A vertical axis wind turbine comprises upper and lower rotor blades and upper and lower bearing assemblies. Horizontal members connect the upper rotor blades to the upper bearing assembly and the lower blades connect the upper rotor blades to the lower bearing assembly. The upper rotor blades can be arranged vertically or non-vertically. In non-vertical arrangements, the upper rotor blades can be twisted or swept back in a straight manner. Sweeping jet actuators are incorporated into the rotor blades to deliver oscillating air jets to surfaces of the rotor blades to delay occurrence of dynamic stall. Conduits in the blades can deliver pressurized flow of air to the actuators. The turbine can be supported by a structure that can exerts only horizontal and/or lifting forces on the rotor blade assembly to reduce the load on the lower bearing.