VSMUT wrote:

You still don't get it, do you? A submarine moving through water displaces water. Move it fast enough, and the bow of the boat will create cavitation, no different from cavitation caused by the screw. That's why even nuclear submarines can't move fast if they are to remain undetected.
Further, that "kettle" in the nuclear reactor, that's a pretty noisy apparatus, much more so than a modern diesel engine.

The diesel engine on a conventional submarine is even louder than a nuclear reactor. For one, the diesel engine vibrates a lot when running, and even though the installations are often rafted, they still transmit vibrations to the hull. Also, when they snorkel, the snorkel transmits vibrations through the water as well. A conventional submarine has to come up to snorkel to recharge the batteries, and if they are pushing the boat fast (say in excess of 5 knots), they are coming up to snorkel at least once a day. And with that noise coming from the engine and snorkel, it renders the sub effectively blind and deaf from using their passive sonars.

In addition, the depth at which the boat operates for snorkelling is usually well above the thermocline, further diminishing the boat's ability to acoustically detect submarine (or surface) threats… including incoming torpedoes.

Also, the snorkel produces a wake on the surface, and if the sub is moving in excess of 5 knots, it produces a fairly large wake that's easily observable from the air.

Nuke subs generally never have any reason to break the surface unless there's a specific need to. That's a big advantage, especially if you have ASW helicopters and aircraft combing the seas with their radars and IR sensors.

The real differentiator would be the quality of the crew; if a particular sub's crew was extremely professional and sound discipline was top notch, it doesn't matter if they are in what should be a noisier boat; they will be a hole in the water.

VSMUT wrote:

Yeah, no. The Soviet coastline is nowhere near as congested as the seas around China. Not in any way comparable.

The Soviets had more assets to search their coastlines, period during the Cold War. They had lots more satellites, and more recon aircraft can cover more ground quicker. And the Soviets were pretty good at their craft.

ThePointblank wrote:

In addition, the depth at which the boat operates for snorkelling is usually well above the thermocline, further diminishing the boat's ability to acoustically detect submarine (or surface) threats… including incoming torpedoes.

Talking about the thermocline in the south china sea is completely irrelevant. It is too shallow.

ThePointblank wrote:

The diesel engine on a conventional submarine is even louder than a nuclear reactor. For one, the diesel engine vibrates a lot when running, and even though the installations are often rafted, they still transmit vibrations to the hull. Also, when they snorkel, the snorkel transmits vibrations through the water as well. A conventional submarine has to come up to snorkel to recharge the batteries, and if they are pushing the boat fast (say in excess of 5 knots), they are coming up to snorkel at least once a day. And with that noise coming from the engine and snorkel, it renders the sub effectively blind and deaf from using their passive sonars.

Also, the snorkel produces a wake on the surface, and if the sub is moving in excess of 5 knots, it produces a fairly large wake that's easily observable from the air.

Ever heard of air independent propulsion? Fuel cells? Snorkels went out of fashion ages ago. Both German and Swedish submarines have crossed the Atlantic without surfacing. IMHO, you are so far behind, you are better off just staying in your official Lockheed Martin F-35 PR fluff thread. Did you know that torpedoes can home in on targets automatically these days? And that deck-guns are no longer fitted?

Diesel engines have become extremely silent and smooth in the past 2 decades, and that's just for cheap commercially available vehicles. You can be dead certain that the latest submarine grade diesels are a lot more silent than a nuclear reactor. Not to mention how various fuel-cell solutions are becoming increasingly widespread. The PLAN has 17 Type 039As (and another 3 inbound) with AIP. The 12 Kilos also have an impressive submerged endurance.

ThePointblank wrote:

The Soviets had more assets to search their coastlines, period during the Cold War. They had lots more satellites, and more recon aircraft can cover more ground quicker. And the Soviets were pretty good at their craft.

China has the biggest fishing fleet in the world. They have the second biggest merchant fleet. That's a pretty extensive "passive-sensor network", far more so than the Soviets ever had. As the millenium challenge proved, it is also something the US Navy is completely unable to counter. Sure, they could start sinking them, but that opens the risk of Chinese retaliation against US civilians, and a risk of involving 3rd part nations in the region who also have vast fishing fleets. There is also a very real chance that the Chinese have planted sonar networks across the SCS, similar to SOSUS.

VSMUT wrote:

Ever heard of air independent propulsion? Fuel cells? Snorkels went out of fashion ages ago. Both German and Swedish submarines have crossed the Atlantic without surfacing. IMHO, you are so far behind, you are better off just staying in your official Lockheed Martin F-35 PR fluff thread. Did you know that torpedoes can home in on targets automatically these days? And that deck-guns are no longer fitted?

Diesel engines have become extremely silent and smooth in the past 2 decades, and that's just for cheap commercially available vehicles. You can be dead certain that the latest submarine grade diesels are a lot more silent than a nuclear reactor. Not to mention how various fuel-cell solutions are becoming increasingly widespread. The PLAN has 17 Type 039As (and another 3 inbound) with AIP. The 12 Kilos also have an impressive submerged endurance.

AIP are not the cure-all that you think they are; for one, they are not meant to be the primary means to charge the batteries when a sub is drawing lots of power. They provide at best a trickle charge, meant for low speed operations and providing limited hotel power.

They also consume a lot of fuel, depending on the type of AIP solution because these systems are generally not very energy dense or efficient; closed cycle diesel requires LOX and inert gas, and the tanks are only so big for that. Stirling engines also require LOX as they use it to support combustion to heat the engine so it can generate power (very limited power mind you). Fuel cells are not particularly energy efficient for their size (best ones out there generate only 0.7 volts DC per cell) and are a very expensive solution.

For example, with the Stirling engine, having enough power generation to tool around at 4 knots completely submerged for 2 weeks may not be enough power generation for combat requirements, and this line of view is apparently supported by a number of engineers (especially those on the Chinese side):

https://apps.dtic.mil/dtic/tr/fulltext/u2/a519346.pdf

An interview with the Han submarine’s chief designer, Huang Xuhua, which appeared in the military periodical (Ordnance Knowledge) in 2000 is more explicit regarding some of the dilemmas confronting China’s naval nuclear propulsion program. Huang discusses the conundrum for naval strategists posed by the option to choose between development of AIP (air-independent propulsion) technology and nuclear propulsion. The interviewer asks Huang directly whether it makes sense to continue with nuclear propulsion development, given recent worldwide advances in AIP technology. Huang points out that nuclear propulsion offers far more power, is likely much safer and more reliable, and enables submarines to stay submerged for longer periods of time. Taking Sweden’s Gotland-class AIP-equipped submarine as an example, he suggests that this submarine’s two weeks of submerged operations at an average speed of four knots might not “be adequate for combat requirements.” Huang accepts that certain bathymetric conditions are ideal for AIP-equipped diesel submarines, such as those prevailing in the Baltic Sea (a small, shallow body of water). For Sweden, therefore, Huang says, “It is scientifically logical to select this type of submarine.” The implicit argument, however, is that China confronts rather different, if not wholly unrelated, maritime challenges and requirements.

Many people just don't understand the amount of investment and effort the US has placed into sound dampening technology, and the resulting technological lead the US has over every other country. The increased size of nuclear submarines also means there's more room to quiet the submarine with more insulation and vibration dampeners compared to a conventional submarine.

It is often said that the USN's Seawolf-class subs are as quiet at 25 knots compared to a Los Angeles class submarine is at pier side. The Virginia class submarines are apparently exceptionally quiet as well, and some people (such as Gabriel Collins, Andrew Erickson, Lyle Goldstein, and William Murray) have said that the Seawolf's and Virginia's are quieter than a Improved Kilo-class submarine. And no, the Chinese are still significantly far behind the US at building quiet subs (the Chinese admit this), and the Russians are in a similar situation.

ThePointblank wrote:

Many people just don't understand the amount of investment and effort the US has placed into sound dampening technology, and the resulting technological lead the US has over every other country. The increased size of nuclear submarines also means there's more room to quiet the submarine with more insulation and vibration dampeners compared to a conventional submarine.

Not a given that the US got equivalent value for money spent

Then you may upgrade your AIP knowledge to state of the art:
https://www.industry.siemens.com/vertic ... ell-en.pdf ( the newer ones top out at 70% conversion efficiency. )

https://en.wikipedia.org/wiki/Type_212_ ... cteristics
Endurance: 3 weeks without snorkeling, 12 weeks overall

WIederling wrote:

ThePointblank wrote:

Many people just don't understand the amount of investment and effort the US has placed into sound dampening technology, and the resulting technological lead the US has over every other country. The increased size of nuclear submarines also means there's more room to quiet the submarine with more insulation and vibration dampeners compared to a conventional submarine.

Not a given that the US got equivalent value for money spent

Then you may upgrade your AIP knowledge to state of the art:
https://www.industry.siemens.com/vertic ... ell-en.pdf ( the newer ones top out at 70% conversion efficiency. )

https://en.wikipedia.org/wiki/Type_212_ ... cteristics
Endurance: 3 weeks without snorkeling, 12 weeks overall

AIP submarines are deadly in any constructed waters at fairly limited outside of it. The 3 weeks endurance is typically calculated at tooling around at 5 knots or so. You can run the AIP, charge the batteries and have enough on hand for some good burst of speed when you want to for a couple hours. But power requirements for ships and subs are merciless and rise very quickly with speeds.

I wouldn’t want to challenge an AIP submarine on short notice or with minimal resources. Very formidable opponents. You want to keep your distance I would think, utilize MPA and drones to either keep them under or localize them if they dare to surface and then pounce on them. If you had to be in an area in 10 days it would be a nightmare. They are going to be quiet by nature.

If you had a couple months to pressure them and adequate resources you could stand off and deal with it. Their strength wouldn’t be closing with a carrier group that kept moving and was utilizing aerial and other assets to force a tactical transit of say 600-900 NM.

So to me it really depends on the objective at hand. AIP subs are going to be good at keeping carriers away until dealt with and if they are already in position they will be tough to deal with for a while. I am reminded of what happened in WWI. The German Navy was quite well suited to combat a close blockade. But the British never came and fought a different war. The effectiveness of AIP submarines against carriers would be very driven by the objectives and time table of the carrier based opponent.

bigjku wrote:

WIederling wrote:

ThePointblank wrote:

Many people just don't understand the amount of investment and effort the US has placed into sound dampening technology, and the resulting technological lead the US has over every other country. The increased size of nuclear submarines also means there's more room to quiet the submarine with more insulation and vibration dampeners compared to a conventional submarine.

Not a given that the US got equivalent value for money spent

Then you may upgrade your AIP knowledge to state of the art:
https://www.industry.siemens.com/vertic ... ell-en.pdf ( the newer ones top out at 70% conversion efficiency. )

https://en.wikipedia.org/wiki/Type_212_ ... cteristics
Endurance: 3 weeks without snorkeling, 12 weeks overall

AIP submarines are deadly in any constructed waters at fairly limited outside of it. The 3 weeks endurance is typically calculated at tooling around at 5 knots or so. You can run the AIP, charge the batteries and have enough on hand for some good burst of speed when you want to for a couple hours. But power requirements for ships and subs are merciless and rise very quickly with speeds.

I wouldn’t want to challenge an AIP submarine on short notice or with minimal resources. Very formidable opponents. You want to keep your distance I would think, utilize MPA and drones to either keep them under or localize them if they dare to surface and then pounce on them. If you had to be in an area in 10 days it would be a nightmare. They are going to be quiet by nature.

If you had a couple months to pressure them and adequate resources you could stand off and deal with it. Their strength wouldn’t be closing with a carrier group that kept moving and was utilizing aerial and other assets to force a tactical transit of say 600-900 NM.

So to me it really depends on the objective at hand. AIP subs are going to be good at keeping carriers away until dealt with and if they are already in position they will be tough to deal with for a while. I am reminded of what happened in WWI. The German Navy was quite well suited to combat a close blockade. But the British never came and fought a different war. The effectiveness of AIP submarines against carriers would be very driven by the objectives and time table of the carrier based opponent.

Also should note that the Japanese are ditching AIP on new construction Soryu class submarines from the 11th unit onwards (JS Oryu), in favour of greater battery density with lithium ion battery technology. By replacing the existing lead-acid batteries and all the space the AIP systems took up, they could significantly increase underwater endurance without resorting to using AIP, and all of the associated problems the technology has.

ThePointblank wrote:

Also should note that the Japanese are ditching AIP on new construction Soryu class submarines from the 11th unit onwards (JS Oryu), in favour of greater battery density with lithium ion battery technology. By replacing the existing lead-acid batteries and all the space the AIP systems took up, they could significantly increase underwater endurance without resorting to using AIP, and all of the associated problems the technology has.

Haven't seen that yet. Thanks for the info.
But whatever: it is not a reduction of submerged capabilities either.

Addendum:
They replaced a Kockums Sterling AIP + LeadAcid batteries solution with a fully LiIon arrangement
for the most recently delivered sub.