Drones are really taking off in the 21st century. The drone market was worth only 1.25 billion in 2020 and is expected to reach over 50 billion by 2025.

They can record breathtaking videos or fly blazing fast, and anybody can learn to pilot them. There’s even a new super fun and action-packed sport of drone racing. 

Though drones can look complicated, the parts, how they work, and flight modes aren’t too hard to understand. Here’s how a drone works and the physics behind how they fly.

What is a Drone

A “drone” is classified as an unmanned aerial vehicle. They can either be built like a plane or have propellers.

MultiRotor Drones

The typical drone has four propellers and is called a quadcopter.

Depending on the number of propellers, the name changes. If the drone has two propellers, it’s called a bi-copter and so on.  

We’ll be talking about multirotors today since they make up the majority of the drone market.

Fixed Wing Drones

Fixed-wing drones are basically unmanned planes. This is the most common drone associated with military use. 

Parts of a Drone

Understanding all the parts of a drone is really helpful to figure out how it works!

Airframe

Drone airframes are usually made of either plastic or carbon fiber and are the backbone of the drone. They need to be strong in order to protect their electronics from impacts and vibrations.

Drone frames are usually made of a central body that contains the main electronics and four arms that hold the motors.

Flight Controller

The flight controller is the brain of the drone and controls all the information required to fly the drone. 

Flight controllers have a gyroscope and accelerometer to figure out how the drone is moving, sometimes a barometer to sense height, and a magnetometer to sense what way the drone’s pointing.  

To control the drone, the flight controller takes information from the pilot’s controller and all the sensors on the drone to tell the ESC how much power to give each motor. 

Electronic Speed Controllers (ESC)

The ESC or electronic speed controller is controlled by the flight controller and is responsible for taking power from the battery and dispersing it to the motors. 

Motors

Motors are the powerhouse of the drone, and take power from the ESC’s to spin a propeller. 

Drone motors are either brushed or brushless. Brushless motors tend to be more powerful, have better efficiency, and last a lot longer.

Propellers

Propellers are shaped like airfoils and make lift by pushing air down when they spin. 

Four numbers determine the stats of a propeller. The first two numbers are the length of the propeller in inches, and the second two are the pitch in inches.

If a propeller is a “5050” propeller, it would be five inches long and could move 5 inches forwards if spun in one full circle.

Video System

The video system consists of two parts, a camera, and a VTX (Video Transmitter). 

When the camera captures an image, the VTX broadcasts it on a frequency that the video monitor can receive.

Receiver

Receivers are responsible for sending the signals from the pilot’s controller to the flight controller. 

GPS

The flight controller’s sensors are very accurate, but can’t tell if the drone is drifting or moving up and down very well. A GPS helps a drone know exactly where it is on the map at all times and sends that information to the flight controller. 

How Drones are Controlled

Radio Controller

A radio controller has two sticks that control the throttle, yaw, pitch, and roll of a drone. Some controllers also receive video as well, like the DJI controllers. 

Video Receiver and Monitor

If you want to see a drone’s video, you need a video receiver and a screen to view it on.

For drones with an FPV system, an FPV receiver with a monitor or FPV goggles are used. Other drones such as DJI have their video receiver built into the controller, and then a phone can be plugged in to see the drone’s video.

Flight Controller

Since a flight controller knows exactly where the drone is and how it’s moving with its GPS and sensors, the flight controller can control the drone.

Most drones have two main functions. Altitude and position hold features keep the drone in the same spot, and a return to home feature marks where the drone launched from, and flies back itself. 

Physics Behind a Drone’s Flight

Lift

Lift is generated by an airfoil (propeller) spinning in a circle, that pushes air down and lifts the drone up.

Turning

A drone doesn’t have a rudder, so to turn two diagonal motors are slowed down, and two are spun up.

When propellers rotating in the same direction push against air, it creates a rotational force in the opposite direction.

Movement

To move a drone around, it needs to be angled towards the direction it’s supposed to go. 

When the drone is angled, the force from its propellers isn’t pushing straight down but pushes to the side. The drone moves in an opposing direction to that the force is pushing. 

How a Motor Works

In order to generate power to spin the propeller, the motor has an electromagnet that creates a magnetic field.

This magnetic field pushes and pulls magnets that are held in the stator of the motor, to spin around. 

How a Flight Controller Works

The flight controller takes the commands from the pilot’s controller, and using the information from the drone’s sensors, moves the drone in the required direction.

If a drone is moving backward and the pilot pushes forwards on the pitch stick to rotate the drone forward so it’s level, the flight controller will give more power to the back motors to bring the back of the drone up.

A PID loop is a feedback loop that the flight controller uses to calculate its position, where it needs to go, and how much power to use to get there.

Drone Flight Modes

There are several different modes that you can use to fly a drone. Different pilots prefer different modes and can find some modes easier than others.

Stabilized or Self Level Mode

Stabilized mode or self-level mode makes the drone level itself out once the pitch and roll control joystick is released. On most camera and DJI drones, the drone will also hover if the throttle is also released.

In stabilized mode, there’s a maximum angle that the drone can rotate. Once you’ve reached this angle, you can’t go faster, and to keep flying at the same angle, you need to hold the stick in whatever direction you’re flying. 

Acro or Manual Mode

Acro or manual mode gives the pilot complete control of the drone. The drone will keep rotating as long as the joystick is being pushed, and it’s the pilot’s duty to keep the drone upright and can flip the drone completely upside down if they want.

You can get smoother flights with acro mode, but it can be tricky to master.

Final Thoughts

Understanding how a drone works is tricky, but it’s a lot easier once you’ve learned about the parts, how they work, and the flight modes.

Not only are drones getting more popular, but they’re also getting cooler as well! Some drones can use smart features to follow you around, running, on a bike, or in a car.

There are also giant human-carrying drones as well!

To learn more about drones, check out our FPV Tutorials and Camera Drone Tutorials!!

Comment below with any questions, and let us know what you’ve learned about drones today!