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Building a quadcopter or drone | Various parts needed

Drones, specifically quadcopters are complex machines in which many parts work together to achieve the same objective which is to fly. So in this post, we will take a look at various drone components or parts that we will need to build one ourselves.

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:

  • Frame
  • Motors
  • ESC (electronic speed controller)
  • Propeller
  • Battery
  • Flight Controller
  • RC Receiver

To get a good view, you’ll need the following components as well:

  • A Camera (preferably HD)
  • Video Transmitter / VTX
  • 5.8 GHz antenna

There are other non-essential but useful hardware for example buzzers, LEDs, HD Camera, GPS, etc.

But before getting into the drone parts, you should always fix the weight or size of the drone that you intend to build. This will help you in deciding everything after that.

Frame

The frame of a quadcopter serves as the main structure or skeleton on which all other components are mounted. When deciding on the purpose of your craft, such as aerial photography, racing, or micro freestyle, it’s important to choose a size that best suits your needs. The size of the frame will determine the size of the props, which in turn affects the size of the motors and the current rating of the ESCs.

A helpful tip for builders is to ensure that the frame’s mounting pattern for the flight controller and motors match your chosen components. Full-featured flight controllers typically have a 30.5 x 30.5mm mounting pattern, while motors for 5” props often have a 19 x 12mm mounting pattern.

First-time builders should consider a well-documented frame that is easy to work with and offers great access to the components. The Diatone 2018 GT M200 is a great example of such a frame. It is both sturdy and spacious, though it may limit the choice of parts. Additionally, this frame offers great protection to the components, which is important as crashes will happen.

Tutorial: How to choose drone frames?

Motors

The motors are the primary source of power consumption on your quadcopter, making it essential to select an efficient combination of propellers and motors. Motor speed is typically measured in kV, with lower kV motors producing more torque and higher kV motors spinning faster. However, this is without the propeller attached.

There are several factors that contribute to motor performance, with the current draw being one of the most important. Be sure to check the specifications of your motors for their maximum amp draw, and ensure that your ESCs are capable of handling this amperage.

A useful tip for builders is to keep in mind that the brushless motors commonly used in mini quads have three wires. The direction of rotation can be set with the software as well.

Note: When installing the motor, be sure to use screws that are the appropriate length to avoid contact with the stator windings. This type of contact can lead to a short circuit and damage the motor. Additionally, make sure any grub screws are securely in place and tightened.

Tutorial: How to choose drone motors?

PDB

A Power Distribution Board (PDB) is a device that distributes power from the battery to various components in the system. The PDB usually connects to the battery through a lead, such as an XT60 connector. However, recent advancements in technology have led to the development of All-In-One (AIO) components that can perform the same function as a PDB. These components, such as Flight Controllers (FC) and Electronic Speed Controllers (ESC), have a wide input voltage range and can output a stable voltage to power other components, such as an FPV camera. Builders tip: Before installing a PDB, consider if it is actually necessary for your build, as many components are now able to distribute power on their own.

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.

Flight Controller

The Flight Controller (FC) is the primary control unit of a quadcopter. It contains sensors that allow it to understand the craft’s movement and, based on the data provided by these sensors, the FC uses algorithms to calculate the required speed of each motor for the craft to respond to the pilot’s input from the Radio Transmitter (TX). Most of the wiring in a quadcopter is connected to the FC. It must be connected to the Receiver (RX) to receive the pilot’s commands, and the signal and ground wires of each Electronic Speed Controller (ESC) must be connected to the FC for the motor commands to be executed. With the introduction of BetaFlight OSD (On-Screen Display), even the video feed from the FPV camera goes through the FC to the Video Transmitter (VTX).

Builders tip: Keep in mind that more functions often mean more wires. For beginners, an “all-in-one” FC might sound appealing, but the wiring can become complex and tightly spaced, making it difficult to solder. Before starting to trim wires, test fit your components to your frame, and remember to measure twice, and cut once!

Note: Some All-In-One FCs integrate various components such as receivers and VTX and even ESCs. This integration is controversial in some circles.

Tutorial: How to choose a flight controller?

RX (Radio Receiver)

Transmitters (TX) and receivers (RX) are not interchangeable and must be matched in order to work together. For example, a FrSky Taranis transmitter cannot be used with a FlySky receiver. Currently, the most common protocols used are PPM or digital Serial, which only require one signal wire for all channels, as well as power (3.3v or 5v) and GND. The signal wire is connected to one of the UART terminals on the Flight Controller (FC). Some FCs have integrated receivers, but it is important to ensure that the protocol used is compatible.

Builders tip: Make note of which UART the RX is connected to, in order to 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, as it can damage the receiver.

Electronic Speed Controller (ESC)

An Electronic Speed Controller (ESC) is an electronic device that receives signals from the flight controller and converts them into timed electrical pulses to control the speed of a brushless motor. When selecting an ESC, ensure that both your FC and ESCs are capable of running the same protocol, such as DShot 600. Additionally, the current rating of the ESC must be higher than the amperage drawn by the combination of motors and propellers.

An ESC typically has four input terminals, two for signals from the FC (signal and signal ground) and two for the power supply from the Power Distribution Board (PDB) (positive and negative). It also has three output terminals, one for each wire of the brushless motor. Some ESCs now offer telemetry, which allows for monitoring and data logging of the ESC’s performance.

Builders tip: If you are using an FC with an integrated PDB, all four wires going to the ESC will come from the FC. 4-in-1 ESCs are becoming popular as they can save weight, but they are not universal, so check compatibility before purchasing. If you’re unsure, it’s best to 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 specifications of motors are usually provided under static thrust test conditions, which can be different from flight conditions. Propellers spin more easily in free air, which means motors use between 20% and 30% less current in flight than under static test conditions. 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.

Propellers

There are thousands of different types of propellers 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 Angle Of Attack (AOA), also known as “aggressive props,” encounter more resistance from the air and require more torque. When a motor has to work harder 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: Make sure that the props are tightened securely, a tool to grip the motors while tightening the prop nuts can be helpful. If the props slip, it can cause erratic behavior in flight.

Note: Props these days are generally well-made, but they may still be unbalanced. If you are experiencing vibration or ‘jello’ in your camera, check that your props are undamaged, unbent, and balanced, before you start disassembling.

Battery

LiPo (Lithium Polymer) batteries are commonly used as the power source in quadcopters due to their high energy density and high discharge rate. LiPo batteries are rated by their nominal voltage (3.7v per cell), cell count in series (indicated by a number followed by ‘S’ such as 4S = 14.8v), capacity in milliampere-hours (mAh, such as 1300mAh), and discharge rate or ‘C’ rating (such as 75C).

Builders tip: Keep in mind that the battery is the single heaviest component of your quadcopter, so a larger battery does not necessarily translate to longer flight time.

Note: It is not recommended to buy cheap “no name” batteries as they often have inconsistencies in cell voltage, inflated claims of capacity, and suffer from “voltage sag.” It is best to invest in reputable battery brands.

Camera

An FPV (First Person View) camera allows the pilot to see the view from onboard the craft, especially in mini quadcopters there are normally 2 cameras: one for real-time video streaming and the other for recording HD footage. FPV cameras are designed to have low latency and wide dynamic range (WDR) which is crucial for 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 the FPV camera capturing the image and displaying that image on the screen or in the goggles.

The FPV camera connects to the Video Transmitter (VTX) often through the Flight Controller (FC) which then overlays On-Screen Display (OSD) information on the image. A camera usually requires 5v to operate, but some cameras are capable of a wide input voltage and can be connected to the battery voltage (VBAT).

Builders tip: If you experience interference in the FPV image when applying power to the motors, a capacitor can be used to filter the noise.

Note: Cameras transmit images in different aspect ratios (such as 16:9 and 4:3), make sure that your FPV display (goggles or screen) is compatible. Different signal formats are also used in image transmission (such as PAL and NTSC), and your FPV display must also be capable of decoding the relevant signal type. Nowadays, cameras are often able to switch between these signal formats and some can even switch between image display ratios.

Video Transmitter

A Video Transmitter (VTX) connects to the FPV camera to transmit video to the FPV goggles or monitor. Most quadcopters use 5.8GHz for video transmission. Some VTXs offer additional functions such as a regulated 5v output that can be used to power the FPV camera. Be aware that if you power your VTX without an antenna connected, it may burn out.

The VTX receives a signal from the FPV camera (often via the Flight Controller) and then broadcasts on one of the channels within the 5.8GHz frequency bracket. Some VTXs run on 5v while others require more. If your VTX runs on 5v, it will be active when you connect your FC to USB, so make sure to have an antenna connected when configuring BetaFlight. 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 the channel, band, and output power.

Builders tip: If your VTX gets hot, it is a good idea to place it in a location on the frame where there is space for airflow to cool it down.

Note: When flying with others, be aware of your VTX power and make sure to check the frequencies being used by others to maintain good signal spacing.

Antenna

Every VTX requires an antenna to transmit a signal. Antennas come in various shapes and sizes, such as directional, linear, and polarized.

Builders tip: Keep in mind that carbon fiber material can block the 5.8GHz signal 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, ensure that both the antenna on your VTX and the one on your goggles are using the same direction of polarization. Left-hand circular polarization (LHCP) works only with LHCP, and right-hand circular polarization (RHCP) only works with RHCP.

Optional Components

Additional components commonly added to a mini quad are LEDs and a lost model buzzer. These are especially important for beginners, as they can help locate the quad if it goes out of sight. Especially when flying FPV, without something to draw your attention, the quad could be lost forever. Another common feature is the Go-Pro or similar action camera, which allows pilots to share their successes and failures on platforms like YouTube.

Builders tip: Keep in mind that smaller quads are better at hiding in tall grass, so be sure to have a way to locate it if it goes out of sight.