As swimmers know, moving cleanly through the water can be a problem due to the huge amounts of drag created - and for submarines, this is even more of a problem. However, US Navy funded researchers say they have a simple solution - a bubble.
Researchers at Penn State Applied Research Laboratory are developing a new system using a technique called supercavitation. The new idea is based on Soviet technology developed during the cold war.
Supercavitation envelopes a submerged vessel inside an air bubble to avoid problems caused by water drag.
A Soviet supercavitation torpedo called Shakval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes. In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h.
This would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.
However, the technique also results in a bumpy ride - something the new team has solved.
'Basically supercavitation is used to significantly reduce drag and increase the speed of bodies in water,' said Grant M. Skidmore, recent Penn State Ph.D. recipient in aerospace engineering. 'However, sometimes these bodies can get locked into a pulsating mode.'
To create the bubble around a vehicle, air is introduced in the front and expands back to encase the entire object.
However, sometimes the bubble will contract, allowing part of the vehicle to get wet. The periodic expansion and contraction of the bubble is known as pulsation and might cause instability. (end of excerpt)
Click here for the full story, on the Daily Mail website.