Quadcopter
[2] 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.
Each rotor produces both lift and torque about its center of rotation, as well as drag opposite to the vehicle's direction of flight.
[3] 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.
Yaw is induced by mismatching the balance in aerodynamic torques (i.e., by offsetting the cumulative thrust commands between the counter-rotating blade pairs).
[citation needed] The main mechanical components are a fuselage or frame, the four rotors (either fixed-pitch or variable-pitch), and motors.
[8] In order to allow more power and stability at reduced weight, a quadcopter, like any other multirotor can employ a coaxial rotor configuration.
[citation needed] The longest flight time achieved by a battery-powered quadcopter was 2 hours, 31 minutes and 30 seconds.
[9] 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.
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).
To be powered by a 105 hp Potez 4E air-cooled flat four-cylinder engine, its 20 gal payload was discharged through a 22 ft spray boom.
However, despite the much simplified design and operational requirements compared to a piloted machine, the parent company board refused to develop it and it remained a paper project.
Airbus is developing a battery-powered quadcopter to act as an urban air taxi, at first with a pilot but potentially autonomous in the future.
Research is continuing to increase the abilities of quadcopters by making advances in multi-craft communication, environment exploration, and maneuverability.
[20][21] Around 2005 to 2010, advances in electronics allowed the production of cheap lightweight flight controllers, accelerometers (IMU), global positioning system and cameras.
Helicopters do not experience this problem as increasing the size of the rotor disk does not significantly impact the ability to control blade pitch.
[24][25] Recreational and commercial drones started to be used, initially by Ukrainian armed forces and then by Russian forces, in the 2022 Russian invasion on Ukraine, initially to compensate for lack of aerial and satellite reconnaissance, and then increasingly as small bombers and loitering munitions on a scale that was described as "game changer".
