An ornithopter is an aircraft that flies by flapping its wings. Designers seek to
imitate the flapping-wing flight of birds, bats, and insects. Though machines may
differ in form, they are usually built on the same scale as these flying
creatures. Manned ornithopters have also been built, and some have been
successful. The machines are of two general types, those with engines and those
powered by the muscles of the pilot.
Some early manned flight attempts may have been intended to achieve flapping-wing
flight though probably only a glide was actually achieved. These include the
flights of the 11th-century monk Eilmer of Malmesbury recorded in the 12th
century and the 9th-century poet Abbas Ibn Firnas recorded in the 17th century.
Roger Bacon, writing in 1260, was also among the first to consider a
technological means of flight. In 1485, Leonardo da Vinci began to study the
flight of birds. He grasped that humans are too heavy, and not strong enough, to
fly using wings simply attached to the arms. He therefore sketched a device in
which the aviator lies down on a plank and works two large, membranous wings
using hand levers, foot pedals, and a system of pulleys.
