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#41
January 30th 05, 05:29 AM
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Guy Alcala wrote:
wrote: On Sun, 30 Jan 2005 01:08:59 GMT, Michael Wise wrote: I seem to recall that they are rather loud when snorting, too. The term is "snorkeling," I guess I'm showing my age, here! :-) snip Or if you ever did an exchange tour with the RN. They call it snorting. Guy Same with Canadian ASW troops...I've been following this thread with interest but with no opinions, my association with the ASW world (for 10 years) was getting the experts and their equip onsite and home again safely. -- -Gord. (use gordon in email) 
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#42
January 30th 05, 02:48 PM
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In article ,
wrote: snipped On the surface you get a radar detection opportunity. You get one on a snorkle mast, too, but it takes a well tuned set with a good operator to hold one at any range. I was blessed with such a No. 3 back in the Old Days; his record was 28 nm. Acoustic stuff of which I know nothing snipped Bill Kambic I only had one flight in an S-3B and was amazed at how good the ISAR radar was. It picked up things like trash bags and coffee can sized fishing floats at pretty amazing ranges, I'm hesitant to say how far as I have no idsea what's classifed about it. I was very impressed given I was used to the Prowlers APS-130 with which,on a good day, you could find the carrier. Pugs
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#43
January 30th 05, 03:19 PM
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On Sun, 30 Jan 2005 05:20:38 GMT, Michael Wise wrote:
The reason is that when a sub is surfaced part of the accoustic energy developed by machinery is radiated into the air. Thus it is not available to accoustic devices in water. In modern terms, the total sound energy is reduced. No argument there. But when its running surfaced, it's also cavitating much more which makes up the machinery noise reduction. No, not really. Cavitation is a function of speed, prop design, and pressure. When a sub is deep they have the advantage of pressure that will help reduce cavitation. The difference in pressure between a sub on the surface and one at snorkel depth is de mininimis. Submerge the hull and now ALL the sound energy develped is radiated into the water. No argument there. The blade cavitation will also be much less. No, it won't. The pressure gradient is way too small to make a difference. And the addition of the machinery noise is not. You may not agree, but it's pretty simple physics and what we used to teach AWANs in basic passive tracking theory. I wasn't taught that as an AW, and it doesn't jibe with my real-world experiences either. Talk to an accoustic AW and they will confirm what I say. They are both easy passive pick-offs with their own weaknesses, however a running (on engines) surfaced sub makes a lot of both engine and cavitation noise. Indeed. But sound energy radiated into the air is no help with passive tracking. What makes you think the blade cavitation noise from a sub running on the surface isn't clear and easily electronically identifiable? It is. We could track lots of vessels (including Mother) using passive accoustics. If you wanted a steer home during EMCON ops just pick up a DIFAR bouy, isolate Mother, and take a bearing. BUT, the sub at snort depth and the sub on the surface will not have any detectable difference in cavitation. They will have a dramatic difference in total noise energy radiated. A good No. 4 can tell if the sub is surfaced or snorting based upon the total presentation. As to the superiority of the helo over the fixed wing aircraft it very much depends on the tactical situation. The helo can get up close and personal, which the fixed wing cannot. The fixed wing has speed that the helo does not. Speed means nothing when ones tactical avionics package cannot be relied on. Indeed. Never flew a Hoover so I don't know how reliable the package was. The large active sonar of the helo is nice, but DICASS can work, too. I'll stick with the 2000 watts of power. Depends. If you are outside the operating range of the helo then you might not have many options. Whether or not an SH-60 (or an SH-3, for that matter) is the better platform is very situation dependant. Obviously. It has been my experience (and that of not a few others) that when you mix them you can turn a sub every which way but loose. One would hope so, but I have to say I was never impressed with the S-3's ASW capabilities (the same goes for the Hooky 2....with no offense to the talented AW's who flew in both). I flew many an ASW exercises (aboard SH-3H and SH-60F's) in open ocean as well as semi-controlled (SOAR range) environments, and it always seemed the VS ASW avionics systems frequently malfunctioned. I never flew any exercise where they acquired the target first...although I have flown more than a few where they lost it after being passed on to them. Again, never having flown the Hoover I can't comment. Bill Kambic
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#44
January 30th 05, 04:03 PM
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#45
January 30th 05, 07:28 PM
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Allen Epps wrote:
I only had one flight in an S-3B and was amazed at how good the ISAR radar was. It picked up things like trash bags and coffee can sized fishing floats at pretty amazing ranges, I'm hesitant to say how far as I have no idsea what's classifed about it. I was very impressed given I was used to the Prowlers APS-130 with which,on a good day, you could find the carrier. Pugs, everything I've heard about ISAR is impressive, and the newest stuff out there supposedly puts even the gear in the S-3 to shame. Radar can do amazing things sometimes. With the radar in the SH-60B (basically an old fashioned 360 degree nav radar with some electronic processing), we found some dolphins one night. It was ridiculously calm out, so there wasn't much in the way of returns (normally the waves in the ocean and dense rain clouds make random clutter). There was some faint intermittent returns in one area for several minutes. With nothing better to do, we went over to have a look with FLIR, and there was a pod of dolphins hopping out of the water as they swam along. I suppose there's the off chance they could have been following a surfaced sub that subsequently dived before we came over.
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#46
January 30th 05, 10:08 PM
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On Sun, 30 Jan 2005 16:03:48 GMT, Michael Wise wrote:
No argument there. But when its running surfaced, it's also cavitating much more which makes up the machinery noise reduction. No, not really. Which is contrary to my experience. It's not contrary to mine. It's also what they teach in the accoustic AW portion at the FASO det. Or at least they used to. Talk to an accoustic AW and they will confirm what I say. What exactly is an "accoustic AW"? When I was in, all AW's received acoustical training in A school and advanced acoustics in Common Core. Once in the fleet, such training is ongoing. Well, maybe training has changed. The AW rate used to have subspecialties of accoustic and non-accoustic (radar, MAD, etc.). I sat through both parts many moons ago when I was a FASO instructor. Maybe I'm really out of date or maybe you are relying much to heavily on personal experience. Since I am relying on what was taught from basic physics, I will presume that while training might change, objective reality does not. What makes you think the blade cavitation noise from a sub running on the surface isn't clear and easily electronically identifiable? It is. We could track lots of vessels (including Mother) using passive accoustics. If you wanted a steer home during EMCON ops just pick up a DIFAR bouy, isolate Mother, and take a bearing. BUT, the sub at snort depth and the sub on the surface will not have any detectable difference in cavitation. They will have a dramatic difference in total noise energy radiated. A good No. 4 can tell if the sub is surfaced or snorting based upon the total presentation. What CV aviation ASW refers to its AW's as number 4 and such? That's what we used to call them in Stoofs. The equipment we used in the S2G was a scaled down version of what is used today in the P3C. The ASW world IS a bit wider than helo ASW. Bill Kambic
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#47
January 30th 05, 10:59 PM
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#48
January 31st 05, 02:34 AM
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Michael Wise wrote:
In article , wrote: Since I am relying on what was taught from basic physics, I will presume that while training might change, objective reality does not. As I have said, I agree on most of what you've said...with the exception that a diesel sub is easier to detect passively when snorkeling than when running on the surface. I don't see any laws of physics supporting that argument. I've heard the same thing (the snorkeling sub is "noisier" in the water than the surfaced one). More hull is in the water, so more noise is transferred to the water and less is transferred to the air. I'm not convinced that there is a great deal of difference, it seems overly simplified to me. I have a feeling that water is better than air at absorbing sound, by which I mean that a surfaced sub probably transfers nearly all of it's engine noise to the water anyway.
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#49
January 31st 05, 03:53 AM
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In article ,
Jim Carriere wrote: Since I am relying on what was taught from basic physics, I will presume that while training might change, objective reality does not. As I have said, I agree on most of what you've said...with the exception that a diesel sub is easier to detect passively when snorkeling than when running on the surface. I don't see any laws of physics supporting that argument. I've heard the same thing (the snorkeling sub is "noisier" in the water than the surfaced one). More hull is in the water, so more noise is transferred to the water and less is transferred to the air. I'm not convinced that there is a great deal of difference, it seems overly simplified to me. I have a feeling that water is better than air at absorbing sound, by which I mean that a surfaced sub probably transfers nearly all of it's engine noise to the water anyway. Indeed. Snorkeling or surfaced, it's noise begs for a couple MK-46's. --Mike
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#50
January 31st 05, 11:27 AM
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On Sun, 30 Jan 2005 22:59:07 GMT, Michael Wise wrote:
That's what we used to call them in Stoofs. The equipment we used in the S2G was a scaled down version of what is used today in the P3C. So you were an S-2 AW? By the time I got in, S-2's were pretty much limited to COD duty. No, I was the S-2 tactics instructor. I saw through most of the AW portion to find would what was taught and learn more about the capabilities of the equipment. The ASW world IS a bit wider than helo ASW. No argument there...although when it comes to active acoustical detection...no other aviation assets can touch an HS asset. Well, mabe so and maybe not. :-) Bill Kambic
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