What is a quadcopter?

Quadcopters are four-rotored flying machines

, they are lifted by four propellers: two spinning clockwise, and two spinning counter-clockwise. As such quadcopters are “rotorcrafts”, and belong to the same family as helicopters do. While helicopters work by changing the pitch of their rotors to control the aircraft, quadcopters usually work changing the RPM of their propellers. The quadcopter’s spread is closely related to the advent of high performance microcontrollers, which are used as the flight controller, the brain of the quadcopter. These tiny computers have the computing power required to balance the quadcopters. Quadcopters are mechanically simple (you do not need pushrods, servos or any kind of complex mechanical devices to make them work), and flight controllers are readily available, making quadcopters easy to build.

Quadcopters have a long history

, they were built from the beginning of the 1900s, with various levels of success. Just as with any new technology, the level of refinement increased gradually. The first quadcopter, the Breguet-Richet Gyroplane built in 1907, could barely fly. 50 years later the Convertawings Model A Quadrotor could already fly fairly well in 1956. However it was just around 2005 that the first electronic quadcopters appeared. Since 2005 the number of quadcopters and manufacturers have grown exponentially, today you can get quadcopters in all shapes and sizes, from palm-sized quadcopters with built-in camera to the huge Kopterworx HammerK8.

As quadcopters are simple, reliable and easy to build you can will surely meet them in new roles the following years.

Two props spin clockwise, and two counter-clockwise.
How do quadcopters work?

Quadcopters use a gyroscope to work out their own tilt angle, and then speed up or slow down their propellers to compensate and keep themselves stable.

The quadcopter’s propellers spin independently using 4 motors, 2 in clockwise, and two in counter-clockwise direction. Would the quadcopter tilt left, it can speed up it’s left side propellers to compensate. Tilting forwards, backwards, and right are taken care of the same way.

In forward flight the rear props speed up, the front props slowdown.
To move forward

the quadrotor will slow down it’s propellers in the front slightly, and speed up the ones in the back. This way it will tilt forward,the props will start pushing the air down and towards the back, which will make the quadcopter fly forward.

To turn left, the quad speeds up it’s props turning right.
To turn left

(counter-clockwise), the quadcopter will speed up the propellers turning right (clockwise), and slow down the props turning left (counter-clockwise). This way the faster turning props will get more resistance from the air, and the quadcopter will start turning counter-clockwise. Turning right is achieved in a similar fashion, by speeding up the counter-clockwise turning props,and slowing down the clockwise turning props.

To ascend, the quadcopter will simply speed up all it’s propellers.
To ascend and descend

the quadcopter will simply speed or slow down all of its propellers.

These are the basic movements a quadcopter is capable to. Fortunately you do not have to take care of the propellers speeds yourself, the flight controller does it all for you based on the stick inputs from the transmitter.

Quadcopters can be equipped with even more advanced electronics, to create a more versatile flying machine. For example by adding a high performance flight controller and a GPS you can program it to follow a pre-determined flight plan.

What are quadcopters good for?

Quadcopters and drones are great for recreation, both flying and building them are lot of fun. Just watching how it reacts to your inputs is a great way to let go after a long day. Some quadcopters support first person view flying too – their on board camera transmits the video signal to the pilot’s goggle which can be even more engaging.

Besides flying for fun, quadcopters are great for aerial photography, for example DJI’s Phantom line of quadcopters are professional video recording machines.

Quadcopters are also used by the law enforcement and the military as a surveillance tool: they can fly fast to the desired location and takeĀ  a photo or video of the bad guys without endangering the pilot’s life.

Drones make good use in the agriculture too, where they can survey the crops or spray pesticides.

Though not yet used for this, drone will probably be used as last-mile delivery agents too.

Finally, quadcopters make great research platform too, scientists and engineers use them to study autonomous and cooperative behavior, object avoidance, and many other subjects.


quadcopters are very cool, and you can get lots of fun and enjoyment out of them. If you find them interesting you may want to check out a few of our reviews too.

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