From "Engineer's Dreams" by Willy Ley.
"A really large wind generator worked faithfully for years on a mountain called Grandpa's Knob, near Rutland Vermont. There is often a steady breeze on top of a ridge of hills even though down in the valley the air seems perfectly quiet. In 1939 a Boston engineer, Palmer Cosslet Putnam, had the idea that a hilltop should be a suitable place for a wind generator. Since aviation engineers had gained considerable knowledge of how air flows around an airplane wing, a wind generator could be designed far more efficiently in 1939 that it could have been two decades earlier.
The tower for the wind turbine on Grandpa's Knob was 125 feet tall, just tall enough to carry the two bladed impeller, which had a diameter of 175 feet. Each blade looked very much like an airplane wing and the whole was mounted in such a way that it turned into the wind automatically. The turbine was ready for operation on October 19, 1941 and ran virtually without serious interruption until March 1945. Then the wind generator on Grandpa's knob became a war casualty. On the twenty sixth of March one of the two blades was torn loose. Since the generator was spinning at the moment, the lower blade smashed into the other one, damaging it badly. If the had happened in normal times the damaged blades would have been carefully inspected, and the accident would have resulted in new and better blades. But it happened during the second world war. Neither material nor labor could be obtained, and since the wind generator could not be classed as "vital" -after all it was mostly experimental even though it did produce current which it fed into the local network - the structure had to be abandoned. "