Abstract: A multi-vane windmill rotating in a horizontal plane on a vertical shaft includes frame supported fabric type vanes with the frame hingedly attached at one end to support arms to swing closed and catch the wind in one position and to swing open under centrifugal and wind forces in another position when coming into the wind to reduce air resistance. Vanes are releasably attached in part to the frame for support in operating position and otherwise slidably secured thereto so as to release and collapse on the frame under extreme wind pressures when the frame is closed and thus spill the wind. Stops on the support arms provide a limit of movment of the vane frames. A second embodiment of the vanes includes two overlapping sections normally held in overlapped or closed position by yielding means that permit the sections to separate under high winds to provide an air passageway through the vane.