making the Seawolf silent speed of 25 knots and doubling the Kilo endurance

[TLAM Strike]

[quote=To be]

Originally Posted by Castout

Additionally, the pump-jet is quieter, but not silent, and has been used on other subs besides the seawolf, such as the British Trafalgar class.

Not to mention the Russian Kilo submarine Alrosia.

BTW a pumpjet is not as efficent as a normal prop so if you had two submarines of the same class and one was outfitted with a pump jet it would be eather slower and quieter or noiser due to the higher amount of turns being put on the shaft for the same speed. Pump jets make a sub quieter but at slower speeds, they are by no means a HFRO style "Silent Drive".

[MBot]

I always wondered what makes the Seawolve so silent. I think the big jump in silent speed should indicate a major revolution in submarine design. Is there something revolutionary in the machinery of the Seawolve? If it is realy "just" the pump-jet then it is strange that the Trafalgar is not famous for a very high silent speed aswell.

[Frame57]

There are other factors that come into play in the noise level a submarine puts out. The electro/mechanical systems like the hydraulic system, the reactor coolant pumps, the ventilation system. Also how well these systems are designed and sound dampened so as not to transfer noise to the hull itself is a critical componant in being quiet.

[Castout]

The Los Angeles class is an old design though continually refitted with updated weaponry and sensors or electronics but it is an old design.

Just look at the comparative differences between the F-15 which is an old design and the new F-22 Raptor. Both are designed as air superiority fighter. But the later which is designed much later has got super cruise ability and stealth built into it. That two alone are major advancement than the F-15. The F-22 is a revolutionary plane despite its enormous cost to build

The same when I look between the Los Angeles class and the Seawolf class submarines. The Seawolf which is a new design would in most probability incorporate features that are non-existent in the old Los Angeles class. So much so that the Seawolf performance is quite revolutionary compared with the Los Angeles class just like the F-22 when compared with the F-15.

In my opinion the RL Seawolf is even quieter than the one I try to imitate through my modification. Perhaps between 2-5 point lower than it is now in my modification.

The Akula II as it is now in LWAMI is already quieter than the Improved Los Angeles class which imo is not accurate as even the noise performance of the Akula II is still lower(noiser) than the improved Los Angeles class though the difference may not be much.

Also can somebody explain to me the high tensile non-magnetic steel that the Germans use in their submarine. Will this material prevent MAD detection?

The thing that disappoint me is the inability to modify the battery capacity of any diesel-electric submarine in the game. That really sucks a lot. Perhpas Sonalysts could make not a patch but rather a battery fix that modify existing battery capaicty of all diesel-electric sub in game to a value closer to RL. Right now the Kilo submerged endurance is half that of what DW writes in the USNI entry.

[LoBlo]

Originally Posted by MBot

I always wondered what makes the Seawolve so silent. I think the big jump in silent speed should indicate a major revolution in submarine design. Is there something revolutionary in the machinery of the Seawolve? If it is realy "just" the pump-jet then it is strange that the Trafalgar is not famous for a very high silent speed aswell.

I think everyone has his/her theories; I certainly have my own... completely speculative albeit.

I've heard one theory is that the Seawolf is using large and extensive raftings which is one reason the Seawolf needed to be so much larger than the 688. (2300 tons heavier).

The other thing that I haven't heard alright but suspect is that the Seawolf is probably using a natural circulating reactor which the 688 class was too small to fit (another explaination for the SW neccesarily larger size). The USNavy was using them in their super quiet SSBNs, but couldn't fit them in the 688 so a bigger, new sub was probably needed.

Those are my theories anyway. All is just guessing.

[Bubblehead Nuke]

Originally Posted by LoBlo

I think everyone has his/her theories; I certainly have my own... completely speculative albeit.

I've heard one theory is that the Seawolf is using large and extensive raftings which is one reason the Seawolf needed to be so much larger than the 688. (2300 tons heavier).

The other thing that I haven't heard alright but suspect is that the Seawolf is probably using a natural circulating reactor which the 688 class was too small to fit (another explaination for the SW neccesarily larger size). The USNavy was using them in their super quiet SSBNs, but couldn't fit them in the 688 so a bigger, new sub was probably needed.

Those are my theories anyway. All is just guessing.

The S6W reactor core was first taken critical in the S8G prototype plant in upstate NY. Seeing as how the S8G is publically stated to be a nactural circ reactor it is a pretty safe bet that the S6W is as well. When you look at the thermal and hydraulic design limits and parameters of a reactor core, you do not just 'drop it in' a plant that does not meet these requirements. A power plant is designed to handle the core, not vice versa. The S6W plant is the one that drives the Seawolf class.

Something else you might not know. A 688 was originally supposed to have a natural circulation plant. When you look at the plant layout there are many similarities with the S8G plant design. However, there was insufficent hydraulic head to get sufficient flow in the plant to conduct power ops. Basically, the hull was not big enough. This meant that the quieter natural circulation could not be used to lower the noise signature.

[To be]

Is the S9G natural circulation? I would hope so, but the VAs are smaller. I do have an extremely hard time visually differentiating the Seawolf and Virginia classes, other than the general perception of the Seawolves as a bit stouter.

[Bubblehead Nuke]

Originally Posted by To be

Is the S9G natural circulation? I would hope so, but the VAs are smaller. I do have an extremely hard time visually differentiating the Seawolf and Virginia classes, other than the general perception of the Seawolves as a bit stouter.

Unfortunately, I got out before the VA class was really being discussed. While I was in they were still calling it the NSSN concept, not the VA class.

However, with the advent of computer aided design (the seawolf was the first US sub to use this btw) I am sure they can pull tricks off that would have been speculation only a decade before. A nuc sub is not designed in a year or 3. It takes a DECADE of planning and engineering analysis before the first order is even made.

[LoBlo]

Thanks for the perspective BH, insightful as always.

As for VA, my guess... as a complete and utter layperson... is that there's probably a reason the Virginia Class has the same payload, crew size, yet is almost 1000 tons larger than the 688 (7800 tons vs 6900 tons). Probably extra room in the engine compartment for a NC reactor (bigger than the LA, but smaller than the SW) and/or other quieting techniques.

[Castout]

I worked on further on my modification with DWEdit. And this is the result.
A very simple mod . Thought I share it with you. Comments are welcome.

http://www.subsim.com/radioroom/show...897#post971897

[TLAM Strike]

Don't forget the steam turbines that actually turn the prop shaft. Bigger sub = more room for queiting those.

Also the 688(i)s and SW have ancotic (sp?) tiles which US subs lacked for a very long time. Those not only absorb active sonar pings they also absorb sub self noise. Which is one of the reasons Russian subs are queit at low speeds (two hulls with these tiles).

[Bubblehead Nuke]

Originally Posted by TLAM Strike

Don't forget the steam turbines that actually turn the prop shaft. Bigger sub = more room for queiting those.

Also the 688(i)s and SW have ancotic (sp?) tiles which US subs lacked for a very long time. Those not only absorb active sonar pings they also absorb sub self noise. Which is one of the reasons Russian subs are queit at low speeds (two hulls with these tiles).

To be quite honest here, the reason they are quieter is due to the MASSIVE improvements in pump impeller designs gained when Toshiba sold them all the fancy metal milling machines. The predominate noise produced by a nuclear sub is not from the screw, but from the gear used to run and support the reactor plant.

While they got the quieter pump impellers, they still have the lousy screw designs that were optimized for speed and acceleration rather than stealth. At a slow enough speed, even these screws were pretty quiet. Thus you have a quiet boat at slow stalking speeds. As soon as they start cranking up the RPM'S they are just as loud as ever. Their reactor plants also have some fundemental differences in operation from the American boats that showed a greater noise impact from the improved impeller construction.

Why did they design the screws for speed and acceleration you ask? The plants were noisy as heck so why not make it a better performer. A quieter screw had no purpose. Thus they were better equipped to runout maneuver a torpedo. If you can get up to top speed fast enough, you could get out of the aquisition cone of the incoming torpedo.

Also, there was a funamentel difference in MISSION between US and the Soviet subs. Ours was a forward offense mission while theirs was more home water defense. A boat had to be able to move QUICKLY to get into an intecept position based on external data. Thier boats works as teams with surface and/or air assets while our boats operated in a more independant ops mode.

[TLAM Strike]

Originally Posted by Bubblehead Nuke

To be quite honest here, the reason they are quieter is due to the MASSIVE improvements in pump impeller designs gained when Toshiba sold them all the fancy metal milling machines. The predominate noise produced by a nuclear sub is not from the screw, but from the gear used to run and support the reactor plant.

While they got the quieter pump impellers, they still have the lousy screw designs that were optimized for speed and acceleration rather than stealth. At a slow enough speed, even these screws were pretty quiet. Thus you have a quiet boat at slow stalking speeds. As soon as they start cranking up the RPM'S they are just as loud as ever. Their reactor plants also have some fundemental differences in operation from the American boats that showed a greater noise impact from the improved impeller construction.

Why did they design the screws for speed and acceleration you ask? The plants were noisy as heck so why not make it a better performer. A quieter screw had no purpose. Thus they were better equipped to runout maneuver a torpedo. If you can get up to top speed fast enough, you could get out of the aquisition cone of the incoming torpedo.

Also, there was a funamentel difference in MISSION between US and the Soviet subs. Ours was a forward offense mission while theirs was more home water defense. A boat had to be able to move QUICKLY to get into an intecept position based on external data. Thier boats works as teams with surface and/or air assets while our boats operated in a more independant ops mode.

Well better screws were a part of it but not as you think, the screws of the 3rd Gen Russian subs (Typhoon, Oscar, Akula, Sierra, Mike) were designed before that, the Japanese and Norwegian “scandals” simply allowed the Russians to build their own designs of better quality and faster.

When I talked about quieting I was thinking of 1st Gen subs. It might be hard to believe but the early Russian subs were stealthy than ours at low speeds thanks to anechoic tiles on that big double hull of theirs. The US 1st gens nucs were noisier than the WWII fleet boats! Nautilus was renowned for its self noise over 8 knots, in fact she was a test bed for experiments relating to that. I know Bill our Master of Defense has shared several stories about their time as a test bed sub.

Back to Russia in the 80's reactors were also quieted the OK-650a was capable of natural circulation for cooling at low speeds. The Sierras used this reactor, the Akula's have a similar plant the OK-650b same as the Oscar. (The Typhoon had the OK-650, the Mike the OK-650b-3) Latter Russian boats also have “Active Noise Cancellation” systems which I've never heard of US boats having.

[tippership]

Yea, this is a few years old, but i'm bumping this -

I'm attempting the same thing in the Reinforce Alert Mod- I have DWedit, and have been doing a ton of 1 on 1's with hostile Virginia's against me driving a Seawolf - and they've been slinging adcaps at me while i couldn't detect their subs, only their torpedoes when they shoot at me- and i'm not close enough for their high frequency sonar to see me, and i usually bounce between 2 knots and 10, but they find me every single time(before i find them)..... at about a nm range of no more than ten or so...(both the base seawolves and the jimmy carter)


Maybe i need to pilot the virginia against a seawolf..and see if it happens again...lol.


-crazy ivan posted the actual sound chart spreadsheet here on this page as a download
http://www.redrodgers.com/forums/sho...d.php?p=137040

-but when i look in DWedit, it doesn't match up- the spreadsheet might be out o date, as i'm on 1.3.7 RA, but...its was hardly 2 pages back...from the 1.3.7 mod...

If you look at the spreadsheet - for the virginia and seawolf at 0 knots
-virginia is at 58, seawolf is at 57 , and the jimmy carter(it's seperate from the first 2 seawolves in the database) is at 57

Now i open up Dwedit, and look at the object dialog menu , and pull up the seawolf and virginia, and the passive sonar SL has the virginia at 53, the seawolf at 54, and the jimmy carter at 57...
I'm having trouble making sense of what this means- it looks like DWedit is saying the virginias emit less sound in general than the seawolves(let alone it's looking like the jimmy carter went BACKWARDS in that it's louder, unless i'm reading this backwards and i dont think i am, as the 688i's have higher numbers.

so i open up the thrust dialog menu in DWedit , and looking at the numbers ,, it has base noise and speed noise
virginia base noise 3, speed noise is 16
seawolf base 0 , speed noise is 17,
and then jimmy carter(under 0044, it shares the same one with 2 other subs, the amethyste and astute) -is set at base 0, speed noise 18


..I don't understand what this means.
Can anyone help me make sense of these numbers?


So if it's thrust dialog- then the seawolf at zero is quieter, but at full speed is louder than the virginia at full speed, and the jimmy is even louder??? Or does the passive Sonar SL thing in the object dialog menu mean the virginia is quieter with it's 53?

My goal is to see if the Virginia are somehow set as quieter, and if so, to use DWEdit to make the seawolves match the virginias ...So i can quit getting owned* by my cheaper , lesser-capable alternative
*to be fair, i have defeated virginias in the seawolves in one on ones, but i'm still suspect about who's superior noise-level wise.


I know the original posters aren't around, 5 years later, but i'm a bit surprised to hear pumpjets aren't as efficient as open propellers - thrust wise, i thought pumpjets are better. Sort of how like turbojets are better than open propellers if they are at high speed(yes in low altitude dense air ,props aren't bad)

Originally Posted by LoBlo

SpeedNoise in the thruster dialog represents how much additional "noise" the platform emits at top speed. For example a SpeedNoise of 10 means that at top speed the platform emits (base sound levelnoise) + 10 additional noise points. A SpeedNoise of 20 means the platform will emit (base sound level) + 20 additional noise points.

The lower the value the less additional noise at top speed the platform will exhibit.

If you want to lower the overal noise of the platform its in the "object" dialog in the valuebox Passive Sonar SL.



After you change a value in one of the dialog, be sure to press the "apply" button, or the changes will be discarded when you switch to a different platform (different than the save button).

Reading this, I still am not sure how to make sure the virginias aren't quieter than the seawolves, because these 1 on 1 fights don't include a lot of running around at top speed, - the passive sonar is what is confusing me. If you add base noise + speed noise, the virginias are indeed louder than the seawolves- but that passive Sonar level thing from the object dialog menu.....???????

[LoBlo]

Originally Posted by tippership

Reading this, I still am not sure how to make sure the virginias aren't quieter than the seawolves, because these 1 on 1 fights don't include a lot of running around at top speed, - the passive sonar is what is confusing me. If you add base noise + speed noise, the virginias are indeed louder than the seawolves- but that passive Sonar level thing from the object dialog menu.....???????

So you will have to decide what "quieter" means. You can give the SW and the Virginia the same passive/base noise level which will make them equally quiet at stop.

Then you will have to calculate the amount of noise added per knot from the thrust menu for the SW (or Virginia, whichever you decide to use as your standard) and decide the value of the "speed noise" in the other boat's thrust menu that will grant the same amount of noise/knot.

They will then have equal noise emissions at each speed, with the caveat that since the SW is faster, as it passes the Virginia's max speed it will then exceed the Virginia's noise levels.

Another approach is to make each boat the same noise at each's respective top speed, but the result will be that the SW will also be quieter than the Virginia at any equal speed.

Hope that makes sense.

LB