ornithopter

An ornithopter is an aircraft that flies by flapping its wings, in contrast to fixed-wing airplanes and rotorcraft. The wings may imitate birds or insects and can be powered by electric motors, internal combustion engines, or human effort in the case of early designs. Ornithopters can be manned or unmanned and range in size from small models to full-scale demonstrations.

Designs vary widely. Some use rigid wings driven by mechanical linkages and actuators to produce lift during the downstroke and thrust during the forward stroke; others use flexible or cambered wings that deform during flapping to improve efficiency. Control systems adjust wing motion to reach stable flight, hover, or rapid maneuvering.

Historically, the idea of wing-flapping flight dates to Leonardo da Vinci's drawings in the 15th century, which described a self-propelled, birdlike machine. During the subsequent centuries, many inventors built experimental ornithopters, primarily for hobbyist or research purposes, but sustained practical flight proved elusive due to structural loads, energy density, and control challenges.

In the modern era, flapping-wing research has advanced through micro air vehicles and biomimetic robotics. Researchers study aerodynamics, wingbeat kinematics, and energy efficiency with applications in surveillance, environmental monitoring, and small-scale unmanned systems. Notable demonstrations include full-size robotic birds developed by engineering firms and academic groups that can take off, sustain flight, and land using flapping wings.