The rotor looks sort of like two ice cream cones, one inverted on the other, and both rotating about a common axis. More accurately, this shape is produced by "pinching" the cylinder ends of a Savonius roter to form oblique conic sections. This triangularization of the basic Savonius shape improves the strength to weight ratio in the moving rotor.
Many Savonius designs have the body of the rotor attached to a rotating shaft which was also the power take off. This modified Savonius rotor, however moves about a fixed shaft which is also the central structural support element. No energy is required to rotate a heavy shaft, thus significantly reducing the minimum start up wind speed.
It was said about the one and only full scale (more or less) prototype, that it would start turning if anyone said the word "wind" in its presence.
Power take off can be from the vertical middle of the rotor or from the either or both ends. As this rotor is relatively low rpm and high torque, some forms of power take off such as hydraulics or compressed air might be better then direct electrical generation. The heating potential of wind has long been ignored.
Fig. 1 above is the only existing piece of documentation from the original project, some twenty one years ago.