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U.S to test bunker-busting 'shkval' missiles later this year

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posted on Jul, 16 2005 @ 11:11 AM
That's the hydrodynamic view. The other one is the momentum transfer view, as expressed from Ctech who are making RAMICS.:

""There appear to be two conceptual ways of approaching supercavitation. The generally accepted one derives from propeller cavitation theory and holds that the water is essentially boiled by dropping its pressure via abrupt acceleration. This creates a source of gaseous water vapor which creates the cavitation bubble. It is generally assumed that the cavitation bubble is filled with this water vapor. Indeed, in low speed (say torpedoes) supercavitation applications the cavity size is usually enhanced with ventilation gases. This fits well with the understanding that gas creates the bubble in the first place and appears to work well within that context. It also fits comfortably in the general framework of marine engineering.

Last September, at an ONR sponsored Supercavitation Conference, Dr. Kirschner (of Anteon Corporation) and I were discussing the idea of a theoretical speed limit for supercavitating objects, assuming material strength issues could be overcome. As previously mentioned, conventional wisdom holds that the cavity is created by the water vapor and therefore, at some speed, the volumetric rate at which vapor can be generated will become insufficient to support the formation of a cavitation bubble which will clear the body. In other words, at some velocity the rate at which the water boils will become insufficient to fill the volume of the "hole" in the water created by the passage of the projectile and the cavity will collapse.

For whatever reason, I have a different mental picture of how the bubble is created, perhaps due to my background in hypersonics in graduate school. In that field discontinuities and rarified flows are encountered in the course of normal business. I do not know if anyone else shares this view but Dr. Kirschner and I have discussed it at some length. In any case, I believe the process is fundamentally one of momentum transfer. The cavitator, be it a disk or cone or whatever, imparts a significant radial velocity (relative to the axis of flight) to the water it comes in contact with. In effect the water is thrown violently to the side. It therefore has a high radial momentum that is resisted by the pressure of the water around it. This pressure serves to slow its radial velocity and will bring it to a stop over a finite time. The accepted definition of cavitation number is compatible with this idea. In the meantime, assuming a circularly symmetric cavitator, a round "hole" has been created in the water. What is in this hole, other than the projectile? I believe it is a vacuum, at least initially. Of course the water on the interior face of the bubble begins to boil, but it can only boil so fast, even in a hard vacuum. At slow velocities the rate of boiling can create a fairly decent partial pressure of water vapor in the cavity. In the limit case, as velocity increases, the pressure inside the cavity in the vicinity of the projectile will go to zero. Eventually the pressure acting on the water will reverse its radial velocity and cause the cavity to close. However, the projectile will be long gone by that point. If this approach is correct then, except for finding a material to withstand the steady state stagnation pressure, there may be no hydrodynamic upper limit to the velocity of a supercavitating body.

In any case, perhaps there is room for both viewpoints. In fact, they may very well be opposite sides of the same theoretical coin."

posted on Jul, 18 2005 @ 12:44 PM

Don't make fun of the name.

posted on Jul, 18 2005 @ 01:35 PM
That looks like the one, though the Lockheed model has a stepped nose pin rather than a flat one.

It could make a lot of defences obsolete. Presumably a small calibre, high-velocity supercavitating round would be able to go through a lot of walls, which would make urban combat a very different game. ((Especially for the civilians)), In fact with an automatic weapon you could just saw through buildings...

posted on Jul, 18 2005 @ 01:36 PM
Well, I'm not a physicist, just an old engineer-bureaucrat; and I don't work for LockMart, but for Boeing.

So probably a lot of you have more education and experience in the field than I do.

However, CH1466, based on what little I know about explosives, makes more sense thatn anything else. I tend to buy into his views as opposed to anyone else's.

[edit on 18-7-2005 by Off_The_Street]

posted on Jul, 18 2005 @ 08:07 PM
Here is the jest of what is said about this missile and supercavitation, something along the lines of that which has already been indicated in this thread by a few of us:

British magazine New Scientist (subscription) reports that Lockheed Martin Missiles and Fire Control has developed a conventional "bunker buster" (right, click for a larger view) using a novel concept:

The design builds on the US navy's work on high-speed torpedoes, which reduce friction around themselves by creating a gas bubble called a supercavity. ...

To create a supercavity that surrounds but doesn't touch the body that created it, the object has to be travelling very fast- at least 180 kilometres an hour if it is in water. And the nose has to be flat to force fluid off the edge with such speed and at such an angle that it avoids hitting the surface of the body. But if this is to be achieved, the result is a supercavitating body with extremely low drag. Instead of being encased in water, it is simply surrounded by water vapour, which is less dense and has less resistance.

But supercavitation may not be limited to liquids. At high enough velocity a blunt-nosed body will force apart any medium it travels through, whether it be water, soil or concrete. If the cavity is large enough, the only surface in contact with the medium will be the blunt tip of the nose.

Joseph Mayersak, Advanced Projects general manager at Lockheed Martin Missiles and Fire Control, calls the phenonmenon "terradynamic cavitation."

.pdf of the patent application

And there you have it.


[edit on 18-7-2005 by Seekerof]

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