Helicoidal structures, useful as wind turbines

A structure which rotates in response to the flow of a fluid against said structure, comprising, in combination:

• a substantially helicoidal member,
• said substantially helicoidal member being formed of an elongated sheet of material and a plurality of reinforcing members attached to said sheet,
• said sheet being impervious to said fluid and freely flexible, warpable, foldable, and incapable of assuming any fixed shape on its own,
• said plurality of reinforcing members being oriented along lines extending generally perpendicular to the direction of elongation of said sheet,
• said reinforcing members being attached to said sheet at a plurality of locations therealong,
• at least one flexible interconnecting member connected between separate turns of said substantially helicoidal member so as to assist in the maintenance of the shape of said helicoidal member,
• said reinforcing members being free of attachment to any rigid supports so that they can move together in absence of any tension applied to opposite ends of said helicoidal member, such that said helicoidal member can be easily collapsed to a compact, folded, non-helicoidal shape in absence of tension at said opposite ends thereof.