Wind turbines look pretty good to me…as long as there aren’t too many of them littering the entire countryside. The most common seem to have a central pole and a three-blade arrangement.
One thing that occurs to me is that these things are made to operate at a fixed height. Today’s invention is to allow the support to be telescopic, thus providing the opportunity to raise the blades to significantly greater heights, where the average wind speed is much higher.
Another factor is that, since the velocity gradient is still quite steep at normal turbine height (it may not flatten out much at less than 1000m), the blade which is at the 12 o’clock position will be much more heavily wind-loaded than those at 4 and 8 o’clock. Another invention is therefore to allow the blades themselves to telescope, so that the 12 o’clock one can be automatically made shorter than the other two, as the rotation progresses.
