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Shrouded Turbine in a Spinnaker under a Lifter

A spinnaker sail is used in downwind sailing and is practical to fly under a lifter kite (or aerostat) as a variable drogue power element that also contributes considerable lift. There is even an old trick of spinnaker-flying whereby sailors fly out from their boat using the sail like a kite.

A shrouded/ducted turbine set at the "belly-button" of a spinnaker sail would have a greatly enhanced output due to the pressure differential between the windward and leeward sides of the sail. In effect the sail acts as an effective concentrator/diffuser structure, but its still just a piece of cloth. Experimenting with this rig would help move forward the debate of "rigid v. soft".

Spinnakers are launched with low actuation forces from tubes or sleeves and doused by a recovery patch (and line) in the belly of the sail. This process would stop and start the turbine under positive control. Trimming the spinnaker's flight angle can tune the turbine output to its load. A properly shrouded turbine would not foul with its spinnaker, and its conductive line can be integrated into the recovery line.

Small used spinnakers are cheap and a small shrouded turbine is not hard to cobble from scrap. This low-complexity concept could scale into the megawatt range.

CoolIP                       ~Dave Santos                 15October2011          AWE4481

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  • The following is different from what DaveS mentions above, but it is involving lifter and huge sails. The inventor is concentrating on hydrogen production. Method is in public domain.