Abstract: Wind energy converting machine comprising a solid rotating ring carrying airfoils which are governed to have an optimal angle of attack to the wind approaching each of them when the wind velocity is below a chosen limit. In stronger wind the angles of attack are decreased to limit the power uptake. The ring is supported by stationary rollers which act as friction wheels to transfer the power to electric generators or the like. An example is described in which 90 airfoils, 30 meters high and with 3.6 meters root chord, perform a track of 200 meters diameter, at a speed of 8 m/sec. This turbine is calculated to produce 3.75 megaWatt in a wind of a velocity of 10 m/sec. or higher.