Freestanding Towers
Modern freestanding towers have 3 legs with diagonal bracing. Three leg towers usually have legs made from pipe or round tubing and angle steel braces connecting the legs. The braces give the appearance of "lattice work", hence the name. The advantage of freestanding towers is that they take up less room than guyed towers. For a turbine the size of the Aerostar 6 Meter, a typical foundation for a 100 foot freestanding tower is three concrete blocsk about 4' deep and 6 feet square. The tower base itself is only about 12 feet across.
Because the tower is so compact, the force from wind loads results in higher forces in the legs and braces than on a guyed tower. The tower must therefore be built using larger members. This results in a heavier and more costly structure.
Where there is not enough room for guy wires, the freestanding tower is the most logical and economical choice.
Aerostar has poineered a tilt option for its freestanding towers. It makes use of a winch and gin pole similar to our tilitng guyed tower. It is very simple and cost effective. Compared to so called "hydraulic tilting towers", which require expensive hydraulic systems and torquing of large bolts, raising and lowing the tower can be done by the average homeowner.
Model W Tower being installed in Colorado. Image Courtesy John Kirchner.
