What Is a Quadcopter?

What is a quadcopter?

What is a quadcopter?

What is a quadcopter?

A quadcopter is a type of multicopter. Multicopter – a multi-engine or multi-rotor aircraft (helicopter), the rotors of which rotate diagonally in opposite directions. Multicopters differ in the number of motors (or in the number of rotors). In our time, multicopters with three or more main rotors have received application.

The most common schemes are: 4/6/8 rotors. An apparatus with three rotors is called a tricopter; with four – quadrocopter; with six – hexacopter and with eight rotors – octocopter. The use of each of the schemes mainly determines such a parameter as the payload mass, or, more simply, the weight that the multicopter can take on board.

Examples of modern multi-rotor solutions.

Modern multi-rotor solutions from different price niches:

tricopter YI ERIDA side view

What is a quadcopter?

What is a quadcopter?

What is a quadcopter?

From the history

It all started back in 1922 with -American aircraft designer Georgy Alexandrovich Botezat. Who invented the first working quadcopter of its kind. His apparatus was able not only to get off the ground, but also to hold out in the air for some time. At that time, such devices had one significant drawback – the principle of operation.

first quadcopter

Of the four rotors, only one was leading (the rotation was set by an internal combustion engine), i.e. torque, through a complex transmission, was transmitted by one motor to the remaining 3 rotors. It did not reach serial development. And such inventions as the “Tail rotor” and “Swashplate” forced to completely abandon the development of multi-rotor aircraft, after which the world’s first helicopter was later created.

With the onset of the 21st century, multicopters came into our lives already as unmanned aerial vehicles or drones.

The main components of multicopters

Purely technically, about 5 years ago, three main components of multicopters (drones) appeared:

  1. The battery is lithium polymer (LiPo), less often lithium-ion (Li-Ion).
  2. Brushless or collector motors on rare earth elements.
  3. Remote controller (Remote control/Instrument/Transmitter)

multicopter technical components

Operating principle

The principle of operation of a modern multicopter is simple. Depending on the application scheme (3/4/6/8-rotor) each main rotor is driven by an electric motor (electric motor). One half of the motors rotates the propellers clockwise and the other half counterclockwise. Thanks to this approach, the control of a multicopter does not require the use of a tail rotor in the drone design and a complicated swashplate.

The principle of operation of multicopters

*The order of the direction of rotation of the main rotors of the multicopter.

Flight control example:

  • Increasing the speed on all rotors – lifting.
  • Reducing the speed on all rotors – reduction.
  • Increasing the speed of one half of the screws and decreasing the speed of the other half will set the movement to the side.
  • Increasing RPM for clockwise propellers and decreasing RPM for counterclockwise propellers will ensure the drone turns.

What is a quadcopter?

*Scheme of flight control by rotation of rotors.


On modern multicopters (drones), two types of electric motors are currently used – collector and brushless. Brushless drones are mainly equipped with expensive and professional drones. Collector motors are equipped only with budget options, toys. You can learn more about their differences here.

bq motors


The multicopter is controlled by a remote controller (it is also a control panel, equipment, transmitter) through outgoing radio waves (usually at frequencies of 2.4GHz or 5.8GHz).

To make the multicopter respond to the requests of the control panel, the drone is equipped with a whole range of electronic systems:

  • The microprocessor (flight controller, implemented as a microcircuit) is responsible for the operation and control of the entire electronic filling of the drone.
  • Gyroscope – responsible for the stable behavior of the drone during the flight (as a rule, it provides stabilization along 6 axes of direction).
  • Accelerometer – Using this sensor, the processor can set the drone to a horizontal position relative to the ground.
  • Barometric sensor (barometer) – provides the drone with a stable hover at the height chosen by the pilot.
  • Sonar (ultrasonic sensor) – provides automatic landing and low altitude hold (1.5 – 3.5 meters), can also be used to fly around obstacles.
  • GPS module – provides the geographic positioning of the drone, using data received from satellite systems. Thanks to its presence, the function of point-to-point flight is implemented, return to the take-off point in case of loss of communication or low battery charge, and also allows you to take flight readings, both at the time of the flight and after.

The simplest scheme of a quadrocopter

* The simplest scheme of a quadrocopter device.

What are there?

Currently, the home drone market offers a huge number of multicopters (drones), but in general they can be divided into three large groups: Beginner/Amateur/Professional.

For newbies – suitable for both children and adults for the purpose of the first acquaintance and training. As a rule, they are equipped with a microprocessor, a 6-axis gyroscope and a simple barometric sensor to provide altitude hold.

amateur – for pilots who already have UAV experience. More suitable for a specific application. For example, for aerial photography, or for sports such as drone racing. Drones of this group can have autonomous flight and shooting functions.

Professional – suitable exclusively for experienced pilots who use the capabilities of multicopters (drones) in the professional field. For example, professional photo and video shooting, geodesy, monitoring of land, traffic, in rescue operations, etc. In most cases, drones have autonomous flight and shooting functions. The electronic filling is assembled from high-precision modern systems that ensure removal over long distances, and the power allows you to spend much more time in flight. A characteristic difference between such multicopters is their price.

For a more complete acquaintance with unmanned systems, we recommend the topic “What is a drone?”.

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