Abstract: A wind driven power plant for the generation of electric power comprising a rotor, a shield, and a fin mounted on a vertical, central shaft, the fin and shield adjustably interconnected via a cog and gear track arrangement affording variable relative alignment of the fin and shield to position the shield relative to the wind. A constant rotor rotation rate is achieved by varying the masking thereof by the shield to compensate for wind speed variations. A hydraulic rotation rate control system senses the rotation rate of the rotor and generates a signal permitting the adjustment of the relative orientation of the fin and the shield. The rotor is coupled to a conventional electric generator for the generation of electric power.