Leonardo da Vinci's Ornithopter
Based on his studies of the flight of the birds, Leonardo da Vinci designed an "ornithopter" (1485), a human-powered machine intended to fly by beating its wings. He realized, however, that a person could not create enough thrust to take the device off the ground. Several designs have been constructed since the mid-1800s, powered by different types of engines.
 NTD Television. Flapping Wings Make Aviation History. [Video] (Oct 14, 2010) www.youtube.com/watch?v=DmzEKRSlA2k&feature=related.
 Wikipedia. "Ornithopter." (Nov 21, 2012). en.wikipedia.org/wiki/Ornithopter.