How Quadcopters Work?
(Last Updated On: February 8, 2018)

Before getting in to the specifics how quadcopters fly, you will need to determine what drag, thrust and lift.


‘Drag’ is largely a mechanical force that opposes the motion associated with a object by way of a fluid. In this context, since were discussing multirotor passing through air, stage system ‘aerodynamic drag’ (in contrast to ‘hydrodynamic drag’ (for objects passing through water).

Aerodynamic drag on multirotor is generated because of the difference in velocity between your multirotor along with the air. This is only when the quadcopter/multirotor was in motion (growing, down, forward, backward and taking turns) in accordance with the environment. If the multirotor is stationary, there’s no drag.

This drag force along with the weight on the multirotor is exactly what is should be overcome, to ensure that the craft to obtain up in the environment and navigate around.


‘Thrust’ could be the force generated through the propellers with the multirotor, to ” cure ” one with the forces that should be overcome: the drag. Note the thrust force isn’t main force accountable for finding the multirotor up in the oxygen. Instead, it would be the force that lets the multirotor travel within mid-air, the industry fluid, overcoming its drag resistance.


The lift would be the force that acts contrary to the weight in the craft, taking it down in air. Like we covered inside quadcopter blade rotation and lift post, the following oversee the lift within a wing:

Newton’s third law (every action comes with a equal and opposite reaction) – generates an enhancement in the wing in the bottom, because the mass of air is pushed down and back (lift and drag).

Bernoulli’s explanation is incomplete, however the pressure difference relating to the air at the pinnacle and in the bottom because of the Coanda Effect generates an enhancement for the lower pressure towards the top (learn more within the quadcopter blade rotation post).

The propellers for the multirotor generates a ‘lift’ force using similar principles (pushing mid-air downwards plus the difference in air pressure).  In order with the multirotor to gain on track and drift and fly around, this force must be in surplus of the weight in the craft.

How do Quadcopter Motors Interact and Rotate to Fly the Craft Desirably?

In a quadcopter, you can find four motors placed close to four arms with the frame. The direction of each one motor’s rotation is really it counteracts the torque generated through the motor that is certainly placed on the opposite side. This is how the quadcopter keeps from spinning because of torque effect – the torque generated by each in the motors cancels out.

How Do Quadcopters/Multi-rotor Hover?

For your quadcopter to hover constantly in place, it’s important in order that:

All the motors rotate in the same speed (or RPM)

The rotation speed need to be sufficient enough for your quadcopter to build a ‘lift’, counteracting a weight, and not a great deal the quadcopter keeps climbing in altitude.

The torque effect acting around the body in the quadcopter by each on the motors needs to be cancelled out. Otherwise, expect the quadcopter to tend to wish to yaw in the certain direction.

Gaining and Losing Altitude

So just how can quadcopters fly high? In order with the quadcopter to realize altitude, all four on the motors must raise the speed of rotation simultaneously. Conversely, to descend, all four from the motors must decrease speed of the rotation simultaneously.

This is the thing that occurs when you increase or reduce the elevator control on your own transmitter – the velocity on the motors change simultaneously.

The ‘pitch’ control tells the quadcopter if you should fly forward or backward. To pitch forward one example is, the pace on the motors for the rear from the quadcopter must increase, compared to the pace with the motors within the front. This ‘pitches’ the nose (front) on the quadcopter down, resulting inside forward movement.

This is achieved by either increasing the interest rate with the rear motors or decreasing the pace from the front motors. Conversely, so that you can ‘pitch’ backwards, the velocity in the motors with the front on the quadcopter must increase in accordance with the interest rate on the motors in the back.


The ‘roll’ control tells the quadcopter to advance laterally. To ‘roll’ to the correct as an example, the rate from the motor on the left from the quadcopters must increase, compared to the velocity from the motors around the right. This ‘rolls down’ the appropriate side in the quadcopter, resulting in the side-ways swaying movement.

Like pitch, this can be done by either increasing the rate with the left motors or decreasing the interest rate in the right motors. Conversely, so that you can ‘roll’ left, the velocity on the motors from the right with the quadcopter should increase compared to the velocity in the motors in the left.


The ‘yaw’ or ‘rudder’ is usually a rotation movement with the quadcopter. In this case, the rotation speed of diametrically opposing pairs of motors are increased or decreased, varying the torque within the direction of rotation of these pair (bear in mind diametrically opposing motors inside a quadcopter rotate inside same direction), allowing the quadcopter to rotate from the direction with the increased torque.

The Drone and Flight Controllers

As discussed before, the flight controller could be the mind or ‘brain’ with the multirotor. This board ‘s what sits in the center, money firmware inside the ESCs, consequently manipulating the spin rate with the motors. The quadcopter cannot function optimally without sensors put into the flight controller. To know the way quadcopters work, you must best its mind!

Most Important Sensors and Their Roles


The accelerometer measures the advance from the object’s speed (to inform whether it be rising or down). It senses both static gravity acceleration (which happens regardless if the thing will not be actively moving) and dynamic acceleration, to detect motion.

The unit of measurement used is g (9.8 m/s^2) or perhaps in meter per second squared. Note that this accelerometer measures acceleration in three different axes inside 3D world (x, y and z axes). The accelerometer senses both what direction the earth is, by sensing the earth’s gravitational pull and linear motion.



Unlike the accelerometer, the gyroscope measures the incidence of rotation of the object about its axis, in degrees per second or rotations a minute (RPM). The gyroscope is mounted for the quadcopter inside a way which it is aligned featuring its axes, giving information for the orientation from the quadcopter.

Three axes of rotations are measured (roll, pitch and yaw).


Inertia Measurement Unit (IMU)

To accurately appraise the orientation, velocity and site from the quadcopter, an accelerometer or maybe a gyroscope alone is probably not enough. This is where the inertia measurement unit (IMU) can be purchased in.

The IMU is really a board that combines both multi axes gyroscope and accelerometer to have the best of both. The IMU can also include a magnetometer to improve the errors within the gyroscope feedback.

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