09V/09VI (095/096) Nuclear Submarine Thread

FairAndUnbiased

Brigadier
Registered Member
What is the role of the Type-054A now?

In the past 5 years, China has launched 25 destroyers (both Type-052D and the Type-055)

But surface ships are acutely vulnerable to surprise submarine torpedo attacks, which the Chinese Navy can expect.

And when I look at the overall PLAN Orbat, I see a shortage of ASW frigates to provide convoy escort, patrol local waters and also provide an ASW screening ship for higher value surface warships.

My guestimate is that a notional Type-054B would approach the same cost as a Type-052D destroyer. That is based on the Type-054B using a comparable level of electronics fitout as the Type-055, European frigates or Japanese destroyer escorts - and their known costs.

So it wouldn't make sense to build Type-054B frigates to screen a Type-052D destroyer.

What you want is a low-value ASW screening ship that an opposing submarine doesn't want to engage.
For that purpose, a cheaper Type-054A has the exact same ASW capabilities as a more expensive Type-054B.

The lower-performing radar and electronics suite of the Type-054A wouldn't be an issue, as the Type-052D would be providing long-range radars and air defence.

Anyway, back on topic.
ASW surface ships has several things they can do that subs can't or shouldn't do:

1. active sonar - unlike subs who would broadcast their location with active sonar, ASW surface ships don't need to worry about that.

2. towed sonar - surface ships can stay in motion and deploy towed sonars

3. range - subs have a difficult time positively identifying targets with sonar alone, and using torpedos is risky since their targetting information is mostly short ranged. surface ships can use helicopters which are inherently long ranged, long range active sonar to scan for subs, and engage subs beyond torpedo range with anti-sub missiles.

A 054A is still a huge threat for hostile subs.
 

AndrewS

Brigadier
Registered Member
Are you saying that 09V might not replace but supplement latest iteration of 09III? If yes then I concur. It is a very likely scenario.

PLAN doesn't have to copy USN's current monolithic fleet structure. Present USN is a product of a very unique and unnatural set of circumstances - the position it found itself after USSR's collapse, the budget cuts and constraints, requirements for power projection etc.

There were proposals to reduce SSN fleet to 48 ships and below - notably in 1993 Bottom-Up Review (Base Force II) which proposed 45 to 55 SSNs and in 2005 when USN considered reduction to 260-325 ships with respectively 37 or 41 SSNs - barely twice the Russian fleet!

The large number of Los Angeles-class subs is misleading because at the time there were 100 SSNs in service and the 62 688s were meant to be supplemented by a 29 Seawolf-class boats for "bastion" runs. Let's also remember that USN no longer operated any conventional submarines while there is no indication that PLAN will retire them once SSNs enter mass production. Russia uses both types and has used in the past even when its nuclear fleet was much larger. China certainly can use conventional subs due to its geography and proximity of other navies. As such the nuclear subs could also fall into categories of cheaper, simpler, less capable 09III and more capable 09V following a form of "hi-lo mix". It might be that in the next two decades there will be very few 09Vs, a lot 09IIIs and a comparable number of conventional subs. Perhaps only after 2040 the number of highly capable subs will increase.

Or perhaps not. Perhaps they're going all in with 09Vs. What do I know?

What we know is that we don't know what 09V's role will be and what capability level it needs to have for that role. That's how weapons are made - as a system, for a purpose. We don't even know if a 09V submarine is considered a single weapon system by PLAN. Maybe it's only a part of a system. Maybe every 09V needs two 09III to work? We know nothing because we have no idea what the general strategy of PLA high command is.

It's the same problem that USN faced in the 70s.

USN looked at Soviet navy activities in the 60s and deduced that in the future Soviet navy would penetrate the North Atlantic and threaten supply lines to Europe. They looked at the Charlies, aircraft carriers and the bombers with cruise missiles and said "they will try to take over the Atlantic because that's how we can defend against them in Europe"

Soviets looked at USN submarine and anti-submarine developments and decided that it's better to build a highly defended area in the Arctic (the "bastion") and protect its nuclear deterrent from US submarines. They looked at the subs, carrier groups with ASW capability and said "we don't want any of that in our waters hunting our SSBNs". Oscars weren't meant killing CVNs in the Atlantic but for when they get close to GIUK. And we know that from declassified Soviet archives in Russia. CIA, DIA and ONI were completely wrong in their assessments and the fleet model which resulted was meant for fighting an enemy that did not exist.

Weapon capability is defined by its intended role and it might be that PLANs requirement will not be top capability that is achievable technologically to China at any given time. After all there's that saying that in military procurement the last 10% of capability costs the cost last 90% of the budget.

If hypothetically 09III is 60% of top capability today then perhaps 09V needs to only be 85%. Let the Americans built 100% boats. War is not a beauty contest.

And finally let's remember that destroying a nuclear submarine is an act of war and the primary purpose of military power is deterrence - preventing war from happening. Once a war starts weapons more destructive than SSNs will be used even if the conflict never leaves conventional stage.

Perhaps what PLAN needs is not a SSN able to track and sink American ships but a SSN able to follow American ships and absorb and exhaust ASW assets. Perhaps once USN is busy doing that the conflict can be settled in the same manner that Cold War was settled: through non-kinetic means.

I think everyone would be happy for a repeat of the Cold War rather than WW2. If this happens it might be a sign that we've found a very dumb way to get smarter as a species.

Anyway, I think that's enough speculation.

My view is that the Chinese Navy will be unable to wrest sea control of the waters past the 2nd Island Chain until 2040 at a bare minimum. That is based on the lead times required to build a sufficiently large blue-water carrier fleet.

At the same time, the global maritime landscape is characterised by a number of key chokepoints, ports and airfields where a few strategically placed submarines could wreak havoc. These sorts of missions do not require ultra-quiet submarines, as they could solely be tasked with attacking soft land targets or commercial shipping. And nuclear-powered submarines are the only realistic way to reach these operating areas. For soft land targets, a stealthy land-attack cruise missile would be very useful.

I expect this specific mission could easily absorb 30 new Chinese SS(G)Ns over the next 10 years.
And that a huge amount of US resources would have to be redeployed from the Western Pacific to protect these maritime chokepoints and also for convoy escort.
 
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plawolf

Lieutenant General
What is the role of the Type-054A now?

In the past 5 years, China has launched 25 destroyers (both Type-052D and the Type-055)

But surface ships are acutely vulnerable to surprise submarine torpedo attacks, which the Chinese Navy can expect.

And when I look at the overall PLAN Orbat, I see a shortage of ASW frigates to provide convoy escort, patrol local waters and also provide an ASW screening ship for higher value surface warships.

My guestimate is that a notional Type-054B would approach the same cost as a Type-052D destroyer. That is based on the Type-054B using a comparable level of electronics fitout as the Type-055, European frigates or Japanese destroyer escorts - and their known costs.

So it wouldn't make sense to build Type-054B frigates to screen a Type-052D destroyer.

What you want is a low-value ASW screening ship that an opposing submarine doesn't want to engage.
For that purpose, a cheaper Type-054A has the exact same ASW capabilities as a more expensive Type-054B.

The lower-performing radar and electronics suite of the Type-054A wouldn't be an issue, as the Type-052D would be providing long-range radars and air defence.

Anyway, back on topic.

The PLAN 054A and 056A fleets would like to have a word with you about the bold part.

Back on subject, there are a few issues with what appears to be generally accepted assumptions I think it is worth clearing up.

On disappearing into ‘black holes’, I think that has always been an exaggeration and mischaracterisation.

The best analogy I can think of is if you are in a crowded ballroom where there are a fair, but not overwhelming background hum of conversation.

If someone was shouting loudly, everyone in the room will hear him. That’s the worst case scenario of ASW where your noise level is above the background ambient ocean noise level.

But you can also pick up a familiar voice close by even if they are speaking well below the noise level of the background hum. This is why the west is so obsessed with getting close to record the specific noise signatures of Russian and Chinese subs. Because once you have those, you can specifically look for that distinctive sound signature and find it even if it is below the background ambient ocean noise level.

As such, achieving noise level below ambient background ocean levels is not the holy grail of sub design. You can and should go even lower such that an enemy would not be able to detect you at operationally relevant distances even if they had your specific noise signature to actively look for in all the background noise.

This also ties into the other key point I wanted to make about the distinction between high and low frequency sound. You can have two subs with exactly the same db noise level, but if one is emitting that in high frequency while the other is in low frequency, their practical detection ranges are going to be vastly different.

The final point I wanted to make is on game theory.

China knows that western subs aggressively patrol close to its shores and go out of their way to record the noise signatures of Chinese subs, SSN/SSBNs especially. Given that fact, does anyone here honestly think China would not take any countermeasures? Just look at how the J20 almost always carry lumberg lenses when flying. How hard would it be for Chinese nuclear subs to mount internal noise makers to deliberately amplify and distort their noise signatures in peacetime to both disguise the true capabilities of their subs and also render any noise signatures collected useless.

Just look at where they chose to locate their nuclear sub production base. The Bohai bay is China’s own private little sea where western subs would not dare to enter (and would almost certainly have all sorts of ASW measures in place to catch any stupid enough to try to enter.

That’s where China could test the true signatures of their new subs safely, and turn on the noise makers when entering/leaving to ensure no foreign sub ever got a clean recording.
 

Tam

Brigadier
Registered Member
ASW surface ships has several things they can do that subs can't or shouldn't do:

1. active sonar - unlike subs who would broadcast their location with active sonar, ASW surface ships don't need to worry about that.

2. towed sonar - surface ships can stay in motion and deploy towed sonars

3. range - subs have a difficult time positively identifying targets with sonar alone, and using torpedos is risky since their targetting information is mostly short ranged. surface ships can use helicopters which are inherently long ranged, long range active sonar to scan for subs, and engage subs beyond torpedo range with anti-sub missiles.

A 054A is still a huge threat for hostile subs.

Forgot to mention that ships hunting in a pack can coordinate and cooperate with each other passing sonar information digitally.

Another thing is that ship sonars can operate in a multistatic manner, particularly with regards to ships that have a VDS. As such, the VDS can broadcast the sonar, and the echoes can be picked up by a towed sonar from a different location from the VDS. This can be a separate tow at a different depth and location, to the TAS for different ships and their helicopters. One ship can ping, and several others can listen for the echoes passively at different locations.

Another reason why numbers matter.

I won't be surprised if they would restart the Type 056A program again, or introduce a new successor to that.
 

ZeEa5KPul

Colonel
Registered Member
How hard would it be for Chinese nuclear subs to mount internal noise makers to deliberately amplify and distort their noise signatures in peacetime to both disguise the true capabilities of their subs and also render any noise signatures collected useless.
I've bounced this idea around in my head before, and I wonder if China can do something more advanced: the sonar equivalent of electronic warfare. Not just a noise emitter, but deliberately jamming enemy active sonar by sending deceptive "returns."
 

FairAndUnbiased

Brigadier
Registered Member
Forgot to mention that ships hunting in a pack can coordinate and cooperate with each other passing sonar information digitally.

Another thing is that ship sonars can operate in a multistatic manner, particularly with regards to ships that have a VDS. As such, the VDS can broadcast the sonar, and the echoes can be picked up by a towed sonar from a different location from the VDS. This can be a separate tow at a different depth and location, to the TAS for different ships and their helicopters. One ship can ping, and several others can listen for the echoes passively at different locations.

Another reason why numbers matter.

I won't be surprised if they would restart the Type 056A program again, or introduce a new successor to that.
true. Ships can communicate with each other much easier than subs, do multistatic sonar or even do distributed synthetic aperture sonar.
 

AndrewS

Brigadier
Registered Member
I've bounced this idea around in my head before, and I wonder if China can do something more advanced: the sonar equivalent of electronic warfare. Not just a noise emitter, but deliberately jamming enemy active sonar by sending deceptive "returns."

That is what towed decoys already do with torpedo sonars.

But I don't see how the physics of *jamming* active sonar would work. The original signal and waveform will make it back, and all you would be doing is adding another signal which is more accurate.

Aircraft can get away with this with EW, because they move so fast, but not ships or submarines.
 

plawolf

Lieutenant General
I've bounced this idea around in my head before, and I wonder if China can do something more advanced: the sonar equivalent of electronic warfare. Not just a noise emitter, but deliberately jamming enemy active sonar by sending deceptive "returns."

Active noise cancellation is an option, but I see that as a last line of defence against active homing torpedos, because while ANC can potentially spoof the active homing seeker of a fish, it’s going to light you up like a lighthouse to everything else out there passively listening, because unlike AESA radars, you cannot beam steer sound waves in water to limit who can detect your active emissions. That’s the biggest difference between water and air. Air doesn’t propagate radio waves like water does sound.

But even then that’s pretty low odds since most modern torpedos are wire guided, meaning even if you can spoof the seeker of the torpedo itself with ANC, the launch sub can still probably steer the torpedo on target with its own passive sonar via wire guidance. So such a system would only really be effective against things like air dropped torpedos and ASROCs. Not useless, but not something you want to rely upon either.
 

MarKoz81

Junior Member
Registered Member
I agree with the general direction of your comment but few technical corrections and explanations are necessary for a more complete picture:

This is why the west is so obsessed with getting close to record the specific noise signatures of Russian and Chinese subs.

1. This "obsession" is the most fundamental thing in submarine warfare.

In surface ASW helicopters and planes can test the unindentified contact with buoys. If it's an allied sub they will have procedures to identify it even if they do not have the signature. If it's not identified and it persists on engagement course you can use small charges to warn it off. You do not have to use lethal force if you are a surface vessel because you do not need to hide your location. You're in the open calling out the other guy hiding underwater : who are you, show yourself.

A submarine can't do the same without revealing its position and once that's done the game for the sub is up. Because of that collecting signatures is the only way in which the submarine can identify targets. If you don't have a matching signature you have an unidentified noise source that may or may not be an enemy ship and considering that there are only so many submarine types in service among many navies of the world it's a mistake you don't want to make. An Indian Kilo, a Russian Kilo and a Vietnamese Kilo won't sound that differently if you have to guess which is which.

2. Not just the west but Russia and China and everyone else do it as well.

For obvious reasons PLAN doesn't use nuclear subs as standard intelligence tool. There's not enough of them and many are too noisy for effective intel gathering. Americans do it on a regular basis because of the relative stealthiness of their subs. Russians track American carriers and subs as much as possible. Everyone uses static networks and sensors planted at key locations to gather data.

Once China has sufficient number of sufficiently quiet SSNs you will see the same "obsession". There's just no other way. Even if you managed to steal the entire databank from your enemy you need to verify it, and then verify it again, and again because you have no idea if this is legitimate information or deliberate disinformation. So in short - nothing beats your own intelligence gathering and even then it's not perfect.

Because once you have those, you can specifically look for that distinctive sound signature and find it even if it is below the background ambient ocean noise level.

The background noise level is a factor in determining detection distance.

This is the passive sonar equation:

SL − PL − NL − AG = DT

SL - source level [dB]
PL - propagation loss (energy over distance in medium) [dB]
NL - noise level (background noise) [dB]
AG - array gain [dB]
DT - detection threshold [dB]

For theoretical maximum range DT=0 which then gives us:

SL-NL + AG = PL

PL = 10 log R


where R is the distance at which the wave will expire (propagation loss is equal to wave energy)

R= 10 ^ (PL /10) [m]

Explanation:

Every soundwave is the wave of linear pressure in a given medium. The pressure is generated by energy radiated from the source. For example a propeller physically moves an amount of water creating increased pressure on one side of the blade and a vacuum on the other side which is the source of cavitation.

A wave is energy propagating in a specific pattern creating a distortion of the medium. This distortion has specific characteristics with which we describe a wave - phase, frequency, amplitude, polarity etc. The distortion is in the behavior of particles that form that medium - here: molecules of water.

The medium at background state has some kind of behavior and an energy level describing it. Then the wave enters the medium and that behavior changes wherever the wave propagates. It's all about the movement and energy of the particles that make the wave possible.

If the particles at "background state" have low energy then a high energy wave can travel very far before it looses its energy by interacting with the inertia of the medium. This is why gamma rays in space travel for lightyears. Not only it's the most energetic wave but there's no background energy to counter it.

In water the acoustic pressure wave (soundwave) has plenty of particles that have their own energy which is why the usual soundwave travels for hundreds of thousands of kilometers at best. After that its energy is expended and the particles that were acted on by the wave's energy take the energy from the background which is now higher.

That's the background noise.

What the background noise does is limiting the distance at which the wave - a very specific pattern - remains that specific pattern or something sufficiently similar that a computer processing that pattern can say "this is 79,5% general match and 95% specific match to this ship signature".

In short if the background noise is strong enough it doesn't matter how well you know the signature. What you will get is the equivalent of a movie with the sound off- a person's mouth will move but no sound will come out, only the background noise.


As such, achieving noise level below ambient background ocean levels is not the holy grail of sub design. You can and should go even lower such that an enemy would not be able to detect you at operationally relevant distances even if they had your specific noise signature to actively look for in all the background noise.

If your sub has source level below background noise level the acoustic wave generated by the submarine will immediately be interfered with by the acoustic waves in the background. If background level is greater than source level there is no propagation. No propagation means no signature. No signature means invisibility.

This is why everyone is researching active sonar and distributed sensor networks. The era of listening in silence is over. The era of poking with sticks begins.

This also ties into the other key point I wanted to make about the distinction between high and low frequency sound. You can have two subs with exactly the same db noise level, but if one is emitting that in high frequency while the other is in low frequency, their practical detection ranges are going to be vastly different.

Every submarine emits low frequency noise. Just the stretching of the hull during change of depth creates a low frequency wave. The standard frequency range for detection is 5 to 200 Hertz.

5 Hertz is not audible but you can feel it.

The reason why lower frequency noise can be heard at larger distances has to do with whether you can tell the wave apart from the background.

That has to do with characteristics of the wave. High frequency sound is high energy wave. That wave goes everywhere and interferes with the medium turning itself into background noise. High frequency waves are like a swarm of bees and the environment around them behaves accordingly but from afar you can't tell if its a swarm of bees or a cloud or just a shadow. Low frequency waves are looooooooooooong waves. Like snakes. You can always tell it's a snake because it's long.

You can tell the wave apart from the background because it doesn't interact well with it. Quite literally many of the waves that carry you as you swim in water are acoustic waves. They don't hurt at all unless they throw you against something. In contrast high frequency sonar pings can physically hurt and raise the temperature of the diver's body if he's nearby in water.


Parting remark:

Good point on the Bohai Sea. Also note that if you have a secure body of water for testing it becomes the ideal honeypot where the enemy will have to use its actual best capability to gather valuable information. And thus - so will you.
 
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