Leonardo da Vinci’s bird-inspired flying-machine concept with flapping wings moved by human muscle was an ornithopter.
An ornithopter is an aircraft designed to fly by beating wings, following the basic motion of birds or insects. Leonardo studied bird anatomy, flight, balance, and air currents while developing several flying-machine ideas. His sketches show a pilot lying or standing within a framework connected to large wings.
The concept was ambitious because human muscles cannot supply enough power for a person-sized flapping aircraft of Leonardo’s proposed scale. His designs therefore remained theoretical and were never demonstrated as successful human-carrying aircraft.
An ornithopter is not the same as a glider. A glider relies on lift while its wings remain essentially rigid, whereas an ornithopter depends on active flapping. Leonardo’s work nevertheless contributed to the long history of studying flight through observation of birds.