Mach 1 torpedoes

I am curious here, does anyone know anything about supercavitating projectiles underwater, I was told by a freind that the USSR developed torpedoes capable of going mach1 by means of this effect. Does this really happen or is it possible in theory? He offered no mathematicl basis for this claim so im curious about this, is it possible or not?
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 I don't believe it, since Mach 1 in water would be 1482 m/s at 20°C or about 2800 knots. This is 60 times the speed of a modern ordinary torpedo (~45 knots).
 Recognitions: Science Advisor I have seen discussions on theory about torpedoes that create an airpocket in front of the nose in an effort to reduce the dynamic drag and thus increase speed. I can't tell you if they have actually been made and/or tested though.

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Mach 1 torpedoes

Coincidentally, this is being disussed HERE. The torpedo is in service and travels at 100m/s.
 100 m/s is much less then the speed of sound in water (152 m/s). So, this torpedo, while 4 times faster then conventional ones is very far from Mach 1.
 I wonder if you heated the front of this torpedo to create a gas bubble if it would work?
 Recognitions: Gold Member Science Advisor The torp discussed in the other thread relies on supercavitation -- http://en.wikipedia.org/wiki/Supercavitation the original info in the other thread was dug up from, which includes a couple of figs about the 100 m/s torpedo : http://warfare.ru/?linkid=1728&catid=267 Interesting feat of engineering.

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