Are there any ships currently in service that are only fitted with a towed array and do not have a hull mounted active/passive sonar for ASW? Would it be correct to say that in most cases a hull mounted sonar and towed array combination would be the ideal arrangement to have as these 2 sonars complement each other?
Hull mounted and towed sonar array combinations?
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IIRC a towed sonar array is quite helpful in conjunction with a hull mounted sonar as a HMS can't cover the ships baffles due to it's position whereas a TSA can.
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If I'm not mistaken, the main value of having a towed array - in addition to it being able to 'clear' the baffles - is that it can detect contacts at a much longer range [no idea about the technacalities involved here though]. A problem is that a ship that needs to rapidly maneuver - for whatever reason - will first have to reel in the towed array.
I could be totally wrong here but I was under the impression that the towed array and the hull mounted sonar are intended to complement each other; the hull mounted sonar will be used at a much closer range to localise and eventually help in persecuting the contact. What I'm very curious about is whether there are any ships that are fitted with only a towed array? Also, apart from Singapore's Victory class corvettes, where there any other ships that only had a variable depth and no hull mounted sonar?
I could be totally wrong here but I was under the impression that the towed array and the hull mounted sonar are intended to complement each other; the hull mounted sonar will be used at a much closer range to localise and eventually help in persecuting the contact. What I'm very curious about is whether there are any ships that are fitted with only a towed array? Also, apart from Singapore's Victory class corvettes, where there any other ships that only had a variable depth and no hull mounted sonar?
Yeah, I was thinking reasons why you would operate the pair rather than the advantages/disadvantages of either type. A TSA offers superior detection & tracking effectiveness due to it's position & superior range, but like you say it imposes limits to ship performance when deployed like course/speed.
But I can't recall a ship only having a TSA and not having a HMS. HMS aren't also neccesarily for ASW work, the Type 45 for example has a HMS but isn't particularly optimised for that type of thing, it's mainly for obstacle/mine detection.
But I can't recall a ship only having a TSA and not having a HMS. HMS aren't also neccesarily for ASW work, the Type 45 for example has a HMS but isn't particularly optimised for that type of thing, it's mainly for obstacle/mine detection.
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I would think that the avantages offered by towed arrays mean that navies are more than happy to live with any disadvantages they offer.
Which in turn raises another question :]! What is the main difference between a hull mounted ASW sonar, an obstacle avoidance sonar and the low frequency [both HMS and VDS] sonars mounted on MCMVs?
The Royal Malaysian Navy [RMN] for example, has fitted the L-3 ELAC Nautik NDS-3060 Obstacle Avoidance sonar on its 6 Kedah class frigates; but I've been led to believe that this particular sonar has no or very little ability for ASW. The reason I started this thread was because the RMN has ordered the Captas towed array - http://www.thalesgroup.com/Portfolio/Documents/Captas_pdf_brochure/ - for its Gowinds but there appears to be no plans for a hull mounted sonar.
The same way a SPS-67 is different than a SPQ-9B and how it is different than AN/SPY-1D(V).
Different sound wave lengths, different signal processors, different resolutions and different costs.
to add to prev
diff energy requirements, diff capabilities, diff companion integration sympathies etc.....
diff energy requirements, diff capabilities, diff companion integration sympathies etc.....
Absolutely, the method i've read about is 'sprint and crawl' or some derivation of it. The ship - as part of a task group - creeps along at slow speed at the edges to listen for submarine activity, then sprints for a period to get ahead in order to keep up with the task group, then creeps again.
AFAIK they are the way to conduct ASW ops (if we're talking about sensors on the ship rather than aircraft).
If CVNs/amphibs are outiftted with SSTD, they would be a towed array only platform.
You don't need to reel in towed arrays to maneuver...at least not with tactical towed arrays. The tactical arrays are designed specifically not to impact the ship's ability to maneuver. The TB-16's (long array) on SSNs seem like they might have an issue though (don't know firsthand). Would expect even more issues with the unbelievably long arrays on T-AGOS platforms.
If you're using hull mounted sonar, you're trying to kill something with shipboard weapons....and you needed targeting data yesterday. Data from the HMS is fast.
Towed array data by contrast is very high resolution data, but also very slow (as you noted, waiting for it to stabilize after maneuvering is an issue itself).
You're also right about range being the primary reason. More specifically, it has to do with environmentals and the isothermal layer, and the fact that a towed array can get underneath it (depth gets controlled by platform speed and cable scope). Hull mounted sonars actually can go out far too, but if there's a layer, it's not going to be able to see deep AND far, which is what you really need (remember USW is 3 dimensional).
Covering the baffles is part of it, but simply looking "behind" isn't really the issue as you can see from the info above. And there are...ways to get around that if you couldn't have a towed array for some reason.
If you're really interested, here's some open source light reading: http://usna.edu/Users/physics/ejtuchol/documents/SP411/Chapter5.pdf
LCS will employ separate towed active PDS and passive MFTA sonar gizmos at depths most conducive to ASW. A lightweight anti-torpedo capability based on Nixie is also provided. In conjunction with it's aviation components, these will pose a formidable challenge to pesky subs. Target delivery is 2016.
http://defensetech.org/2013/05/30/lcs-pursues-next-generation-submarine-sonar/
LCS Pursues Next-Generation Submarine Sonar
Published on May 30th, 2013
Written by: Kris Osborn
Navy leaders want the latest Anti-Submarine Warfare Mission Package in development for the Littoral Combat Ship to detect even the quietest of submarines, service officials explained.
The ASW Mission Package — part of the interchangeable sets of technologies being designed for both the USS Freedom and USS Independence variants of the LCS — is being engineered such that it can detect submarines with a Multi-Function Towed Array (MFTA) and what’s called Variable Depth Sonar (VDS), said Capt. John Ailes, LCS Mission Modules program manager.
“Variable Depth Sonar allows us to put the sound down where the submarine is. If you look on current destroyers, they have a hull-mounted sonar on the bow. It turns out that there are acoustic layers based on temperature and pressure that bend the sound up. A submarine can dive below this layer and there is a lot of attenuation and signal loss from a hull-mounted sonar,” Ailes explained.
The Variable Depth Sonar allows sailors to place the sonar “beneath this layer,” Ailes said.
MFTA is a towed array sonar system, tethered to the ship, that is able to receive and transmit signals, including sounds and signals emerging from the VDS, Ailes explained.
The MFTA, called the AN/TB-37, is currently fielded on 30 US Navy cruisers and destroyers, said Navy spokesman Matt Leonard.
“The VDS variable depth sonar is an active sound producing system that provides the acoustic signal that is sent out and reflected back from the target submarine. The reflected sound is received on the MFTA. The VDS and the MFTA are towed separately but they can be towed at the same depth, or at different depths. Generally they are towed independently at the same depth,” Leonard said in written statement.
The combination of these two detection systems will allow the LCS to better detect quiet submarines such as diesel subs running only on batteries, Ailes added.
“Together, the VDS and MFTA provide both a transit speed ASW escort, and a barrier/area search capability, as well as a torpedo alert capability,” Leonard said.
Don’t mistake the capabilities of the VDS with the hull mounted SQS-53C sonar on cruisers and destroyers. The VDS can be towed at depth.
“Cruisers and destroyers can tow their MFTA’s at depth, but if the submarine is deep, they can only receive the sound the sub makes. In comparison, the VDS is effective against quiet submarines as it produces the sound which is then received on the MFTA,” Leonard added.
The Navy is currently testing with a VDS that is made by Thales, Leonard indicated.
“This system has been in service since 2004, but this is the first time it has been used by the U.S. Navy. We will be having a competition for the Mission Package’s production VDS and it is likely that Thales will be one of the offerers,” Leonard added.
Overall, the Navy plans to acquire as many as 16 Anti-Submarine Warfare Mission Packages to serve on portions of the planned-for 55 LCS ships.
The ASW mission package is also configured to work in tandem with UAS such as the Fire Scout and airborne torpedoes on-board the Navy’s MH-60R helicopter.
The MH-60R can also lower active and passive sonar sensors using a sonobouy device; in fact, the MH-60R can make use of a dipping Variable Depth Sonar which drops into deep water from the air, Ailes added.
In addition, the ASW Mission Package is equipped with a defensive technology called Light-Weight Tow that is able to defeat incoming enemy torpedoes, Ailes explained.
“It defeats a torpedo when it is shot at the ship. If there is an torpedo inbound, it defeats it and there is no operator action required,” said Ailes.
http://defensetech.org/2013/05/30/lcs-pursues-next-generation-submarine-sonar/
LCS Pursues Next-Generation Submarine Sonar
Published on May 30th, 2013
Written by: Kris Osborn
Navy leaders want the latest Anti-Submarine Warfare Mission Package in development for the Littoral Combat Ship to detect even the quietest of submarines, service officials explained.
The ASW Mission Package — part of the interchangeable sets of technologies being designed for both the USS Freedom and USS Independence variants of the LCS — is being engineered such that it can detect submarines with a Multi-Function Towed Array (MFTA) and what’s called Variable Depth Sonar (VDS), said Capt. John Ailes, LCS Mission Modules program manager.
“Variable Depth Sonar allows us to put the sound down where the submarine is. If you look on current destroyers, they have a hull-mounted sonar on the bow. It turns out that there are acoustic layers based on temperature and pressure that bend the sound up. A submarine can dive below this layer and there is a lot of attenuation and signal loss from a hull-mounted sonar,” Ailes explained.
The Variable Depth Sonar allows sailors to place the sonar “beneath this layer,” Ailes said.
MFTA is a towed array sonar system, tethered to the ship, that is able to receive and transmit signals, including sounds and signals emerging from the VDS, Ailes explained.
The MFTA, called the AN/TB-37, is currently fielded on 30 US Navy cruisers and destroyers, said Navy spokesman Matt Leonard.
“The VDS variable depth sonar is an active sound producing system that provides the acoustic signal that is sent out and reflected back from the target submarine. The reflected sound is received on the MFTA. The VDS and the MFTA are towed separately but they can be towed at the same depth, or at different depths. Generally they are towed independently at the same depth,” Leonard said in written statement.
The combination of these two detection systems will allow the LCS to better detect quiet submarines such as diesel subs running only on batteries, Ailes added.
“Together, the VDS and MFTA provide both a transit speed ASW escort, and a barrier/area search capability, as well as a torpedo alert capability,” Leonard said.
Don’t mistake the capabilities of the VDS with the hull mounted SQS-53C sonar on cruisers and destroyers. The VDS can be towed at depth.
“Cruisers and destroyers can tow their MFTA’s at depth, but if the submarine is deep, they can only receive the sound the sub makes. In comparison, the VDS is effective against quiet submarines as it produces the sound which is then received on the MFTA,” Leonard added.
The Navy is currently testing with a VDS that is made by Thales, Leonard indicated.
“This system has been in service since 2004, but this is the first time it has been used by the U.S. Navy. We will be having a competition for the Mission Package’s production VDS and it is likely that Thales will be one of the offerers,” Leonard added.
Overall, the Navy plans to acquire as many as 16 Anti-Submarine Warfare Mission Packages to serve on portions of the planned-for 55 LCS ships.
The ASW mission package is also configured to work in tandem with UAS such as the Fire Scout and airborne torpedoes on-board the Navy’s MH-60R helicopter.
The MH-60R can also lower active and passive sonar sensors using a sonobouy device; in fact, the MH-60R can make use of a dipping Variable Depth Sonar which drops into deep water from the air, Ailes added.
In addition, the ASW Mission Package is equipped with a defensive technology called Light-Weight Tow that is able to defeat incoming enemy torpedoes, Ailes explained.
“It defeats a torpedo when it is shot at the ship. If there is an torpedo inbound, it defeats it and there is no operator action required,” said Ailes.
Slightly off topic but I might recommend a dated techno-thriller from Tom Clancy "Red Storm Rising." Although it's dated (1986) the novel gives the reader an idea of what ASW operations might look like. Basically everything on this thread was covered minus the latest gadgets and gizmos. The thermocline layer was where-in the novel-soviet subs would hide. large portions followed the U.S.S. Chicago (a 688 class SSN), the U.S.S. Pharris (an older Knox class) and the U.S.S. Oliver Hazard Perry (Perry class).
The novel was based on a simulation of how a modern battle of the Atlantic might play out and for anyone with the time I'd highly recommend it.
Another was "Red Phoenix" by Larry Bond around the same time. This showed the complexities of ASW ops in constricted shallow waters like the Sea of Japan. Great reads, very informative I felt.
The novel was based on a simulation of how a modern battle of the Atlantic might play out and for anyone with the time I'd highly recommend it.
Another was "Red Phoenix" by Larry Bond around the same time. This showed the complexities of ASW ops in constricted shallow waters like the Sea of Japan. Great reads, very informative I felt.