The longn range would be for lower speed (don't know it but probably around 30kts or maybe 25?), but you can't set parameters for subroc payload so I even didn't bother to model both modes and set fast mode only for UGMT-1 (41kts and 8000yd).

Yes, it was from there, I don't have Janes subscription :-(

I got my undergraduate degree in engineering. In almost all cases of structural design work I've seen we usually see about a 100-200% safety margin. But those were all civillian engineering applications (bridges, building frames, etc.) We calculated the maximum stress that the structure needed to withstand and then designed the loading points to fail under twice that amount. However, estimation, conservative guessimates and worst case scenario are factored into just about every point in those estimates with the true failure stress of a load point really an unknown. It really is a shot in the dark, but one could probably be reasonable to think that a new sub without any damage could sustain alot more than its crush depth and live to tell about it, like you've already mentioned.

As far as Russian subs go... man, its hard to say. The russians don't have a very good reputation for safety that's for sure. One *could* think that the double hull design of the Russian subs would give them a relatively deep crush depth... but then again would the same stress safety margins apply to their structural design in the first place? Perhaps the russian *crush depth* isn't as conservative an estimate... or maybe its more conservative... impossible to tell. I wouldn't be opposed to a 2000ft ingame crush depth for the Akula. Perhaps if even just an ingame reflection of the will of the Russian navy to push safety limits... (also a blatant stereotype)

I'm going to go with Henson as far as Seawolf's speed. It just has that reputation. That 12ft diameter hull isn't for nothing and it probably has a pretty large peak power output when compared to smaller reactors. The internal volume of its reactor compartment is substancially greater that of the other subs... which may support an pretty good advantage in power output.

Considering the fact that the Akula is larger, with more drag, but with a relatively small reactor when compared to the SW, (remember that the Akula's is double hulled, so the internal volume of its pressure hull isn't that large), I'ld support a greater peak power output for the SW coupled with a better power/weight (power/drag) ratio would result in a 4-6 knot speed advantage.

As far as the Akula II over the Akula Ii. My intuition is that the size increase is purely quieting measures (better reduction gearing, better rafting) with no change in peak reactor power. The Akula II hull size (and therefore hull drag) has been suggested to be greater than the Akula Ii as well.

All you say is truth... Me too thinks that NEW sub can withstand little more... But what you say that nobody really knows what is the real load at which structure fails... If you are designing a bridge, and are not sure if your safe margin is perfectly safe, and are not sure if it REALLY can withstand what numbers say... you just increase the margin. You don't have money to build whole section of a bridge and make destructive test on it anyway...
But you can't make it with submarine, or airplane - just increase the margin to be sure. You have to be quite sure what it can take. So for so important projects like aircrafts and submarines people from time to time test such things just to have idea of what they REALLY can withstand :-), and then base on those tests for some time, and then make new tests while designing new construction... I know that whole sections of submarines were tested for fail pressure when designing really NEW (new designs, new materials) constructions, like when the Russians tested sections (or maybe whole hull?) of first titanium submarine. I could bet that sections of hull from new (HY-100?) steel were tested to fail too... and maybe even material tiring tests - somone someday tested this to know today what limits put on aging sub...
When they build new aircraft today, B-777 or Airbus A380, they know really good what the plane can withstand. I remember an destructive test of wing strength made on whole big passenger airplane airframe. They were bending the wing to the point it failed. This point was, if I remember, around 102% of calculated value... so it was calculated quite precisely :-).
I - personally - wouldn't try do dive a sub below given crush depth, even new one... but of course it's an open question and either of us can be right :-)
Probably it can really withstand some more, if new... but on the other hand, just like you said, even if the hull as a whole take it, one of thousands small thing like opening in the hull or internal pipe that is weaker... and it can kill whole sub and crew... remember the australian Collins accident lately...? They said they were close, very close... :dead: It can happen even on less than crush depth, but while closing and passing crush the probability of such thing increases by factor of ten probably...

About Seawolf speed - yes, it can have much more powerfull reactor, but it is also much bigger than LA. And correct me if I'm wrong, it's not reactor that counts, it's first the steam turbines limit (this is reason that nuclear carriers had same max speed as conventional - they had different steam generators, one conventional, second nuclear, but the turbines were the same and had same output power...) and secondly how much power the propeller can transfer to the water... (but yes, IIRC the LA is rather reactor-limited, all other parts of chain being more capable).

The Alfa and Papa, speed record breaking subs, were just big metal-cooling reactors and machinery monsters with not much place left for other things... SW is normal submarine with much place for weapons, sensors ect. similar like LA class... I really wouldn't expect it to break those records... it can be quite possibly the fastest OPERATIONAL sub in the world (with all Alfas decommisioned long ago), but wouldn't take the words as absolute record breaker...

I think if we have an hydro enginer here, with help of few smart programs like NavCad or it's free analogs, can quite accurately estimate drag of SW hull (or at least difference between LA hull and SW hull) and maybe even the propeller efficiency, although it's a water jet... there are good programs for determining ordinary propeller performance but don't know if for waterjets... In most simple case we could compare drag increase of SW hull to LA hull and compare this with official data of output shaft power, and see what speed could we get... the question is if we can trust the values that are given for SW propulsion...? ;-)

I'm not correcting, I'm just asking: are not the nuclear carriers bigger than conventional ones?
If so, the engine power of the nuclear reactor should be bigger than conventional to move them at same speed.

I was talking about the case when they were same or very similar type of carrier, older units with conventional and newer ones with nuclear (was that te case?). People tend think (after reading Clancy's books) that nuclear carriers are capable of much higher speeds, some people claim 37 some even over 40kts "in emergency". But they all forget that those carriers shared the same steam turbines and all other machinery, only the steam generators were different (conventional or nuclear). The turbines had the same maximum power output so max speed was in fact the same.... Nuclear not faster than conventional ones...
But what was true that nuclear ones can accelerate much faster from low to high speed (leaving all other conventional ships in group behind, that could make false impression that they are much faster - even though fast conventional ships eventually speeded up and could even overtake the carrier at max) and can keep those max speed for long periods without worring for fuel efficiency.

Where was am reading about this... :hmm: same site as "russian post-wwII torpedos" page... NavWeaps... O here it is:

http://www.navweaps.com/index_tech/index_tech.htm

search for 'Speed Thrills III - Max speed of nuclear-powered aircraft carriers"

:)

P.S. I have read that again and indeed - seems that some CVNs are little bigger than older CVs and actually - yes, slower, with the same power output. So you are right :)

Enterprise 33.6 knots (actual after last refit)
JFK 33.5 (design speed)
Kitty Hawks 33.6 (design speed)
Forrestal 32.0 knots (design speed, lower because of only 260k HP compared to 280k for above)

Nimitz 31.5 knots (actual)
Theodore Roosevelt 31.3 knots (actual)
Harry S Truman 30.9 knots (actual)

I also red once on an spanish defence magazine that the other "problem" with the nuclear powered carriers is the escort.
While the engine endurance is "unlimited", the carrier needs to be resuplied with food and water. And the escorts need also fuel.
And there's other thing about non-superfast nuclear carriers: some escorts could not follow it so, where's the need of developing a faster carrier? That only will be a waste of time and money (and probably reactor safety) for having a 40knot carrier wich could never use that speed. :shifty:

That magazine also compared the time spent on deploying nuclear and non nuclear carrier groups from its bases... and the difference was very few...

[quote=Amizaur]yep, :yep: In fact, I'm almost 100% certain that that's the origins of both the SW's quieting and its improved poweroutput of its S6W reactor over the older S6G reactor of the LA, I'ld garantee that the S6W has supplemented a traditional coolant loop cycle (like the S6G) with an additional natural circulation cooling loop providing a "silent" (i.e. no coolant pump needed) mode to 20 knots with activation of its traditional coolant pumps for full power. The combination of the two is what neccessitated the larger diameter hull and would also provided increased peak turbine flow (with the maximum flow volume of the steam turbine cycle dictated by the maxmum steam -> water cooling rate of the sub). The addition of a NC cycle, provides a "quiet mode" and boost the maximum steam flow rates at the same time.

At least that's my completely and utterly amateur theory anyway. :)

The SW, when compared to the Akula II, is smaller, lighter, has a more advanced propulsor, larger "powerplant" spacing, and I believe a improved peak output power. A 4-6 knot speed advantage is reasonable to me. (33 knots for the Akula II vs 38knots for the SW, or 35knots for the AkulaII vs 40knots for the SW).

btw, I'm not an expert by any means, but I did do some elementary fluid dynamics training in college. I could share some of the simple and basic stuff I remember if it would help and if anyones interested. Don't remember enough to give any hard calculations though.