One hundred years ago Frenchman Paul Cornu piloted a twin-rotor helicopter of his own design, and rose about one foot (0.3 meter) off the ground. He hovered for about 20 seconds. Or he didn't. A century after that maiden flight, some engineers and historians question whether Cornu's craft could have taken wing as he described it.
But despite the skepticism, most helicopter historians -- especially in France -- still mark the first helicopter flight on Nov. 13, 1907. That makes this centennial the perfect time to take a look back at the long history of stationary flight, from its roots in ancient China, to concept vehicles being touted as the flying cars of the future.