Abstract: A power-producing windmill is disclosed. A paddle assembly having a central axis is supported for rotation on a frame. Two spaced-apart lateral sides supports the central axis and forms a channel in which the paddle assembly rotates. A pivotal vane is connected on one end of the channel for regulating the amount of air entering the channel is operated such as to regulate the rotational speed of the paddle assembly. A unique paddle configuration is provided which provides first and second wind-capturing cavities for increasing the total energy conversion efficiency of the wind to electromotive energy.