Horizontal axis wind machine with multiple rotors

Abstract

A horizontal-shaft wind machine having improved low wind speed performance and greater overall efficiency consists of multiple rotors, wherein each successive rotor is larger in diameter than the previous rotor moving from the most windward rotor to the most leeward rotor. Each rotor may be coupled to a separate concentric shaft, and all rotors may rotate in the same direction with the output shafts of each rotor coupled via an overrunning clutch to a single shaft, the output of which is used to drive the load. Winglets attached to the leading edge and tip of the rotor sails improve low wind startup torque.

1 - 3 . (canceled) 
     
     
         4 . A wind machine adapted to extract work from wind blowing from a windward direction toward a leeward direction, the wind machine comprising:
 a rotor shaft having a substantially horizontal axis of rotation;   a bearing support capable of aligning the axis of rotation of said rotor shaft with the wind direction;   a wind machine rotor rotatable about said rotor shaft, said wind machine rotor comprising a hub attached to said rotor shaft and a plurality of sails attached to said hub;   each of said plurality of sails comprising a sail having a concave front surface facing the windward direction, said sail further comprising a leading edge, a trailing edge, a root a tip and a winglet that extends windward of and curls back over the front surface of the sail.   
     
     
         5 . The wind machine of  claim 4 , wherein:
 said winglet extends in the windward direction from the leading edge of said sail.   
     
     
         6 . The wind machine of  claim 4 , wherein:
 said winglet extends in the windward direction from the tip of said sail.   
     
     
         7 . The wind machine of  claim 4 , wherein:
 The winglet has a substantially circular curled portion and extends back over the front surface of said sail a distance of no more than 10% of the maximum chord width of said sail.   
     
     
         12 - 19 . (canceled) 
     
     
         20 . The wind machine of  claim 4 , wherein:
 said plurality of sails extend substantially radially outward substantially equidistant from said hub along a conical surface centered around said rotor shaft extending in a leeward direction, said conical surface having a conical angle of at least 8 degrees relative to a plane extending perpendicular to the axis of rotation of said rotor shaft.