Rumoured "mini-nuke/diesel" Submarine SSK-N(?) thread

[Maikeru]

I've reconsidered my view on the rumoured "mini-nuke". I had thought that if you were going to incur all the penalties of having a reactor then you might as well go the whole hog and just have a pure Rubis-size SSN. However, I hadn't factored in that SSK's are inherently quieter on batteries than SSNs, and the only way to really mitigate this is going for a much larger hull on the SSN. In that case the hybrid SSK/N makes sense, swap out the Stirling engine/fuel cells for a reactor and hey presto, you've got a very high endurance SSK which retains the silence advantage of running on batteries in a (reasonably) small hull. Of course there's still a cost downside. Anyway, we still await some kind of evidence that this concept even exists in PLAN.

 

[ACuriousPLAFan]

Some new updates on the "mini-nuke" SSK-N.

https://twitter.com/i/web/status/1775812769058824199

https://twitter.com/i/web/status/1775814051098182075

https://twitter.com/i/web/status/1775815611639296301

Roughly translated:

Based on the information available, it is estimated that the 1st batch of "mini-nuke" SSK-N boats will use a small nuclear reactor heat source + 4x 320 kW Stirling engine with a total power of 1715 shp, with a top speed of about 14 knots when the underwater displacement is 2500 tons, and the noise in this state is still very small, basically achieving a high tactical silent speed. Except for the top speed which is not comparable to the regular nuclear submarines, other tactical indicators are completely comparable, even beating other conventional submarines currently in service around the world.

If a Stirling engine with a power output of 1 MW is developed in the future, four such units can push a "mini-nuke" SSK-N boat with an underwater displacement of 2,500 tons to a top speed of 21 knots, or a sustained top speed of 20 knots by increasing the underwater displacement to 3,100 tons.

Note: The above-mentioned "top speed" refers to the top speed that does not rely on air and does not use batteries. If battery discharge and electric motor output are added, the short-duration top speed can be increased to 20 or even 25 knots.

At present, the 1st batch "mini-nuke" SSK-N is rumored to consist of two boats. According to @伏尔戈星图 on Weibo, the production line procurement of the "04X submarines" (notional designation of the "mini-nuke" SSK-N) has also been accelerated.

 

[Maikeru]

Some new updates on the "mini-nuke" SSK-N.

https://twitter.com/i/web/status/1775812769058824199

https://twitter.com/i/web/status/1775814051098182075

https://twitter.com/i/web/status/1775815611639296301

Roughly translated:




At present, the 1st batch "mini-nuke" SSK-N is rumored to consist of two boats. According to @伏尔戈星图 on Weibo, the production line procurement of the "04X submarines" (notional designation of the "mini-nuke" SSK-N) has also been accelerated.

OK so basically the reactor replaces the diesel engine, but why still the need for Sterling engines in that case? Why not just replace the lot? With a Sterling engine you still need to lug around the O2 for it. You can still have a battery for high-speed dashes.

Also, where are these being built? Wuchang?

 

[ACuriousPLAFan]

Also, where are these being built? Wuchang?

(Mostly) said to be at Jiangnan, bit I doubt that Wuchang would be left out of this.

 

[Moonscape]

OK so basically the reactor replaces the diesel engine, but why still the need for Sterling engines in that case? Why not just replace the lot? With a Sterling engine you still need to lug around the O2 for it. You can still have a battery for high-speed dashes.

Because a nuclear reactor by itself only produces thermal energy, and you need to turn the heat into a more useful form of energy. Most of the time, you use a steam turbine to turn thermal energy into rotational energy, which can then be used to turn a generator or propellor.

In this proposal, the reactor is being used as the heat source that powers the Sterling engine, probably because that's both quieter and requires less re-design. So the Sterling engine is taking the place of the steam turbine in a more typical SSN as the device that converts thermal energy from the nuclear reactor into rotational energy that can be used to generate electricity and power the propeller.

 

[gelgoog]

OK so basically the reactor replaces the diesel engine, but why still the need for Sterling engines in that case? Why not just replace the lot? With a Sterling engine you still need to lug around the O2 for it. You can still have a battery for high-speed dashes.

You don't need oxygen to run a Stirling engine I think. You just need a heat source. One example of this is solar thermal Stirling generators. In the case of burning diesel you are using the oxygen to be able to combust it to get heat out.

My guess is this way the submarine can either run on nuclear power or use diesel as backup. Which means they don't need a backup diesel engine like all submarines have. Nuclear attack submarines typically have a steam turbine to convert nuclear generated heat into propulsion, and backup diesel generators. Maybe they think this way they can merge what would be the steam turbine and the diesel engine into a single unit.

Some new updates on the "mini-nuke" SSK-N.
" Based on the information available, it is estimated that the 1st batch of "mini-nuke" SSK-N boats will use a small nuclear reactor heat source + 4x 320 kW Stirling engine with a total power of 1715 shp, with a top speed of about 14 knots when the underwater displacement is 2500 tons, and the noise in this state is still very small, basically achieving a high tactical silent speed. Except for the top speed which is not comparable to the regular nuclear submarines, other tactical indicators are completely comparable, even beating other conventional submarines currently in service around the world."

That is god awful slow. Regular diesel subs can achieve 21 kn submerged.

 

[CrazyHorse]

You don't need oxygen to run a Stirling engine I think. You just need a heat source. One example of this is solar thermal Stirling generators. In the case of burning diesel you are using the oxygen to be able to combust it to get heat out.

My guess is this way the submarine can either run on nuclear power or use diesel as backup. Which means they don't need a backup diesel engine like all submarines have. Nuclear attack submarines typically have a steam turbine to convert nuclear generated heat into propulsion, and backup diesel generators. Maybe they think this way they can merge what would be the steam turbine and the diesel engine into a single unit.


That is god awful slow. Regular diesel subs can achieve 21 kn submerged.

Very slow, but I guess the longer loiter time available means they can sort of sit in a body of water and wait rather than sprint towards a target and then slow down when you need to be quiet.

 

[by78]

Some new updates on the "mini-nuke" SSK-N.

https://twitter.com/i/web/status/1775812769058824199

https://twitter.com/i/web/status/1775814051098182075

https://twitter.com/i/web/status/1775815611639296301

Roughly translated:




At present, the 1st batch "mini-nuke" SSK-N is rumored to consist of two boats. According to @伏尔戈星图 on Weibo, the production line procurement of the "04X submarines" (notional designation of the "mini-nuke" SSK-N) has also been accelerated.

Could you please stop embedding these long Twitter threads and instead provide a simple text link with your summary/translation instead? Or maybe put the embedded tweets in a quote so that the forum software can automatically truncate/hide the mile-long ugly tweet vomit. As it stands, the embedded formatting is just asinine.

 

[Jason_]

That is god awful slow. Regular diesel subs can achieve 21 kn submerged.

For like 10 hours on battery.

The SSKN could sustain 14 kn indefinitely. If it is equipped with a large battery as envisioned, it too can dash at 20+ kn for some time when needed.

 

[Gloire_bb]

For like 10 hours on battery.

That's quite optimistic for non-li ion boats