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Brumby said:

Just an add on. Mk 48 ADCAP supposedly has a speed of 63 knots (source : Milford, "US Navy Torpedoes; Part Five" Sumarine Review, July 1997, p.81.)

The basic problem with ASW torpedo specs is that it needs a 50 percent margin of superiority in speed over its target in order to assure that the target does not escape once alerted to the attack. Nuclear submarines were achieving 30 knot speeds. (Source : Innovation in the U.S. Navy's Silent Cold War Struggle with Soviet Submarines; by Dr. Owen R. Cote, Jr.)

I should also add that the Soviet Alfa program was a failure. The 4000 feet would be crush depth and not operating depth which was around 2000 to 2500 feet

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To be fair to the Alfa program, its biggest problem was financial and not that of technical or scientific. By the standards of the day it was pretty darn impressive. Just because on one side it fail to meet a certain requirement does not dismiss the other achievements it had acquired. The level of automation in its design is clearly shown on its successors which is really something the USN still have not worked around to doing. On a sub with limited spacing that counts for much. And the titanium hull design was by all accounts revolutionary and pushes the boundary of what is thought possible for sub design.
By all accounts what the Yasen really needs would be just some minor tweaking to put it on an even more competitive level to that of the Virginia, which in all honesty is a very fiercely contested one to begin with. I would not be suprised if Russia unveils a updated variant of the Yasen with a pump jet and lessons learned from the last 3 hulls, if they can get the money for it.
Also a difference in 1500 feet of operational depth is still rather darn impressive. I can imagine the number of thermal layers than goes between that length of depth to hide a sub. Once these things got loose in the Atlantic they did be next to impossible to stamp out and the pain would be considerable for trans Atlantic shipping.

Viktor Jav said:

To be fair to the Alfa program, its biggest problem was financial and not that of technical or scientific. By the standards of the day it was pretty darn impressive. Just because on one side it fail to meet a certain requirement does not dismiss the other achievements it had acquired. The level of automation in its design is clearly shown on its successors which is really something the USN still have not worked around to doing. On a sub with limited spacing that counts for much. And the titanium hull design was by all accounts revolutionary and pushes the boundary of what is thought possible for sub design.
By all accounts what the Yasen really needs would be just some minor tweaking to put it on an even more competitive level to that of the Virginia, which in all honesty is a very fiercely contested one to begin with. I would not be suprised if Russia unveils a updated variant of the Yasen with a pump jet and lessons learned from the last 3 hulls, if they can get the money for it.
Also a difference in 1500 feet of operational depth is still rather darn impressive. I can imagine the number of thermal layers than goes between that length of depth to hide a sub. Once these things got loose in the Atlantic they did be next to impossible to stamp out and the pain would be considerable for trans Atlantic shipping.

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There is a principle I consistently apply i.e. there are no free lunches. You will eventually pay the bill somewhere, sometime and in someway.

The Alpha sub when it was introduced appears to have leapfrogged the US in terms of Titanium welding. It allowed the Alpha subs to remain impervious due to its diving depth. The problem as was later evident, the Soviets never solved the creep fatigue interaction problem with Titanium welding. This means that every time Titanium is compressed, it becomes more brittle. In other words whenever a Titanium-hulled sub goes deep, it reduces how deep it can go next time. The submarines quickly developed fatigue cracks all over so they were extremely noisy because these cracks would rub against each other. It became noisy and easily detectable and it was losing it’s ability to dive deep. Very soon all the Alpha submarines were docked.

asif iqbal said:

how likely is that Russia will build 2 x LHD at Crimea next year :?

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I took an interest myself, to find 11 сен - РИА Новости
В ОСК опровергли сообщения о планах строительства вертолетоносцев в Крыму

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Brumby said:

There is a principle I consistently apply i.e. there are no free lunches. You will eventually pay the bill somewhere, sometime and in someway.

The Alpha sub when it was introduced appears to have leapfrogged the US in terms of Titanium welding. It allowed the Alpha subs to remain impervious due to its diving depth. The problem as was later evident, the Soviets never solved the creep fatigue interaction problem with Titanium welding. This means that every time Titanium is compressed, it becomes more brittle. In other words whenever a Titanium-hulled sub goes deep, it reduces how deep it can go next time. The submarines quickly developed fatigue cracks all over so they were extremely noisy because these cracks would rub against each other. It became noisy and easily detectable and it was losing it’s ability to dive deep. Very soon all the Alpha submarines were docked.

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Really ? From what I can gather, the main reason why the Alfa's are docked at port for extended periods boils down to 2 facts
1) Their role as a "interceptor" : The Afla was never going to be as stealthy as contemporary NATO subs, but that was never their goal. Their's was to make a mad dash into as soon as hostilities broke out to prey on trans Atlantic shipping. So to give them the best chance, the most optimal solution was to launch them fully supplied and fresh crews. Factors which necessitate more frequent port docks.
2) The revolutionary lead bismuth reactor : As far as 1970 was concern, this kind of reactors was literally rocket science. But the problem was it necessitate adequate facilities to maintain the functionality of the reactors. In a stunning but not suprising oversight, the USSR like a many other nations that I can point fingers at, neglected to allocate sufficient funding for those said facilities, with the navy being more focus on having the weapon rather than the means to maintain them. This lead to the expected backlog of maintenance for the Alfa's and subsequently their extended port leaves. Again this is not so much the submarine's fault, but rather external factors.

By all accounts the Alfas performed as what was to be expected from them. It was really only the Leningrad that suffered some issue regarding the titanium welds as you described, but being the lead boat and prototype of the series that was to be expected. The subsequent boats all have that problem rectified.

Brumby said:

There is a principle I consistently apply i.e. there are no free lunches. You will eventually pay the bill somewhere, sometime and in someway.

The Alpha sub when it was introduced appears to have leapfrogged the US in terms of Titanium welding. It allowed the Alpha subs to remain impervious due to its diving depth. The problem as was later evident, the Soviets never solved the creep fatigue interaction problem with Titanium welding. This means that every time Titanium is compressed, it becomes more brittle. In other words whenever a Titanium-hulled sub goes deep, it reduces how deep it can go next time. The submarines quickly developed fatigue cracks all over so they were extremely noisy because these cracks would rub against each other. It became noisy and easily detectable and it was losing it’s ability to dive deep. Very soon all the Alpha submarines were docked.

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If the problem is welding cracks then how could be the Sierras still in service?

The Sierra has bigger diameter , so the hull stress is the same .

Viktor Jav said:

Really ? From what I can gather, the main reason why the Alfa's are docked at port for extended periods boils down to 2 facts
1) Their role as a "interceptor" : The Afla was never going to be as stealthy as contemporary NATO subs, but that was never their goal. Their's was to make a mad dash into as soon as hostilities broke out to prey on trans Atlantic shipping. So to give them the best chance, the most optimal solution was to launch them fully supplied and fresh crews. Factors which necessitate more frequent port docks.
2) The revolutionary lead bismuth reactor : As far as 1970 was concern, this kind of reactors was literally rocket science. But the problem was it necessitate adequate facilities to maintain the functionality of the reactors. In a stunning but not suprising oversight, the USSR like a many other nations that I can point fingers at, neglected to allocate sufficient funding for those said facilities, with the navy being more focus on having the weapon rather than the means to maintain them. This lead to the expected backlog of maintenance for the Alfa's and subsequently their extended port leaves. Again this is not so much the submarine's fault, but rather external factors.

By all accounts the Alfas performed as what was to be expected from them. It was really only the Leningrad that suffered some issue regarding the titanium welds as you described, but being the lead boat and prototype of the series that was to be expected. The subsequent boats all have that problem rectified.

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The Soviets had problems with the lead bismuth reactors


Source : Page 48, SUBMARINES AN ILLUSTRATED HISTORY OF THEIR IMPACT by Paul E. Fontenoy

Brumby said:

The Soviets had problems with the lead bismuth reactors
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Source : Page 48, SUBMARINES AN ILLUSTRATED HISTORY OF THEIR IMPACT by Paul E. Fontenoy

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The book pretty much summed up my point that the problems with the reactors lies with their maintenance issues, rather than actual failures for their systems. That is the problem with certain authors and publications : in that they say that a certain system has problems but then fail to clarify the nature and depth of the said problem which leads to a whole sale assumption that the system was entirely faulty when in reality it isn't.
The K-27 was the first submarine to trial the new reactor, so of course problems are to be expected. But the subsequent boats that uses the same reactors does not suffer the same issues.

HI Sutton summed it up pretty accurately
"This last feature of the lead-bismuth reactor was also its Achilles’ heel. If the temperature of the reactor dropped below 125 °C (257 °F) then the reactor solidifies and cannot be brought back. Ever. This happened to the lead boat, K-64, in 1972, resulting in an early departure from service."
The USSR had designed steam stations at port for the purpose of heating the reactors when not in use but the lack of funding meant that the facilities never performed as expected.
Does this mean that the reactor's design is defective ? Of course no,the Alfa sub, like any other weapon system, does not exist in a void. It dependent on the network of other systems in order to function. Again, the system works perfectly well with the appropriate facilities and if you have a problem with that, then you did have a problem with a heck of a lot of modern weapon systems that are veritably green house plants atm.
The simple fact is that the USSR at that time cannot afford an whole horde of steam yards functioning for the Alfa's. But the Alfa cannot be faulted for USSR's budgetary concerns which are entirely separate from its capabilities.

Viktor Jav said:

And countless time again and again, size does not dictate the level of quietness, but rather it is to do with design. You can scream that to high heavens but it will never ever change. I can bring up countless examples like how the Borei is considered to be more quieter than the Typhoon subs despite the former being 50 percent more heavier and much larger than latter. Or the earlier example of the U212 and the Victor III class.

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Well, duh - Borei is technologically a generation ahead of Typhoon and similarly U212 is two generations newer than Tango (in fact your other examples on this point suffer from the same basic fallacy). All else equal, more space does mean more opportunity for machinery silencing measures (whether that opportunity is taken up or the additional room used for other purposes is another matter entirely).

We do know from leaked CAD images that for at least the engineering sections, Yasen uses raft-mounted machinery and pipework inside compartments that are themselves built as raft-mounted frames and then encloses those in acoustic cladding. They sure aren't half messing about with respect to machinery noise reduction, but without more detailed info on the Virginia-class it is difficult to make an objective comparison.

Viktor Jav said:

Space which the Yasen's extra 6 torpedo tubes, 10-20 torpedos and countermeasures plus the extra 36 missiles and VLS silos on the back will have taken up. But they all seem to vanish into a black hole for all that you are concerned. And a double hull designs makes up at least 20-30 percent of a sub which is fill with nothing but an empty clanking void.

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Virginia has countermeasures launchers too, and adding a VLS with similar capacity still leaves a gap to Yasen in terms of size. Yeah, it has fewer torpedo tubes, but then the Yasen complement is *half* that of Virginia (with all the knock-on effects that has in terms of life support system, galley, mess and sanitary installation sizing). That's one of the useful legacies from Alfa-class, as you correctly mention yourself.

Tirdent said:

Avangard intercontinental HGV officially assumes nuclear alert duty on SS-19 boosters:

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C'mon, nobody's interested?!

BTW, there are a couple of errors in that post: at 6000km downrange the HGV has already endured more than 10 (as opposed to 5) minutes of heating but the speed difference to a ballistic RV at low altitude is probably more like <20%. Also, the requirement for improved warhead TPS in depressed trajectory SLBMs is due not to higher speed (missile burn-out velocity is the same, and a ballistic trajectory means the RV initially reenters the atmosphere at roughly that speed) but the longer endo-atmospheric path length.

Just to make sure it's all correct for the record.

Tirdent said:

C'mon, nobody's interested?!

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I guess the disbelief toward the Kremlin announcements is rather total