Windmill with direction-controlled feathering

Claim 1

A windmill comprising: a. a tower; b. a chassis mounted on said tower for pivoting with respect thereto in response to wind direction; c. a turbine, including a turbine shaft and blades extending outward from said shaft, mounted on said chassis for rotation with respect to said chassis about the axis of said shaft, said chassis and turbine being aerodynamically arranged for said chassis normally to pivot into an orientation in which the axis of said shaft is approximately parallel to the wind direction and a front end of said chassis faces into the wind, said blades being attached to said shaft for rotation about longitudinal axes thereof between active positions, in which said blades experience a relatively high force from wind whose direction is parallel to said turbine shaft, and a feather position, in which the wind force experienced by said blades is substantially at a minimum when the axis of said shaft is approximately parallel to the wind direction, both when the front end of said chassis faces into the wind and when it faces away from the wind, said blades being inclined rearward from a plane perpedicular to the axis of said shaft so that centrifugal force tends to counteract the bending force applied by the wind when the front end of said chassis faces into the wind but not when it faces away from the wind; d. a wind vane mounted on said chassis for rotation with respect to said chassis in a plane substantially parallel to the plane in which said chassis pivots, said wind vane indicating the angle of the wind with respect to the axis of said turbine shaft; and e. a pitch-control mechanism for monitoring the angle between the directions of said wind vane and said turbine shaft and for adjusting said turbine blades to their feathered positions when that angle exceeds a predetermined maximum so that said blades present minimum wind resistance when the front of said chassis faces away from the wind.