This tutorial explains the basics of quadcopter hardware, what each component does and how they connect with each other. There is a lot to cover, make sure to check out the links for more information on each quadcopter component.
After you have a basic understanding of quadcopter hardware, check out my step-by-step tutorial about how to build a quadcopter (drone) from scratch.
The first step to building a quadcopter is to understand the components that it uses to fly.
A quadcopter consists of the following essential parts:
- ESC (electronic speed controller)
- Flight Controller
- RC Receiver
To Fly FPV (first person view), you will also need the following parts:
- FPV Camera
- Video Transmitter / VTX
- 5.8gHz antenna
There are other non-essential but useful hardware for example buzzer, LED’s, HD Camera, GPS etc.
Choosing Quadcopter Components
The frame of a quadcopter is the main structure, or the skeleton upon which the rest of components will be attached. Once you have decided on what you want your craft to do (Aerial Photography, Racing, Micro Freestyle etc.), you need to decide what size best suits your requirements. The size of the frame will determine what size props you will use (or vice versa), in turn the size of the props will determine the size of the motors, which will specify the current rating of your ESC’s.
Builders tip: When choosing a frame it is important to check that the mounting for the FC (Flight Controller) and the motors match your choice for these components. Full featured flight controllers are most common with 30.5 x 30.5mm mounting pattern. Motors for 5” props often have a 19 x 12mm mounting pattern.
Note : 1st time builders should choose a well documented frame that is easy to work with. This is a great looking frame that is robust and spacious with great access to the components, but a little limiting on the choice of parts. Check out the review of the Diatone 2018 GT M200. This frame also offers great protection to the components which is important because you will crash it!!
PDB stands for Power Distribution Board and it is often where the battery power lead (ie. XT60) is connected. As its name suggests, the PDB distributes power to the components at the voltages they require. These days the necessity of using a PDB is being negated by FC’s, ESC’s and other (dubbed AIO or All-In-One) components providing the same function. These components have a wide input voltage range and can be connected to battery voltage (aka VBAT), they can then output a stable voltage ie. 5v to power an FPV camera or other components.
Builders tip: Make sure that your PDB is actually necessary, nowadays it is likely that you will be able to distribute power to your components by other means. Ie. some VTX have a wide input range and can output a regulated 5v to power your FPV camera.
Note : AIO is a common term used for components that can fulfill more than 1 function, ie. an AIO FPV camera will be a camera and VTX (video transmitter) integrated into one unit.
The Flight Controller (aka “FC”) is the brain of a quadcopter, it has sensors on the board so it can understand how the craft is moving. Using the data provided by these sensors, the FC uses algorithms to calculate how fast each motor should be spinning for the craft to behave as the pilot is instructing via stick inputs on the TX (Radio Transmitter). Most of the wiring on your quad will be focussed around the FC. It needs to have the RX (receiver) connected, so it can be told what the pilot wants the craft to do. Each of the ESC signal and ground wires need to be connected for the FC commands to be carried out by the motors. With the introduction of BetaFlight OSD (On Screen Display), even the video feed from the FPV camera goes via the FC to the VTX (Video Transmitter).
Builders tip: More functions often means more wires. For beginners an “all singing, all dancing” FC might sound fantastic, but the wiring might become very tightly spaced making it difficult to solder. Remember to test fit your components to your frame before you start trimming wires. measure twice, cut once!
Note : Some AIO FC’s will have a selection of various different components integrated onto the board from receivers to VTX, now even ESC’s are being integrated with FC’s though this is quite controversial.
RX (Radio Receiver)
Transmitters (TX) and receivers (RX) are not universal and you need to buy an RX that is compatible with your TX, an FrSky Taranis transmitter cannot work with a FlySky receiver. These days it is most likely that you will be using either PPM or a digital Serial protocol, which will only require 1 signal wire for all of the channels, plus power (3.3v or 5v) and GND.The signal wire will be connected to one of the UART terminals on your FC (Flight Controller). Some FC’s actually have integrated receivers, if you are taking this route make sure that it is using a compatible protocol.
Builders tip : Make a note of which UART you have connected your RX to, so you can easily configure the FC to communicate with the RX in BetaFlight Configurator.
Note : Spektrum based receivers usually require 3.3v while FrSky and FlySky RX require 5v. Never supply 5v to an RX that only requires 3.3v!
ESC – Electronic Speed Controller
An ESC is a device that interprets signals from the flight controller, and translates those signals into phased electrical pulses to determine the speed of a brushless motor. Make sure that both your FC and ESC’s are capable of running the same ESC protocol ie. DShot 600. When selecting an ESC, remember that the current rating must be higher than the amperage drawn by your combination of motors and props.
These days an ESC has 4 input terminals, 2 are for signals coming from the FC. Signal and signal ground are wired to the FC, the 2 heavier wires are for Positive and Negative, they carry the high current to the ESC to supply the motor. These Positive and negative are wired to the PDB. An ESC has 3 output terminals, one for each of the wires of a brushless motor. Some ESC’s now offer telemetry, for more info see – How to set up ESC telemetry
Builders tip : If you are using an FC with an integrated PDB then all 4 wires going to the ESC input will come from the FC. 4-in-1 ESC’s are becoming popular as they can shave a few grams off your AUW (All Up Weight or takeoff weight *inc. Battery and other peripherals). A 4-in-1 ESC can connect to the FC in different ways, and they are not universal – Unless you know exactly what you are getting, I advise you purchase a 4-in-1 ESC as a stack combined with the FC such as the Holybro Kakute FC and tekkoS 4-in-1 ESC.
Note : The specs provided on the data sheets of motors are under static thrust test conditions. Props spin easier in free air and therefore motors use between 20% and 30% less current in flight conditions than that shown in static tests. If the maximum amperage draw of a motor is the same or just under the maximum current rating of your ESC it should be fine.
The motors are the main drain of battery power on your quad, therefore getting an efficient combination of propeller and motor is very important. Motor speed is rated in kV, generally a lower kV motor will produce more torque and a higher kV will spin faster, this however is without the prop attached.
There are many aspects to motor performance aside from raw thrust, high among these is how much current the motor draws from the battery. Remember to check the specs of your motors for their maximum amp draw, and ensure that your ESC’s are rated to withstand this amperage.
Builders tip: The brushless motors that are most commonly used on a miniquad have 3 wires, it doesn’t really matter which of the 3 output terminals these are connected to on the ESC, swapping any of the 3 will change the direction of rotation. Motor rotation can be set in BL_Heli configurator.
Note : Remember to ensure that the motor mounting screws are not too long and that they do not touch the stator windings of the motor. This contact can cause a short in the windings, spelling the end for your motor, also make sure that any grub screws are fitted and tightened.
There are possibly thousands of different types of propeller for quadcopters, with multiple options in almost every size. A heavier propeller will require more torque from the motor than a lighter prop, also blades with a higher AOA (Angle Of Attack – aka “aggressive props”) encounter more resistance from the air and require more torque. When a motor has to work hard to turn, it draws more Amps. Finding a balance between the thrust produced and the amperage used by the prop and motor combination is a balancing act that every quad pilot goes through, there is no “right answer”.
Builders tip : Remember that your props have to be really tight, it helps to have a tool to grip the motors while tightening the prop nuts. If the props slip this will cause erratic behaviour in flight.
Note : Props these days are generally well made, but they may still be unbalanced. If you are getting vibration or ‘jello’ in your camera, check your props are undamaged, unbent and balanced, before your start disassembling!
LiPo batteries are the power sources of the quadcopters. LiPo is used because of the high energy density and high discharge rate. LiPo batteries are rated by their nominal voltage (3.7v per cell), cell count in series, (shown as a number followed by ‘S’) ie 4S = 14.8v, capacity in mAh (ie.1300mAh) and discharge rate or ‘C’ rating (ie. 75C). If you want to know more here is an article on LiPo battery C ratings.
Builders tip: The battery is the single heaviest component of your quad, just because you put a bigger battery on it, it doesn’t mean it will fly longer.
Note : buying cheap “no name” batteries is not recommended you will find inconsistencies in cell voltage, inflated claims of capacity, and they will suffer from “voltage sag”.
An FPV camera allows the pilot to see the view from onboard the craft. On an FPV mini quad, there are normally 2 cameras, one for real time video streaming, and the other for recording HD footage.
FPV cameras don’t have great video quality – they are designed for WDR (Wide Dynamic Range) and low latency, which is extremely important to FPV. WDR refers to a camera’s ability to display changes in lighting conditions, and areas of shadow and light in the same image. Latency is the amount of time between your FPV camera capturing the image, and display that image on your screen or in your goggles.
The FPV camera will connect to the VTX (Video Transmitter), often via the FC which then overlay’s OSD (On-Screen Display) information on the image. A camera usually requires 5v to operate but some are capable of wide input voltage and can be connected to VBAT.
Builders tip: If you are getting interference in your FPV image when applying power to your motors you should fit a capacitor to filter the noise. Here is an article to tell you more about capacitors for noise filtering.
Note: Cameras transmit images in different size ratios (ie. 16:9 & 4:3), check and make sure that your FPV display (goggles or screen) is compatible. Different signal formats are used in image transmission too, (ie PAL & NTSC) your FPV display must also be capable of decoding the relevant signal type. These days cameras are often able to switch between these signal formats, and some are now even able to switch between image display ratios as well.
Video transmitter, or VTX, connects to the FPV camera to transmit video to the FPV goggles or monitor. Most quadcopters these days use the 5.8GHz for video transmission. You may find that your VTX can offer other functions such as a regulated 5v output that can be used to power your FPV camera. Remember that if you power your VTX without an antenna connected, it may burn out!
The VTX will receive a signal from the FPV camera (often via the FC) which it then broadcasts on one of a number of channels incorperated by the 5.8gHz frequency bracket. Some VTX run on 5v some require more. Be aware that if your VTX does run on 5v that it will be active when you connect your FC to USB, so you should have an antenna connected when configuring BetaFlight. Remember that if your VTX requires more than 5v it will not function with USB power and you will need to connect a battery to set up your channel, band and output power.
Builders tip: Your VTX gets hot, it is a good idea to place it somewhere on the frame where it has some space for airflow to cool it down.
Note: If you are flying with others be aware of your VTX power, make sure that you are aware of the frequencies being used by others, so you can maintain good signal spacing.
Every VTX requires an Antenna to transmit signal. This guide explains the basics of FPV antennas. Antennas come in various shapes and sizes, directional, linear and polarized.
Builders tip : Carbon Fiber will block the 5.8gHz signal that is used by the VTX, make sure that the antenna is far enough away from the frame to be able to transmit without the signal being blocked.
Note : If you are using polarized antennas, make sure that both the antenna on your VTX and the one on your goggles are using the same direction of polarization. LHCP works only with LHCP, and RHCP only works with RHCP.
The most common additional components added to a mini quad are LED’s and a lost model buzzer. These are really important for a beginner, especially if you don’t have a nice flat area of mown grass, your quad can go really quickly which means it can be far away quite fast.
Especially if you are a beginner and are disoriented flying FPV, without something to draw your attention, your quad could be gone forever! Of course the Go-Pro or similar action camera is is a common feature. so we can show off all our successes and failures to our like minded youtube subscribers!
Builders tip: Smaller quads are better at hiding in long grass! :p
Hopefully this article has given you a better understanding how a quadcopter works, how the various components communicate and physically connect. To learn more about flying a Quadcopter, see this beginner guide about control.
Please do not hesitate to comment or provide feedback on this article.
- Jun 2013 – Article created
- Apr 2018 – Updated info, URL changed