Supercavitation
Supercavitation is the use of cavitation effects to create a bubble of low-pressure gas (ideally vacuum) wherein an object may travel at great speed while submerged in a liquid. This cavity reduces the drag on the object, which is normally about 1,000 times greater in water than in air.In 1977, Russian engineers developed the first projectile to use supercavitation: the VA-111 Shkval (squall) torpedo. This can travel at 230 mph (100 m/s), compared to the top speed of about 80 mph (35 m/s) for conventional craft, but is not steerable. News of the device reached the West in the 1990s. Its malfunction was supposedly the cause of the destruction of the K-141 Kursk submarine.
The Naval Undersea Warfare Center in Rhode Island, USA is also working on the phenomenon.
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