The modern mechanical marvel we know as the helicopter began as a Chinese top consisting of a shaft -- a stick -- adorned with feathers on one end. Really. When a person placed the stick between his hands and spun it rapidly, the top would rise vertically into the air. Try it for yourself if you're feeling experimental.
Eventually, a few inventors decided to give the Chinese top a power boost. In 1754, a Russian by the name of Mikhail Lomonosov modeled a small rotor on the design of a Chinese top, then used a windup spring to power the device. (A helicopter rotor, by the way, just refers to a rotating part with airfoils, or blades.) Approximately 30 years later, the French naturalist Christian de Launoy built a similar rotor using turkey feathers mounted to both ends of an axle. A string, wound round the axle and tensioned by a crossbow, generated the power. When the tension was released, the counterrotating blades generated lift and carried the device vertically.
These early designs were more toy than transport, but some of the greatest minds in the history of science and engineering were working hard to make vertical-lift flight something humans could enjoy as passengers. Leonardo da Vinci created elaborate sketches for several flying machines, including one he dubbed the aerial screw. The contraption consisted of a linen wing wrapped around an axis, or screw. Four pilots aboard the machine would turn the axis using a pumping action. As the screw turned, so da Vinci theorized, the machine would lift from the ground. And perhaps if the design were lighter, it would have. Sir George Cayley came up with another fanciful machine -- the aerial carriage -- that had two counterrotating rotors mounted on each side of the craft. He attempted to power the device using a gunpowder-based engine, but the results were far from satisfactory.
Eventually, engines evolved enough to move helicopters from the theoretical to the practical. Thomas Edison, who experimented with several helicopter designs in the early 1900s, demonstrated that both high aerodynamic efficiency of the rotor and serious power from an engine were required for successful vertical flight. Other innovations and design refinements quickly followed. The first generation of engine-powered helicopters -- known as hoppers -- emerged between about 1904 and the 1920s. The engineers who built these machines hailed from France, Great Britain, Russia and the Netherlands, and their inventions could make short, tethered flights of just a few seconds. Some of the machines carried pilots, while some were unmanned. Almost all of them were unreliable and difficult to control.
And then along came a man named Igor, who was about to change the fate of these flying machines.