Drone industry is growing at a fast pace. Drones have been adopted in several verticals, including real estate, healthcare, military, transport, surveying, retail delivery, construction, and infrastructure. There are 1.1 million drones registered with Federal Aviation Administration in the United States. There are more than a million active drones in India. There were 430,700 drones in Europe in 2021. The drone industry has just set about. Many more drones will be operating commercially in multiple sectors and owned privately by the end of this decade.
The most common type of drone is a quadcopter. The quadcopters do not just dominate recreational drones; these are common drones used in commercial drone services. Quadcopter is the simplest UAV helicopter having four motors. You can learn about the physics and working behind the flight of a quadcopter from this link. Building a quadcopter is one of the favorite projects of electronic engineers and hobbyists. But do you know what components or parts are required to build a radio-controlled quadcopter. Well, we will discuss the same in this article.
Fortunately, you will not need to collect the parts mentioned here from different sources. Several drone kits are available that pack all these essential parts and electronic components in one kit. If you are experimenting with a custom drone design, you may only need to collect the parts and electronics required for building a quadcopter separately. You definitely need to match the compatibility of the components from different sources in that case. For instance, you will need to check whether the motors you selected are compatible with the battery system and electronic speed controller.
Similarly, the battery and charger must be compatible with each other. You may build a quadcopter out of an assembly kit or gather parts and electronic components from different sources; the list of parts and components will remain almost the same. Let’s get started.
Parts of a drone
If you plan to build a radio-controlled quadcopter drone, you require the following parts.
- Quadcopter frame
- Drone motors
- Electronic Speed Controller (ESC)
- Flight Controller Board
- Radio transmitter & receiver
- Battery and power distribution cables
- Landing gear
- Battery charger
The following parts are required to add remote vision to the drone.
- First-person video
The frame forms the skeleton of the drone. The drones used in different commercial applications have frames that suit specific usage. The frame supports motors and provides chassis to fit the flight controller, radio receiver, battery, etc. The frame not just lets you assemble other components; it plays a vital role in maintaining the center of gravity and the aerial stability of the drone.
The quadcopter frames are available in many different materials like Aluminum, Carbon Fiber, Plastic, Glass fiber, PCB fiber, etc. Each material has some pros and some cons. Ideally, the frame material should be lightweight, robust, and steady. The material should not have any radio interference. Aluminum frames are stronger and robust but are heavy and prone to vibrations. With an aluminum frame, strong motors are required to propel the drone. The carbon fiber frames are lightweight and strong but have the problem of radio interference. The plastic frames are lightweight and free from radio interference, they lack strength and robustness. A poor plastic frame could even crack or fade due to excessive exposure to sunlight.
The quadcopter frames cost anywhere between $10 to $500. The metal and carbon fiber frames are costlier. You always need to make a bargain between good frame material and the cost. The selection of a good frame must depend upon the optimization for strength, robustness, steadiness/stability, weight, cost, and radio frequency interference for the intended application.
The drones use brushless motors to propel. The selection of proper motors is very important. A quadcopter has four rotors, so four motors are required. Essential characteristics of a drone motor are KV rating, voltage, amperage, recommended propeller size, and torque. The KV rating and torque are inversely proportional to each other. The higher the KV rating, the faster the motor RPM will be, but the less will be the motor torque. So, a motor with a higher RPM can run faster but carry less load for a given voltage. The recommended propeller size must comply with the drone frame. The motors must be placed in drones at least 3-propeller distance from each other.
Once you have selected a frame, you can sort motors by their recommended propeller size. Further, you can shortlist the motor according to the size, KV rating, and required torque according to the specific application. Finally, a suitable motor can be selected based on ESC amperage and voltage.
Electronic Speed Controller (ESC)
The electronic speed controller (ESC) controls the speed and direction of the BLDC motors. The ESC unit’s amperage must always be higher than the total current drawn by all engines and other components. The more power the motors consume as the drone flies at a higher altitude. Therefore, the ESC selection determines the height the drone can fly.
The ESC is interfaced between the flight controller board and the drone motor. It converts the DC power from the battery to a 3-phase AC to drive the drone motors. ESC has four input terminals. Out of these, two terminals connect with the LiPo battery. Then, two terminals connect with the flight controller board and carry PWM and ground signals. For interfacing with a 3-phase BLDC motor, there are three output terminals on the other side. Some ESCs include a battery eliminator that can supply power to other electronic components.
Flight controller board
The flight controller is a microcomputer board that controls the entire flight of the drone. It is equipped with multiple sensors like an accelerometer, gyroscope, barometer, and digital compass/magnetometer, which all are used to track and record the drone’s position, altitude, rotation, and orientation. Many flight controllers also include GPS sensors and a ‘return to home feature.’ Using this feature, the drone returns to precisely the exact GPS location; it has taken off.
Flight controllers are usually generic microcomputer boards loaded with flight control software. Usually, flight controllers have no compatibility issues with other parts of the drone. Still, the selection could be based on preferred flight control software and the microcomputer specifications. The other vital criteria could be the sensors integrated into a flight controller board.
The propellers produce downward thrust to lift the drone in the air. These are also called pushers because the drone propellers come in pairs of two pairs. One pair of propellers rotate clockwise, and the other pair rotate anti-clockwise. When propellers rotate, they create a low-pressure region above and a high-pressure region downside. This lets the drone lift in the air.
The critical factors to consider while selecting propellers are their length and pitch. The better the pitch, the better the propeller will cut through the air and create more pressure difference. The other important factor is the length of the propeller. Longer propellers give more substantial lift even at lower RPM. However, they force motors to consume more power and have a lower rate of change in RPM. Shorter propellers let quickly change the drone’s speed and even put less load on the BLDC motors; they lower the load capacity of the drone.
Radio transmitter & receiver
A radio transmitter-receiver or radio controller is a remote controller connecting the pilot with the drone. It is only possible with a radio controller that a drone pilot can maneuver the drone. The radio controllers operate at one of the fixed radio frequencies. The frequency used by the radio controller depends upon its geographical location and regulations.
The compatible receiver unit is interfaced with the flight controller board on the drone. The transmitter, which looks like a gamepad, is used by the drone pilot to change the drone’s altitude, speed, direction, and orientation. The radio controller must have at least four channels to control the quadcopter effectively.
Battery & power distribution cables
Generally, Lithium Polymer batteries are used in drones. The LiPo batteries have high energy density and provide a higher voltage of 3.7V per cell. A pack of three or four batteries in series and two or three batteries in parallel, like a 3S2P or 4S configuration of LiPo battery, is sufficient to power a drone flight. The capacity of the battery determines the flight time of the drone.
The battery is specified by its amperage configuration/voltage and current rating. For example, a LiPo battery for a drone with specification 2200 mAh 3S 30C has a capacity of 2200 mAh, a voltage output of 3*3.7V or 11.1V, and current production of 30*2200 mA or 66A. Similarly, a LiPo battery for a drone with specification 8000 mAh 4S 35C has a capacity of 8000 mAh, a voltage output of 4*3.7 or 14.8V, and a current rating of 35*8000 mA or 280A.
The higher will be the capacity of the battery, the more significant could be the flight time. The higher the voltage and current, the more power it could supply to BLDC motors. The battery must be selected based on the combined current consumption of the BLDC motors and other components and the desired flight time. The power distribution cable is required to connect the battery to ESC and other components.
The landing gear is required for the safe landing of the quadcopter. It may be necessary or may not be, depending upon the specific application as well as the expertise of the drone pilot. There are two types of landing gears – fixed and retractable. The landing gear must be selected according to the frame of the drone. If the landing fear is installed on a drone, the material of the gear also plays a vital role in the stability and steadiness of the drone. Installing the landing gear adds some extra load to the drone. So, it must be installed only if required and must be selected wisely.
A compatible battery charger must charge the LiPo battery pack. Usually, the battery packs are accompanied by a compatible charger. Otherwise, it is not much difficult to find one for any LiPo battery chosen for a drone.
You need a camera if you wish to take video footage from your drone. Many people use their camera or Go Pros with the drone. The footage is sent to a First Person Video (FPV) device. There are also many FPV cameras available that are capable of not only recording but also transmitting video footage. The camera or FPV camera can be installed on a drone according to the requirement and budget.
FPV is a ground station that consists of a video receiver and display. It receives the video footage from an FPV camera over drone frequency and lives telecast on a display unit. Many FPV units only display 2D video footage, while VR-set type FPV units provide an immersive 3D view. The commonly used drone frequencies for video transmission include 433MHz, 869 MHz, 900 MHz, 1.2 GHz, 2.4 GHz, or 5.8 GHz. The FPV can be added to a drone according to requirements and budget.
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