Abstract: A wind turbine includes a yaw spring return assembly to return the nacelle from a position to which it has been rotated by yawing forces, thus preventing excessive twisting of the power cables and control cables. It also includes negative coning restrainers to limit the bending of the flexible arms of the rotor towards the tower, and stop means on the rotor shaft to orient the blades in a vertical position during periods when the unit is upwind when the wind commences. A pendulum pitch control mechanism is improved by orienting the pivot axis for the pendulum arm at an angle to the longitudinal axis of its support arm, and excessive creep is of the synthetic resin flexible beam support for the blades is prevented by a restraining cable which limits the extent of pivoting of the pendulum during normal operation but which will permit further pivoting under abnormal conditions to cause the rotor to stall.

Abstract: A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Abstract: A flexbeam having matched in-plane and out-of-plane stiffness is described extending at least partway between the tips of a pair of rotor blades bonded thereto. The flexbeam so constituted produces a blade system with a primary in-plane frequency less than the primary forcing frequency. The matched stiffness of the flexbeam is provided by admixing, either compositionally or by laminating, materials of differing flexibilities to produce a high damping material of symmetrical stiffness.

Abstract: An epoxy resin based composite is described with improved damping properties along with good strength and modulus of elasticity. The composition comprises a stiff epoxy such as epichlorohydrin-bisphenol A diglycydyl ether epoxy mixed with a flexible epoxy such as linoleic dimer acid glycidyl ester epoxy and a flexible cross-linking agent such as a long chain amine-fatty acid amide. The composition in admixture with high modulus fibers such as graphite forms composites with high damping properties, good strength and high modulus of elasticity. Typical uses for the composites of the present invention are flexural beams for hingeless-bearingless rotors and acoustical barrier material.