The Plan View Guy Radius is wrong. It takes six cables, not three, to prevent torquing around the vertical axis.
The tower has to be that massive to accommodate the radius of the blade's swing. A vertical axis windmill would require a shorter tower. Replace the tower with a huuuge hemisphere and not only does it absorb ground level turbulence but also increase wind speed normal to its direction, e.g., at the very top. Plus which, the vibrations tangent to the hemisphere are resisted instead of absorbed by it's shape.
Actually, if you put the turbine in the toroidal airflow inside the hemisphere, suddenly all your maintenance is indoors and there is no insult to our avian friends .
