PLAN Catapult Development Thread, News, etc.


nlalyst

Junior Member
Registered Member
...
6. In the last highlight, you once again repeated a claim not backed up by an official document, while disregarding statements in two official documents.
Which one was that now? The 1kV threshold for high-voltage, as per USN? I mentioned my source for that. He's the same person who wrote the paragraph that you highlighted in red.
Nobody could be so patient to talk to a pretending deaf (that is you), if you do it once or twice I can accept you are making honest mistakes, but third and forth time, I take that you are being deliberate and trolling, what else do you expect?
You started patronizing me after my second post yesterday. Yes, I was wrong in my understanding of the MVDC definition (by 1V), but that's no justification. Now that I look back, you seem to have been tripped by the keyword 'rich'. That wasn't aimed at you, but at Gen Ma.

Because you are doing the following:
1. inserting an off topic subject (IEPS and MVDC) into the discussion of Catapult
But it's OK when you insert off-topic discussions and then go on dozens of posts off-topic in this very thread on exactly the same subject:
Finally the official evidence that USN is pursuing "MVDC" as well after PLAN has leapfrogged.
PLAN Catapult Development Thread, News, etc.
 
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taxiya

Brigadier
Registered Member
Which one was that now? The 1kV threshold for high-voltage, as per USN? I mentioned my source for that. He's the same person who wrote the paragraph that you highlighted in red.

You started patronizing me after my second post yesterday. Yes, I was wrong in my understanding of the MVDC definition (by 1V), but that's no justification. Now that I look back, you seem to have been tripped by the keyword 'rich'. That wasn't aimed at you, but at Gen Ma.


But it's OK when you insert off-topic discussions and then go on dozens of posts off-topic in this very thread on exactly the same subject:

PLAN Catapult Development Thread, News, etc.
Are you mocking yourself? 1kV is LVDC as per USN military standard. Did you even read the article I posted? Or are you trying to muddy the water by cycling and ignoring?

As "being rich" not aiming at me, but aiming at Gen Ma. That is even worse. I could make lots of mistakes in my statement, but Gen Ma is the lead scientist who is on par or ahead of the top scientists in the area all over the world. Calling Gen Ma "that's rich" by a person who has no education in the field, practical experience and decades of research background is plain ignorant and presumptuous. And that is the trigger to me patronizing you as you deserve.

Can you see that in your second sentence you are admitting being wrong of 1V (1KV) being MVDC defition? Then read your first sentence 1KV being high-voltage. See your problem? You don't dig into the details of document, not checking back and forth of what you are trying to present. And you don't have the gut to admit being wrong until someone begin to "patronize" you, then you behave like a victim.

Am I inserting off-topic? Or you insert then expect no rebuttal?

It is enough for me with you, I leave the whole stage to you, happy? :cool:
 

nlalyst

Junior Member
Registered Member
Are you mocking yourself? 1kV is LVDC as per USN military standard. Did you even read the article I posted? Or are you trying to muddy the water by cycling and ignoring?
AFAIK, that's not a standard yet. It's still in draft status and subject to change. According to the guy who you quoted, and who wrote the new draft standards, 1kV and above is considered high voltage by the USN. Here is a NAVSEA publication from 2020. MIL-STD 1399 is still referred to as the current interface:
1613330283700.png

As for Gen. Ma I am still waiting to see his MVDC solution on a commissioned PLAN vessel, before I can conclude that he indeed "leapfrogged", while others are making incremental steps in onboard DC grids both in commercial (Dina Star, 2013) and naval (Zumwalt, 2016) vessels.
 
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Higgle

Junior Member
Registered Member
Most of this is just semantics. Regardless of the classification of the voltage, the fact is that Zumwalt runs a 1kV grid and Chinese ships will run (at minimum) a 3kV grid.

Regarding the catapult competition, I doubt that they would bother testing AC versus DC. We've known that it would be DC for almost as long as we've known about the catapult itself. I also don't think it's worth looking too deeply into the speech. I watched the whole video and what he said about the steam catapult is pretty vague.

Taken in context, he was making the point that the steam catapult was invented decades ago, and the Ford is the first carrier to use EMALS which came with a ton of problems, whereas China went straight for the EM option because they could, and taking that into consideration, there was no reason to continue working on the steam catapult, which sounds like they ran into some difficulties on.

It still makes the most sense that they'd test it against a steam catapult. After all, steam is proven technology but the Ford showed that EMALS has all sorts of issues. There was no way the PLAN could have known that their own catapult wouldn't be plagued by problems too. So the only way to find out must have been to test Ma Weiming's EM technology against an existing technology as a baseline, and the only existing catapult technology in China was a half-developed steam design.

Had the steam catapult been successful and developed on-schedule, the 003 would be fitting them on at around this time. However, as we all know, EMALS was proven superior - maybe it simply performed better, or maybe they never got the steam catapult to work as intended, or both. But the only way they could know for sure was to test steam vs EMALS, not AC vs DC.
 

nlalyst

Junior Member
Registered Member
Most of this is just semantics. Regardless of the classification of the voltage, the fact is that Zumwalt runs a 1kV grid and Chinese ships will run (at minimum) a 3kV grid.

Regarding the catapult competition, I doubt that they would bother testing AC versus DC. We've known that it would be DC for almost as long as we've known about the catapult itself. I also don't think it's worth looking too deeply into the speech. I watched the whole video and what he said about the steam catapult is pretty vague.
What I am curious about is whether going DC was in any way predicated on availability of a MVDC grid solution and whether we will see the MVDC IPS grid debut on the Type 003.

According to a 2018 globaltimes article, Rear Admiral Ma's team developed a MVDC IPS grid back in 2003, a full 10 years ahead of foreign competition. Since that was written in retrospect, who owns the foreign MVDC IPS tech?
The team led by Ma has been recognized and awarded frequently in recent years. The team spent eight years developing the first double winding AC-DC generator system in the world in 2002, a core Chinese-developed technology with proprietary intellectual property rights.

A year later, the team created and successfully developed a medium voltage DC integrated power system, which was ahead of foreign technology by 10 years.

According to the article, his team developed yet another MVDC transmission network in 2017 "to replace the older alternating current system for the country's domestically built Type 002 carrier, which could provide more power for its electromagnetic aircraft launch system (EMALS)." Source:
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.
 
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taxiya

Brigadier
Registered Member
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.
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Here is the difference between the US EMALS and China's.

US.
The motor itself is a dual, vertical stator configuration with the active area facing outwards. The rotor, or carriage, sits over the stators much like a saddle

China.
Only the section of the coils surrounding the carriage is energized through the corresponding block switches at any given time
lu2-2416356-large.gif


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.

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it can be found that the radiation effect of the EMALS has a strong magnetic field intensity in the range of about 2m from the gap. People, handheld devices and low-lying equipment need to be protected. Although the attenuation is very fast, it is still very strong. At the distance of 5 m from the EMALS, these two harmonics still have a strong magnetic field about 263.5 uT, about 5 times the intensity of the geomagnetic field, which will cause greater interference to the instruments and equipment operating in the geomagnetic field.

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.
 
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latenlazy

Brigadier
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.
Please, Log in or Register to view URLs content!


Here is the difference between the US EMALS and China's.

US.


China.

lu2-2416356-large.gif


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.

Please, Log in or Register to view URLs content!



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.
So yeah, sounds like bad requirements leading to design oversights.
 

davidau

Junior Member
Registered Member
AFAIK, that's not a standard yet. It's still in draft status and subject to change. According to the guy who you quoted, and who wrote the new draft standards, 1kV and above is considered high voltage by the USN. Here is a NAVSEA publication from 2020. MIL-STD 1399 is still referred to as the current interface:
View attachment 68757

As for Gen. Ma I am still waiting to see his MVDC solution on a commissioned PLAN vessel, before I can conclude that he indeed "leapfrogged", while others are making incremental steps in onboard DC grids both in commercial (Dina Star, 2013) and naval (Zumwalt, 2016) vessels.
Have faith. China does not utter empty words! He will prove it in deeds.
 

Matheus S

New Member
Registered Member
I have a doubt.

Does the US EMALS have 4 rotors for each catapult or only 4 rotors for the 4 catapults? I couldn't find this information.
 

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