The quadcopter is multi-rotor aircraft which as its name implies has four propellers in a cross type design.
This aircraft has various uses from entertaining both children and adults, for research and for military and law enforcement agencies.
If the typical helicopter moves due to one large single rotor, then the case is different for quadcopters. Quadcopters have four propellers and two fixed propellers spin in clockwise motion while the two others move in a counterclockwise motion. These propellers make precise and accurate spinning motions regardless of speed in order to fly.
Quadcopters like DJI Phantom and Hubsan X4 H107L are complex aircrafts as it requires a lot of complicated calculations of algorithms to ensure that the propellers spin precisely and accurately; otherwise the quadcopters will not be able to hover at all. Multiple rotor copters are basically unstable aerial vehicles and as such they need computer controls to for stable flight.
The flight controller, autopilot or the computer is the brain that allows quadcopters to function well.
The flight controllers are needed as they connect to the sensors for the automatic control mechanism of the aerial vehicle. It is considered as the brain of the quadcopter since it interacts with the motors, radio control receiver, and camera controls, among others.
Each of the rotor of the quadcopter has both the thrust and torque at around the middle of the rotaion and the drag force which is across the aircraft’s flight direction. The movements of the rotors are crucial since they determine the movement of the entire quadcopter.
The quadcopter turns (or Yaws) right or left when one pair of propeller speeds up while the other pair slows down.
To move horizontally, the motors on one side have to speed up to increase the thrust, while the other side reduces the motor speeds which allow the copter to tilt.
To withstand disturbances like gusty winds, the quadcopter has to tilt automatically against the disturbance’s direction.
To change altitude, the motors have to either slow down or speed up simultaneously.
The frame, electric motors and the propellers are the main mechanical modules of a quadcopter. Manufacturers ensure that the motors and propellants are placed halfway of each other to achieve the maximum performance and the most basic algorithms.
In addition, the electrical parts requirements of a quadcopter are the same as those needed for modern radio-controlled helicopters. These electrical components include on-board computer or controller board, electronic speed control module, as well as battery.