US Patent 6902370 Telescoping wind turbine blade

A wind turbine blade made of a fixed blade section with an integral mounting flange for attachment to a wind turbine hub. A moveable blade section is attached to the fixed blade section and is free to move in a longitudinal direction relative to the fixed blade section. A positioning device controllably positions the moveable blade section to vary the overall length of the blade. This allows the wind turbine's rotor diameter to be adjusted. The rotor diameter can be increased in order to provide high power output in low wind conditions and it can be decreased in order to minimize loads in high wind conditions.