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How many test subs do they need? They already had the sail-less sub to test single hull design and (probably) new propulsion.

tphuang said:

What?
Single hull design is not advanced? blended sail is not advanced? If anything, this is the most advanced submarine design I have ever seen out of China. Due to its size, it's not that capable. Calling it not advanced would be grossly overestimating China's current fleet of submarines.

I see this as an experimental project to test out these new concepts, before moving on to the next generation SSK and SSN. Those should all be single hulled with more modern sail and propulsion.

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What's wrong with double hull? There's some valid reasons to go with double hull such as the ability to customize the hydrodynamic shape, mounting equipment without creating new hydrodynamic noise sources or differential stresses (from an uneven weld or fastener hole) on the pressure hull, etc.

Would love to see a larger version in service. Looks incredibly futuristic, even more so than the 039c

FairAndUnbiased said:

What's wrong with double hull? There's some valid reasons to go with double hull such as the ability to customize the hydrodynamic shape, mounting equipment without creating new hydrodynamic noise sources or differential stresses (from an uneven weld or fastener hole) on the pressure hull, etc.

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All the noise isolation equipment have to be done inside the pressurized hull. In submarine world, the wider the pressurized hull is, the more space you have to install noise isolation technology. So generally speaking, if you generate the same amount of noise inside a submarine, the larger the pressurized hull is, the quieter it will be for the outside world. That's why the Akula and seawolf are huge.

When you go with double hull, you have to build a larger submarine in order to have the same space inside as a single hull. Which adds requirement to the engine, turbine generators and reduction gears to be able to move as fast. That's why you see the Russians going to single hull with Lada class and why Lada has a shorter beam than Kilo class. And why all the advanced Western subs are single hull.

For something as small as this new boat, you pretty much have to do single hull. As long as its power generation requirements are low and it can run on battery, it can probably be very quiet in littoral waters. It's definitely not going to move fast though.

To a layman like me a single hulled submarine just seems crazy, it feels as if any tiny bump or hole could cause the entire tube to implode, though that's probably not the case since western submarines have switched to single hulled

sndef888 said:

To a layman like me a single hulled submarine just seems crazy, it feels as if any tiny bump or hole could cause the entire tube to implode, though that's probably not the case since western submarines have switched to single hulled

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Single hull has internal reinforcing rings that add to compressive resistance.

Double hulls have reinforcing rings outside the pressure hull.

tphuang said:

All the noise isolation equipment have to be done inside the pressurized hull. In submarine world, the wider the pressurized hull is, the more space you have to install noise isolation technology. So generally speaking, if you generate the same amount of noise inside a submarine, the larger the pressurized hull is, the quieter it will be for the outside world.

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That only applies for internal noise sources. It ignores hydrodynamic noise and active sonar resistance. In addition the single hull subs have internal bracing while the double hull subs put bracing outside, which makes the space tradeoff difference a bit smaller.

I think this new boat might be a testbed, not a production model, for that reason. A single hull may not fit doctrine or other requirements/constraints such as hydrodynamic noise or lack of feedthroughs and weak points.

Maikeru said:

Disappointing that a brand new submarine class hasn't generated more traffic on here - I suppose many posters just come to spout BS about politics or whatever. Anyway, I would like to speculate that this is a Lithium Ion battery powered SSK without AIP, similar to the sail-less sub it appears to be based on, and the latest Japanese boats.

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The difficulty is that we have so little context. It's difficult to infer technology, capabilities, role, numbers and production rate, significance in the context of the existing inventory...

Is it a one-off test submarine for an as-yet unspecified technology, an export project, or the harbinger of dozens of new light SSKs that will fundamentally reshape PLAN's submarine inventory? Until we have more information, it is little more than a curiousity.

Is it possible that this smaller submarine can be used in infiltration missions? Load it up with spec ops and sneak into hostile waters using stealth?

bustead said:

Is it possible that this smaller submarine can be used in infiltration missions? Load it up with spec ops and sneak into hostile waters using stealth?

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how far is this hostile waters? Not everything China builds needs to be for world domination.

There is a need for everything. Be patient. If this thing turns out to be a demonstrator that gets leverage later for next generation subs, then great. If it's a small littoral sub that appeals to export market, that's great too.