I always meant to ask about this post, but never got around to do it. Those dB values mentioned are some very exact figures. It would be of immense value if the figures could be corroborated by actual links to official materials or names of official publications that the figures were taken from. Could you provide those? Thanks.
From what I could find in my archive the table comes from this book:
"Корабельная гидроакустическая техника. Состояние и актуальные проблемы"
Ю.А. Корякин, С.А. Смирнов, Г.В. Яковлев
ЦНИИ Морфизприбор, 2004
"Ship-based hydroacoustic technology. State and topical problems"
Yu.A. Koryakin, S.A. Smirnov, G.V. Yakovlev.
Central Research Institute of Morphizpribor, 2004.
CSRI Morphispribor stands for Central State Research Institute "Morphizpribor". Since 2006 it has been consolidated under the stock company Okeanpribor:
I don't have it so I can't confirm if the table is indeed from it, but I have other information that is attributed to this publication and so I have no reason to think it's from somewhere else.
I chose this particular table to illustrate the principles of passive sonar detection because it lists figures which are higher compared to for example "E.V. Miasnikov, The Future of Russia's Strategic Nuclear Forces: Discussions and Arguments" which has the "971 (Akula)" at 110dB in the 5-200Hz range, and not at 120dB as the above book.
Also - in case I forgot to add this in the description in my original post - the figures in the table are just the last two digits above 100dB level. Add 100dB to each figure for proper value. So it is not "20dB" but "120dB".
Apologies if I forgot to mention it.
For a sub to disappear like a "black hole" in the ocean, its noise level should match that of the ocean's underwater background or ambient level of noise. That's around 60 to 90db. So its safe to say, if you want to disappear like a black hole, 85db to 90db is the minimum. I would think the Kilos, which are nicknamed "black hole", achieved this level.
For a sub to disappear like a "black hole" you need a seaman with penchant for storytelling.
For a sub to genuinely disappear like a "black hole" you need it to turn on electric motor and reduce the speed to 2kt (3,7km/h) Cavitation almost disappears at this rotation rate and your noise is limited to what is generated by the rotating shaft which at this rate is not much.
However - the same book, the same principle (add 100dB):
I don't know if this refers to diesel or electric motor or at what speed it was measured.
136dB on electric or AIP seems too loud. Conventional subs traveling under electric power or fuel cells are quieter than nuclear subs. However, if this data is correct it might be explained by lower levels of silencing that conventional subs receive simply because unlike nuclear subs they do not travel long distances at higher speeds while submerged. The most reliable AIP until recently was the stirling engine which could reliably only propel submarines at 5knots. Until Li-Ion batteries were tested on Japanese subs it was impossible for a conventional sub to go on long sprints due to low energy density of conventional batteries. At 20kt it would only last for less than 100-150km. That means that traditionally the default manner of avoiding detection for a conventional sub was to become a "black hole" which was not necessarily possible for a nuclear sub due to the profile of its mission. After all a conventional sub can just stop all movement and noise while a nuclear sub will always have its reactor on even if it doesn't move.
Note: I'm speculating. I have no idea what this table indicates because I have only citations from the book.
Back to the topic:
It will be more like a 055 DF-41 etc analogy compared to mass produce a very cheap but effective and capable enough "legacy gen" platform to serve in numbers.
For that role 093 improved is probably going to be produced in numbers as a capable enough SSN between improved LA class and Virginia hopefully in terms of stealthiness (technologies and manufacturing demands that are well below China's current abilities) and above Virginia in terms of subsystems.
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.
