LuftWolf and Amizaur's Realism Mod Poll #11: Nuke Speeds

[Kazuaki Shimazaki II]

Originally Posted by Amizaur

Only most modern electric torps like MU-90 with very advanced batteries are said to be in 50kts class speed. The torpedo used in SS-N-27 system is MPT-1UE very small electric torpedo, not designed for it and used previously in russian eqiuvalent of CAPTOR mine. Not most modern probably, some years design.
Very small, very light (that's why they used it instead of great APR family - oh yes, APRs ARE fast, but too heavy for that system... but APRs could be raplacement for Stallion torps).

We can try that last too as a hypo. In my experience at least, the present situation is such that you basically would never carry a Stallion. Its torpedo is inferior (and will remain so after even this latest downgrade of the torp on the SS-N-27). The missile itself has greater range but of limited utilitity since you won't really shoot that far anyway and the SS-N-27 has more than enough reach...

From the link you gave, do you thought about 400 mm (15.75") APSET-95
torp ? Come on, 30.000m of range for 400mm torp ? It's very questionable one, probably two different torpedos are mixed here, the name from one and specs (guessed) from another...

Well, I suppose it won't be at 50 knots for 30000 (too far out of the zone for battery driven), but if I assume it can run 10-12 km at 50 knots (reasonable considering it is supposed to be a 90s torp itself and larger than Mu-90), 30000 yards may well be possible at say 30-35.

[Bubblehead Nuke]

Originally Posted by Amizaur

Yes, but crush depth is a depth at which sub is supposed to collapse, it's designed to it... of course it can withstand little more, but maybe little less... So I don't think anyone would dive to crush depth even if a evading torpedo, because... shipyard can't fix this kind of damage and you won't get back.
Something like diving a fighter plane below ground level to avoid a missile... or better, to dive a fighter plane, in a fog, to or below 0ft altitude to avoid a missile...

P.S. After reading the add on I see that actually we agree in general

As was pointed out in an earlier post, there is a HUGE amount of hull penetrations in the pressure hull of a submarine. There is no 'designed' hull crush depth. They factor cyclic stress from surfacing and diving over the projected life of the hull, add a few fudge factors for the estimated weakest penetration and then put in a 30% safety margin (30% is a GUESS here folks). They call this number on american subs test depth. It is the normal maximum operational depth that a sub can operate at.

Everything is calculated by some big egg head in the sky and we only hope they lubed up the slide rule before they figured all this out. As the ship age and go thru ship alts they modify this number. Some of the older nuke boats actually had their max depth REDUCED because they had exceeded the calculations based on life of the ship.

This is exactly what I had in mind writing. There are NO operational limits in game, that anyone would care about them. Maybe if game penalized after the mission if operational limits were exceeded... something like with friendly fire but not that serious. So we have ABSOLUTE limits only in game. To get people to behave realisticaly (and dive within operational or emergency limits, but NOT crush depth) we would probably have to set not exceeded in real life even in emergency... isn't it called "safe excursion depth" or something like that ? Never exceed depth ?

See above. We called it test depth. The number by the way is variable based on ships speed. As a general rule, the deeper we went, the slower we operated. It had to do with PEACETIME rules and our ability to recover from certain casualties

There is IIRC 150% safe margin in US designs between operational (test?) depth and crush depth... Or was it 175% ? I remember german standards are 200% of operational depth.

Sorry, can't help you there. I can not tell you if you are even close.

Any OPERATIONAL limit would have to be self imposed by the player as it is a set of numbers designed to keep you operating in a safe enviroment (such as it is). It could be imposed by the manuevering limits of the ship. If you go back thru my posts you will see me commenting on the depth excursions exibited by a sub throwing a hard rudder on at high speed. As I said, this comes on MUCH faster and creats FAR more of a depth excursion than is currently modelled in game.

Want to know what I like about this dicussion? With all of the THOUSAND of ex-bubbleheads out there, nobody has given out the real numbers.

That makes me PROUD of the Silent Service.

[Amizaur]

Originally Posted by Kazuaki Shimazaki II

Well, I suppose it won't be at 50 knots for 30000 (too far out of the zone for battery driven), but if I assume it can run 10-12 km at 50 knots (reasonable considering it is supposed to be a 90s torp itself and larger than Mu-90), 30000 yards may well be possible at say 30-35.

The page

(http://www.navweaps.com/Weapons/WTRussian_post-WWII.htm)

is very good, but there are few mistakes. for example UMGT-1 torpedo is listed as 450mm torp. And the APSET-95 torpedo (last on page) is just an error. The APSET-95 torpedo is just an export version of UMGT-1 torpedo that is listed above. You can see it has max speed of 41kts. I thought the specs may be mistaken with USET-95 torpedo (which is export version of old SET-40 or SEAT-40) but it's older and has even lower performance...
Don't know where the 50kts speed and 30km of range was taken from, but most probably the info was about different torp or just plain wrong.

Mybe from here:
http://www.strategypage.com/htmw/hts.../20030108.aspx
then it's plain wrong

or maybe someone mistaken APSET-95 with USET-95 from Janes that sometimes give 50kts and 30.000m specs for it (but first it's different torpedo!! and second this data is probably also wrong because it's rather old design, based on SET-40 or SEAT-40).

APSET-95 is not separate design, just export version of UMGT-1 (Stallion payload).
If UMGT-1 had max speed of 41kts, then improved version can have 45kts but seems unlikely 50kts. UMGT-1 range was 13.000m at slow speed, so seems highly unlikely that it could be made 30.000m in improved export version.
The best and most modern current lightweight torpedo, Eurotorp MU-90 Impact, has max range of 25.000m at slowest speed...

Yes, there are high-performance Russian torps... For example USET-80 that makes about 50kts. But it's a heavyweight torpedo. We don't have any example of lightweight russian electric ASW torpedo that can do 50kts...
There are very fast rocket powered torps only.

Some info from Janes on Russian LWT's

SET-40 (USET-95)

A battery-powered weapon with active seeker which has a range of 585 m. It has a maximum operating depth of 200 m and a 60 to 80 kg warhead. It is launched from surface ships. The SET-72 is a dual-role version with slightly improved performance, operating down to 300 m. Externally it is a traditional design of a long slim cylinder with pointed nose, fins in cruciform configuration and twin contra-rotating propellers in front of a rudder. Internally the active/passive seeker is in the front of the weapon. Behind it is the warhead with impact and proximity fuzes and then the guidance section. The middle of the weapon has the batteries, possibly silver-zinc oxide, while the rear of the weapon contains the electric motor and the actuators. Publicity material from the manufacturers suggests that the weapon might also be a wake-homer for use against surface ships. Both weapons were later upgraded with the Sapfir guidance system.

SET-40 has a top speed of 28knts, a range of about 8000 yards and weighs in at about 650kgs. SET-72 is about 2ft longer - offers a 2knt improvement in speed and an increase in range to about 14000 yards.


UMGT-1 (APSET-95)

Air-launched weapon. Externally it is a short, fat cylinder with pointed nose, a sea-water scoop on the underside, four cropped-delta fins in cruciform configuration, a shrouded propulsor and a parachute pack at the rear. Internally the active/passive seeker is in the front of the weapon with guidance section behind it. Near the middle of the weapon is the 60 kg warhead with both impact and proximity fuzes. A seawater-activated copper-magnesium battery occupies the middle of the weapon with the electric motor and actuators in the rear. It can operate to a depth of 400 m.

Janes statistics list two ranges for UGMT-1 - one of 8000yds and one of 13000yds presumably this means two speed settings on the weapon. They list 41knts as the weapons top speed though.

and data of MPT-1UE torp, payload of SS-N-27 ASW:

Torpedo data:
weight, kg 285
calibre, m 0.324
length, m 3.05

"little" lighter and smaller than UMGT-1 and APR's, don't you think ?

The british Stingray torp is similar in weight and dimensions, very very modern in it's time (80's) and it's rated at 45kts. 324mm MU-90 is said to be 50+ kts but it's a generation ahead...

I think 45kts for SS-N-27 ASW payload is very good deal

[LuftWolf]

I think 45kts for SS-N-27 ASW payload is very good deal

I agree, and it's electric!

Originally Posted by Kazuaki Shimazaki II

In my experience at least, the present situation is such that you basically would never carry a Stallion. Its torpedo is inferior (and will remain so after even this latest downgrade of the torp on the SS-N-27). The missile itself has greater range but of limited utilitity since you won't really shoot that far anyway and the SS-N-27 has more than enough reach...

Correct. The Stallion is a remant of the era when nukes would detect each other across CV's, and then practice firing nuclear SUBROC's at each other.

The nuclear SUBROC was the PRIMARY ASW weapon of the Cold War Era.

In fact, it's even likely that having the SS-N-27 in the game is anacronistic boardering on quaint.

In ASW terms, the Stallion has such a range to be considered perhaps in DW as an "operational level weapon", something like the mines. Generally speaking, unless you have intel that the acoustic conditions are producing a CV of such and such range band for the CV1 and you know there is a nuke coming your way, the Stallion just isn't going to be much use.

In terms of the mod, there isn't much we can do about this. Unlike the MK46 to Mk54 conversion, or the SET-53 to YU-8 conversion, the Stallion is not COMPLETELY useless, and it is not likely to be replaced by anything in the near future. In fact, it does/did it's job quite well, it's just that it's job doesn't come up very often in most DW missions. But if you find a nice fat CV with a nuke you want to torpedo... you've got the right weapon in the Stallion.

[LuftWolf]

Then again, I could put an APR-2 on the Stallion... that's likely. The Stallion could deliver this weapon.

I'll get back to you all about how this would impact balance.

[LuftWolf]

Ok, how about a Stallion with an APR-2, retaining it's original range (which is no great advantage usually anyway).

The APR-2 is a rocket powered torpedo with a max speed of 55kts (in real life it is much higher, but for us it is in the band where the DW physics engine doesn't work very well and produces wild speed oscillations) and range 3000m. The torpedo will run in a straight line when dropped by the Stallion, unless it acquires a target.

Yes, this does allow for someone tracking the torpedo to get your bearing.

PS The mass of the APR-2 and the UMGT-1 are exactly the same, so this is a nice switch to make. Thanks for the suggestion Kaz.

PPS Actually there is no reason not to upgrade all the APR-2 to APR-3 standard, so I'll do that too.

[LuftWolf]

OMIGAWD LWAMI4 is going to have so many changes... the readme is going to be nearly impossible to write this time.

Keeping track of everything for you guys is important...

[Amizaur]

Originally Posted by LuftWolf

Ok, how about a Stallion with an APR-2, retaining it's original range (which is no great advantage usually anyway).

The APR-2 is a rocket powered torpedo with a max speed of 55kts (in real life it is much higher, but for us it is in the band where the DW physics engine doesn't work very well and produces wild speed oscillations) and range 3000m. The torpedo will run in a straight line when dropped by the Stallion, unless it acquires a target.

Maybe make it working like the real one - after entering water it is not starting it's engine, but it is falling slowly in the water circling (making no sound!) and scanning for targets (not sure first passive and then active, or only active) and only after detection it starts it's solid fuel engine and attacks target at a speed over 70kts. Much less time for reaction (no TIW message probably and no engine sound) and after hearing active pings, torp is attacking you at over 70kts already... absolutely deadly weapon...

But... rearming the Stallions with them was for sure considered, but this requires money... and we all know that Russian navy don't have it even for proper maintenance of what it already has... :-/ There were rumours that 70% of all launched USET-80s (primary russian universal ASW torp, but torps are old and not maintained properly) used in practice or tests, fails and sinks after launch...

[Kazuaki Shimazaki II]

Originally Posted by Amizaur

There were rumours that 70% of all launched USET-80s (primary russian universal ASW torp, but torps are old and not maintained properly) used in practice or tests, fails and sinks after launch...

On the other hand, on such exercises you'd probably sacrifices your oldest missiles first - the ones ones most likely to fail.

Besides, if the USET-80s are really all in such a bad state, so would the UMGT-1s of similar vintage on the Stallions, which are also battery powered. So they either change the torpedo or take the weapon out of service. Since we can't take a weapon out of service in the game or have them fail 70% of the time , we might as well upgrade it, methinks.

Janes statistics list two ranges for UGMT-1 - one of 8000yds and one of 13000yds presumably this means two speed settings on the weapon. They list 41knts as the weapons top speed though.

Just a nit here, but if I see two ranges for a torp but a single listed speed, I'd assume the longer range represents a later configuration.

Oh, BTW, did you quote the above from here?
forum.keypublishing.co.uk/archive/index.php?t-32945.html
and
forum.keypublishing.co.uk/showthread.php?t=3449

[Deathblow]

Originally Posted by LuftWolf

Well, the ranges for all the submarines are about 28-35 for 688i, 28-35 for the Akula, and 35-47 for the SW.

Anyone could reasonably justify setting the speeds for the subs anywhere in here.

Now, it just so happens that one can reasonably project for the 688 from the previous US classes, and also one can suspect that the 688i is no faster than the 688, based on the specific improvements known to be done to that class. My estimates, and about 75% of the opinions I have read, place the 688i speed at 31-32 kts.

For the Akula, the generally reported speed for the original Akula is 33kts. In regards to the Akula ImpI/II, there is a lot of dispute over just what the difference between ImpI and II is exactly, but the best sources place the speed of the Akula II at about 35kts. However, since the sources also show that the ImpI and II have more in common than the I and ImpI, it stands to reason that the reactor and major drive elements are shared more or less the same between Imp I and II, with the differences mainly being in the transmission and active sound reduction systems.

For the SeaWolf, that really is anyone's guess...

There is no single source that one can point to most of the time and say that this value should be used over another, but rather a process or sorting through the data and deciding on what would work best in game.

And since I'm the one currently doing the work, I get to make those calls. It's a bitch, but someone has to do it.

That sounds reasonable.:hmm: Always nice to see reasoning/sources to support stats...

...But not in my game! Deathblow's own personal "Mod of Awesomenss" says

SW 41knots
LA 37knots
Akula 27knots
Kilo 15knots

j/k

[Amizaur]

Originally Posted by Kazuaki Shimazaki II

Just a nit here, but if I see two ranges for a torp but a single listed speed, I'd assume the longer range represents a later configuration.

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).

Oh, BTW, did you quote the above from here?
forum.keypublishing.co.uk/archive/index.php?t-32945.html
and
forum.keypublishing.co.uk/showthread.php?t=3449

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

[LoBlo]

Originally Posted by Bubblehead Nuke

They factor cyclic stress from surfacing and diving over the projected life of the hull, add a few fudge factors for the estimated weakest penetration and then put in a 30% safety margin (30% is a GUESS here folks). They call this number on american subs test depth. It is the normal maximum operational depth that a sub can operate at.

Everything is calculated by some big egg head in the sky and we only hope they lubed up the slide rule before they figured all this out. As the ship age and go thru ship alts they modify this number. Some of the older nuke boats actually had their max depth REDUCED because they had exceeded the calculations based on life of the ship.

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)

[LoBlo]

Originally Posted by Henson

688's can go pretty fast. Seawolf can go ungodly fast. Akula? I have no idea.

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.

[Amizaur]

Originally Posted by LoBlo

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.

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... 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...? ;-)

[FERdeBOER]

Originally Posted by Amizaur

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).

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.