If Bltizo is willing to engage with him/her that's good enough for me.
09III/09IV (093/094) Nuclear Submarine Thread
- Thread starter SinoSoldier
- Start date
I think his 09IV SSBN diameter estimate is definitely an underestimate -- he doesn't measure the part under the shadow as part of the hull diameter.
As for his 12.3-12.6m measurement, I think that's also a bit of an overestimate.
Horobeyo in particular has interesting takes.
But just because I interact with someone doesn't mean they're credible, people should use their own critical judgement for that...
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I'm open to the idea of 09V having a wider diameter pressure hull than Virginia class (and to be something closer to Seawolf class or even Yasen as well), but over the last few pages I can't quite pin down the reasons why you think it's necessary or likely.
The Yasen class is a huge submarine, but it is also because it is intended to be a large diameter high performance attack submarine similar to the likes of Seawolf. Yasen has a whopping 10 torpedo tubes, and dedicated countermeasure launchers.
If the goal for 09V is a large, high performance, 8-10 torpedo tubes, Virginia/SSN-killer, then I certainly agree that a submarine of that type would warrant a larger pressure hull diameter.
But if the goal for 09V is a Virginia/Astute category peer, I think a 09III family 11m-ish pressure hull diameter should be sufficient, even in a hybrid single/double hull configuration.
If your primary argument is that a 09V needs a Yasen sized pressure hull for acoustic/stealth purposes (rather than seeking to have an 8-10 torpedo tube uber-SSN killer), then I have to say I can't quite agree with that.
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If you think 11m pressure hull is enough for them to have comparable noise level to the recent Virginia boat, that's because you have stronger opinion in china's submarine quieting technology than I do. I think they need 12m, so like seawolf class to have similar noise level to seawolf and recent Virginia boat. I think we have had enough discussion on this topic for you to notice that I am less positive of china's stealth technology than you are. That's why I put type 093g in the same level as sturgeon in stealth.
And I think if china has a reactor that can power a larger sub, then they will do so. I think yasen is that wide because that enabled Russians to reach Virginia level of stealth. Having more torpedo tubes is just an additional benefit.
It's fine if you believe that 09V needs a 12m pressure hull diameter just to reach Virginia levels of acoustic stealth due to technological backwardsness.
But in the last few pages of the exchange between us prior to your post in 2537, you never specified that you believed technological backwardsness was the basis of requiring a larger diameter hull.
I was just wanting to clarify that -- because there are multiple reasons for why a SSN may be required to have a larger diameter pressure hull.
Why larger hull can fix the tech gap? I have little knowledge about that but what I heard is: larger hull normally means more place for vibration isolation system, however once the place is enough for your most advanced active system, larger hull is meaningless because then (almost)no energy is leaked from the hull and most tone noise are from propeller and shaft(they also drive the hull to make noise through water flow and shaft junction but obviously larger hull doesn’t help here) it that true?
We've had several discussions before regarding this topic. I thought it's pretty apparent we had different opinions on where China is in terms of submarine stealth technology.
Now, if they are further ahead than I think they are, I still think it's beneficial to build something close to seawolf class in pressure hull diameter since that could possibly offer them an advantage over Virginia class.
In general, the more internal space you have, the more space you can have for passive noise isolation technology. It takes a lot of space to isolate all the noisy stuff in the engine room. It should not be surprising that both usn and Russian navy made significant improvement in their sub when the pressure hull increased by 1 to 2m in seawolf and yasen over la class and akula.
What do you mean exactly by passive noise isolation technology?
Years ago I asked that exact question to the people who worked on the boats in Groton. The answer was that this 2m difference in diameter required change to everything in terms of hull production - from the layout of the workstations to the established procedures for quality control. Humans are always the biggest cost factor and human error is the biggest risk factor and most people have no idea just how much of a factor until it hits them with the bill.
Economy of scale is everything:
- Skipjack (1956-1961) - 9,65m beam, 6 hulls built
- Thresher (1958-1967) - 9,63m beam, 14 hulls built
- Sturgeon (1963-1975) - 9,65m beam, 38 hulls built
- Los Angeles (1972-1996) - 10m beam, 62 hulls built
- Virginia (1999-...) - 10m beam, approx. 40 hulls minimum planned
- Seawolf (1989-2005) - 12m beam, 12 hulls planned
Furthermore Seawolf was built only in Groton (GD Electric Boat) which already is limiting the cost of retooling to half. Virginia-class could be built at both Groton and Newport News like Los Angeles-class without retooling. The difference in production from Los Angeles to Virginia is in modularity of hull sections, but hull modules end up being made and joined together with the same control procedures as a single hull.
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There are other reasons why bigger hull is not always better.
Submarine hull has to move through viscous medium which requires force. That force has to be generated externally which translates to noise in medium, as well as internally which translates to the reactor, cooling and power transmission.
10m diameter is 314m2 area. 12m diameter is 452m2 area. But water resistance is also calculated from hull area and that same 100m cylindrical hull gives you 6280m2 area for 10m beam and 7536m2 area for 12m. That's 44% and 20% increase in section area and hull area respectively.
Active sonar returns follow the same principles as radar cross section being directly related to the reflecting surfaces. More hull is worse and statistically submarines are located with airborne active sonar at safe distances from surface vessels. As noise levels approach reliably ocean background noise, active sonar becomes the only option and that's where hull shaping becomes a factor - new German designs already have hulls optimized for active sonar reduction. Where that leads in terms of overall size in future submarines is a question for thorough quantitative analysis, not an internet post.
Soviets used missiles because technology gap and higher noise levels prevented them from getting close enough to use torpedoes. They also used multiple submarines and waves of bombers to exhaust the defenses of carriers approaching Soviet-controlled waters and airspace. It was always defense in depth at sea. If PLAN contests USN carrier groups it will be close to enemy waters or in international waters at open sea. They will be as exposed as USN and at a weaker position.
For every group of 3-4 submarines that is necessary to credibly threaten an USN carrier group with saturation strike there's one large sub with heavy long-range torpedoes that is both a much bigger problem for USN and much lower cost for PLAN. No matter how effective active sonar becomes in the future the problem is still orders of magnitude more complex than countering missiles with currently available technology. To paraphrase the most amazing woman of all time: when enemy goes high, we go low.
Russians lag behind USN in all possible metrics so they utilized the advantage that physics provides and developed the Status-6 supertorpedo and Khabarovsk-class submarine.
Russians predictably went overboard but PLAN only needs to match it half-way to become a credible threat. And if we think AShBMs with a glider warhead then submarines are superfluous.
Seawolf wasn't a SSN-killer. Seawolf was a Bastion-penetrating SSBN-killer that was capable of matching perceived Soviet solutions to American advantages in sonar and silencing.
When Soviets learnt through espionage about the level and nature of technological gap between them and the US they realized that to close the gap will take 1-2 decades with no guarantee of success. During that time they had to have some options as well as backup plans and from those emerged high performance submarines like Lira/Alfa, Komsomolets/Mike, Sierra etc. If Americans could hear them futher Soviet made sure that it wouldn't matter because no American torpedo could catch Liras which led to huge modernization program for Mk48. Komsomolets could dive twice as deep as American subs and if Soviets didn't start catching up in silencing and sonar thanks to the machines they were buying from the west, they'd probably develop dedicated titanium-hulled hunter subs with operating depths of 600m or so to better use layers of water and depth for hiding.
Seawolf wasn't designed based on the actual capabilities of Soviet subs at the time but what US intelligence thought Soviet subs could be capable of when Seawolf entered service. Seawolf was USN future proofing for Improved Akula (Project 971M) which would enter service around that time and had noise levels of Improved Los Angeles.
It also was designed specifically to operate at longer periods of time than the usual Sturgeon/LosAngeles missions and with more tactical options available. If not for that USN would order a Virginia, just without all the littoral/spec-ops profile. They would anyway as there was no plan to ever build more than 30 Seawolf-type SSNs out of a fleet of ~100 SSNs. Seawolf would replace Sturgeons and a smaller boat would replace Los Angeles in due time.
Hull size isn't a problem except for energy issues that affect the economy of reactor design, but I don't think PLAN will design 09V like a Seawolf because I don't think 09III is a Los Angeles. Seawolf didn't exist in a vacuum but was a high part of another hi-lo mix. A reliable, good performance sub produced in large numbers is of more importance than a lower number of very high performance submarines. No matter how good a submarine is it will always be found in the end which makes it at best a short-lived tactical victory. A large number of "good enough" submarines is a long-lived strategic freedom of choice. Once 09V enters service we might see plans for a "large payload submarine" 09VII but I think that will follow the Russian thinking of SSBN-sized hunter subs designed from the start for working with UUVs.
Also... isn't this a 09III/09IV thread? Oh no... it is! Emergency dive!