The basic setup of a quadcopter is four rotors, two spinning clockwise and two counter-clockwise. The counter spinning rotors allow the copter to maintain neutral yaw rate. Thus allowing the copter to remain in a stationary position while in flight. The previous picture shows the counter spinning blades, assuming all of the blades are keeping the copter stationary. This image depicts a ‘plus’ orientation copter, an ‘X’ orientation copter would have similar dynamics. The image indicates rotors 1 and 3 spinning clockwise and 2 and 4 counter.
In order to move to the right. The copter will spin the left rotor faster, generating more thrust. The left rotor will raise, rolling the copter to the right. In order to move the copter to the left, the reverse is required.
In order to fly forward. The copter will need to pitch forward in order to allow the thrust of the copter to push the copter in a forward direction. The following picture shows how, rotor 3 would spin faster than 1, 2, and 4. The increased speed of the rotor will result in increased thrust, pitching the copter forward and thus moving the copter in a forward direction.
In order to rotate the copter level to the ground. The copter will ‘yaw’. To rotate the copter to the right, rotors 2 and 4 will spin faster, creating more rotational torque. Rotors 2 and 4 spin counter-clockwise. For every force, there is an equal, opposite force… this pushes the copter in the opposite direction.
In order to rotate the copter to the left… everthing is reversed.
Typically, flight controller orientation will be equally placed between each of the rotors.
Altitude is controlled by applying thrust to all rotors, increasing thrust and lifting the copter.
Movement is controlled by applying all of the previous roll, pitch and yaw actions at the same time.