Can I postulate from this post that the US EMALS catapult suffers from fundamental design problems and any solutions would be a patch job? They would have to abandon this catapult and start all over?I was watching this.
At 4:07 it is said that US EMALS LIM (linear Induction Motor) has open magnetic circuit. So I re-read "Electromagnetic Aircraft Launch System - EMALS by Michael R. Doyle et al." And also found a research papers from China published in IEEE.
Here is the difference between the US EMALS and China's.
The difference is apparent that US EMALS has its magnetic field going outwards through the air to create a loop. China's magnetic field is almost closed except the gap where the carriage is inserted.
Here comes the interesting and important part, the EM interference of LIM to aircraft's and missiles' electronics. So I found another Chinese research paper on the subject from IEEE.
It means, from the gap within 2m working equipment need to be shielded. Within 5 meters equipment not shielded at all will be interfered. I think this means civilian grade equipment, not military grade which should always have some kind of shielding.
I remember an old topic about the EM interference of US EMALS which is troubling Ford class. The design difference above could be the fundamental cause. The Chinese approach has that small gap being the source of the EM leak. In the gap most magnetic flux reaches the other ends, only small portion leaks. Most of that gap is filled by the carriage blocking the leak. While in the American approach the saddle carriage only cover the top and side but leaving the bottom opened. The opening is much much larger than the gap. Also the carriage (as the LIM rotor) is always shorter than the excited stator coil winding. The exposed stator coils are totally free to emit EM field to the surrounding area. Even in the Chinese design, interference within 2m is unbearable that need shielding. One can imagine the much stronger interference in the US design and how difficult to deal with.
This again proves why Admiral Ma said that China is leading in the field. It also dismissed the notion "US can't so China must not".
Some other difference interesting but not necessarily related to the above.
US: 149 stator segments each 0.64m long. 8 poles per segment. Using Hall effect sensor to control the speed.
China: 24 stator segments each 4.07m long. 28 poles per segment. DSP analyzing the interference of stator current by the carriage to control the speed. Sensorless.