America’s first turbine engineers were aeronautical engineers who had opted out of working for Vietnam-era helicopter companies. As a result they designed their turbines with floppy flexible blades based on the aerodynamics of helicopters. It turns out that the blades you need on a helicopter are the exact opposite of the ones that make for a successful wind turbine. “On a helicopter,” Cashman explains, “you need lightness because you have to get off the ground, but you don’t want lightness in a wind turbine. Heavy is what you want, brute force,
