What animal-inspired flying machine did Leonardo da Vinci design?

Leonardo da Vinci designed an ornithopter, a flying machine inspired by the flapping wings of birds.

The word ornithopter comes from Greek roots meaning “bird” and “wing.” Leonardo’s studies of human flight included several machines with wings intended to flap through mechanical action. He examined birds, bats, and the structure of their wings while trying to understand how lift and propulsion might be produced.

Leonardo’s ornithopters were designs rather than successful aircraft. Human muscle power is not sufficient to operate wings large enough to lift a person in the way a bird’s muscles lift its body. Modern aircraft therefore use engines and fixed wings, while experimental ornithopters use mechanical or powered systems.

The ornithopter should not be confused with Leonardo’s aerial screw, a separate design sometimes described as an early helicopter concept. The ornithopter depends on flapping wings; the aerial screw depends on a rotating helical surface. Both came from Leonardo’s investigations into flight, but they use different principles.