How does a quadcopter fly?

SAMRAJ S
Jun 27, 2020
2 min read

A quadcopter as the word denotes consists of four rotating motors with a propeller to produce lift. These four motors vary according to the user's input to manipulate the movement of the quadcopter.

For any object to fly it needs 6 DoF (i.e. Degree of Freedom) consisting of three translational degrees of freedom (vertical, lateral, and longitudinal) and three rotational degrees of freedom (pitch, roll, and yaw).

6 Degrees of Freedom
6 Degrees of Freedom

The quadcopter gains the ability to lift or descend itself due to the motor rotation wherein motor A and motor C rotates in the clockwise direction, motor B and motor D rotates in the anti-clockwise direction.

motor rotation iin a quadcopter — Motor Rotation in a Quadcopter

Now we will analyse how a quadcopter is maneuvered with respect to the RC transmitter. There are 4 important forces which govern the maneuvering of a quadcopter:

THROTTLE,
PITCH,
ROLL, and
YAW

THROTTLE

Most of the quadcopter Motor rotation sequence of the quadcopter is motor A and motor C rotates in the clockwise direction and motor B and motor D will rotate in the anticlockwise direction. In the above mention cases, the clockwise and anticlockwise motion produce equal lift.

Throttling of a drone — Source: Drone Riot

PITCH

Pitch up movement that means quadcopter moves in forward direction. For pitch up movement, motor D and motor C will produce high lift force and motor A and motor B will produce low lift force. This will create speed variations in the motors. So that motor A and B tilt downwards and motor C and D tilts upwards then the quadcopter will move in forward direction. Similarly, pitch down movement makes the quadcopter move in a backward direction.

ROLL

Actuating right makes the quadcopter move in the right side direction. For that motor A and motor, D will produce high lift force and motor B and motor C produce low lift force. Due to this motor A and motor D tilts right side and motor C and motor B tilts upwards then the quadcopter will move in right side directions. Similarly, actuating left makes the quadcopter to move left side.

YAW

Actuating the Yaw stick right makes the whole quadcopter rotate towards the clockwise direction. For that motor A and motor C will produce a high lift force and motor B and motor D will produce a low lift force. Due to this, the quadcopter will rotate in the clockwise direction. Similarly, actuating the yaw stick to the left makes the whole quadcopter rotate towards the anti-clockwise direction.