Octopus inspires silent propulsion system for boats and subs
By Ben Coxworth
July 2, 2013
Along with their writhing tentacles, octopi and squid sport another interesting feature – they swim not by swishing a tail, but by expelling a jet of water. This allows them to move very quickly and quietly. Scientists from Germany’s Fraunhofer Institute for Manufacturing Engineering and Automation have now copied this system, in a propulsion system that could ultimately find use in boats, recreational watercraft, or submarines.
Known as the Octopus Siphon Actuator, the miniature prototype system consists of four joined 20 x 6-cm (7.9 x 2.4-in) elastomer balls, each with a hydraulic piston inside. Initially, water is sucked in through an opening in each ball – just as a squid or octopus draws water into its mantle. Cables integrated into the balls then cause them to contract, rapidly expelling the water.
In the same way that the animals steer themselves by moving the funnel that the water comes out of, the Fraunhofer system can also be steered, using a motor to selectively point the balls in the desired direction(s).
The whole apparatus can be fabricated in one step, using a 3D printer. Production could reportedly be scaled up to the point of producing balls measuring two meters (6.6 ft) across. According to Fraunhofer, not only would a commercial version of the technology allow for fast and near-silent travel, but there would also be no danger of sea creatures being cut by propellers.
Interestingly enough, the German researchers aren’t the only people currently developing such systems. As part of the recent Google Science Fair, Texas teen Alex Spiride recently showed off his own bio-inspired Squid-Jet underwater vehicle.
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