Georges J. M. Darrieus was the French engineer who designed the first modern vertical axis wind turbine (patented 1931). Of the several rotors Darrieus designed, the most important one is a rotor made of slender, curved, airfoil-section blades attached at the top and bottom of a rotating vertical tube. Compared to the more common horizontal axis turbine, the Darrieus design has several attractive features. First, the blade operates at very high tension, so a relatively light, inexpensive blade is sufficient. Second, by locating the power train, generator and controls near ground level, they are easier to construct and maintain. Howerver, a principal disadvantage of the Darrieus is that it is not normally self-starting and needs an induction motor connected to the local power network.