Leonardo da Vinci sketched an ornithopter, a flying machine with bird-like wings operated by a person.
An ornithopter is an aircraft designed to fly by flapping its wings, imitating birds, bats, or insects. Leonardo studied birds in detail and filled notebooks with observations about wing movement, balance, and air resistance. His proposed machines used a human pilot’s muscles to move large wings through mechanical linkages.
The idea was ingenious but impractical with human power alone. Human muscles cannot produce enough sustained power to lift a person and a heavy wooden mechanism by flapping wings. Leonardo’s drawings therefore represent attempts to understand flight rather than proven aircraft designs.
The term ornithopter applies to both historical concepts and later experimental aircraft. Modern ornithopters can fly using motors or other power sources, and small radio-controlled models have demonstrated the principle. They are distinct from airplanes, whose fixed wings generate lift while engines provide forward thrust.