Abstract: A windmill design in which all rigid blades are replaced by sail-type Blades that are only supported by tension. Each Blade is connected to a central Hub and outer Rim by means of two Spokes, and is twisted in shape to maintain a materially constant free wheeling angular velocity at any radial location along the Blade while preserving a near-constant width. The cross section of the Rim is wing-shaped to produce laminar flow of air over the Blades.