Abstract: A vertical axis windmill wherein the blades pivot between a power delivery and a recovery position with air gates associated with a non-rotating chamber containing the windmill acting to preclude airflow over the blades while in the recovery position. The blades either include chambers therein configured to receive a fluid moveable between the chambers as dictated by rotational speed of the windmill, or the blades are connected in pairs with elevational motion of one blade to a power delivery position assists the other blade of the pair in returning from the power delivery position to the recovery position.