Abstract: A method of mounting windmill blades their enhance performance is disclosed. The blades have a transverse cross-sectional shape having a predominately flat chord section and are mounted such that the chord section lies in a plane that is substantially at 90 degrees to the axis of the shaft upon which they are mounted.
Abstract: A small windmill is provided upstream of a damper in an air duct. When air flows in the duct it rotates the windmill. The windmill shaft is connected by a cable to the damper operator through a transmission means, such that, as the shaft turns, it takes-up the cable an opens the damper.