You’ve binge watched FPV Quadcopter racing videos for the past few hours (or days) and now you’re ready to go from spectator to participant with your own quadcopter! In the following post I’ll describe the basic parts needed to build your own quadcopter and what they each do.
This is all based on my own research as I build my own first quadcopter. I’ve decided to go the DIY route primarily because I enjoy the process of learning and building new things. That’s probably my hobby more so than anything else. If you’re not sure you want to go the DIY quadcopter route, there are many ready to fly options available – start by checking out this post on getting started with quadcopters.
At first glance, quadcopters are deceptively complex – Flight controllers, ESC, TX, RX, KV ratings, Telemetry, BEC, Opto, 2.4 Ghz, voltage regulator, blah, blah, blah. High, the geek barrier to entry this hobby is.
Don’t let all the jargon dissuade you from getting started, it’s not nearly as complicated as it seems.
Just realize this: at the basic level quadcopters are extremely simple. You need some motors and propellers, something to control the speed of each motor (ESC), something to tell the motors what to do (Flight Controller), a frame to hold it all together, a radio (transmitter/receiver) to send and receive your commands, and a battery to power it. Six parts.
If you just want the quick and dirty here’s the basics, more details follow:
- Quadcopter Frame
- 4 Motors –appropriately sized for your frame.
- 4 Electronic Speed Controls (ESC)– appropriately sized for your motors
- 1 Flight Controller Board (FC) – chosen based on personal preference.
- Transmitter and Receiver – with an appropriate number of channels.
- Battery – appropriately sized for your motors
Note: this is meant to be a beginners guide for quadcopter parts based on my own journey to build a quadcopter – there are many more things that you can add to make your quadcopter more functional like low voltage regulators, etc. There are also many more details that can be considered for each part. But, for now we’re going to keep it simple.
Let’s briefly talk about each part, the order to consider them in, and some initial considerations.
The Quadcopter Frame
This is the part that holds everything together. It should also be the first part you should consider since many other choices will be driven by which frame you choose.
Since we’re talking about Quadcopters – this frame will have four arms to hold four motors (i.e. quad). You can also have tri-copters (3 arms, 3 motors) all the way up to octocopter (8 arms, 8 motors). The general term that is used is a multi-rotor.
There are two basic things to consider when choosing a frame: the design and the size.
There are lots of different designs for quadcopters – but they all are basic variations of an X-frame or H-Frame design. I chose an H-Frame design because I wanted some extra storage space for extra things. Different designs will have slightly different flight characteristics – but for the beginner I don’t really think you can go wrong with whatever you choose.
Size is the second consideration. Generally this is the number in the frame name like: F450 or H250. This number represents the approximate size of the quadcopter in millimeters.
The bigger the number, the bigger the quadcopter. A bigger size means it’s generally more stable but you give up maneuverability and your costs increase potentially because you have to buy bigger motors, etc. A smaller size means greater maneuverability, but less stability and potentially lower costs. For myself, I picked the 250 size because I want something that is small and maneuverable.
You want to choose your frame first because this will then dictate the other parts you choose.
In general, most frames will come with recommendations on motor size. Frankly, for beginners the best way to choose your motors is to use the frame manufacturer’s recommendation. Motor choice can get complex quickly with a number of interdependent variables that come into play such as frame weight, prop size, KV, etc. We’ll detail that all in a later post – for now choose the manufacturer’s recommended motor size that goes with your frame.
If your frame doesn’t have recommendations find a similar sized frame that does and use the same motors.
The Flight Controller
The Flight Controller is the brain of the quadcopter. It takes your input (e.g. turn) from your radio and figures out which motors need to be sped up or slowed to get the quadcopter to do what you intended. Many flight controllers also have additional sensors such as gyroscopes, accelerometers and more to supplement commands you send it.
There are many Flight Controllers out there, from OpenSource versions like CC3D to commercial versions like Naze32. It seems to be mostly personal preference that will drive your choice.
The Transmitter and Receiver
While the flight controller is the brain of the quadcopter. The transmitter (commonly referred to as the radio – or the thingy you hold in your hands) and the receiver are the things that allow your brain to communicate with the flight controller.
The transmitter takes your movements of the control sticks, converts it to data, and sends that to the receiver which sits on the quadcopter. The receiver then gives that data to the flight controller which makes the quadcopter do what you intended it to.
For beginners, the primary consideration is the number of channels a quadcopter can handle. Each channel on a transmitter is responsible for performing a different function (e.g. throttle, pitch, and yaw are each channels).
The general guideline is to buy a transmitter with as many channels as you can afford – 6 channels being the minimum, and 9 channels being the recommended.
The Electronic Speed Control
Next up is the Electronic Speed Control or ESC. Simply said, the ESC is in charge of controlling the speed of your motor based on input from your Flight Controller. You need one ESC for each motor.
A key consideration is the number of amps the ESC can handle. This will be driven by the number of maximum amps that your particular motor pulls. In general you want to choose an ESC with amps slightly more than the maximum your model motor pulls. For example, if your model motor pulls a maximum of 7.6A, you could choose a 10A ESC.
In the example above you could also choose a 30A ESC, and it would work, but it would be quite a bit bigger and heavier and potentially not fit on your frame. A rule of thumb is to choose something that is greater than, but close to, the maximum number of amps your motor will pull.
For beginners (and most people), you also want to choose an ESC with a Battery Eliminator Circuit (BEC). A BEC allows your ESC to do two additional things: 1) provide power to other circuitry in your quadcopter without the need for a second battery, 2) Lower the voltage from the battery to other circuitry so you don’t fry it. You want to choose a BEC that provides the voltage your other electronics such as the receiver require and that the flight controller can handle– typically this is 5V.
For example, the CC3D flight controller can handle 5V – 15V input power and passes this voltage along to other electronics connected to it such as the receiver. So, if we have a receiver rated for 5V, we want the ESC to provide 5V of power from the battery to the Flight Controller.
It looks like 5V BECs are pretty much standard so I wouldn’t sweat it too much in a basic setup.
If you’re unclear what a battery is, you may want to take a break from quadcopters and focus on integrating yourself better in modern society. I’ll assume you have the basics down.
The industry standard is lithium-ion polymer (LiPo) batteries. There are three things to note about a LiPo battery when choosing what to buy.
First, is the number of cells it has. Each cell in a Lipo battery is responsible for providing 3.7V. So a 3 cell Lipo will provide 3.7 x 3 = 11.1V and so on.
The voltage rating for your model of motor is what determines the maximum amount of voltage your battery should provide. On your quadcopter, if your motor model is rated only up to 11.1V and you buy a 4 cell Lipo you will fry your motors. You can provide less voltage than your motor is rated for, but don’t supply more.
Second, is the capacity of the battery designated in milliamp hours (mAh). This is a way to tell how long the battery will last. For example, a 2200 mAh battery will provide 2200 milliamps over 1 hour before it can longer provide any juice. To further the example it could provide twice as much milliamps (4400ma) in half the time (30 mins).
Your electronics will only draw as much amperage as they need, so you won’t fry your electronics by buying higher capacity batteries. But, you won’t necessarily get longer flight times: the higher the capacity the greater the weight which means your motors will work harder thus pulling more amps and draining a higher capacity battery faster.
Third is the C rating you the maximum number of amps you can discharge continuously from a battery without damaging it.
If we have a 2200mAh battery with a 10 C rating this battery can continuously supply (discharge) 2.2A x 10 = 22 amps without getting damaged.
The C Rating you want is once again driven by your motors (do you see a pattern here). If you have a motor that has a maximum pull of 7.6A, and you have four motors, than you need a battery that can supply 7.6A x 4 = 30.4 Amps to really get everything out of that motor. A battery that can provide 30Amps to all four motors at full speed won’t hurt anything, it just means you’re not getting full performance out of the motor.
It took me quite a bit of research to figure all of this out. But, once I got past all the jargon I realized that quadcopters are really simple. Of course, like any hobby there is lots more to consider, details to agonize over, and acronyms to memorize, but with these basics you can easily get started.
Hopefully, this simplifies some of it for you as well and puts you on the path to building your own quadcopter.