Abstract: This invention relates to a flexible tethered wind turbine useful, among other things, for generating electricity. A flexible shaft supported by guy wires is provided at its upper end with a flexible rotor and an airfoil assembly. Rotation of the airfoils in response to wind creates centrifugal force and tension which causes the rotor to become rigid during use. The light flexible shaft easily follows the rotating sails, which permits the entire turbine to automatically track the wind as it changes direction. As the rotor spins, its rotational energy is transferred to the shaft, which rotates along its entire flexible length.