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Codename "Shkval-Torpedo": Super-cavitation is a loop-hole in physics

Shkval is faster than Concorde. Underwater: Engineers have discovered a loophole in physics that is giving Marine soldiers the creeps. The USA and Russia are now working meticulously on classified military projects.

Super-cavitation: an air-jacket surrounds the underwater missile
Picture by Deepangel

Maximum speed of 60 to 80 km/h! Whether submarine or torpedo – it is not possible to go faster under water according to the established rules of physics. Friction and turbulence prevent higher speeds in such a "dense" medium. In addition, a well-known problem that submarine engineers have been fighting with for centuries emerges, because it can destroy any normal ship's propeller at too high a rotational speed: cavitation – a rare phenomenon that the Russian Marines and the US Navy now want to use for firing underwater and maybe even high-speed submarines.

Dipl.-Eng. Martin Mann, hydrodynamics expert from "Austrian Research Centres", explains the effect: "water boils and turns to steam quicker the lower the pressure in the surrounding area. If you prepare your boiled egg for breakfast in a mountain hut, where the air pressure is lower than it is in the valley, the water boils between 80 and 90 degrees. Short-lived, extreme low pressure forms in certain places around fast-rotating ship’s propellers. This means that the water there boils at around 10 to 20 degrees, for example. Small steam bubbles (cavitation bubbles) form, which immediately implode if the pressure increases."

This happens with an "elemental force" of a few thousand bars pressure, which causes damage to, and even in extreme cases holes in the propellers. During the hot phase of the Cold War in the 60s, using the motto "If you can't prevent it, use it," the Russian scientist Mikhail Merkulov came upon the bold idea of artificially generating such a cavitation bubble, which is so big that a torpedo has space inside, where it is protected and virtually free from friction and turbulence, to reach speeds beyond those that had up till then been possible.

In practice, this admittedly turned out to be difficult: the specially formed missile must first be placed in the torpedo tube at high speed, so that outside, in the water, such a super-cavitation bubble can form. Again, in the bubble itself, a conventional propeller would have been pointless as the drive-mechanism, because if everything were to work properly, it would have no more contact with the water. So they installed a rocket-unit that, just like when in the air, provided the necessary thrust. – In the test-phase this was a fairly explosive mix, which until today was held responsible by certain experts for the catastrophe of the Russian nuclear submarine "Kursk." It was presumed that on board there were prototypes of these so-called "Shkval" torpedoes (or "Barracudas"), one of which possibly detonated too early during the tests. It is self-explanatory that the Russians consequently did not want help in rescue and salvage from the West.

Sketch: The construction of a Shkval torpedo like the Russians tested on their nuclear submarine.
Picture by Austrian Research Centers

Meanwhile in America and England they are working hard and very successfully on the revolutionary Russian technique, with which in practice torpedoes have already reached from 300 to 400 km/h. – The absolute nightmare for all ship commandants, who according to "good old military practice" still always had minutes to spare, is having to react to an approaching torpedo travelling at 60-80 km/h.

Dr. Ivan Kirschner, one of the leading American experts in the field, works on defence systems for the firm "Anteon" on behalf of the US Army, Navy and Air Force. He succeeded in making a super-cavitation-projectile, which could be used to detonate underwater mines in the future, accelerate in water to a record speed of 5400 km/h: "Unfortunately I am not allowed to explain very much, because a lot of what we are working on is top secret. But this much I can say: the real problem with this technique is how to safely steer such an object. Traditional side rudders had to rise out of the super-cavitation bubble into the water, meaning that the material would not last very long. Another possibility would be to change the shape of the bubble, and therefore the direction, through controllable gas injectors on the front. This is currently being meticulously worked on in the various laboratories.

Cavitation bubbles on the example of a motorboat propeller
Picture by Schiffsbautechnische Versuchsanstalt Wien

In the Austrian ship construction experimental station they are researching around cavitation. Dr. Gerhard Strasser, professor at the Technical University, a man of hydrodynamics who in his time consulted for the successful Lucona quest: "The application of super-cavitation is not only highly interesting in such military fields. They have already developed special propellers for fast hydrofoils that are constructed in such a way that the unwanted steam bubbles will not implode until they are behind the propeller and thus will cause no further damage." To optimise these and other similar propellers a test plant worth millions has been set up on Vienna's Danube canal, which should make the devilish steam bubbles visible and thus their effects to be researched.

Super-cavitation in the future: This is how extremely fast, "flying" passenger-submarines might look
Picture by Deepangel

Australian research-visionaries have in the meantime already designed whole fleets of supersonic submarines, so called "Supercav-Subs," on the computer that could possibly in the distant future accomplish journey distances such as London to New York faster than Concord. Eng. Vincent Kotwicki, who also presents the spectacular constructions and futuristic ideas of his team in great detail on the Internet ( "One day this technique will open up a whole new dimension to mankind. We could construct a network of underwater highways that connect the continents, invisible corridors, which could be kept free from sea dwellers with the help of supersonic signals." – Plans that not only animal rights activists hope never to be put into practice...

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© A report by Tobias Micke (06-10-02) – Contact