09III/09IV (093/094) Nuclear Submarine Thread


OppositeDay

Junior Member
Registered Member
After realizing I was fooled by Wikipedia (and perhaps some other sources) into thinking Chinese nuclear subs are all turbo-electric, I thought a bit more about explanations for the seeming delay apparent Huludao expansion and Type 09IIIB's construction.

As has already been discussed in this thread, one plausible explanation is that the delay was partially because PLAN wanted to wait a bit longer for better technology. If we look at the timeline of 09IIIB's construction, we see the construction began roughly the same time as Type 039C, if we account for that design approval process and construction should take longer for nuclear submarines. This matched timeline give credence to the theory that 09IIIB and 039C were waiting for some same technology.

In the 039C thread, I explained four new technologies 039C is potentially using
Lithium batteries and fuel cell AIP are irrelevant for nuclear submarine. The 2MW high speed PMSG is mated to diesel engines. So this left us with the 5MW permanent magnet marine propulsion motor. We know from official news reports that this motor was tested onboard of a submarine in Sanya in 2017. This is compatible with 09IIIB's development timeline. But is there a place for a 5MW PMM in a 6,000 - 7,000 ton nuclear submarine?

Well Shilao and crew claimed on multiple episodes of their podcast that 1) The design goal of Type 09V is for it be a state-of-the-art platform, like the J-20 of Chinese nuclear submarines. 2) Type 09V is still years away. 3) Type 09IIIB is a stopgap measure. but 4) nevertheless PLAN is satisfied with Type 09IIIB design and it will be produced in significant number.

We can expect Type 09V to be an IEPS nuclear submarine with pump-jet propulsion. What can be done with the Type 09IIIB to make it a satisfactory stopgap? Well, there's no space for IEPS unless PLAN's ready to accept lower top speed. Even turning the existing propulsion turbines to turbogenerators will probably take additional space, and the space saving from removing the mechanical transmission system is probably not enough. IEPS has its own complex power control system which is not space free either.

Well, what could be a stopgap between mechanical propulsion and IEPS? Hybrid propulsion, of course! All non-turboelectric nuclear submarines are already hybrid in a weak sense. They all have emergency/low speed electric motors. Soviet designs (Victor & Akula) have twin electric motors powering two small propellers. US designs, on the other hand, mount a small induction motor directly on the main shaft. This is where the new 5MW PMM comes in. I don't know what low speed electric motor configuration China uses, but PMMs are overall much smaller in size than induction motors of the same power and torque. I expect it won't take much additional space to replace 09IIIA's old low speed electric motor(s) with the 5MW PMM. Maybe it requires slightly lengthening the hull, or maybe not.

In the hybrid system, the 5MW PMM is mounted directly on the main shaft after the reduction gearbox, i.e. American-style. This is also the configuration of ABB's Permanent Magnet Shaft Generator. The PDF files on ABB's web page explain how it works
Please, Log in or Register to view URLs content!

To make this work 09IIIB will need less powerful propulsion turbines and more powerful generator turbines. This modification is probably space neutral. And given Chinese industry's advances since Type 09IIIA's turbines were designed, new turbine designs are desirable anyway.

In the new "real hybrid" propulsion system, the 5MW PMM can either assist the propulsion turbines in driving the propeller or drive the propeller on its own once the reduction gears on the main shaft are disengaged to decouple the PMM from the propulsion turbines. My completely unscientific guesstimate is 5MW is enough to drive Type 09IIIB to about 13 knots in this turbo-electric mode.

Oh, with the right control system the PMM can do the regenerative braking thing to help speeding down the propeller and recharge battery at the same time, so the submarine can decelerate faster.

Turbo-electric propulsion mode eliminates noise from propulsion turbines and mechanical transmission (esp. the reduction gears). If 09IIIB features new coolant pumps and turbogenerators that are quieter under low loads (quite possible given China's advances in computing power, electric machines design, material & manufacturing capabilities), 09IIIB can be fairly quiet in turbo-electric mode (still noisier than Type 039C obviously, but it can move faster in electric propulsion mode than 039C can in AIP mode for a much longer period of time).

The hybrid propulsion system I purposed is definitely technologically feasible as ABB is already offering something similar as off-the-shelf commercial product. We already have the 5MW PMM ready for use, all it takes is some power control magic, which is one of the things Ma Weiming's team is very good at. Given that a full electric propulsion system is out of question due to space constrain (unless PLAN is willing to settle for a much lower top speed), a 5MW electric + 15+MW mechanical hybrid propulsion system is a very good compromise between quietness and space. All enabled by the power/torque dense PMM technology and Ma Weiming team's work on IEPS.

In conclusion, if we accept the thesis that the 09IIIB's development timeline reflected PLAN decision to wait a bit longer for a better design, then I think the development in PMM is possibly what PLAN was waiting for. I don't think PLAN would mass produce some slightly tweaked Type 09IIIA in 2020s. I expect substantial improvements. But new reactor design takes a long time to develop and test. Full electric propulsion requires either significantly enlarged hull or significantly reduced top speed. Hybrid propulsion offers quieter performance at lower speed with minimal reduction in top speed, and it uses only publicly reported hardware that we know (or highly certain) to be ready.

Last I want to say a bit on the IEPS possibility. I suppose if PLAN's ready to accept an IEPS submarine with much lower top speed (say 22 knots), I can imagine a configuration where the reactor is connected to one 20MW or two 10MW turbogenerators to power three 5MW PMMs in series. We save space by installing less powerful turbines and removing the entire mechanical transmission and the original low speed electric motor, we then use the saved space to install three PMMs (IEPS's power equipment can be distributed to some other parts of the submarine). Maybe it's doable. Whether it's worth it depends on the reactor's noise curve and how much PLAN values top speed vs quietness at medium speed. The hybrid propulsion system is potentially a significant upgrade in low speed quietness with minimal drawback, the IEPS option involves serious tradeoffs (IEPS's trade-off in top speed could be less or nil if China has pump-jet ready for use, but we have no evidence for Chinese pump-jet).
 

Blitzo

Lieutenant General
Staff member
Super Moderator
Registered Member
After realizing I was fooled by Wikipedia (and perhaps some other sources) into thinking Chinese nuclear subs are all turbo-electric, I thought a bit more about explanations for the seeming delay apparent Huludao expansion and Type 09IIIB's construction.

I don't know why people think there is a "delay" in Huludao/Bohai's expansion and nuclear submarine production.

What exactly were people expecting, to view it as a "delay"?


---

Also, I do not understand why you think 09IIIB must feature a new type of propulsion compared to 09III/A variants and subvariants to see a meaningful advancement in capability or stealth.
 

davidau

Senior Member
Registered Member
I don't know why people think there is a "delay" in Huludao/Bohai's expansion and nuclear submarine production.

What exactly were people expecting, to view it as a "delay"?


---

Also, I do not understand why you think 09IIIB must feature a new type of propulsion compared to 09III/A variants and subvariants to see a meaningful advancement in capability or stealth.
May be just a natural progression to reduce acoustic signature and makes it morer deadly.
 

gelgoog

Brigadier
Registered Member
Having buildings finished, moving tooling in, training people, even with Chinese time, it takes a while.
We will see it happen eventually. Heck, we are still waiting for H-20 to come out, and that should not take any less than a new submarine class.

I think Xi needs to push the Russians into coughing up a nuclear submarine design for China or two. Kind of like what happened with other large programs which used Antonov, Kamov, whatever as a 3rd party design bureau. Just convince him to make Rubin or Malakhit design something for the PLAN. Just kick the whole thing up a notch. The Russians can't out build the US in terms of attack subs. That is for sure. Since only China can do it, I mean, only China has the money, the need to secure shipping lanes, and so on, just convince them.
 

tphuang

Brigadier
VIP Professional
Registered Member
reactor itself is not the main source of noise. It's all that stuff in the engine room. Which they should be able to make quieter just based on their improved precision tooling and machineries. I'm not sure why 093B needs pumpjet? It may make sense or may not. Really depends on the design goals. As for IEPS, we haven't even seen them putting it on any surface combatant using gas turbines. Hard to see them going to IEPS with nuclear power submarine first.
 

OppositeDay

Junior Member
Registered Member
I don't know why people think there is a "delay" in Huludao/Bohai's expansion and nuclear submarine production.

What exactly were people expecting, to view it as a "delay"?


---

Also, I do not understand why you think 09IIIB must feature a new type of propulsion compared to 09III/A variants and subvariants to see a meaningful advancement in capability or stealth.

Let's ignore the timeline of Huludao/09IIIB constructions as a data point from this discussion. And I'll concede that there could be enough advances in noise control/weapon/sonar/etc technologies for 09IIIB to be meaningfully more capable and quieter than 09IIIA.

Still, a (IMO) good case can be made that 09IIIB is likely to feature a hybrid system like what I've described. I'll format my argument as a checklist

1) Does this hybrid propulsion system, CONLAN (combined nuclear-electric and nuclear) with permanent magnet motors, offer significant benefits? YES.
It has potential to significantly lowers low-speed noise (by decoupling the mechanical transmission) and improves acceleration/deceleration and control.
My original suggested design can be further improved by removing all generator turbines and connect high speed PMSGs to the propulsion shaft directly after the propulsion turbines and before any gear. These shaft generators can switch to motor mode and draw power from the energy storage subsystem to provide additional torque during acceleration. The electric motor can switch to generator mode to provide regenerative braking during deceleration. Those control options are in addition to reactor power adjustments, which might take time even in a submarine reactor.
In the case of Type 09IIIB there are certainly variables that we don't know. In particular, we don't know type 09IIIB reactors' noise curve. Maybe the reactors are so noisy that reactor noises dominate every other source and noise reductions in other systems just don't matter. But even then, CONLAN with PMMs would still have significant advantages in acceleration and control.

2) Is this technologically feasible? YES
A primitive version of CONLAN already exists in every non-turboelectric nuclear submarine. ABB offers a similar system with PMM as commercial off-shelf product one can fit to any prime mover. A closely related system, DODLAG (combined diesel-electric and gas), is widely used in surface combatant design.

3) Is China capable of implementing such a system in time for Type 09IIIB? YES
The major hardware requirement (PMM of sufficient power) was tested in 2017, in time to fit into Type 09IIIB's development timeline. Required power control system is well within Chinese capability. The power grid on Type 003 is certainly far more sophisticated than what's needed for high performance version of CONLAN.

4) Is there a good explanation why such a system has not been implemented before despite its supposed advantages? YES
PMM is a significant technological breakthrough for high performance CONLAN with propellers because of PMM's torque density. It's claimed that some PMM design can offer up to 3 times the torque density of traditional induction motor. This means such a PMM can use 1/3 of space/weight to provide the same torque as an induction motor, and space is scarce on submarines. High torque is essential for driving propeller with any acceptable acceleration/deceleration rates. The first (conventional) submarine with PMM (Type 212A) only started construction in late 1990s. But by then all leading operators of nuclear submarines have moved to pump-jet. Pump-jets are less efficient at lower speed (slower turbo-electric mode) and uses impellers driven by high-speed source, removing the reduction gearbox and its associated noises (far less benefits from turbo-electric mode). PLAN at present (2022) has demonstrated PMM of required power and has yet to demonstrate pump-jet technology for nuclear submarines. It's in a very unique situation.

5) Is the technology easy to implement in an upgrade of an existing design? YES
All major changes are in the propulsion part. No change to the reactor is needed. The coolant loop stays untorched. Only major changes are made to the steam loop, the transmission and the emergency motor. They are all in the section between the reactor and the tail. I'm no engineer but I think the system can be designed to not require additional space. It might even be possible to retrofit the system to existing Type 09IIIAs without touching the reactor.

6) Is there any direct evidence suggesting PLAN is looking into such a system? NO, but...
We know from official reports a PMM is tested on a submarine in Sanya, but it's probably a conventional submarine. There's no official source (that I'm aware of) stating PLAN is looking into a high performance CONLAN system. However, PLAN acquired this new PMM technology, and if they were considering to apply this technology to their nuclear submarines, what I suggested (or a more sophisticated version of it) would be a very obvious option. I cannot imagine that such a system has not been proposed by someone to PLAN (assuming no pump-jet).

7) Are there influential people who might back such a design? YES
Ma Weiming obviously has huge influence. He convinced PLAN to go directly to EMALS, after all. He's also big on electric propulsion. His team works on this very area. I bet he will support this or a even better hybrid propulsion system if full electric propulsion is ruled out, assuming 09IIIB still uses propellers.

For all those reasons I have listed, I think there's a good chance 09IIIB could feature a system similar to or better tan what I've described. As long as there's no pump-jet...
 

Blitzo

Lieutenant General
Staff member
Super Moderator
Registered Member
Let's ignore the timeline of Huludao/09IIIB constructions as a data point from this discussion. And I'll concede that there could be enough advances in noise control/weapon/sonar/etc technologies for 09IIIB to be meaningfully more capable and quieter than 09IIIA.

Still, a (IMO) good case can be made that 09IIIB is likely to feature a hybrid system like what I've described. I'll format my argument as a checklist

1) Does this hybrid propulsion system, CONLAN (combined nuclear-electric and nuclear) with permanent magnet motors, offer significant benefits? YES.
It has potential to significantly lowers low-speed noise (by decoupling the mechanical transmission) and improves acceleration/deceleration and control.
My original suggested design can be further improved by removing all generator turbines and connect high speed PMSGs to the propulsion shaft directly after the propulsion turbines and before any gear. These shaft generators can switch to motor mode and draw power from the energy storage subsystem to provide additional torque during acceleration. The electric motor can switch to generator mode to provide regenerative braking during deceleration. Those control options are in addition to reactor power adjustments, which might take time even in a submarine reactor.
In the case of Type 09IIIB there are certainly variables that we don't know. In particular, we don't know type 09IIIB reactors' noise curve. Maybe the reactors are so noisy that reactor noises dominate every other source and noise reductions in other systems just don't matter. But even then, CONLAN with PMMs would still have significant advantages in acceleration and control.

2) Is this technologically feasible? YES
A primitive version of CONLAN already exists in every non-turboelectric nuclear submarine. ABB offers a similar system with PMM as commercial off-shelf product one can fit to any prime mover. A closely related system, DODLAG (combined diesel-electric and gas), is widely used in surface combatant design.

3) Is China capable of implementing such a system in time for Type 09IIIB? YES
The major hardware requirement (PMM of sufficient power) was tested in 2017, in time to fit into Type 09IIIB's development timeline. Required power control system is well within Chinese capability. The power grid on Type 003 is certainly far more sophisticated than what's needed for high performance version of CONLAN.

4) Is there a good explanation why such a system has not been implemented before despite its supposed advantages? YES
PMM is a significant technological breakthrough for high performance CONLAN with propellers because of PMM's torque density. It's claimed that some PMM design can offer up to 3 times the torque density of traditional induction motor. This means such a PMM can use 1/3 of space/weight to provide the same torque as an induction motor, and space is scarce on submarines. High torque is essential for driving propeller with any acceptable acceleration/deceleration rates. The first (conventional) submarine with PMM (Type 212A) only started construction in late 1990s. But by then all leading operators of nuclear submarines have moved to pump-jet. Pump-jets are less efficient at lower speed (slower turbo-electric mode) and uses impellers driven by high-speed source, removing the reduction gearbox and its associated noises (far less benefits from turbo-electric mode). PLAN at present (2022) has demonstrated PMM of required power and has yet to demonstrate pump-jet technology for nuclear submarines. It's in a very unique situation.

5) Is the technology easy to implement in an upgrade of an existing design? YES
All major changes are in the propulsion part. No change to the reactor is needed. The coolant loop stays untorched. Only major changes are made to the steam loop, the transmission and the emergency motor. They are all in the section between the reactor and the tail. I'm no engineer but I think the system can be designed to not require additional space. It might even be possible to retrofit the system to existing Type 09IIIAs without touching the reactor.

6) Is there any direct evidence suggesting PLAN is looking into such a system? NO, but...
We know from official reports a PMM is tested on a submarine in Sanya, but it's probably a conventional submarine. There's no official source (that I'm aware of) stating PLAN is looking into a high performance CONLAN system. However, PLAN acquired this new PMM technology, and if they were considering to apply this technology to their nuclear submarines, what I suggested (or a more sophisticated version of it) would be a very obvious option. I cannot imagine that such a system has not been proposed by someone to PLAN (assuming no pump-jet).

7) Are there influential people who might back such a design? YES
Ma Weiming obviously has huge influence. He convinced PLAN to go directly to EMALS, after all. He's also big on electric propulsion. His team works on this very area. I bet he will support this or a even better hybrid propulsion system if full electric propulsion is ruled out, assuming 09IIIB still uses propellers.

For all those reasons I have listed, I think there's a good chance 09IIIB could feature a system similar to or better tan what I've described. As long as there's no pump-jet...

Thanks for your reply.

Your thoughts are fairly reasoned, but the underlying question that I am contesting, is what you wrote is in your previous post, here:
"What can be done with the Type 09IIIB to make it a satisfactory stopgap? Well, there's no space for IEPS unless PLAN's ready to accept lower top speed. Even turning the existing propulsion turbines to turbogenerators will probably take additional space, and the space saving from removing the mechanical transmission system is probably not enough. IEPS has its own complex power control system which is not space free either.

Well, what could be a stopgap between mechanical propulsion and IEPS? Hybrid propulsion, of course!"

Specifically, you are speculating as to what the meaning of 09IIIB being a "satisfactory stopgap" for the PLAN could mean prior to 09V.

Now, I have no issue with speculation, but for the purposes of PLA watching, our speculation needs to be guided by rumours.


Your arguments are essentially resting on the two premises that:
1. 09IIIB is meant to have sufficiently capable performance (relative to the even more superior 09V), thus it should involve the configuration of its propulsion system, and
2. A hybrid propulsion system is technologically feasible and potentially operationally viable and beneficial.

All that these two premises allow us to conclude, is: "we cannot rule out that among the 09IIIB's various improvements, it may include an improvement to configuration of its propulsion system, and we cannot rule out that of the various types of improvements that could have been implemented, a hybrid system is not impossible".


However, there are many -- frankly innumerable -- potential applications of technology, projects, upgrades and systems that could be developed and procured simply on the basis of something being technologically feasible and potentially operationally viable and beneficial.

However whether a military ultimately implements or procures something, ultimately is dependent, well... on the military.


In the case of PLA watching, for a new project/aircraft/submarine class that is well underway in development (if not already had its lead boat launched earlier this year as has been heavily speculated, for the 09IIIB) -- our speculation has to be guided by credible rumours or credible indications. Without credible rumours or indicators to guide us, then we are left with speculating about what is "technically applicable" rather than what is "likely occurring".


So, my reply to you is:
At best, we can argue that a hybrid nuclear propulsion configuration may be a technically applicable upgrade -- among many other hypothetical, technologically feasible and useful upgrades to 09IIIB compared to its predecessors.
But at the current point in time, there are no credible rumours or indications that 09IIIB features a hybrid nuclear propulsion system.
 

sunnymaxi

Junior Member
Registered Member
Having buildings finished, moving tooling in, training people, even with Chinese time, it takes a while.
We will see it happen eventually. Heck, we are still waiting for H-20 to come out, and that should not take any less than a new submarine class.

I think Xi needs to push the Russians into coughing up a nuclear submarine design for China or two. Kind of like what happened with other large programs which used Antonov, Kamov, whatever as a 3rd party design bureau. Just convince him to make Rubin or Malakhit design something for the PLAN. Just kick the whole thing up a notch. The Russians can't out build the US in terms of attack subs. That is for sure. Since only China can do it, I mean, only China has the money, the need to secure shipping lanes, and so on, just convince them.
you are so innocent. do you think Russian will provide China their nuke submarine design or help China.

neither Russia will help nor China need any kind of help from Russia. you gave examples how Antonov, Kamov helped China. but time has changed man. do you seriously think China need any Russian technology in 2022. LOOL

did Russian help China to design type 095/type 096 submarines ? its purely domestic design.
 

OppositeDay

Junior Member
Registered Member
Thanks for your reply.

Your thoughts are fairly reasoned, but the underlying question that I am contesting, is what you wrote is in your previous post, here:
"What can be done with the Type 09IIIB to make it a satisfactory stopgap? Well, there's no space for IEPS unless PLAN's ready to accept lower top speed. Even turning the existing propulsion turbines to turbogenerators will probably take additional space, and the space saving from removing the mechanical transmission system is probably not enough. IEPS has its own complex power control system which is not space free either.

Well, what could be a stopgap between mechanical propulsion and IEPS? Hybrid propulsion, of course!"

Specifically, you are speculating as to what the meaning of 09IIIB being a "satisfactory stopgap" for the PLAN could mean prior to 09V.

Now, I have no issue with speculation, but for the purposes of PLA watching, our speculation needs to be guided by rumours.


Your arguments are essentially resting on the two premises that:
1. 09IIIB is meant to have sufficiently capable performance (relative to the even more superior 09V), thus it should involve the configuration of its propulsion system, and
2. A hybrid propulsion system is technologically feasible and potentially operationally viable and beneficial.

All that these two premises allow us to conclude, is: "we cannot rule out that among the 09IIIB's various improvements, it may include an improvement to configuration of its propulsion system, and we cannot rule out that of the various types of improvements that could have been implemented, a hybrid system is not impossible".


However, there are many -- frankly innumerable -- potential applications of technology, projects, upgrades and systems that could be developed and procured simply on the basis of something being technologically feasible and potentially operationally viable and beneficial.

However whether a military ultimately implements or procures something, ultimately is dependent, well... on the military.


In the case of PLA watching, for a new project/aircraft/submarine class that is well underway in development (if not already had its lead boat launched earlier this year as has been heavily speculated, for the 09IIIB) -- our speculation has to be guided by credible rumours or credible indications. Without credible rumours or indicators to guide us, then we are left with speculating about what is "technically applicable" rather than what is "likely occurring".


So, my reply to you is:
At best, we can argue that a hybrid nuclear propulsion configuration may be a technically applicable upgrade -- among many other hypothetical, technologically feasible and useful upgrades to 09IIIB compared to its predecessors.
But at the current point in time, there are no credible rumours or indications that 09IIIB features a hybrid nuclear propulsion system.
Thank you for your reply. I agree there are general pitfalls of inductive reasoning which we should stay away from. In particular it's difficult to judge what are in the space of possibilities and what prior probability we should assign to each of them. Credible rumors/indications are certainly helpful in this regard.

But in this particular case, we have more than just credible rumor/indication that PLAN is considering using PMM in its nuclear submarines. Recall the official news release I was referring to
Please, Log in or Register to view URLs content!

I hadn't fully grasped what this news implied until now. Why would a group of engineers from CSSC 712th Institute, which is located in Wuhan, go to Sanya to test their new motor? Couldn't they test it on some submarine test platform right next door? The only explanation is they went to Sanya to retrofit it onto a submarine in the Yulin naval base. Indeed, the news release stated it was a case of "实艇安装", i.e. installation on a submarine that the motor was designed to be installed on. I had thought until now that the testing had to do with China's conventional submarine program. But of course no, the test of the PMM was done in Sanya! Yulin submarine base is a nuclear submarine base, which means that (drumroll) in 2017 a permanent magnet motor was retrofitted onto a in service PLAN nuclear submarine!

Now the report didn't give any specs of the PMM that was successfully tested. It could be some tiny 800kW emergency motor. But the only permanent magnet motor listed on CSSC 712th Institute website's product page is the 5MW propulsion PM motor. So it's reasonable to infer that the PMM retrofitted onto a nuclear submarine at Yulin naval base was a 5MW motor. The retrofit plan either turns the submarine's propulsion system into to a hybrid system or an IEPS, depending whether additional PMM would be installed to completely replace the propulsion turbine. I have already listed what I took to be the pros and cons of hybrid vs IEPS. We know from the news release that the PMM was used to drive a propeller, so no pump-jet. According to my layman's analysis, due to space constraint IEPS will likely require using small turbogenerators with significantly lower total power output and thus significantly lower top speed. Hybrid or IEPS depends on PLAN's performance requirements.

This new evidence (or corrected reading of old evidence) significantly increased my credence that 09IIIB features a hybrid propulsion system.
 
Last edited:

MarKoz81

Junior Member
Registered Member
Well Shilao and crew claimed on multiple episodes of their podcast that 1) The design goal of Type 09V is for it be a state-of-the-art platform, like the J-20 of Chinese nuclear submarines. 2) Type 09V is still years away. 3) Type 09IIIB is a stopgap measure. but 4) nevertheless PLAN is satisfied with Type 09IIIB design and it will be produced in significant number.

On that:

What can be done with the Type 09IIIB to make it a satisfactory stopgap?

This is not a question that can be meaningfully answered by technical solutions. Warfare is not a beauty contest. It's the ultimate test of practicality. Anyone who is not watching the war in Ukraine should start right now and pay attention to the numbers. The lessons of all basic principles warfare couldn't be better demonstrated.

Per 30-year shipbuilding plan from 2020:

USN will have 54 SSNs in 2030 and 64 in 2040.

Currently USN has 4 SSN688, 22 SSN688i, 3 SSN21 and 21 SSN774 (Bl. I-IV). So far including Bl.V only 38 Virginias have been ordered:
  • 4 Bl.I
  • 6 Bl.II
  • 8 Bl.III
  • 10 Bl.IV (3 in service)
  • 10 Bl.V
At current build rate of 1 sub per 3-4 years and comissioning of 2 new subs per year Block V won't be completed before 2030 which means 688i won't be retired until 2034 earliest if shipyards can deliver 3 SSNs per year, which is doubtful considering delays and issues with Columbia, refits with active submarines and supply chain issues for increased production.

Per zh.wikipedia.org:

typecommissionedretired (hypothetical - after 25 years service)
09III20062031
09III20082033
09III20122037
09IIIA (1st)20142039
09IIIA (6th)20182042

PLAN nominally has ~12 SSNs but practically only 6: 09IIIAs

What PLAN needs is a minimum of 12 09IIIB entering service before 2030 with minimum service life of 25 years. 18 SSNs (09IIIA and 09IIIB) will sufficiently absorb USN and RN submarine fleets in WestPac considering the distances required for regular operation.

An essential factor is that PLAN will have to expand its submarine force by a minimum of 20 SSNs in 2030-40 period and optimally 30 boats. That is a tremendous organizational effort which requires three capacities that don't exist in China at the moment:
  • mass production of submarines
  • ability to retain increased production rate and proportionally growing maintenance workload (USN hit that bottleneck recently)
  • ability to generate and train submarine and maintenance crews at higher rate
Those three can only be developed with a well understood design. This means that even if 09IIIB doesn't match Virginia's performance it is a necessary cost for PLAN to have an effective fleet of 09Vs in 2040s and 50s.

It took the USN ~20 years to build a fleet of 8 supercarriers (late 1960s) after WW2 but it was possible only because of 30 years of continuous service of carriers in the fleet.

You can build new 09Vs but you won't be able to use them to the best of their capacity. One average SSN with experienced crew and command is better than two great SSN with poor crews and command so you're cutting fleet capabilities by 50% by putting weapons before the warriors who will use them.

There's no better evidence for that than the failure of Soviet submarine fleet which never managed to match the USN level of competence because of constant radical changes to design and production method. Soviet submarines were also more expensive in relative terms (although you have to believe my word here, I can't find the historical data at the moment). USN maintained essentially the same general design throughout the Cold War which made it more economical for manufacturers, crews or support. Soviets had November, Alfa, Victor, Sierra and Akula - each with distinctly different requirements forcing everyone to re-learn everything (and on top of that Soviets used conscripts).

My completely unscientific guesstimate is 5MW is enough to drive Type 09IIIB to about 13 knots in this turbo-electric mode.

It doesn't need to be that high. Silence beats speed because of the mathematics of detection. Noise level is what matters.

Let's assume a sensor can detect a submarine moving at 5 knots at 10 km and a submarine moving at 20 knots at 40km.

5 knots and 20 knots are respectively ~220km and ~880km per day. The respective search area is ~152 000km2 and ~2 432 000km2.
Detection area for radius of 10km is 314 km2, for 40km it's 5024km2. Both scenarios require 484 sensors to search the area because the detection radius grows arithmetically.

But considering that due to physics of wave propagation it grows geometrically let's assume that subs moving at 20 knots can be detected at 60km with a detection zone of 11 300 km2. The number of sensors drops to ~216. At 80km the number drops to ~120 sensors etc. In reality the distances are greater because of how acoustic wave energy propagates in water.

Now the table
  • first column - target levels compared to own levels
  • second column minimum detection distance for passive sonar
  • third column - minimum detection distance for active sonar
For passive buoy own level is background noise (~90dB).

320px dystanse.jpg

Notional minimum noise level of Virginia is 110dB and of 688i is 125dB. At higher speeds those levels increase by as much as 20-30dB and more.

This means that at minimum noise buoy (own level 90dB) detects 688i (+35dB) at 31km and Virginia (+20) at 100m. At +20dB it detects 688i at 316km and Virginia at 10km. For levels approaching background noise you have to almost touch it to hear it.

Once PLAN SSNs reach certain noise threshold USN will have to shadow each of them because otherwise they will be extremely difficult to find - save some revolutionary breakthrough in science.

If 09IIIB is at 688i level but can reach Virginia levels or below with that electric motor it doesn't matter that it only moves at 5knots. There simply isn't enough buoys in a base to find it in one day. And every following day is geometric growth of search area. And so on. And then USN has to shadow each sub or it's impossible to find them.

Also I think by now 09IIIB can be below 688i levels simply due to technology available. SSN-751 was commissioned in 1988.

Also, I do not understand why you think 09IIIB must feature a new type of propulsion compared to 09III/A variants and subvariants to see a meaningful advancement in capability or stealth.

A pump-jet usually translates to 5-10dB reduction in noise. It also offers a flatter and smoother gradient of noise due to speed variance.

PLAN will have to adopt it sooner or later because of that even if now there are other considerations that make it impractical.
 

Top