Why four rotors?

The team under Botezat guidance began testing the unmanned helicopter with four screws in 1922. The drone device with a four-screw design in those days was recognized as the most stable and optimal regarding flight characteristics.

Due to the multi-screw principle of operation, the device was easily controllable. To turn it in the air, it was enough to change the position of the drone nose cone.

In later times, when the first drones on the radio control got a four-wheel-drive helical system installed, they got an absolute balance and maximum flight control. All the disadvantages of drones with four motors were minimized by installing the new technologies and electronics. To this day, the 4-motor device is the best and most reliable in terms of design, flight, and technical characteristics.



Multicopter is an alternative, the optional type of the four-screw drones. It surpasses them in the number of motors. Its supporting screws rotate diagonally and in opposite directions to each other.

The multicopters differ between each other with the number of motors. In modern practice, in addition to three and four-screw models, there are hexacopters and octocopters. The number of screw elements determines the peak weight of the device can lift and carry.

How does a drone fly?

The drone is controlled using a remote control panel. Its signals go to the onboard aircraft computer. The installed sensors can correct the drone flight. Each control panel is tuned to a certain number of channels. The minimum number of channels for the drone is four. It depends on the number of engines. The more engines, the more channels.

Having processed the received signals, the drone flight controllers send the instructions to the speed regulators, and they, in turn, change the rotational parameters of the drone propellers.

In order the drone could fly in a balanced and well-controlled manner, its propellers rotate in different directions — one pair clockwise, the other one against it. The propellers rotation parameters impact how the drone flies:

•    If all the screws rotate at the same speed, the aircraft takes off.

•    If one of the propellers rotates faster — the drone leans and moves to that side.

•    If a pair of propellers moves faster — the drone turns to that direction.

In general, the drone can:

•    Take off upwards.

•    Go down.

•    Move horizontally.

•    Move forward and backward.

•    Move left and right.

•    Lean.

Some models can spin on the spot, flip, and even turn upside-down.

If we talk about the drone speed, they differ depending on the device. At the moment, these figures are zero (hanging on the spot) to 100 mph.

All modern devices are equipped with safe flight software. If the battery is low, the drone will notify the operator, and when the charge level is near zero, the monitoring system will direct the drone to the starting point. The GPS navigator will control it. Also, the security software does not let the drones fly outside the sensitivity zone. At the moment, this zone can be up to several kilometers depending on the drone model.


Why can it be difficult to control?

A beginner may face some control difficulties. They relate to the device orientation and the movements coordination. To control the drone with the sticks can be unusual at first.

However, for such users, many manufacturers have provided the Headless Mode feature. It changes the drone orientation in a way the pilot does not need to think about both sides of the drone.


Recording the video

At the moment, the market has a whole segment of professional drones, equipped with high-quality video cameras. Images from the video camera recorded in first person view mode are broadcasted to the control panel, smartphone, tablet or another output device. The radio-controlled drone, equipped with a video camera, allows using first-person view mode to control the shooting process completely.

In most cases, the video is transmitted via a Wi-Fi network. For that, the drone has a special transmitter, and the control panel has a receiver. The sensitivity zone can reach up to 5 kilometers. On average, the video can be transmitted without quality loss to up to 500-1000 meters.

For more realistic control, a video can be transmitted to specialized glasses. However, it is worth noting that their use is not always practical because if the operator has some vision problems, it will be more convenient to look at a screen at some distance.


What parts does the drone consist of?

Modern models of drones can have both a simple design, just for entertainment, and consist of complex components that make it possible to turn these aircraft into the professional devices.

Despite the drone construction can be different from the model to model, its basic components are always the same. In general, each drone consists of the following parts:

1.  Engines.

2.  Speed controller.

3.  Propellers.

4.  Flight controller.

5.  Frame.


Drone engines, propellers, and speed controller

Each engine (in most cases, the drone has four engines) is connected to one propeller and drives it at speed generated by the speed controllers. The speed controller sets the speed based on the commands coming from the flight controller.

It is worth noting that propellers and engines are the most quick-wearing parts of a drone since during its flight they get the highest load. So, when some emergency situation happens, for example, the drone falls, the unprotected parts such as propellers, break above all others. Therefore, for beginners, the drone developers recommend buying devices equipped with special propellers protection. These can be arcs or shrouds that are impacts-protected and can protect the propellers from breakage.

Speed governors or flight speed controllers are responsible for monitoring the engine power. The total run current of these elements must exceed the maximum current of electric motors. Among the main parameters that you should know about when selecting revolving regulators yourself, are the maximum run current and the range of operating voltages.


Flight controller

The flight controller is the brain of the drone. It is programmed to process various signals coming from the remote operator’s console and the sensors installed on it. The more signals a controller can handle, the more universal the drone is. The flight controller is connected to each of the four motors through a bus line, which allows you to send control signals to them.

Since the stability of the entire flight depends on the flight controller, when developing drones, the manufacturers actively use various methods to make the elements vibro isolated. As a rule, the better the controller is isolated from the vibration, the more stable the drone will fly. Recently, high-end flight controllers are already manufactured with built-in vibration isolation.

A set of various sensors (GPS, gyroscopes, barometer, accelerometer, etc.) are connected to the flight controller. The controller gets the indications from the sensors. Feedback with the operator is carried out through the special transmitter installed on the case. Depending on the received indications, the operator changes the drone flight parameters. If the drone flight controller is sufficiently intelligent, then, based on the sensors indications and program algorithms, it can independently change the drone’s flight parameters without the operator.

The final set of the flight controller components depends on the drone cost. The simplest drones can only control the engine’s rotation depending on the incoming commands. At the same time, the most advanced can, for example, independently return to the start point. The basic structure of the flight controller is as follows:

•    The main processor is responsible for processing the commands.

•    The gyroscope is the sensor for determining the position of the drone in space.

•    The altimeter is a device that determines the flight height.

•    The accelerometer is a device that analyzes the acceleration of a device in three planes (x, y, z).

•    Direction arrow indicates the direction the drone should fly (located at one of the corners of the board’s base).

•    GPS-navigator determines the location of the drone.

•    Wi-Fi to communicate with external devices like tablet, smartphone, laptop.

•    Operating memory. The more RAM you have, the more operations it can manage simultaneously.


The drone frame

The frame is the basic drone component. All other elements are attached to it. The main manufacturer’s goal is to make the drone impact-resistant, light, and durable device. And the frame is the most important element to reach this goal.

They use the polymers or strong but light alloys to produce the frame. Also, they actively use the carbon, fiberglass and other modern materials. They have to ensure the maximum structural rigidity.

In general, the frame consists of many parts which allow getting the greater device maneuverability and control. Also, there are holes for electrical wiring. It connects the flight controller to all other parts of the drone.


Lifting bar with a camera

This is an important part of any multicopter with shooting feature. A lifting bar serves to connect the video camera to the device frame. It can have several axes (usually two or three) that allow rotating the camera to capture images in different directions.

Often, the lifting bar is equipped with special dampers which are designed to dampen vibration and ensure a high-quality video stabilization.


Drone batteries

The rechargeable battery is another important drone element. Its capacity impacts the maximum height the drone can fly, as well as the flight range and time.

All drone batteries are quite heavy, so the construction to mount them should be strong enough. This is another reason why the frame should be made of reliable and strong materials.

Due to the small capacity and small battery size, small drones can still stay in the air for no more than 3-5 minutes. Amateur models can stay in the air for about 12-15 minutes. The flight time of professional drones is at the moment no more than half an hour. As you can see, the flight time is now one of the most problematic factors to develop the industry. However, the problem is going to be sold in the near future.


What is a drone and why may you need it?

Drone is also known as quadcopter or multicopter. What does this mean? This is an unmanned aircraft controlled using a special remote console from the ground. The signals are transmitted via the radio channel. Usually, it is equipped with four screw propellers.

Most modern models of drones contain miniature video cameras installed in the bottom part. They provide the ability to shoot photo and record video right in the air.

As soon as the first drones appeared in the store grounds and filled departments of the unmanned devices on the radio control, their price could hardly attract the buyers. But over time, the cost of such gadgets continued to fall continuously. It keeps falling since its appearance so far, and the price range is expanding to infinite limits. Today they are available to many people with an average income.

There are also drones with a camera, which became a real boom among the broad masses of unmanned aircrafts fans. Thus, the scope of their usage has significantly developed, attracting the attention of people of all ages, from schoolchildren and preschoolers to retired people, unmanned flights amateurs and professionals, fans of multicopters sports competitions, journalists, bloggers, reporters and even militaries and secret service agents.

Modern drone technologies have stepped far ahead in recent years. But in most cases, people tend to respond the question of what a drone is and how to use that it’s a gadget for entertainment and exciting amateur air shooting.


Who invented a drone?

The history of the drone creation and development goes back to the first half of the last century. The first acting prototype of all current amateur and professional drones, as well as helicopters, appeared in 1922 and was called the Botezat helicopter. Within the first test flights, he managed not only to fly into the air successfully but also to lift up a cargo weighing about 450 kilograms at an altitude of four meters.

George A. Botezat – the one who invented the drone, was a US citizen of Russian origin, inventor, naturalist, and professor of the Petrograd Institute of High Technologies. The development of the world’s first drone under his leadership was conducted with the financial support of the US Army. The military needed an aircraft, which could produce vertical takeoffs and landings. Over time, the project was stopped due to certain technical difficulties.

The device needed the fair wind for flights, and it was the main problem. The scientist did not manage to complete the development and optimization of the engine rotation scheme to the end.


The future of drones

How can the people use the drones except for entertainment? Today, such aircraft are used successfully to help construction crews to install the complex, composite structures, in agriculture, and even to carry people.


At the moment, the variety of drones on the market is really impressive. They can be small for children, an amateur with a camera, and with intelligent flight features. However, despite all the diversity, the general principles of how the drone fly is fairly simple. Good luck with your drone!