SSN Seawolf Class Attack Submarine, USA

last SG · 2008-12-12T01:55:56+00:00

and your purpose of pasting the whole article from naval-technology is ... ?anyway, just to liven it up ...2-1 odds that LN will post here1-1 odds that LN wi...

Fingolfin_Noldor SG

I'm not really very current with Russian Subs... but even their Akula II SSNs didn't have comparable detection capabilities compared to the SeaWolf or Virginia. They caught up with the 688i, but it seems like the Americans are still ahead.

Says who? Even the Americans have been careful about disclosing any of their weaknesses. The public estimate is the Akula I alone if I am not wrong is as good/nearly as the 688I if not better. Also, it is not so much a matter of who is extremely quieter than who now, but whether the submarine captain is smart enough to utilize his submarine effectively. All submarines have a silent cruise speed and when stalking the prey, no submarine captain will breach that speed but rather stay below that. High silent speeds are of course useful but by no means a definite game changer. The Russians have for the last few decades worked pretty hard to match the West and they have quite a few innovations. For example, they have one torpedo that has two stages and can be launched from a few tens of kilometers before striking the enemy ship, thereby keeping the submarine as far away from the enemy vessel.

At this point of time, it has come down to a game of tactics. Russian submarine reactors now have an air-circulation mode similar to that of the Ohio submarines (and no doubt the Seawolf). They can be damn bloody quiet when they want to be. It should be telling that the trend is heading towards a towed active sonar array in part to look for diesel subs but also nuclear submarines as well.

Fingolfin_Noldor SG

To reinforce this, read this article by Norman Polmar, a US naval anaylst (who apparently was notorious for leaking classified information)

http://www.fas.org/man/congress/1997/h970318n.htm

sgstars SG

interesting.

i thought the trend was to go into ULF sonar or VLF sonar arrays ? strategypage has an interesting articles about heavyweight torpedos today.

apparently no modern wire guided torpedo has been fired since wwII if you take the strategypage article seriouslly and dont count the USS Scorpion.

i'd like to add it has to do with the salinity of the water and the various thermoinclines. hardware will only take you so far. under the cooler and denser (supposedly more saline layer), the sub is more quieter than one which is in the warmer and less dense thermoincline layer (im not too sure on this, my knowledge of this is pretty vague)

anyone knows what are the thermoinclines for our waters ? our Sjoormens/Vastergotlands were adapted and Tropicalized to adapt for our waters right ?or was it more of a install air-conditioning for warmer waters in singapore vs cold baltic waters ?

what about the indonesian Kilos and Malaysian Scorpenes ? are they adapted too ? ATM RTN has no submarine vessels right ?

Fingolfin_Noldor SG

interesting.

i thought the trend was to go into ULF sonar or VLF sonar arrays ? strategypage has an interesting articles about heavyweight torpedos today.

apparently no modern wire guided torpedo has been fired since wwII if you take the strategypage article seriouslly and dont count the USS Scorpion.

http://en.wikipedia.org/wiki/Sonar_2087

http://fas.org/irp/program/collect/lfa.htm

It's Ultra Low Frequency Active Towed Sonar Array.

The Sonar 2087 being installed on the British Type 23 frigates is a Towed Low Frequency Active Sonar. These days subs are so bloody quiet, it's time to go back to the good o' Active Sonar.

As for torpedoes, they have their own acoustic homing, or wake homing (for Russians only).

A decent book to read on Submarine design is again by Norman Polmar: Cold War Submarines.

Shotgun SG

I was referring to the Akula II's ability to detect, hence detection capabilities. Its been long acknowledged that Russians have been building very quiet and capable boats. However, last I heard anything about this (hence I am a little out of date), is that the Americans still had better sonars and other forms of detection methods.

Its not just about towed sonar arrays, but the quality of the hydrophones and acoustics analysis capabilities as well.

Shotgun SG

interesting.

i thought the trend was to go into ULF sonar or VLF sonar arrays ? strategypage has an interesting articles about heavyweight torpedos today.

apparently no modern wire guided torpedo has been fired since wwII if you take the strategypage article seriouslly and dont count the USS Scorpion.

what about the indonesian Kilos and Malaysian Scorpenes ? are they adapted too ? ATM RTN has no submarine vessels right ?

sg waters are too shallow to have thermoclines which is layer of distinct change in water temperature (and sometimes even temperature inversion).

Both salinity, density and temperature of water has large effects on the speed of sound travels under water. It is possible to mask a submarine's presence by dodging below the layer because of the change in the speed of sound at the layer causes the sound to be largely contained to one side of it.

To investigagte POSSUB contacts in such an evironment will require sonobouys to be dropped at depths both above and below the layer, hence making it more tedious.

The problem with Active Sonar is that everybody know's you're in the neighborhood, the fairly large neighborhood. Most submarines have active-intercept arrays that tell them the bearing of the Active sonar ping, and can relay such information to their surface counter parts or fleet intelligence.

With 2 or 3 other submarines just sitting around, a fleet that goes around active-pinging at ghosts will allow the enemy to triangulate their positions and heading easily. Hence active sonar isn't the solution to the submarine problem.

http://en.wikipedia.org/wiki/Thermocline

As for this page -> http://www.fas.org/man/congress/1997/h970318n.htm

The information there is almost 11 years old and slightly dated to the point of inaccurate. Would appreciate if you have more current information.

The USN Improved LA class Subs have already gained abilities deploy underwater mines (gps guided) as well as UUVs (unmanned under water vehicles) as off-ship sensors.

Of course, this is not to say the Russians aren't keeping up.

3 new classes of Russian submarines to look out for: The Amur (SSK export name Lada), Borei (SSBN) and the Graney (i think...). The Graney might actually be a smoke screen for another SSN that may supersede the Akula II. The class name popped up over the net some time ago but I can't seem to recall it for the life of me.

Still, the Kilos and Akulas (I and IIs) were relatively successful and are now heading for the export market. It seems that the Russians have something better coming up.

slim10 SG

The Sonar 2087 being installed on the British Type 23 frigates is a Towed Low Frequency Active Sonar. These days subs are so bloody quiet, it's time to go back to the good o' Active Sonar.

There's a lot of research going into sonar-armed UUVs. Basically, these unmanned vessels will scout around. If they trigger an attack from enemy subs, then asw assets can focus on the attack area. Kinda like UAVs do with SAMs. Also much better than static hydrophone lines as the patrolling area is flexible.

Fingolfin_Noldor SG

Ah.. you forget a few things. There's no reliable IFF that exists underwater, nor is there a viable long range communication system. Short range is possible, but you must know where the other submarine is. In fact, friendly fire incidents between submarines is quite possible. Also, there's no way that a ship can possibly travel quietly. Propellors near the surface generate too much cavitation and noise. There's also the option of having a wave following sensor which the Russians have.

Active sonar on the other hand provides high resolution acoustic images. Something passive cannot achieve right now.

Fingolfin_Noldor SG

You guys should also note that recent filed lawsuits against the USN were also over active sonar testing: http://www.nrdc.org/wildlife/marine/sonar.asp

And you can't kill whales with passive. You kill them by making them deaf with a loud ping at resonant frequency!

Shotgun SG

Thats true. Theres been lots of concern over the use of Active Sonar and its impact on biologicals in the area.

In any case, I guess you've reinforced my point that even the use of Active Sonar does not really help in locating submarines. Fleets pinging away trying to look for submarines will only expose their positions. For now, submarines have the advantage...

I have heard of a satellite based method of hunting subs though... I'm not sure what level of development thats at..

slim10 SG

"There's no reliable IFF that exists underwater"

Always tot the US subs used the AN/BRA-34 (Demand assigned multiple access module) as send signals for sat based IFF.

Fingolfin_Noldor SG

Thats true. Theres been lots of concern over the use of Active Sonar and its impact on biologicals in the area.

I have heard of a satellite based method of hunting subs though... I'm not sure what level of development thats at..

How does this reinforce anything? I have said time and again that only active sonar can give accurate image of the area. Why do you think ultrasound provides pretty decent images of babies these days? The processing technology is already there. Passive sonar cannot work at all well in a littoral environment.

Ships are never quiet. Wave homing technology already allows the Russians to track waves made by ships and thus the ships in question.

Fingolfin_Noldor SG

"There's no reliable IFF that exists underwater"

Always tot the US subs used the AN/BRA-34 (Demand assigned multiple access module) as send signals for sat based IFF.

The surface of the water is notorious for blocking signals by virtue of reflections. You probably have to go near the surface to use it.

Shotgun SG

Ships are never quiet. Wave homing technology already allows the Russians to track waves made by ships and thus the ships in question.

No thats not true at all. In fact, an sonar echo return from an active sonar only tells you there is an object there, IF it even returns an echo. Active Sonars faces severe limitations in littoral evironments and even open oceans where thermocline layers can reflect active sonar pulses.

An Active Sonar does not serve in any purpose as an IFF. Passive Sonar does that when we do blade count analysis, Turns Per Knot, and frequency analysis of engine noises etc. Correct me if I'm mistaken, another problem with Active Sonar is that it transmits over long distances, but the echo returns attenuate easily and is lost over a considerable short distance.

Wave homing technology is not reliable at best. Towed Decoys have demonstrated to be effective in spoofing wave-homing torpedoes. There are several other countermeasures as well.

sgstars SG

Just curious Fingolfin_noldor, not too sure if i m right on this

if you are saying that passive sonar technology has plateaued and the new developmental trends are in active sonar or ultra low frequency active phased arrays.

then why do destroyer doctrines focus on rabid active pinging of a sea area to hunt for subs and subs focus on passive sonar for detection and hunting of surface fleets and subsurface combatants ? the sub stays passive to avoid detection from surface and potential protector subs.

to suggest that subs are using active sonar to search and detect enemy surface and subsurface combatants seems like a complete abandonment of the traditional hunter-killer sub doctrine ?

instead of stealth and hunt, now you have an active, create a helluva lot of noise and draw attention to yourself hunt ? its turning classic anti sub doctrine on its head isnt it ?

this is the bit i dont understand. seems to conflict with what little i know about sub hunting doctrines.

unless u mean the new type low frequency active sonars cannot be detected by other combatants in the area (surface or subsurface). but surely the target that is being pinged, can identify the general direction and threat in the area ?

Fingolfin_Noldor SG

Wave homing technology is not reliable at best. Towed Decoys have demonstrated to be effective in spoofing wave-homing torpedoes. There are several other countermeasures as well.

I never said Active Sonar ever served as an IFF. How do you suggest using a Passive sonar to detect anything if a skilled Submarine captain chooses to go into his silent mode? Passive sonar is only as useful as the sensitivity and how stupid the submarine crew in question, and because of the increasing level of quietness, the USN has resorted to working on active sonar again. Norman Polmar explicitly stated that the USN has to revamp its entire detection paradigm.

Let's take a look at this sonar system: http://www.globalsecurity.org/intell/systems/lfa.htm

This sonar system was installed on the USN's small fleet of ocean surveillance vessels. It is meant to operate alongside the SURTASS passive system.

Note these paragraphs:

The U.S. Navy plans to deploy a new submarine detection system, known as Low Frequency Active Sonar (LFA), throughout 80% of the world's oceans. LFA is based on the fact that very low frequency sound [100-1000 Hz] can travel great distances and detect quiet submarines. The LFA system uses intense sound, reportedly [the Navy has given a figure of 160 dB at about 2 km from the LFA] at levels in the range of 235 decibels or greater [the noise level of a jet engine is about 120 dB] generated by massive sound transmitters towed behind TAGOS-class ships.

Current passive SURTASS towed array sonars are limited in their capability to detect quiet submarines. Thus research has been going on for some time in the area of low frequency active (LFA) towed array sonar. LFA offers the potential for TAGOS ships to make longer range detections of quiet submarines.

The shallow-water acoustics problem has risen in importance due to the increased salience of regional conflicts where the US Navy may to encounter slow, diesel submarines close to shore. The shallow-water, slow submarine is significantly more difficult to detect and classify acoustically than the cold war threat, due to the complex propagation, high clutter, and low target Doppler. Effective sonar performance requires new processing algorithms which cannot be implemented on current Naval platforms due the high processing requirements. A Hybrid Digital/Optical Processor (HyDOP) is to demonstrate the feasibility of using embedded scalable high performance digital and optical processing to solve this problem. This requires application of computationally intensive algorithms which cannot be implemented in real time using conventional processors. A high-speed optical correlator being developed by the Naval Research Laboratory (NRL) will act as a coprocessor to an Intel Paragon XP/S-25 computer.

The TAGOS ships by the way, is probably the most capable vessels when it comes to detecting submarines. They are as large as a large frigate, and they don't carry anything else beyond the sonar and the processing computers. You can read more of the system in question here:

http://www.globalsecurity.org/intell/systems/surtass.htm

I'm not saying that passive sonar is altogether useless, but in this day of age, you use every single tool available to detect incoming threats. Of course there's still the option of using ASROC if all things fail...

Fingolfin_Noldor SG

Just curious Fingolfin_noldor, not too sure if i m right on this

if you are saying that passive sonar technology has plateaued and the new developmental trends are in active sonar or ultra low frequency active phased arrays.

to suggest that subs are using active sonar to search and detect enemy surface and subsurface combatants seems like a complete abandonment of the traditional hunter-killer sub doctrine ?

instead of stealth and hunt, now you have an active, create a helluva lot of noise and draw attention to yourself hunt ? its turning classic anti sub doctrine on its head isnt it ?

this is the bit i dont understand. seems to conflict with what little i know about sub hunting doctrines.

I believe there's still work done on passive arrays, but there's certainly more work on active arrays done these days than before. No, submarines will not go active since it will compromise their stealth. Ships on the other hand, especially when you are talking about the average destroyer/frigate and not those corvettes that may come with water jets etc. to minimize their noise profile (though how much is another thing), have a lot fewer options and they need to maximise their abilities to detect submarines. To do that, you have to resort to developing new technologies that can do the trick. Though I have heard of Russian acheonic coatings that try to reduce the reflection of active sonar.

Shotgun SG

Let's take a look at this sonar system: http://www.globalsecurity.org/intell/systems/lfa.htm

This sonar system was installed on the USN's small fleet of ocean surveillance vessels. It is meant to operate alongside the SURTASS passive system.

Note these paragraphs:

http://www.globalsecurity.org/intell/systems/surtass.htm

Well thats true. However, it has always been true that the USN would ping away with Active Sonar whenever they feel that they have been detected (which is often). So there isn't really much of a change in how a surface force would hunt submarines, even with this LFA technology.

The problem posed by the new generation of ultra-quiet submarines has already gone through much research as shown by the USN and RSwN's cooperation when they started "hunting" the Gotland. The problem so far identified is not just a problem with technology, but the lost of skill, and knowledge in ASW after the Cold War ended.

Still, there are good reasons to avoid the Active Option when hunting for submarines. Chinese call it, dun wanna "beat grass scare snake." It helps that your prey isn't aware that you are stalking it. =D

Fingolfin_Noldor SG

Sometimes you need to "carpet bomb" the snake to kill it. :P

But the Gotland and the Kilo is interesting. The Gotland's performance in one of the recent excercises was interesting in that the sub single handedly defeated a beach landing. The Kilo, because of its size, incorporated lots of acoustic quietening features that alowed it to stay silent (in fact, it can be described as a shrunken version of a Nuclear submarine since it uses the same hull form) and apparently in one Russian navy exercise, sunk quite a lot of ships on its own. The West is quite afraid of the submarine, especially when China has quite a few of them.

Fingolfin_Noldor SG

Sometimes you need to "carpet bomb" the snake to kill it. :P

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