A maximally efficient vertical axis wind turbine (MEVAWT) includes a rotatable circular frame having upper and lower concentric flat rings or disks which support a plurality of, typically three, four, five or six, pivotable cascades, each including a plurality of fixed, configurable airfoils. The airfoils preferably include a single, pivotable trailing flap and may include lateral extensions. The center and periphery of the lower ring are supported in suitable bearings to facilitate free rotation of the frame. Wind direction and velocity sensors provide data utilized to control drive mechanisms which orient each cascade and the flap of each airfoil to maximize the resultant power produced by the turbine.
