A vertical axis wind turbine includes an upstanding support structure, a plurality of generators disposed on the support structure, a central shaft in rotatable communication with the generators and positioned along a central axis of the vertical-axis wind turbine, a plurality of struts extending from the central shaft, and a plurality of blades, each blade positioned at an end of a corresponding strut and oriented substantially vertically. The vertical axis wind turbine optionally includes strut ailerons, blade extension elements, or blade ailerons to increase the efficiency and duty cycle of the wind turbine.