Leonardo da Vinci designed an ornithopter, a machine intended to fly by flapping mechanical wings.
The word ornithopter means a flying machine that gains thrust from wing-beating motion, resembling the flight of birds or insects. Leonardo studied birds closely and made numerous sketches of wings, joints, muscles, and flight mechanics. His proposed machines used human power and mechanical linkages to imitate those movements.
Leonardo’s ornithopters were never proven capable of carrying a person into sustained flight. Human muscles cannot provide the power-to-weight ratio needed for a practical flapping aircraft of the kind he imagined, and the proposed structures were too heavy. His investigations nevertheless helped organize observations about lift, balance, and wing motion.
An ornithopter is not the same as a glider. A glider relies on aerodynamic lift while moving forward, whereas an ornithopter actively flaps its wings. Leonardo’s surviving notebooks contain several related flying-machine studies rather than one single finished aircraft.