Wind Turbine Company

The compelling advantage of downwind turbine orientation is the machine can shed or mitigate wind- induced loads. The wind will bend the tower and rotor blades in the direction it is blowing. Upwind machines must resist bending, but downwind blades and towers can be allowed to bend. The commonsense of this approach is immortalized in the old Irish toast "May the wind always be at your back."

As our hinged rotor design has successfully demonstrated, the blades can also be articulated to further reduce bending loads.

WTC's proprietary technology is a hydraulically controlled, hinged-blade system that allows the blades to "flap" in the out-of-rotating-plane direction, causing the cone angle between the blades to vary continuously with changing wind and rotational speeds. This feature results in an enormous reduction of the blade-root bending loads. Reducing these loads allows us to safely reduce the amount of material employed in the blades, drivetrain, and throughout the turbine. This patented innovation, based on a concept previously employed in the helicopter industry, was the result of a thorough system level design of the 2-blade downwind turbine.

WTC takes advantage of the fact that downwind wind turbines tend to self-orient. Turbine yawing is not unrestrained, but we have eliminated the use of the costly, load-inducing mechanical yawing system found on all upwind machines.

Downwind turbines have another compelling advantage--the tower can be allowed to bend in the wind, permitting the use of guy-cables to hold it upright. Unlike freestanding towers, the guy-cable supported tower is a pipe--a manufactured product. Pipe sections are shipped to the site and joined together like a pipeline. The foundation supports the weight; the guy-cables keep the tower upright, permitting downwind turbines to more economically employ taller towers to take advantage of generally higher wind speeds found aloft. Higher winds result in more electricity production. WTC can also employ a freestanding tower where use of guy-cables is inappropriate.

It is well known that 2-blade turbines capture approximately 97% as much energy as 3-blade machines with the same rotor diameter.

The lineage of 2-blade downwind machine dates to at least 1939 (the Smith-Putnam machine). It has long been recognized that taking advantage of the lighter weight structural benefits of the downwind design is not an easy engineering undertaking. The upwind design prevails today because in the late 1970s when the modern wind industry was born, development of the upwind design did not require the sophisticated engineering tools that have since become available. These new tools help make today's wind turbines more reliable and economic than turbines produced even five years ago. WTC has taken full advantage of the tremendous increase in computing power in recent years to tackle the more challenging downwind design in order to produce a truly state-of-the-art wind turbine.

WTC's potential for cost reduction is compelling when compared with the now 25-year old upwind technology.