DWFTW: Down Wind Faster Than the Wind

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Can a wind powered vehicle sail faster than the wind? Yes - it can!
"The key point is that the propeller is a propeller, not a wind vane, and when the cart is rolling, the wheels are powering the propeller, not the other way around. With the right gearing, the propeller will always push backwards against the air, whether or not the air is moving forwards or backwards relative to the cart. The tailwind and the propeller action combine to make the wheels spin fast enough to keep the whole system rolling faster than the wind". Definitely counter-intuitive."(Jack Goodman)
More info at the Journal of the Amateur Yacht Research Society (pdf)

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