If you just bought your first drone or have been using them for some time but don’t know how they really work and you’re curious to know more, you’ve come to the right place.
The controllers, joysticks, and apps make flying a drone as easy as playing a video game. But within the drone, there are small parts that all work together to make sure the drone can fly. So, how do drones work?
The most important parts of a drone are the operating system and the flight controller. Batteries power the rotors causing them to spin the propellers and generate lift. The flight controller uses the data collected by accelerometers, barometers, magnetometers, gyroscopes, and the controller to stay in the air.
Other important features that enhance the functioning of a drone include GPS, obstacle detection and collision avoidance, cameras, and software.
Please keep reading to find out how all components of a drone work and how they all contribute to a drone’s flight.
How drones fly (UAV drone propulsion technology)
A lot goes into the drone generating upward lift and performing various movements. And in this section, we will discuss how all that works. But before that, let’s first list all the components that play a role in the propulsion of a drone:
- Motor Bell
- Motor Stator
- Flight controller
Also, before we discuss how each of these parts works, let’s define some common drone movements:
- Yaw – This is when the drone’s front section rotates in a clockwise or counter-clockwise direction.
- Pitch – This is the tilt the drone assumes depending on the direction it’s moving. To accelerate forward, drones lower the front section and lift the rear section. To reverse, they lift the front section and lower the rear section.
- Roll – This is the movement in which a drone moves to the left or the right.
I will explain the role of propellers and motors in each of these movements later in the article.
This is one of the most crucial parts of the propulsion system. Batteries power the motors, causing them to rotate at high speeds. As a result, the motors rotate the propellers, creating lift. Quite easy, right? Not really.
There are two main types of motors; brushless and brushed motors. Brushless motors are the most commonly used because they’re efficient, durable, and can rotate at very high speeds.
So, what’s the difference between brushed and brushless motors? It all comes down to how they function. But before I explain the differences, let’s define the main parts that differentiate them.
- Stator – A stator is the section of a motor that has windings. It’s the part that provides a magnetic field, which then initiates rotation in the rotor. To create a magnetic field, stators have windings of copper wire which turn into magnets every time a current runs through them. In most cases, the stator is stationary.
- Rotor – The rotor is the part that rotates, causing a rotation in the shaft, which then causes a rotation of the propellers.
- Air Gap – This is the distance between the rotor and the stator. The larger it is, the less effective the motors will be.
- Motor Bell – This is the part that causes the propellers to rotate either clockwise or counter-clockwise.
Both brushed and brushless motors have a stator and a rotor. But in the brushed motors, the stator constantly provides a permanent magnetic field. Stators surround a rotor, which will have opposite polarity, and a rotation in the rotor will occur when the commutator brushes interact with a power supply.
The contact of these brushes with the power supply makes brushed motors ineffective since they wear out faster, and the heat produced hastens the wearing of the drone.
On the other hand, brushless motors lack brushes. Instead, the stator goes on and off, providing a magnetic field when necessary. Attraction and repelling between the stator and rotor are what cause the rotation. And since there’s no contact, like with the brushes in the brushed motors, there’s no heat generation, and there’s minimal wearing out.
Drone motor bearings
Bearings are often overlooked, and you may not know they exist unless you check the motors. Still, they are very helpful in minimizing the air gap mentioned earlier and keeping the rotors in place as they rotate.
As a matter of fact, if your motors fail, chances are bearings are the issue. When it comes to bearings, there are shielded and unshielded bearings. Shielded bearings work best for drone motors since the motors rotate at high speeds, generating very high temperatures that could destroy the bearings.
The propellers have to rotate in different directions to generate lift and maintain the drone in the air. In each pair of propellers, one is rotating clockwise (CW), and the other one is rotating counter-clockwise (CCW).
As they rotate, they create a zone of low pressure. Air moves from low-pressure regions to high-pressure regions. That’s how the drone is able to move up, down, forward, or backward depending on how the speeds at which the propellers rotate.
Also, the amount of thrust generated needs to balance out the drone’s weight, causing it to be dislodged into the air.
Number of propellers
Most drones have 4 propellers, and are known as quadcopters. This didn’t happen by chance or as a way to give the drones their signature look. There’s a reason behind it. To explain it better, let’s start by assuming a drone had one propeller.
Such a drone would generate enough lift to propel the drone into the air, but it will be very difficult to control the drone since it has no way to move forward or in reverse. Besides, the drone will continuously be rotating in the opposite direction. This is actually according to Newton’s 3rd Law of Motion; when two objects interact and are in motion, they will affect each other in opposite directions.
Having a drone with two propellers would also be an option. And as a matter of fact, it would help save on battery power. Besides, when you get the propellers rotating in different directions, you cancel the torque exhibited by the single-rotor drone. However, it’s still difficult to control such a drone since it’s not stable.
Unlike the 2-propeller drone, a 3-propeller drone isn’t an option since it undoes everything that the 2-propeller drone solves.
And this leaves us with only four propellers or more. Quadcopters have the perfect balance to allow the drones to hover, speed forward, and make maneuvers without crashing. What happens is that all the motors cancel each other out, maintaining stability and preventing unwanted rotation.
More propellers create more stability, but also create more draw on the battery. Therefore 4 propellers is the ideal number.
To hover, all motors receive equal power and rotate at the same speed.
To move forward, the front propellers slow down, while the rear propellers increase their speed. This makes the drone pitch forward by lowering the front part.
To yaw, motors in a diagonal pattern will slow down, allowing the drone to rotate on an axis to the left or the right.
To roll, the rotors on the left or the right are slowed down depending on the direction you want to roll in.
How flight controllers work (Transmitter, Receiver, and Smartphone Apps)
Now, all the maneuvers explained above are built into the drone, but there’s another piece of the puzzle; the flight controllers. Can you imagine having to manually control the speeds of various rotors just to turn the drone right or left?
And that’s why drones need a flight controller, a device that collects data from the various sensors and uses this data to control the drone’s motion. The flight controller is a combination of hardware and firmware that contains algorithms that enable it to make sense of all the data it receives from the sensors and the controllers.
Through a process called sensor fusion, the flight controller collects all the data and uses it to make decisions in real-time. A good example of algorithms is the Kalman Filter that enables the controller to use past and present data to make accurate decisions.
How it all works
As mentioned earlier, drones speed, turn, slow drown, or roll by changing the speed of the motors. So, once the flight controller collects data from sensors, it sends it to the Electronic Speed Controller (ESC), which then interprets it by increasing or reducing the voltage depending on the action you want to take.
For instance, if you want to accelerate forward, the ESC will reduce the voltage of the front rotors to slow them down and increase the voltage of the rear propellers.
The flight controller also receives information from the remote controllers. All you need to do is push the joysticks up, down, left, or right, and the remote controller will send these commands through a radio signal to the drone. On the other end, the drone has a receiver that receives these signals, interprets them, and effects the command on the drone.
If your drone is controlled through a smartphone, the drone and the device generally communicate through Wi-Fi. Most drones have their own drone apps, which, when you install them on your smartphone, allow you to easily control the drone with or without the remote controller. But the range may be limited compared to using the controller.
Speaking of range (the furthest distance a drone can travel from a controller), it can vary from a few feet to several miles depending on the drone you’re using and the strength of the connection. For toy drones, it’s usually a few feet, but for consumer and prosumer drones like DJI drones, it can be as far as 5 miles.
To learn more about the range of common drone models, check out our article about how far a drone can fly from the controller »
DJI has made a name for themselves in the consumer drone world by building OcuSync, an advanced communication system that allows them to have a long operating range.
For some drones, you can also purchase range extenders to allow the drone to operate further than initially stipulated. However, you should also pay attention to the regulations since, unless authorized, you should always fly your drone within visual line of sight.
How sensors work (The IMU system)
Now let’s talk about the various sensors you’ll find in a drone. But before we do that, it’s important to acknowledge that a drone can’t effectively fly without sensors. These devices are as small as the size of an ant, but they are minicomputers that help measure the surroundings and send accurate data to the flight controller, which goes a long way in stabilizing a drone’s flight. The more sensors a drone has, the more it will account for errors or forces that act on the drone as it flies. Let’s look at each of them.
Also known as MEMS (micro electrical mechanical systems), accelerometers use capacitive and piezoelectric technology to detect linear acceleration due to gravity. In capacitive technology, capacitors are placed in a parallel pattern. Any change in acceleration forces affects the distance between these capacitors, affecting their capacitance and sending the signals to the flight controller.
On the other hand, piezoelectric measures orientation using microscopic crystals compacted as a result of acceleration. A change in the acceleration forces impacts pressure, which changes the weight and resistance of these crystals. Accelerometers are placed in a 3-axis pattern so that they can detect the motion and orientation of a drone in all directions.
Gyroscopes are another vital feature that helps stabilize a drone. They consist of a wheel rotating on an axis. This wheel rotates in such a way that, even if the drone tilts, it will still maintain its balance.
Drones face a wide range of forces in the air, including wind and gravity. As a result, it can become very difficult to control the drone, especially when there are big wind gusts. Gyroscopes are designed to detect all these forces and compensate for them, so the drone will appear unaffected.
Of course, other factors such as the strength of the wind and the drone’s weight will apply. But for the most part, drones will appear stable in moderate winds. Gyroscopes also convert these motions into signals and send them to the ESC.
You may have heard of 3-axis gyroscopes and 6-axis gyroscopes. A drone only needs the 3-axis gyroscopes, but most drone manufacturers will mention a 6-axis gyro because they’re taking into account both the gyroscopes and the accelerometers.
Magnetometers measure the magnetic flux along the pitch, yaw, and roll axis, which helps detect the drone’s orientation in relation to the magnetic North Pole. When flying in areas with lots of electromagnetic interference, or any other kind of interference, magnetometers help collect this data and send it to the flight controller.
Also known as pressure sensors, barometers measure the atmospheric pressure to help determine the drone’s altitude. If you’ve come across a feature known as altitude hold in most drones for sale, then this is one of the sensors that make this feature possible. Sometimes, barometric sensors work alongside GPS sensors to determine a drone’s altitude and maintain it.
These sensors use lasers, Lidar, or ultrasonic waves to measure the distance ahead of a drone and detect any obstacles.
Drone LED lights
All drones come with LED lights. And even though they can be viewed as decorations, these LED lights serve a purpose. In most cases, they are used to inform you of the status of the drone. We have covered a lot about drone LED lights in this post, but below are the main ones and what they mean.
- Red could mean low battery levels, IMU or other system errors, RTH mode, or agility mode.
- Green is also a common color that often shows the battery levels are suitable for taking off or for showing that the GPS has connected to enough satellites.
- White – White colored LEDs may mean a poor GPS connection or lack thereof, or that the transmitter is off.
- Blue – Blue can mean Blind Mode or Stability Mode.
- Orange/Yellow – These colors can mean a poor GPS connection or poor compass calibration that needs to be rectified.
- Purple – This color is used to show Return to Home or Follow-Me modes are working. But if it’s blinking, it may mean there’s an issue with these modes. It is also used to signify AP Mode in some drones.
Below is another type of LED lights.
- Anti-Collision Lights – Sometimes referred to as navigation lights, these are the lights that make your drone visible from far away, helping the operator prevent it from crashing into other drones or other objects. According to the FAA regulations, including the recent Remote ID regulations, you must have these lights if you want to fly at night. They can be blue, red, white, flashing, or not flashing, depending on the drone model.
Note: Different colors could mean different things depending on the drone you’re using. That’s why it’s important to always check your specific manual for guidelines.
You are of course familiar with the GPS on your phone or car that helps you navigate, but drones have it too. The installation of GPS in drones is one of the reasons drones are able to perform location-based data collection such as surveying and aerial imagery. So, how does it work?
For GPS to work, there needs to be a GPS module or chip placed in the drone and satellites orbiting the earth. Currently, at least 32 GPS satellites orbit the earth, also known as the GLONASS (Global Navigation Satellite System). GLONASS is a Russian-based satellite system designed for positioning applications by the military and civilians.
However, only about 24 will be functioning at any given time. Now, a drone doesn’t have to connect to all 24 satellites. They need to connect to at least 8, but the more satellites the module can connect to, the better. The module communicates with these satellites to calculate its position.
In the drone apps, there are bars showing the strength of a GPS connection. And as mentioned earlier, there are even LED lights that will alert you of any issues with GPS. If your drone doesn’t have access to enough satellites, it may not take off. Some of the reasons you may be getting a poor GPS connection include cloud cover, tall trees, tall buildings, or mountains.
Now that you know how GPS works, below are some of the ways it helps the drone’s functioning.
As mentioned earlier, GPS and barometric sensors can help maintain the drone’s altitude. Some drones come with an altitude limit, and the FAA also requires drones to maintain an altitude of less than 400 ft. This being the case, GPS can help detect and limit a drone to a certain altitude.
Also known as position hold, this is where a drone takes off and remains in the same location and altitude until you start feeding instructions into it. This makes it very easy even for beginners to fly a drone.
When you’re not sure of the controls, the drone will not move, it may drift a little, especially when it’s windy, but it will always correct that.
Return to home
This is another quite necessary feature, especially in emergencies such as low battery levels. Return to home allows the drone to return to the take off point, and the best way to do that is to have the coordinates of that location.
That’s why it’s important to calibrate the GPS correctly and allow it to lock the take-off location. When you’ve done this, once you initiate the RTH feature, you will not lose the drone along the way.
Some drones will automatically initiate the RTH if they lose connection, have low battery levels, or experience interference.
Autonomous flying (Waypoints)
A drone can now fly on autopilot thanks to GPS. How? All you have to do is assign waypoints, which are coordinates that the drone can fly through. If you’re using it for filming, mapping, or surveying, you can focus on producing high-quality footage while the drone flies on its own.
Like airplanes or ships, drones can be detected by radar. It all boils down to how radar works. Radar systems are designed to detect bodies emitting radio signals. And as mentioned earlier, drones communicate with controllers through radio signals.
So, you can design a system that identifies signals within the drone communication signal ranges and other behavior that drones exhibit. As a matter of fact, such systems already exist. Good examples include DJI’s Aeroscope, AirSpace Galaxy, and DeDrone.
Internal compass and failsafe features
Drones also have internal compasses which work together with GPS to enhance stability and ensure the drone is in the proper orientation. More often than not, the compass comes with the GPS module.
When setting up a drone, one of the most vital things to do includes calibrating the compass. Most drones will not take off unless the compass is calibrated, so make sure you check how to do that.
To effectively calibrate the compass, make sure you are in a wide-open area, an area with no magnetic interference and no electronic equipment. Calibration is also important when you move to a different location.
Remember, if the compass is incorrectly calibrated, most GPS functions, including finding the satellites, won’t work.
Drone compasses also have magnetometers, which, as I mentioned earlier, will detect any anomalies and help the flight controllers consider all factors. All this is to make sure the drone is properly oriented and prevent any fly-aways that are often caused by poor GPS and electromagnetic interference.
Obstacle detection and collision avoidance technology
When talking about sensors, I mentioned that drones use a wide range of technologies to detect obstacles. These include LiDAR, monocular vision, time-of-flight, ultrasonic, stereo vision, and infrared.
But that’s a whole lot of sensors., So, how do drones utilize all of them to avoid obstacles? By using a combination of modeling, algorithms, machine learning, and AI. Algorithms can be trained on how various objects look, and they’ll “learn” to associate every object they see with what they already know to determine whether it’s an obstacle or not.
Another fascinating technology that makes obstacle avoidance possible is SLAM (Simultaneous Localization and Mapping). This feature allows drones to map their current environment based on a pre-installed pre-existing environment and the data collected by sensors.
Now, what I’ve just explained only helps a drone detect an object ahead. But for it to avoid the object, it will need to calculate where exactly this object is and find an alternative route. One way drones achieve that is through stereopsis or stereo vision.
You’ll find that most advanced drones will have two cameras at the front. Once they get the image of the object in 2 perspectives, they can calculate the 3D perspective by triangulation. This allows them to view their environment in 3D, perceiving both distance and depth.
Intelligent flight modes
As highlighted several times in this article, drones are actively collecting data, which can then be used to map out a path that the drone will follow, with minimal input from the pilot. With the help of an operating system (more on this later), you can also pre-program various flight patterns that a drone can accomplish on its own. These are also known as intelligent flight modes.
Besides detecting objects, this technology also allows drones to identify objects, also known as Follow-Me, or ActiveTrack in DJI drones. As such, you can lock yourself as the POI and jog, skate, or participate in any activity, and the drone will follow you while filming while also avoiding any obstacles along the way.
Other intelligent flight modes include;
- Altitude Hold
- Auto-Return Home
- Position Mode (P-Mode)
- Attitude Mode (ATTI Mode)
- TapFly –
- Quickshots – Dronies, Helix, Circle, Rocket, etc.
- Cinematic Mode
Nowadays, drones are designed to communicate their real-time telemetry information to the controller or the app. This includes battery levels, GPS connection, altitude, and other aspects of the drone.
You can also get alerts when you exceed an operating range, when you fly too high or even when you fly in restricted areas. All this information makes it easier to monitor the drone and minimizes crashes.
Geofencing is a feature that enforces restrictions and alerts when a drone enters restricted airspace, also known as No-Fly Zones. These zones include military bases, the White House, airports, prisons, etc. Unless you find a way to bypass this restriction, your drone will not take off when in these regions.
However, not all drones are restricted by geofencing. For it to work, the drone needs to have GPS, and it needs to be integrated with the map containing No-Fly Zones.
Drone operating systems (Firmware)
Drones can most simply be thought of as flying computers. As we’ve established, a lot goes on when a drone takes off and while it’s in the air. There are sensors collecting data, communications with the controller, propellers, batteries, and many other functions.
But what powers this whole system? Drones have firmware, often built on the Linux operating system, though some use MS Windows. There are also several open-source drone operating systems that manufacturers can use instead of building one from scratch. These include;
- Linux’s Dronecode
Drone firmware needs to be updated regularly to ensure all the drone components are working as they should, or to introduce new features.
Software and firmware
To effectively fit in in various industries, there has been increased development of software for drones. Below are some of the most popular industries where drones are applicable, and the software drones can use.
- Filming and Photography – Lightworks, iMovie, VSDC Free Video Editor, HitFilm Express, and Davinci Resolve.
- Surveying, Mapping, and Aerial Photography – DroneDeploy, Pix4D, ArcGIS, Maps Made Easy, and PrecisionHawk.
- Construction – 3DR, PixPro, and Datumate.
- Agriculture – SLANTRANGE, AgEagle.
Thanks to technological advancements, it’s now possible to attach high-quality cameras to drones. As already mentioned, drones now play a major role in filming and photography, where we previously needed helicopters and other expensive equipment.
For a moderate price, it’s possible to find a drone that can film in 4K at 30fps. A good example that’s both a hobby drone and a professional drone is the DJI Mavic Mini 2. The Mavic series, especially the Mavic Air drones, are some of the best photography drones for beginners and experienced photographers thanks to their ease of use, extended flight times, excellent cameras, and advanced flight control systems.
Drones like the Autel Robotics EVO II series can even film in 8K resolution. And drones like the Inspire series from DJI feature the Zenmuse X7, which can film in 6K resolution, and they’ve been instrumental in filming many blockbuster movies.
Besides shooting in high-resolution, some drones also have a zoom feature, which enables drones to have a close look at objects, even when they’re at a distance. Depending on the drone you’re using, the zoom feature can either have a mild loss or lossless zoom. DJI has the Zenmuse Z30 with a zoom of up to 180x, which is one of the largest you’ll find in a prosumer drone.
For more about the best camera drones available, check out our article here »
Gimbals and tilt control
As much as drones have advanced stability systems, they are still not very steady, which would be bad for filming since that movement would make the footage useless. Thankfully, there are gimbals that help stabilize the cameras regardless of the turbulence.
Even cheap drones now have gimbals, mostly 3-axis gimbals, that stabilize the cameras in all directions. These gimbals allow for smooth, clear images, compensating for the movement of the drone.
For those with no gimbals, some are compatible with third-party gimbal systems.
Live video transmission
It’s now very common to find drones that can relay video footage, also known as FPV (First Person View).
All of this is made possible by Wi-Fi connectivity and radio signals between the drone and the controllers. Drones have a transmitter that collects the video footage and sends it as a signal to the controller.
At the other end, the drone will have an antenna or receiver that will receive the signal and convert it to a video that you can view on the smartphone’s screen. Or you can purchase FPV goggles that make it feel like you’re sitting in the drone’s cockpit. FPV is also a major component of drone racing, a fast-growing sport.
Despite being only a few years old, there are several drone racing leagues such as the Multi GP and DRL, where drone pilots compete for thousands of dollars and enjoy sponsorship deals just as regular professional athletes. These races are also streamed on live TV, giving other pilots and hobbyists a view and feel of the adrenaline involved in such a race.
Other drone sensors
One of the best things about drones is the ability to carry a payload. Therefore, if you want to extend its application and usefulness, all you have to do is find a suitable device to add to the drone, and one of those devices is sensors.
Besides the sensors I mentioned earlier that help the drone navigate, you can attach multispectral sensors for agricultural applications, Lidar sensors for construction inspection, or thermal sensors for fire analysis.
Even cameras are sensors that work in visible light. These sensors are hardware, and the data you get from them can be analyzed using the software I mentioned earlier to get meaningful information crucial in decision making.
Security and hacking
Since they’re flying computers, drones can be hacked, and they can also be used to hack into other systems or even spy on other people. And the bad news is that it’s not that difficult to hack into a drone.
A hacker can hack into your drone and download footage that you’ve been taking or even use the drone to hack into your home network. They can also hack and take control of the drone through a process known as GPS Spoofing, where they guide the drone to “false” coordinates. With that in mind, below are some ways you can prevent your drone from being hacked.
- Firmware upgrades – As mentioned earlier, drone manufacturers update firmware regularly. To make sure your drone is protected, always make sure you’re using the most recent firmware.
- Use a VPN to block your network from being accessed by outsiders.
- Protect your smartphone and laptops with Anti-Virus. When transferring footage between the drone and the smartphone or using the smartphone to control the drone, you’re exposing your drone to malware attacks.
- If possible, manually set the Return to Home point.
- Use a strong password on your app and home network.
- Limit the number of people using the home network at a given time.
Drone Types and Uses
Now that we know how drones work, let’s look at the main types of drones and how they’re best used.
Also known as quadcopters, these are the most popular types of drones. They are also the drones I was talking about when explaining the propulsion system. They have at least four rotors, though some of them can have more rotors.
Their small size, agility, speed, and maneuverability allow them to find applications in many industries, including agriculture, filming, and industrial inspection. The only issue with these drones is the propulsion system consumes a lot of energy. As a result, their batteries don’t last long.
This is another popular type of drone. Unlike the multi-rotor drones that have propellers, these drones have fixed wings, similar to those you’ll find on planes. They need some sort of runway or catapult system to take off. But once they do, they conserve energy, allowing them to fly for long.
They’ve been quite useful in agriculture, such as the SenseFly drones, and in land survey, such as the Delair drones.
These are simply tiny helicopters that rely on one rotor. They control their speed, roll, pitch, and yaw by adjusting the angle of the rotor. Most of the single-rotor drones you’ll find are toys. Still, there are also larger advanced models with the ability to carry heavy payloads, and they can also be powered by gas instead of regular batteries.
Hybrid or VTOL drones
VTOL stands for Vertical Take-Off and Landing, which are drones that utilize the extended flight time of a fixed-wing drone and the vertical taking off and maneuverability of a multirotor. This makes them the most versatile drones, but they are also quite expensive. A good example is the Wingtra drones, which are very useful in surveying and mapping.
You can also categorize drones based on how they are used, which include:
- Toy drones
- Consumer drones
- Professional drones
- Racing drones
- GPS drones
Fixed-wing, multi-rotor, single-rotor, and VTOL drones can fit in any of these categories depending on how they are built and their features.
For more about types of drones and their uses, check out our post here »
And there you have it. If you are new to the world of drones, you can bookmark this post, for I went all out to explain how every aspect works, the types, and some issues associated with drones. Is there any aspect that you think I missed and you would like me to address? Please let us know!