Quadrotor

A quadrotor, also known as a quadcopter, is a rotorcraft with four rotors mounted to a rigid frame. Each rotor is powered by its own motor and propeller. Rotors are arranged in a square footprint, commonly in a plus (+) or an X configuration. The rotors are paired so that two rotate clockwise and two counterclockwise to balance torque.

Flight is achieved by varying thrust across the four motors. The collective control increases or decreases overall lift, while differential thrust controls roll, pitch, and yaw. Modern quadrotors rely on a flight controller that processes data from sensors such as an inertial measurement unit, barometer, and sometimes vision systems or GPS to maintain stability and execute commands. Propulsion is managed by electronic speed controllers, powered by a rechargeable battery, typically LiPo.

Quadrotors are valued for simplicity, stability, and maneuverability. Their payload capacity is limited by weight and battery life, but they provide rapid deployment and precise control. They are widely used in hobbyist drones, professional cinematography, surveying, inspection, agriculture, and research.

Regulatory considerations include flight rules, airspace restrictions, and, in many jurisdictions, registration and remote identification requirements. See also: multirotor drone, unmanned aerial vehicle.