A quadcopter, also called quadrocopter, or quadrotor is a type of helicopter or multicopter that has four rotors. Although quadrotor helicopters and convertiplanes have long been flown experimentally, the configuration remained a curiosity until the arrival of the modern unmanned aerial vehicle or drone. The small size and low inertia of drones allows use of a particularly simple flight control system, which has greatly increased the practicality of the small quadrotor in this application.
Design principles Each rotor produces both lift and torque about its center of rotation, as well as drag opposite to the vehicle's direction of flight. Quadcopters generally have two rotors spinning clockwise (CW) and two counterclockwise (CCW). Flight control is provided by independent variation of the speed and hence lift and torque of each rotor. Pitch and roll are controlled by varying the net centre of thrust, with yaw controlled by varying the net torque. Unlike conventional helicopters, quadcopters do not usually have cyclic pitch control, in which the angle of the blades varies dynamically as they turn around the rotor hub. In the early days of flight, quadcopters (then referred to either as quadrotors or simply as helicopters) were seen as a possible solution to some of the persistent problems in vertical flight. Torque-induced control issues (as well as efficiency issues originating from the tail rotor, which generates no useful lift) can be eliminated by counter-rotation, and the relatively short blades are much easier to construct. A number of manned designs appeared in the 1920s and 1930s. These vehicles were among the first successful heavier-than-air vertical take off and landing (VTOL) vehicles. However, early prototypes suffered from poor performance, and latter prototypes required too much pilot work load, due to poor stability augmentation and limited control authority.
Torque If all four rotors are spinning at the same angular velocity, with two rotating clockwise and two counterclockwise, the net torque about the yaw axis is zero, which means there is no need for a tail rotor as on conventional helicopters. Yaw is induced by mismatching the balance in aerodynamic torques (i.e., by offsetting the cumulative thrust commands between the counter-rotating blade pairs).
Vortex ring state All quadcopters are subject to normal rotorcraft aerodynamics, including the vortex ring state.
Mechanical structure The main mechanical components are a fuselage or frame, the four rotors (either fixed-pitch or variable-pitch), and motors. For best performance and simplest control algorithms, the motors and propellers are equidistant.
Coaxial rotors
In order to allow more power and stability at reduced weight, a quadcopter, like any other multirotor can employ a coaxial rotor configuration. In this case, each arm has two motors running in opposite directions (one facing up and one facing down).
Operations
Autonomous flight The quadcopter configuration is relatively simple to program for autonomous flight. This has allowed experiments with complex swarming behaviour based on basic sensing of the adjacent drones.
Records
Endurance The longest flight time achieved by a battery-powered quadcopter was 2 hours, 31 minutes and 30 seconds. The record was set by Ferdinand Kickinger of Germany in 2016. In setting the record, Kickinger used low discharge-rate, high-capacity lithium-ion batteries and stripped the airframe of non-essential weight to reduce power draw and extend endurance. Alternative power sources like hydrogen fuel cells and hybrid gas-electric generators have been used to dramatically extend endurance because of the increased energy density of both hydrogen and gasoline, respectively.
Speed The fastest speed achieved by a quadcopter is 685 km/h (426 mph) by Benjamin Biggs and Aidan Kelly in Australia on 20 May 2026. The progression of the Guinness World Record is shown below. A record is done by taking the average of two 100m runs in level flight. The two runs must be done in opposing directions to account for wind.
History
Pioneers The first heavier-than-air aerodyne to take off vertically was a four-rotor helicopter designed by Louis Breguet. It was tested only in tethered flight and to an altitude of a few feet. In 1908 it was reported as having flown 'several times', although details are sparse. Etienne Oehmichen experimented with rotorcraft designs in the 1920s. Among the designs he tried was the Oehmichen No. 2, which employed four two-blade rotors and eight propellers, all driven by a single engine. The angle of the rotor blades could be varied by warping. Five of the propellers, spinning in the horizontal plane, stabilized the machine laterally. Another propeller was mounted at the nose for steering. The remaining pair of propellers functioned as its forward propulsion. The aircraft exhibited a considerable degree of stability and increase in control-accuracy for its time, and made over a thousand test flights during the middle 1920s. By 1923 it was able to remain airborne for several minutes at a time, and on April 14, 1924, it established the first-ever FAI distance record for helicopters of 360 m (390 yd). It demonstrated the ability to complete a circular course and later, it completed the first 1 kilometre (0.62 mi) closed-circuit flight by a rotorcraft.
Dr. George de Bothezat and Ivan Jerome developed the de Bothezat helicopter, with six-bladed rotors at the end of an X-shaped structure. Two small propellers with variable pitch were used for thrust and yaw control. The vehicle used collective pitch control. Built by the United States Army Air Service, it made its first flight in October 1922. About 100 flights were made by the end of 1923. The highest it ever reached was about 5 m (16 ft 5 in). Although demonstrating feasibility, it was underpowered, unresponsive, mechanically complex and susceptible to reliability problems. Pilot workload was too high during hover to attempt lateral motion.
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