Windmill

A variable pitch turbine blade system, comprising:

• a blade, including a radially inner fixed end and a radially outer free end, said blade being continuously torsionally flexible between said fixed end and said free end;
• and
• an out-of-plane weight means, attached to said blade, for continuously varying a pitch of said blade in response to a variation in rotational speed of said turbine blade system, said pitch being continuously varied between a zero pitch variation at said fixed end and a maximum pitch variation adjacent said weight means for a given variation of said rotational speed of said turbine blade system;
• wherein said weight means includes a mass with center of mass thereof leading an elastic axis of said blade so that said turbine blade system operates free from flutter, and with said center of mass located out of a plane of rotation of said elastic axis of said blade so that a component of a centrifugal force acting on said mass acts to twist said blade about said elastic axis to vary the pitch of said blade.

A windmill, comprising:

• a shaft;
• a turbine blade system;
• first and second permanent magnet alternators, each of said alternators including a multiple pole stator fixedly mounted on said shaft and a multiple magnet permanent magnet structure rotatably mounted coaxial with said stator, said turbine blade system being connected to said magnet structures to rotate therewith, the poles of said stator of said second alternator being angularly offset from the poles of said first alternator;
• wherein said turbine blade system includes:
• a central hub, attached to said magnet structures;
• a torsionally flexible blade having a radially inner end, fixedly attached to said hub, and a radially outer free end;
• and
• an out-of-plane weight attached to a radially outer location on said blade, so that the pitch of said blade is continuously decreased, with increasing rotational velocity of said turbine blade system, until a portion of said blade is stalled causing the turbine blade system to be self-governing at approximately the rotational velocity at which said stall occurs.