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

[Blitzo]

Submarines pressure hulls are not tapered like this. You need a hemisphere capping each end of a cylinder. You also cannot easily use the space outside the pressure hull because they contain important things like sonar, ballast tanks, etc.

I am aware that the ends of the pressure hull are capped cylindrically -- as I wrote, it is intended to be a rather simple diagram done in like three minutes, to visualize the ability to change the pressure hull volume without actually increasing the maximal pressure hull diameter by extending the portion of the pressure hull length that has the existing maximal pressure hull diameter.
I'm also aware that the changes between the pressure hull sections are not actual 90 degrees as depicted but more gradual.

If we look at a depiction of a Soryu for example:




If I was to spend five minutes instead of three minutes on paint, it might look something more like this, below.
As I said, the details aren't as important as demonstrating the principle of increasing the volume inside the pressure hull (green line) without increasing the maximal pressure hull diameter, and instead just lengthening the proportion of the pressure hull which has the existing maximal pressure hull diameter.







As for the space between the pressure hull and the outer hull -- I agree, that space is important for various systems including sonar etc. However as the 09III family is a double hull submarine by design, they should have reserve buoyancy and volume to make up for it, particularly in context of miniaturization of key components, and accepting a lower (but still sufficient) reserve buoyancy.

 

[kwaigonegin]

So my point is that the utility of nuclear subs that's not horribly loud is quite apparent. It doesn't need to surface except maybe for short period of time to communicate with satellites every once in a while. It's really hard to find in the middle of a large water body because it can go sustained 20 knots+. Even going sustained 10 knots for stealth purposes is way harder to track than any diesel submarine. So inherently, it is an attack platform.

America has its Asian SOSUS, on the Japan side of things and quite a few subs there, but its coverage in South China Sea is much weaker just due to the infrastructure that PLA has built there. So, a 093B in the future can get into southern edges of SCS and then decide where to go. It can go to Indian Ocean, it can go to Pacific Islands. It can turn around and head to Hawaii. It can go to both side of Australia or even just go check out Darwin surroundings.

Once you have enough 093B in force, it's a huge game changer.

I agree. Even just a dozen++ new 093Bs in addition to current force level would shift the balance of power in the westpac in the foreseeable future.

 

[Jason_]

I am aware that the ends of the pressure hull are capped cylindrically -- as I wrote, it is intended to be a rather simple diagram done in like three minutes, to visualize the ability to change the pressure hull volume without actually increasing the maximal pressure hull diameter by extending the portion of the pressure hull length that has the existing maximal pressure hull diameter.
I'm also aware that the changes between the pressure hull sections are not actual 90 degrees as depicted but more gradual.

If we look at a depiction of a Soryu for example:
View attachment 146777



If I was to spend five minutes instead of three minutes on paint, it might look something more like this, below.
As I said, the details aren't as important as demonstrating the principle of increasing the volume inside the pressure hull (green line) without increasing the maximal pressure hull diameter, and instead just lengthening the proportion of the pressure hull which has the existing maximal pressure hull diameter.


View attachment 146778




As for the space between the pressure hull and the outer hull -- I agree, that space is important for various systems including sonar etc. However as the 09III family is a double hull submarine by design, they should have reserve buoyancy and volume to make up for it, particularly in context of miniaturization of key components, and accepting a lower (but still sufficient) reserve buoyancy.

I find it most likely that Chinese SSNs starting from at least the 09III already have a uniformly 9-10m pressure hull enclosed in a 10-11m outer hull throughout the length of the boat except for the non-pressurized bow and stern portions. Is there any indication that the 09III (or any modern SSN) have a tapered pressure hull?

 

[Blitzo]

I find it most likely that Chinese SSNs starting from at least the 09III already have a uniformly 9-10m pressure hull enclosed in a 10-11m outer hull throughout the length of the boat except for the non-pressurized bow and stern portions. Is there any indication that the 09III (or any modern SSN) have a tapered pressure hull?

I think that's a fair question -- the problem for us is we simply don't know.

What we do know is that there do exist the so called "hybrid hull" submarines which have a pressure hull which is wider in the central portion of the hull to an extent where it is single hull in that area, while having narrower pressure hull sections in the bow and aft which are double hull. (Soryu and Yasen being examples of these, and Yasen being an example of a modern SSN that utilizes a tapered pressure hull albeit in a hybrid configuration rather than a double hull configuration).

For 09III, we have no definitive evidence as to what its double hull geometry is like.
My idea for 09III having a tapered double hull geometry is partially based off this speculative art (I believe it was included in an ONI report of the late 90s), which of course is not viewed by myself as definitive by any means of the word, but if it did originally have such a geometry, it would offer opportunity for pressure hull volume increase without technically increasing the overall dimensions of the overall submarine or increasing the overall maximal pressure hull diameter either.

 

[antiterror13]

Do you guys think that 093B may have better Nuclear reactor? more compact and more power? so more internal space for other things

 

[para80]

Thats at least one of my theories and its IMO notionally possible a different reactor may have gone onto the A-boats already. But its all totally speculative.

 

[tphuang]

Do you guys think that 093B may have better Nuclear reactor? more compact and more power? so more internal space for other things

I think we have to assume that everything internally power and compute wise has gotten more compact in order to fit VLS section without notably increasing pressure hull dimensions by that much.
In addition to VLS section presence, one would imagine that greater automation allows for fewer crew members. So with the same cabin section & fewer people, you can theoretically do longer deployment and such.
Also, I do wonder about compute. My understanding is that a decent sized portion of modern Western SSN is dedicated for their computation servers and such.
But given the modern compute technology and cooling tech, it is entirely plausible PLAN can fit a similarly powerful platform in a much smaller real estate than before. Also given the efficiency gains, it would not use as much electric power.

And finally, I also wonder about nuclear electric. I could see that a change from nuclear to nuclear electric would reduce the number of parts needed and achieve space savings that way. But at this point, this is just me hoping they use something like that. I don't have any evidence in that direction.

 

[Jason_]

I think that's a fair question -- the problem for us is we simply don't know.

What we do know is that there do exist the so called "hybrid hull" submarines which have a pressure hull which is wider in the central portion of the hull to an extent where it is single hull in that area, while having narrower pressure hull sections in the bow and aft which are double hull. (Soryu and Yasen being examples of these, and Yasen being an example of a modern SSN that utilizes a tapered pressure hull albeit in a hybrid configuration rather than a double hull configuration).

For 09III, we have no definitive evidence as to what its double hull geometry is like.
My idea for 09III having a tapered double hull geometry is partially based off this speculative art (I believe it was included in an ONI report of the late 90s), which of course is not viewed by myself as definitive by any means of the word, but if it did originally have such a geometry, it would offer opportunity for pressure hull volume increase without technically increasing the overall dimensions of the overall submarine or increasing the overall maximal pressure hull diameter either.

View attachment 146790

The issue with this illustration is that the 09III clearly doesn't look like this. It looks more like

And you can quite easily visualize a constant diameter pressure hull going from in front of the sail and ending where the tapering starts.

I think you identified the only rationale to build a non-uniform pressure hull, which is to have a hybrid single-double hull configuration like Yasen and Soryu. There is no rationale to have two different diameter in a double-hull design. (Theoretically, tapering would also allows for the construction of a more hydrodynamically optimal boat with a tear-drop shape, but every navy abandoned the tear-drop in favor of the cylinder for simplicity and maximal pressurized volume. )

 

[Blitzo]

The issue with this illustration is that the 09III clearly doesn't look like this. It looks more like
View attachment 146812
And you can quite easily visualize a constant diameter pressure hull going from in front of the sail and ending where the tapering starts.

I think you identified the only rationale to build a non-uniform pressure hull, which is to have a hybrid single-double hull configuration like Yasen and Soryu. There is no rationale to have two different diameter in a double-hull design. (Theoretically, tapering would also allows for the construction of a more hydrodynamically optimal boat with a tear-drop shape, but every navy abandoned the tear-drop in favor of the cylinder for simplicity and maximal pressurized volume. )

The shape of the external hull doesn't necessarily have any relation to the internal pressure hull -- taken to the extreme for example, the Russian special mission submarine Losharik has a "continuous" external hull as well but its internal pressure hull is made up of connected spheres.

In the case of Yasen and Soryu, I see no reason why their configuration of variable pressure hull diameter geometry through their hull length is something that has to be consigned to a hybrid hull configuration.


That said, I am happy to agree that in the case of 09III family we simply don't know -- it is as possible that the internal pressure hull has always been more uniform in configuration from the outset... in which case the ability for the 09IIIB to have a greater pressure hull volume would be limited due to being unable to lengthen the maximal pressure hull diameter region outwards as I proposed, and due to the low likelihood of them actually increasing the maximal diameter of the pressure hull overall.