Yuan Class AIP & Kilo Submarine Thread


OppositeDay

Junior Member
Registered Member
Thanks for your analysis. I discussed this with @FairAndUnbiased a while back on the possibility of different motor on 039C. To me, it makes no sense for them to declassify engine/AIP performance on 039B and take 4 more years to develop 039C. A while back, there was speculation that they'd use a mini nuke for 039C, but I don't think that happened here. Based on the shape of the mast, it seems like they want to reduce radar reflection, which could indicate their willingness to recharge frequently. That would only make sense if they were moving to lithium ion batteries (which China is very far ahead in). So, we speculated that they went with either pure LIB or fuel cell + LIB. Stirling AIP doesn't make sense for submarines built in 2020s. Here are things to think about.

I'm not aware of any drawback of the stealthy mast. If there's no drawback (other than development cost), then lower radar signature is a net positive and it doesn't imply an expectation of frequent recharges.

712th Institute does produce a lithium batteries system.
Please, Log in or Register to view URLs content!
1662267747756.png


Oh here's another thing I think Type 039C is likely using: permanent magnet synchronous generators. Here's a 2020 press release about a 2mW Chinese PMSG on a civilian ship
Please, Log in or Register to view URLs content!
1662270997685.png
2mW happens to be exactly the power output of the MTU 396V16 diesels engine on Type 039s, and a 2020 installation on a civilian ship also fits the timeline of Type 039C's development. Since PMSGs are much smaller, lighter, quieter and more efficient than traditional alternators, I consider it highly likely that Type 039C uses this technology. I won't rate it as almost certain because it's developed by CRRC, the high speed train maker, not CSSC.
The news release says the PMSG is compatible with four different diesel engines. My bet is on MTU 396V16 and CHD 620V16CR are two of the four. I don't know if Type 039C uses CHD 620V16CR, but using CHD620 would help Chinese SSK exports and contribute to future development of China's domestic diesel engines. 4 x MTU, 4 x CHD or a mix of 2 MTU and 2 CHD are all possible, I think. I bet if the first 039C uses all MTU there will be later ships with CHD. I think it's likely that China has offered a PMSG upgrade to the Thailand, perhaps even at no additional charge and that's why Thailand has indicted it's considering CHD620.

To sum up, potential new power/propulsion technologies on Type 039C
1. 5mW PMM: significant advantages (space and endurance, quietness, mobility - faster acceleration because PMM packs a lot of torque!), no drawback.
Evidence: development timeline, power rating, official news report, 712th Institute involvement.
My assessment: almost certain.

2. 140 kW x3 fuel cell AIP: significant advantages (space and/or endurance, quietness, mobility - higher output so charges the batteries faster), different safety tradeoffs compared to Stirling engine .
Evidence: development timeline, power rating, securities research report, 712th Institute involvement.
My assessment: almost certain.

3. Lithium batteries: significant advantages (space and/or endurance, mobility - faster charging and higher output) , safety drawbacks compared to lead acid.
Evidence: development timeline, 712th Institute involvement.
My assessment: likely.

4. 2mW x 4 PMSG: significant advantages (space and endurance, quietness, mobility - higher efficiency = higher output with the same prime mover = faster charging), no drawback.
Evidence: development timeline, power rating.
My assessment: highly likely.

If 039C ticks all four, it's on the cutting edge of conventional submarine propulsion.

The winding we are so used to in electric motors has been replaced by permanent magnets (PM). The Type 212 submarine (used by the German and Italian navies) and the Type 214 (used by Greece, Portugal, and South Korea), use the Siemens Permasyn PM Motor. This motor, says Jurgen Rohweder, “has particularly low vibrations and emits little heat and noise, which together further contribute to a submarine’s undetectability.”
Here's a real-life story. My parents' place uses Xiaomi's smart home ecosystem, I use Huawei's HiLink. I bought two smart fans for the recent heat wave, one from each ecosystem. Xiaomi's fan has VFD controlled PMM and my HiLink fan has VFD controlled induction motor. The difference in noise levels at the lowest fan speed (where the fan blades move slowly and motor noises dominate) is just night and day. Noise from the PMM is completely imperceivable for me and I hear the induction motor from a meter away.
 

tphuang

Brigadier
VIP Professional
Registered Member
I'm not aware of any drawback of the stealthy mast. If there's no drawback (other than development cost), then lower radar signature is a net positive and it doesn't imply an expectation of frequent recharges.

712th Institute does produce a lithium batteries system.
Please, Log in or Register to view URLs content!
View attachment 96863


Oh here's another thing I think Type 039C is likely using: permanent magnet synchronous generators. Here's a 2020 press release about a 2mW Chinese PMSG on a civilian ship
Please, Log in or Register to view URLs content!
View attachment 96867
2mW happens to be exactly the power output of the MTU 396V16 diesels engine on Type 039s, and a 2020 installation on a civilian ship also fits the timeline of Type 039C's development. Since PMSGs are much smaller, lighter, quieter and more efficient than traditional alternators, I consider it highly likely that Type 039C uses this technology. I won't rate it as almost certain because it's developed by CRRC, the high speed train maker, not CSSC.
The news release says the PMSG is compatible with four different diesel engines. My bet is on MTU 396V16 and CHD 620V16CR are two of the four. I don't know if Type 039C uses CHD 620V16CR, but using CHD620 would help Chinese SSK exports and contribute to future development of China's domestic diesel engines. 4 x MTU, 4 x CHD or a mix of 2 MTU and 2 CHD are all possible, I think. I bet if the first 039C uses all MTU there will be later ships with CHD. I think it's likely that China has offered a PMSG upgrade to the Thailand, perhaps even at no additional charge and that's why Thailand has indicted it's considering CHD620.

To sum up, potential new power/propulsion technologies on Type 039C
1. 5mW PMM: significant advantages (space and endurance, quietness, mobility - faster acceleration because PMM packs a lot of torque!), no drawback.
Evidence: development timeline, power rating, official news report, 712th Institute involvement.
My assessment: almost certain.

2. 140 kW x3 fuel cell AIP: significant advantages (space and/or endurance, quietness, mobility - higher output so charges the batteries faster), different safety tradeoffs compared to Stirling engine .
Evidence: development timeline, power rating, securities research report, 712th Institute involvement.
My assessment: almost certain.

3. Lithium batteries: significant advantages (space and/or endurance, mobility - faster charging and higher output) , safety drawbacks compared to lead acid.
Evidence: development timeline, 712th Institute involvement.
My assessment: likely.

4. 2mW x 4 PMSG: significant advantages (space and endurance, quietness, mobility - higher efficiency = higher output with the same prime mover = faster charging), no drawback.
Evidence: development timeline, power rating.
My assessment: highly likely.

If 039C ticks all four, it's on the cutting edge of conventional submarine propulsion.


Here's a real-life story. My parents' place uses Xiaomi's smart home ecosystem, I use Huawei's HiLink. I bought two smart fans for the recent heat wave, one from each ecosystem. Xiaomi's fan has VFD controlled PMM and my HiLink fan has VFD controlled induction motor. The difference in noise levels at the lowest fan speed (where the fan blades move slowly and motor noises dominate) is just night and day. Noise from the PMM is completely imperceivable for me and I hear the induction motor from a meter away.

They don't need 712th Institute involvement in LIB. China leads the world in LIB technology. They have already put much larger battery packs on electric ships with IEP. We've also seen posters about "Winston" LIB that was advertised back in 2014 claiming to put 300 Kwh battery packs in Yuan class, but there hasn't been any evidence to corroborate with this. There is basically no reason to use LAB anymore.

It seems like PMM is quite likely at this point, which is likely the biggest noise level difference between 039B and 039C. In the future, it might make sense for them to build new ASW ships using PMM if they can develop larger sized motors.

Also, I don't see any reason for them to export PWM to Thailand. This would probably be considered too sensitive technology at the moment. They just declassified the entire 039B submarine performance when they offered it for export back a few years ago. It's unlikely they will do the same with their new submarine class.
 

OppositeDay

Junior Member
Registered Member
They don't need 712th Institute involvement in LIB. China leads the world in LIB technology. They have already put much larger battery packs on electric ships with IEP. We've also seen posters about "Winston" LIB that was advertised back in 2014 claiming to put 300 Kwh battery packs in Yuan class, but there hasn't been any evidence to corroborate with this. There is basically no reason to use LAB anymore.

It seems like PMM is quite likely at this point, which is likely the biggest noise level difference between 039B and 039C. In the future, it might make sense for them to build new ASW ships using PMM if they can develop larger sized motors.

Also, I don't see any reason for them to export PWM to Thailand. This would probably be considered too sensitive technology at the moment. They just declassified the entire 039B submarine performance when they offered it for export back a few years ago. It's unlikely they will do the same with their new submarine class.

712th Institute's work was on the enclosure. The battery packs are enclosed in an oxygen-free environment to prevent combustion and there is a heat control system to prevent one overheated unit from in turn overheating its neighbors.

I don't think PMSGs are particularly sensitive. They're located in the engine room with plenty of dampening applied. Just use a different engine room quieting design on domestic subs and they can't identify the signature. I don't think German subs' sonar signatures are compromised by MTU selling diesel engines to China.

If CHD620 is noisier than MTU396 then that's a reason for China to offer quieter alternators to offset noisier prime movers. Even if CHD620 is as quiet as MTU396, it's better both economically and geopolitically to get Thailand to alter the contract than letting Thailand cancel the order and demand compensation. Throwing in some alternator upgrades for free is probably cheaper than paying compensation for failing to fulfill the contract. Also China gets more money from selling CHD620s to Thailand than being a middleman for German made MTUs.
 

tphuang

Brigadier
VIP Professional
Registered Member
712th Institute's work was on the enclosure. The battery packs are enclosed in an oxygen-free environment to prevent combustion and there is a heat control system to prevent one overheated unit from in turn overheating its neighbors.

I don't think PMSGs are particularly sensitive. They're located in the engine room with plenty of dampening applied. Just use a different engine room quieting design on domestic subs and they can't identify the signature. I don't think German subs' sonar signatures are compromised by MTU selling diesel engines to China.

If CHD620 is noisier than MTU396 then that's a reason for China to offer quieter alternators to offset noisier prime movers. Even if CHD620 is as quiet as MTU396, it's better both economically and geopolitically to get Thailand to alter the contract than letting Thailand cancel the order and demand compensation. Throwing in some alternator upgrades for free is probably cheaper than paying compensation for failing to fulfill the contract. Also China gets more money from selling CHD620s to Thailand than being a middleman for German made MTUs.
in that case then, they are probably not using LFP technology. Because LFP wouldn't have those overheating issues.

As for Thailand, it's just very unusual for China to be exporting their latest technology, because they don't want those numbers to be released to Western military. If you think about it, the noise level of the motor that 039C uses wouldn't be something China want to be known since that would allow USN or JMSDF to find tactics around hunting down 039C.
 

OppositeDay

Junior Member
Registered Member
in that case then, they are probably not using LFP technology. Because LFP wouldn't have those overheating issues.

As for Thailand, it's just very unusual for China to be exporting their latest technology, because they don't want those numbers to be released to Western military. If you think about it, the noise level of the motor that 039C uses wouldn't be something China want to be known since that would allow USN or JMSDF to find tactics around hunting down 039C.

The motor is mechanically coupled to the propeller, you can't vibration isolate that. Alternators stay in vibration controlled engine room in the middle of the submarine.

Also you can't reliably deduce the noise characteristics of CSSC 712th Institute's 5MW PMM from CRRC's 2MW PMSG.

EDIT: just realized I used mW when I meant MW in all my earlier posts. As someone who made to math grad school without taking even a single university class in physics, I despise units.
 
Last edited:

tphuang

Brigadier
VIP Professional
Registered Member
The motor is mechanically coupled to the propeller, you can't vibration isolate that. Alternators stay in vibration controlled engine room in the middle of the submarine.

Also you can't reliably deduce the noise characteristics of CSSC 712th Institute's 5MW PMM from CRRC's 2MW PMSG.

EDIT: just realized I used mW when I meant MW in all my earlier posts. As someone who made to math grad school without taking even a single university class in physics, I despise units.
Again, there is no chance china will let something like this get exported to a country that has defense pact with America while it has just joined service with plan. Why is this so hard to understand?
 

OppositeDay

Junior Member
Registered Member
Again, there is no chance china will let something like this get exported to a country that has defense pact with America while it has just joined service with plan. Why is this so hard to understand?
Because non-nuclear power plants are not that sensitive. Germans not only sell but license their best diesel engines to China. South Korea uses the same MTU396 on their subs as China does. I bet Taiwan will also use MTU396 on their new domestic subs too. PLAN doesn't consider using a well-known MTU diesel as a risk, alternators have even smaller impact on noise than prime movers.

PMSG itself is not a sensitive technology. High tech yes, but not sensitive. Any billionaire who's not Russian can probably buy a 2MW PMSG from ABB or Siemens to power their yacht. It's not sonar or torpedo. It's widely available dual use technology.
 

tphuang

Brigadier
VIP Professional
Registered Member
Because non-nuclear power plants are not that sensitive. Germans not only sell but license their best diesel engines to China. South Korea uses the same MTU396 on their subs as China does. I bet Taiwan will also use MTU396 on their new domestic subs too. PLAN doesn't consider using a well-known MTU diesel as a risk, alternators have even smaller impact on noise than prime movers.

PMSG itself is not a sensitive technology. High tech yes, but not sensitive. Any billionaire who's not Russian can probably buy a 2MW PMSG from ABB or Siemens to power their yacht. It's not sonar or torpedo. It's widely available dual use technology.
I bet you if America can get close to the same PMM used on the latest PLAN diesel submarine, they would test the heck out of it. As a submarine that will likely be ambushing US carriers in SCS and west pacific, PLAN is going to keep things secret until it's close to being out of production. They did not release stiriling AIP details until they stopped 039B production. I will stop here.
 

OppositeDay

Junior Member
Registered Member
I bet you if America can get close to the same PMM used on the latest PLAN diesel submarine, they would test the heck out of it. As a submarine that will likely be ambushing US carriers in SCS and west pacific, PLAN is going to keep things secret until it's close to being out of production. They did not release stiriling AIP details until they stopped 039B production. I will stop here.

Yes but as I said the alternator in question are not even made by the same company as the motor (CRRC vs CSSC). If US can deduce performance info of CSSC's 5MW PMM from CRRC's 2MW PMSG, it can just buy Chinese wind turbines of every power rating and test every PMSG inside them.
 

Top