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Sonic Torpedo Defense
dylanduck writes "How do you defend a ship against torpedoes? According to the US Navy, you line the hull with loudspeakers and blast the incoming missile with such a devastating blast of sounds that it explodes." When asked about the possible ecological effects on marine life the military had no comment.
Except in this case you get both.. ( even the summary stated this ).
But, its once again a trade off.. Man or Animal.
War isnt always fair.
---- Booth was a patriot ----
Would this damage submarines sonar or other listening devices?
Actually, being an acoustician, I would be willing to bet that they would use a phased array of loudspeakers. With the correct phasing of the speakers, some pre-determined "point" in the water could be driven to very high sound pressure levels, while the remaining ambient noise, while still loud, may not be all that dangerous. This would occur as a transient excitation from the various loudspeakers propagates away from the source and coalesces at the point in the water where the torpedo is located, the point where a very large pressure spike is generated. There are plenty of smart researchers in the navy and I have my doubts that they would use anything other than a phased array. And by the way, this is the same methodology that they use to destroy kidney stones.
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I've asked him about how powerful the sonar was and to give you an idea how dangerous it is he told me about some standard submarine procedure. Basically, if a submarine comes under threat from enemy frogmen or divers, the defence the sub has is to turn the active sonar on and start pinging. If a diver is underwater and within a couple hundred yards, he will die from the intensity of the sound under water. In other words the sonar is VERY powerful. Trust me a 200db blast will likely give someone a very bad day if they are near by.
and currently stationed by iraq. While I say the more defensive weapons the better, if we have to do it at the expense of making all the whales extinct I say its not worth it. This isnt about saving plankton here, this is about not accidently blowing away the eardrums and thus killing thousands of whales and other marine creatures. There have been experiments with this technology and coincidentally there were massive beachings as the marine mammals could no longer navigate correctly. There are billions of us, I can't say the same for the whales.
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Just about anyone with a relatively big boat has to repaint the hull with antifoul paint every couple years. Not really that nasty, now, it's simply marine paint mixed with a bunch of (correct me if i'm wrong) aluminium dust. The older stuff used primarily copper, which had a few adverse effects on sea life.
Apparently some of the Cajuns down south use cayenne pepper, and they claim it works the best, but hey, to a cajun, cayenne pepper's good for damn near anything.
The navy these days has actually been using some pretty wierd coatings for ships, although mainly subs, in order to reduce friction.
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I'm 90% sure I know what this is for. I'm not a naval warfare specialist, but I am a scientist with an interest in these things.
In the 1990s, the Russians developed the prototype for what would later be termed the Shkval or Squall supercavitation torpedo. Knowing the Russians, the Chinese probably have them too.
Cavitation is a phenomena where a body moving through the water pushes the water out of the way so fast that it creates bubbles around the object (fast = lower pressure = water vaporization = bubbles). You may have heard of propellers cavitating - that's where small bubbles of water vapor form then burst on the low pressure side of a prop blade, causing lots of noise and even damage to the blade when they implode.
Supercavitation, on the other hand, is an intentional phenomena where a blunt-nosed object is shot through the water, creating low pressure vortices on the sides. Air or exhaust gases are injected into these vortices, creating a static "bubble" around the object that drastically reduces friction - perhaps up to an order of magnitude. You have to fire these things at about 50mph or greater to start the supercav effect going, effectively "handing off" the bubble to the torpedo, which then sustains it.
The numbers on these torpedoes are incredible: we're talking about a 300mph torp carrying a 460lb warhead with a range in excess of 7000 yards. That's the tame version - others carry nukes. In other words, carrier-killers.
Supercavitation torpedoes, as you can imagine, are incredibly noisy and easy to detect - you just can't get away from them because they're so fast. This sonic projector essentially sends a high-energy single pulse through the water directed at an incoming torpedo. That pulse probably wouldn't be able to crack a torpedo - you'd probably need on the order of 250-500PSIG overpressure to do that, (scuba tanks contain 2000PSIG regularly). You wouldn't be able to detonate the high explosive, because you need a wavefront speed above the detonation velocity, which for C4 is about 7000m/s (much slower than the speed of sound in water, 1482m/s).
I don't have the time right now to spin the equations, so I could be wrong.
However, you would be able to disrupt and dissipate that bubble around an incoming supercavitation weapon with a high-energy sonic pulse. Break that bubble, and the torp stops dead in the water because it can't reform the bubble around itself. If it mistakes that sudden stop for a ship hull - boom.
'Be always mindful, even when ditch-digging.' --D. T. Suzuki