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Supercavitation-alisticexpealidocious

CavPen.jpg
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.”

Mayersak claims the Kinetic Energy Cavity Penetrator Weapon “offers the ability to penetrate with a drag factor one-tenth of that associated with other penetrators and the ability to penetrate into targets at an overall depth of ten times that which can be reached by other penetrator geometries.”

One thing: Did he have to call it a “cavity penetrator”?

New Scientist reports that Lockheed plans to test four prototypes by the end of the year.

Mayersak filed a patent application, which I have posted as a .pdf at my website, Arms Control Wonk​.com.

–Jeffrey Lewis

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{ 18 comments… read them below or add one }

David July 18, 2005 at 8:31 pm

easy way to protect against it…build the bunker underground, but then cover it with a manmade lake. any projectile entering the water will immediately either be destroyed or lose almost all momentum. harder to detect a bunker of this kind as well.

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Shade July 19, 2005 at 11:10 am

One thing: Did he have to call it a “cavity penetrator”?
A friend of mine at Lockheed worked on the (I kid you not) NAD Grabber, (non-acoustical data grabber). I figure if I was an enemy of america and hear they had nad grabbers and cavity pentrators I’d think twice about trying anything.

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Wembley July 19, 2005 at 12:14 pm

The supercavitator will work equally well through water or sand.
However, nobody outside of Lockheed or the US Navy seems convinced by the factor-of-ten claim, especially though hard materials. (So the correct title, should be:
supercavitation-ballistics-experts-say-atrocious)
It will be very interesting to see.
The patent claim suggests that it can be retrofitted to BLU-109s and other hard-target bombs, at least doubling their penetration.
There is also a special supercavitating round for shooting elephants…

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Bob July 21, 2005 at 6:13 pm

David - your missing the point, water won’t stop this when the original design was to use it IN water.
All the typical stopping effects attributed to water are eliminated by the very concept of this, it eliminates friction (semantics aside, eliminates), it carries a fairly substantial amount of inhertia with it, and is a powered thrust device, so it won’t have to worry about “slowing down”.
This thing will fall from the sky, power down toward the earth, go through a lake like pacman through little yellow dots, slam into the lake bottom and keep going without missing a beat.
Although I’m sure enough of any hard material will stop it, so honestly I’d build my bunker under an iron deposit, although enough bauxite would probably stop this pretty good.
Materials with strange reactions to pressure would probably stop this better than a hard material, certain types of petrolium products come to mind, I’d like to know how well this would work with hydraulic fluid.
That’s if it works the way it’s designed.
I’ve worked with the LM guys on a few projects, lets just say their idea of reality, and the facts of reality vary somewhat, especially the lab bound ones, when you can custom design the rules of creation to fit your project, of course it will work in the lab, but not work when fired from a Galaxy.

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B July 21, 2005 at 7:43 pm

Either way if they’re lookin to blast you with a cavity penetrator I think they’ll find your ass under a man made lake. Bombs away!!!!

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F July 22, 2005 at 12:01 am

Ok, if this works so well, why hasn’t a meteor zipped right through the Moon or the Earth?
This process has to generate a lot of heat in a very concentrated area. Seems like it would be one of the success limiting factors.

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Worcester July 22, 2005 at 12:58 am

The Russian’s torpedos that the US Navy was copying were capable of going 230 mph underwater. Scientific American did a story 4-5 years ago. The link is to an article on the subject. There was also work being done on supercavitating ammo for macine gun defence of ships, i.e. projectiles that don’t slow down immediately under water.

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tokamak July 22, 2005 at 6:16 am

The American Supercav and the Russian VA-111 Shkval are both high-speed supercavitating torpedoes, 250 mph class (more recently, there are also the English MK70 SpearFish TL8 and the German Barracuda). They don’t use blade propellers to move, but powerful powder rocket motors. A fewer part of the generated hot gas is also projected in a front outlet on their nozzle, and the water in contact is vaporized, surronding the entire body, creating very low drag, thus high speed capabilities.
Russia has sold about 40 Shkval-E to China in the 90′s.
http://www.periscope.ucg.com/mdb-smpl/weapons/minetorp/torpedo/w0004768.shtml
But think this is old tech: Shkval is more than thirty years old… Its developement program began at Soviet Research Institute NII-24 in the 60′s, and a LOT of work, completly different, has since been done. In particular with magnetohydrodynamic torpedoes, made in the 80′s, that literally suck water amount of the body and all along of it, with strong electromagnetic forces.
The Russian MHD torpedo codename would be translated in English as “the Big One” or “the Fat One”.
MHD torpedoes can travel at very high speed under water such as 1700 mph, because drag is not just reduced as supercavs, but completely eliminated. The drag is even negative, providing up to 70% of thrust thanks to MHD apsiration (around 30% provided by the rocket engine).
MHD propulsion requires large amount of electric power, and the very clever idea of these torpedoes lays in the way how the current is generated: they don’t stock it in batteries, nor any capacitors. They create it in situ, extracting electric charges from the exhaust hot (very hot) gas, with an efficient MHD converter that relies on electrodes and magnetic coils. Due to the temperature, the whole system has a very short lifespan (10 seconds or so) but who cares since with such ultra speed you need 3 to 6 seconds to destroy submarine nuclear platforms ? The enemy just cannot react quickly enough.
Now, think that US Navy has since replaced copper coils by superconducting coils, and you can imagine where they are today. Think that the limit is the sound barrier under water and that this speed, unlike in air, is… 3315 mph.
As for transposing this supercavitating device in air for high speed bunker penetrators, this is a little weird. Perhaps they use a plasma torch in front of the missile (as the gaz in front of these old torpedoes). The best and most efficient way would remain using an antimatter-plasma torch, but… ;-)

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Joe July 22, 2005 at 8:59 am

Better get some protection - I bet it wouldn’t do so well if it had to penetrate rubber.

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Durex July 22, 2005 at 9:17 am

Not rubber. I think it is latex that is best suited for an optimal penetration.

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Mr. Raymond Kenneth Petry April 4, 2006 at 9:18 pm

So,- Why don’t supersonic jets have flat noses to create an ablation bubble … at-least usable in emergency-escape mode …?
Ray.

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Mr. Raymond Kenneth Petry April 4, 2006 at 9:54 pm

Also, -before leaving this discussion,- It seems to me that canted plates of depleted-uranium over a bunker would throw a buster off target.
Likewise underwater, a sonic burster from offside a submarine might change the hydroscopic pressure sufficiently to break the cavitation symmetry….
Ray.

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Mr. Raymond Kenneth Petry April 6, 2006 at 5:14 pm

Thinking about this an hour further, yesterday-
1. The optimal general spike would be slightly rounded so that as the wake separates from the tip the remaining blunt of the spike is out of the path of injecta and ejecta,- but until it does separate, tip curvature remains blunt.
2. A bunker solution:- a foot-thick mattress of styrofoam-embedded depleted-uranium blunt-tipped counter-spikes, buried sub-surface in layers, to destroy incoming bunkerbusters … the styrofoam (very-low-density; ceramic foam at great depths) offers virtually no shockwave, thus allowing the counter-spikes to penetrate straight “up” ….
3. Some of the explanations deserve further work: In the case of the water spike, eg. Shkval, where its medium is uncompressed (lowish velocity), the wake and vapor go supersonic passing the vehicle. Apparently that offers less resistance, as such,- but it factors-in new-theoretic dynamics regimes: Maybe they should apply coke-bottle area-shaping.
__
4. I wished those charts plotted area not radius.
PS. Spell “supercavi[t]ation”, please.
Ray.

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Wadim May 8, 2006 at 4:07 am

This very GooD idea IMHO :)

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Novihirsk March 3, 2008 at 4:54 pm

We as Russian must consider to sell Iran, India and China. New weapons like the Shkval and a lot more weapons too. Thank You

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Rom Gold May 18, 2009 at 1:43 am

Rom Gold which I have spent much more in this game it is necessary.

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dennymack October 7, 2009 at 6:50 pm

We will know they are onto us when they pile up a 50 ft. layer of bubblegum over the site. Or maybe peanut butter.
Or if they are worried about rodents (or their starving people) eating the edible armor, they could use layers of aramid fibers and something stretchy, with air gaps and corrugation. Anything to get the penetrator tipped off of its axis.
I hope these guys have an equally genius team working on sounter measures. I am sure the targets do.
Dennymack

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Ryan January 12, 2010 at 6:45 am

Along the lines of bunkerbuster. I would think it would be more effective to use, say a 48,000 lb projectile similar to the MOP only attached to an ICBM instead. greater speed and mass

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