sixth-generation aircraft.
Additionally, this catapult is compact, with a simple structure, lightweight, and does not require a complex power supply system. This means it does not occupy valuable space on aircraft carriers, or it can be installed on smaller combat ships, such as amphibious assault ships. It could even be installed on smaller carriers, ranging from lightweight carriers of 20,000 to 30,000 tons to medium-sized carriers of 40,000 to 60,000 tons, according to demand.
The researchers, led by Associate Professor Ye from the School of Mechanical and Energy Engineering at Beijing University of Technology, published their paper in the domestic academic journal “Ordnance Industry Science and Technology.” Following this lead, I found a paper titled “Integrated Electromagnetic Catapult Device for Launching and Arresting XXXX,” which introduces the components of this catapult:
The device consists of key components such as a permanent magnet energy storage motor, an eddy current clutch, an eddy current brake, and a winding wheel. Based on Ampère’s circuital law, the electromagnetic theoretical models of the eddy current clutch and eddy current brake are established. There are two operating modes: electromagnetic launching mode, which assists in the takeoff of fighter jets, and arresting mode, which assists in landing. One device can achieve both functions simultaneously, which is quite excellent in design!
Takeoff catapult mode:
The core of this device is a flywheel energy storage system integrated with a motor and generator. Before launching, the flywheel needs to be “charged” by accelerating it to its rated speed using the motor and maintaining this speed. Since the space where the flywheel is located can be evacuated, the flywheel speed will not decay for a long time.
During launching, the flywheel motor uses the current output by the generator to provide excitation current to the excitation winding of the eddy current clutch, which, under the action of the eddy current force, outputs a downward rotational torque. The kinetic energy of the flywheel is transmitted to the winding wheel, rapidly tightening the steel cable to accelerate the aircraft gradually until it reaches the launch speed.
After the aircraft is launched, the eddy current clutch is de-energized, and the eddy current brakes on both sides are powered on to rapidly stop the rotation of the winding wheel. Then, the steel cable is reset to the takeoff position by the reset motor, completing one takeoff cycle.
Landing arresting mode:
During arresting, when the aircraft lands, it hooks the steel cable with its tail hook, driving the winding wheel to rotate rapidly. At this time, the eddy current clutch operates in braking mode, gradually decelerating the aircraft until it stops. After the arrest, the cable can be reset by the reset motor for the next arresting cycle, and this process can be repeated continuously.
The entire system’s structure is quite simple. However, there are some follow-up considerations, but the latter part of the article focuses extensively on the discussion of how large the flywheel should be, how much power the motor should have, how strong the electromagnets should be, and how much power input is required to meet operational requirements, etc. We are not interested in these details; the main focus is on the structural principles and stable operational performance.
Based on the principle description, this structure is very compact, with only one large and massive flywheel energy storage device integrated with a few meters long shaft. The overall diameter is only a few meters, and the length may be less than 10 meters. All of this is contained within this system. Although it may seem relatively large, for aircraft carriers with compartments hundreds of meters long and seventy to eighty meters wide, this is extremely convenient. You can just cram it into any available space.
Compared to conventional electromagnetic catapults: What are the advantages and disadvantages of this electric bullet?
You’re probably already murmuring, thinking that such a simple electromagnetic catapult system couldn’t have been overlooked by everyone, right? Why is everyone working on conventional electromagnetic catapult systems and not on this “integrated electromagnetic catapult device for launching and arresting”? Because compared to this integrated device, conventional electromagnetic catapults are indeed somewhat complex:
Currently, conventional electromagnetic catapult systems mainly fall into two categories. One is the electromagnetic catapult system used on the U.S. Ford-class carriers, and the other is the electromagnetic catapult system used on China’s Type 003 carrier, the Fujian ship. Both are typical electromagnetic systems, but they don’t differ much in their main structural principles. For instance, the electromagnetic system on the Ford-class carriers includes the following subsystems:
Prime Power Interface: The main power interface, which connects to the carrier’s power multi-power system, such as from the carrier’s power distribution system and gas turbine generator specially prepared for the electromagnetic catapult.
Launch Motor: Linear motor (launch motor), which converts electrical energy into mechanical energy for linear movement.
Power Conversion Electronics: Converts AC or DC power sources into controlled intermediate frequency power required by the system.
Launch Control: Controls the launching system’s feedback signals to control the launching acceleration of different weight and takeoff requirements of aircraft.
Energy Storage: Forced energy storage system. The electromagnetic catapult system has a very high short-term power, and the carrier’s power system cannot provide such high power. Therefore, only the energy storage system can temporarily store energy between launches.
Energy Distribution System: Distributes energy through cables, circuit breakers, etc., connecting power regulation subsystems and linear motor subsystems.
Advanced Arresting Gear (AAG) program: High-level electromagnetic arresting system, not included in the diagram above, used for arresting landing aircraft.
The principle is to use the power supply to charge the energy storage system before launching. Within an allowed launch cycle interval (approximately 40 to 50 seconds), it is fully charged, and then the power electronic conversion equipment is used to convert the power into a form that the linear motor can use, and the motor is started to drag the launching slide to launch the fighter jet. The feedback from the launch control adjusts and controls the output power, making the fighter jet take off smoothly. The comfort level of the pilot is several orders of magnitude higher than that of steam catapults, and it can be adjusted according to the weight of the launch.
This process is the same for both systems. The difference lies in the energy storage system, which has two main types: one uses flywheel energy storage, and
the other uses supercapacitors or lithium batteries for energy storage. The former has the advantage of strong maintainability, while the latter has the advantage of not requiring AC-DC conversion, being friendly to power sources, but has the disadvantages of larger volume and requiring higher-level maintenance.
Due to the existence of huge subsystems, the entire volume of conventional electromagnetic catapult systems can reach about 80% of that of steam catapults, which is about 400 cubic meters. Although it is much smaller than steam catapults, it is still very large. However, the integrated electromagnetic catapult device for launching and arresting has a very compact volume. The estimated volume is only about 1/5 to 1/10 of that of conventional electromagnetic catapults, which is undoubtedly a gospel for lightweight carriers or medium-sized carriers with limited compartment space.
Another advantage is the simple structure and low threshold. The major challenges of the entire system are the flywheel motor and the eddy current clutch. Compared with conventional electromagnetic catapults, it eliminates nearly 100 meters long linear motors and does not have the extremely demanding launch control and energy distribution systems. The subsystems are estimated to be only a fraction of those of conventional electromagnetic catapults, making it particularly suitable for countries like India, which urgently need electromagnetic systems but have insufficient carrier volume.
However, the integrated electromagnetic catapult device for launching and arresting also has its drawbacks. For example, it lacks a feedback control system. Because the subsystems only include motors driving the turntable to drive the steel cable, even if there is negative feedback, precise adjustment of the launch speed is difficult. This results in a feeling of dizziness or acceleration stagger for the pilots. This feeling is not very pleasant, and it is also difficult to achieve smooth transitions for aircraft of different sizes and tonnages during launch. This problem is likely to be challenging to solve unless the launch mode is changed to use linear motors, which can adjust and feedback the system in real-time. However, this will significantly increase the complexity of the structure.
This structure is very suitable for solving whether there is a problem. As mentioned earlier, amphibious assault ships are very suitable for this system. According to rumors, China’s new amphibious assault ship only has one catapult. If this compact but slightly less adjustable catapult is used, two units can be installed to ensure that one can still maintain a high frequency of carrier-based aircraft takeoffs in the event of a failure, which is combat effectiveness in wartime. Sometimes performance is essential, but sometimes ensuring more quantity under certain performance is more advantageous.
There are also rumors that the failure rate of the electromagnetic catapult on the Ford-class carrier is too high, with one major maintenance process required every 614 launches, which is far from the U.S. military’s requirement for 4000 launches before major maintenance. Another problem is the arresting system, with a failure rate as high as one failure every 46 landings. Even if this integrated electromagnetic catapult device for launching and arresting is used as a backup or as a separate arresting system, it is still cost-effective.
Finally, let’s briefly discuss the “charging system.” The charging power source type of this integrated electromagnetic catapult device for launching and arresting should be similar to that of conventional electromagnetic catapult systems, after all, the launch requirements are similar, and the charging interval is also similar. Therefore, the charging system should also require a relatively high-power power source. However, compared to conventional electromagnetic catapult systems, the efficiency of the linear motors used for launching is slightly lower. Therefore, the generator used as the charging power source for this integrated electromagnetic catapult device can be slightly smaller than that for conventional electromagnetic catapult systems. For example, 1 to 2 small gas turbines can provide redundant power for it.
This electromagnetic catapult method is not entirely considered electromagnetic catapults but rather a variant that directly uses mechanical energy from flywheel energy storage. It eliminates the energy conversion process, which has its advantages, as the conversion efficiency will be very high! As for the disadvantages, as mentioned earlier, it lacks adjustability. It can solve the question of whether it exists but not guarantee its quality. Further improvements can be made to strive for its application on future amphibious assault ships. (Xing Chen)
