So just what is a racing drone and what makes it work?
I know that when I was first getting into the hobby I thought these machines were sophisticated electronics finally tuned to work together to defy gravity. A black box of technology that mere mortal could never hope to understand. That why I bought a bundle: A TBS Discovery with DJI flight controller, ESC and mortars included because I knew that all that would work together.
Since then I have learnt that while a drone is sophisticated, they are a lot more approachable and understandable than I thought.
To get a quad in the air you need seven things. To make it FPV you need two more. Let’s go through them one by one.
The Frame
Without this you just have a bundle of electronics flopping around but choosing one can be tricky. Firstly you have a range of sizes to chose from. Frame sizes are most commonly described by the size of propellor they can take. A typical FPV quad is a “5 inch” - it’s the sweet spot of size, weight, and power. You can go bigger or smaller, but if you are thinking about your first build, a 5 inch is a good place to start.
Flight Controller
Now we have our frame, let’s start right in the middle with the Flight Controller. This is the brain of the machine. It has built in sensors to measure angles and speeds and runs software that knows how to use those measurements to keep the quad in the air by changing the speed of each motor. In FPV we use flight controllers that don’t have al the bells and whistles of the ones you may have seen or used before fro the likes of DJI and Parrot. There’s no altitude or position hold and there’s no return to home or auto land on the controllers we use, they are built for performance.
If you think of a DJI controller as a luxury car with air con, heated seats and cruise control, our flight controllers are stripped down track cars with anything that doesn’t made the car go faster or handle better stripped out.
We go into flight controller in greater depth here.
ESCs
We’re onto the parts you need four of now (Or a 4-in1 - foure ESCs on a single board). ESCs (or Electronic Speed Controllers) are what take the signals from your Flight Controller and current from your battery to control the speed of each of your motors. Developments in ESC technology like DSHOT mean they can react incredibly quickly to what the flight controller is asking them to do.
You can find out more about ESCs here
Motors
The engines of your quad, motors vary in size and speed. The size is measured in diameter and the height of the magnets (the stator) so you’ll see things like “2204” and “1806” bandied about. The speed of the motor is also a factor and it’s measured in Kv which means 1000 revolutions per minute per volt. 2300Kv is a pretty typical speed and quite impressive when you think that can mean over 30,000rpm!
If you want more info, we have a post explaining motors in more detail here
Propellers
If you have looked around the store here you’ll see there is a huge choice when if comes to props. Even when you know what size you need you still need to decide on the pitch - how titled the blades are which determines how much of a bite they’ll take of the air. More bite gives you more thrust. Thrust is great of course but it comes at a price - your motors and ESCs will need to be able to handle the extra current a high thrust prop will draw. There’s another wealth of numbers here and it’s not helped when different manufacturers use differing naming conventions but we explain it all here.
Receiver
This is the small device with one or 2 antenna that sits on your quad and passes commands from your radio to the flight controller. Not that long ago there would be a bundle of wires carrying signals for pitch, roll, yaw, throttle and switch channels but now can stuff them l down and single wire at much higher speeds.
Battery
When looking at a LiPo (the common abbreviation for a Lithium Polymer battery) battery size and weight are obviously important but there are three other numbers to consider that you might not have come across before: The cell count, capacity and discharge rate. For a FPV quad your cell count, particularly for a first build, is most likely to be 4S although there is a move to 6S for racing. Put simply, the “S” means the voltage of the battery and we saw earlier how a motors speed is rated per volt.
The capacity is how much charge the battery can hold measures in mAh -milliampere hours. The higher the capacity the longer you can fly but the heavier it is. There’s not point in being in the air for 15 mins if it feels like you are flying a bus so we generally keep battery sizes down to 1300-1800mAh for a 4S. 6S tend to be lower capacity are they are physically bigger and heavier but give higher efficiency.
That little lot will get you an LoS (line of sight) quad up in the air. If you want to fly FPV, you need a few more things:
Camera
While HD cameras from GoPro and RunCam give you a video out feed from their USB ports you don’t want to fly a mini quad with one of these due to latency. This means the image coming out of the camera is anything us to a second behind what the quad is actually doing. Instead we use analog cameras. Over the last few years these have improved massively, we used to use repurposed security cameras but now have specially made FPV cameras that are very low latency and handle extremes of dark and light very well. We talk more about FPV cameras in this article.
Video Transmitter
The final piece of the puzzle. This is the device that takes the signal from the camera and transmits it back to you. You can then view it however you want - typically via a set of video goggles or a ground station comprising a receiver and screen. To find out more about channels, power output and SmartAudio take a look here.
Antenna
In order to get that signal back to you in the clearest way possible you need an antenna on the quad and receiving end. Again there is a world of jargon here so we have a guide for antennae too here.
That’s a high level overview of what goes into a typical mini quad. There are many more bells and whistles you can add but this is the minimum you need to get flying FPV. I hope that’s demystified things a little and if you want to know more, check of the rest of the guides in our “Intro to FPV” section.
As always, if you have any questions or comments, leave them below, use our contact form or get in touch on Facebook, Twitter or Instagram.
Happy flying, Simon