Lumenier QAV250 Build Guide
So the mail came today and all those parts you ordered two, three weeks ago have finally arrived. Your DIY Quadcopter journey can finaly start. As you rip open the boxes feeling like Christmas morning your looking at these parts, and you're a little puzzled. Well, no worries, in this guide we’ll walk you through one of many ways to show you how to assemble QAV250 Drone Racer and get you and your little beast up in the sky.
The following table of contents can help you zero in on information if you're having trouble with a specific area.
To begin, we’re going to need tools. For most builds you’ll need a Hex driver set. A 1.5, and 2.5 are very important, other sizes are great to have, Philips and flat head screwdrivers, soldering iron, solder and soldering arms, Heat gun, shrink tubing, wire, pliers, wire cutters, electrical tape, wire sheathing, exacto knife.
These are a few of the tools you’ll need for the build. You want to make sure you have a flat and open work space. As you get into your build, you need to stay focused and organized. Parts just wind up spread out around you.
If you want more insight in different options when building your fpv quadcopter for racing/freestyle we made a indepth guide that goes through recommended parts we used and tested, both for advanced and experienced user's as well as for novice building your first FPV drone. If you're more into Tiny Whoop's check out micro fpv drones.
First FPV Drone
For this drone build, I’ve chosen the QAV250 3mm carbon fiber frame. I love this frame; this frame is pretty close to being indestructible. I have personally somersaulted this frame and have crashed into trees and have only had to replace props and was able to get back in the air.
This is mostly because of the solid unibody bottom plate. Where the arms are part of the body instead of being added to the frame. On frames like the ZMR250 where the arms are attached to the frame with screws. That becomes a weak point. Now yes even a solid carbon fiber frame will get tore up if you hit a tree or a wall really hard at high speed.
Your motors along with the combination of propellers is what gets your little racer off the ground. If you don’t have the proper motor/ prop setup, you will not get the desired effect.
This could be one of several effects. The one most important being not even getting off the ground. Also important to note: some motors come with different color prop nuts. These different nuts determine the direction of threading. Left or Right.
Clockwise motors take a right threaded nut and counter clockwise is a left threaded nut. That way as the motor spins it self-tightens.
So for this drone build, I’ve chosen the 2204/2300kv Cobra Motors. I have used these motors on two other builds, and they are great. They give a high amount of thrust on a 3s battery with 5045 props. If you decide to use a 4s battery I hear they scream.
However, that goes into the battery section.
There're a few things to think about when it comes to quadcopter motors, the first numbers on a motor is the size. 2204 and 2206 are the most common.
The numbers are width and height. The 22 is the diameter of the motor 04/06 are the height. The second number is the Kv rating which the easiest way to explain this is. As voltage increases, so does the rate of spin, logical. This rate of spin quantified using revolutions per minute or RPM.
This Kv rating gives you the rpm a motor will spin at full throttle, given a certain voltage. So again the Kv number for you is dependent on what you're looking for.
If you're looking for high performance, acrobatics, and high speed a higher Kv rating is what you're looking for. On the other side if you want a craft that is more stable and lasts longer in the air a lower rpm is ideal. However, a smaller rpm means bigger props in order to create the amount of thrust needed to fly. Most aerial photography drones use motors in the 700- 1000 Kv ratings. So again because I love these motors on the 250mm frame. I'm going to use the 2204 2300Kv Cobra motors.
Next, we have the ESC (Electronic Speed Controller). The ESC is an electronic circuit with the purpose to vary an electric motor's speed, direction and possibly also to act as a dynamic brake.
These Esc’s use BLHeli firmware. Now you’ll hear BLHeli and Simon K in regards to ESC’s. Simon K has been around forever and is tried and tested. With the use of BLHeli Suite though you can tweak any BLHeli flashed ESC. Which is useful to adjust timing and reversing motors instead of tearing apart your build to switch some wires.
A Lot of newer ESC’s also have a feature called Oneshot 125 which is a faster communication protocol between the flight controller and the ESC. Basically, it’ll allow your flight controller to send commands to your ESC which should allow your quad to respond quicker.
The flight controller Which again there's so many different Flight controllers on the market nowadays, and the technology of these are rapidly changing.
Moreover, that's because of a huge supporting Open source community. Naze32 is one of the most popular. It’s tried and tested and is very user-friendly. However, becoming just as popular and really is a better choice as far as performance is the seriously pro racing F3.
The Naze32 uses an STM32F1 CPU whereas the SP Racing F3 board uses a ARM Cortex-M4 72 Mhz CPU with a math co-processor (FPU) which allows for loop times that are up to two times as fast.
It also allows you to be able to completely hook up anything and everything you want to your quad all at once. OSD, Smart port, Sbus, GPS, Led strips, battery monitoring, sonar plus up to 8 motors.
Whereas the Naze32 can't do all this. Simply because it's not powerful enough and you run out of space to plug items in at. I also have to mention though, that there are F4 flight controllers available as well.
Many Flight Controllers have similar hardware or sensors, but they have different software and calculation algorithms, which results in different flight characteristics and user interface.
So propellers are just as important to your quad as any other component. A quadcopter uses two clockwise(CW) and two counterclockwise(CCW) propellers.
Propellers are generally classified by length and pitch. For example 5030 propeller is a 5-inch length 30-degree pitch. Generally, increased propeller pitch and length draw more current.
The pitch, which can be defined as the travel distance of one single prop rotation. So a higher pitch means slower rotation but will increase vehicle speed which also uses more power from the system… means the battery drains faster.
A lower pitch will give more torque. So there is a fine balance of choosing your length and pitch, not to mention material that it’s made from. Carbon Fiber or Plastic.
Carbon fiber props are ideal for racers. But they’re expensive! So if you are breaking props, you’re looking at some money. What makes them perfect for the racer is that they are stiff. With plastic props, they will have some bend to them in flight. But they are cheap. They are definitely great for learning and practicing.
Lipo Battery is a type of rechargeable battery that is commonly used throughout the RC hobby. From Helicopters, Planes and of course Quads.
The three main reasons that make LiPo Batteries so great compared to other rechargeable batteries are the fact that
1. They are lightweight and can be made into almost any shape and size.
2. They have a large capacity, which means they hold a lot of energy in a small package.
3. They have a high discharge rate that can power some of the most demanding electric motors.
Just as a LiPo battery is great, it can turn on you and be your worst nightmare. Not just out on the field but also at home. If not cared for properly, while i.e. Charging, Storing and even using. It can become a hazard.
LiPo's have a short life span roughly about 400-500 charging cycles, if treated properly. They can also lead to fire if punctured. Again LiPo's need care in the way they are charged, discharged and stored. The way we define any battery is with ratings. With a LiPo battery, the ratings are Voltage, Capacity, and Discharge rating.
A LiPo cell has a standard voltage of 3.7V so depending on a number of cells you have you would just take that 3.7V and multiply it by how many cells you have.
So a 3S battery which is a 3 Cell battery would have 11.1V 3.7 X 3 = 11.1 So now the voltage of your battery pack will essentially determine how fast your racer is going to go.
Your voltage directly influences the RPM of your motor. So our brushless motors have a KV rating of 2,300. which means our motor will spin 2,300 RPM per a volt. So 2,300 X 11.1V = 25,530RPM per a motor.
The Capacity of a battery is a measure of how much power it can hold. This is usually measured in milliamp hours (mAh) This is the amount of drain that can be put on the battery to discharge it in one hour.
So 1000mAh = 1 Amp (1A) So we have a 3S 1300mAh battery for this build. This means that a load of 1.3 A would drain our battery in 1 hour.
So if you do the math, it's not long that we have to fly with this battery roughly 4-6 mins. It varies because you're not always on the throttle and not always through your flight using the whole 20a from your ESC.
But from personal experience, that's about how long of a flight I get. Now I'm sure you're saying that's not that long I want to fly longer. Well, of course, you can get a larger battery but a larger battery means larger size along with more weight and even on these 250mm frames it may seem large, but space is limited.
Discharge Rating ( C rating )
So the C Rating is the measure of how fast your battery can be drained or discharged in a safe manner without harming the battery. So say our battery has a 20C rating we take that 20C and multiply it by our battery capacity in Amps, (not mAh) and that will give you the amount of amps you can continuously pull from the battery without harming it.20X1.3=26aSo I hope this helps give a little understanding on how your battery works and also how important it is to choose the proper battery for your setup.
Video Transmitter (VTX)
VTX/Video Transmitter allows you to see the video in your goggles or on the monitor that's coming from the flight camera. A 5.8Ghz transmitter is the most popular for FPV but isn't necessarily the best. A higher frequency signal can carry more bandwidth (which is good) but has more difficulty penetrating objects such as trees and walls. You can use a lower frequency such as 900Mhz, 1.3Ghz, or 2.4Ghz to transmit your FPV signal.
Remote Transmitter (TX)
This is your remote but people in the hobby don't call it a remote it's called a TX or transmitter. This is what allows you to control your craft. There are the computer transmitters such as the Tarranis X9. Which is amazing. It allows you full customization, and it's also open sourced firmware. Just like your flight controller.
Radio Receiver (RX)
RX/Radio Receiver is the device that you bind to your Transmitter. It can be anything from a four to a sixteen channel receiver. You can also set it up through either a PWM signal, PPM signal or SBUS signal.
SBUS being a more popular one. Being that it's a digital signal. A PPM signal is a single wire signal where one wire controls all of the channels. And then PWM, which is where you have one wire per a channel that has to be connected to the correct channels on both the receiver and flight controller.
So with some VTX’s they come with a little black antenna. These are called whip antenna’s. These are the lower end of the antenna’s and generally don’t have good distance. Next, would be the Skew Planar, which has 4 lobes.
Then you have Cloverleaf, which has 3 lobes and then Array’s. These are all Omnidirectional Antenna’s. There are Directional Antennas as well which include Helical, Patch and Crosshair and Yagi. The complete guide to FPV antennas for your drone … this is a great place for full information on how the different antennas work.
FPV Goggles or Monitor
There is nothing more immersive as using the goggles. Flying with goggles basically put you in the pilot’s seat. Which is most of the fun of this sport. In my opinion, it is good to have a monitor as a backup as well. It allows people watching to see what you're also seeing, it's a good backup in case your goggles die, or you lose range in the middle of flight. I use personally use both. I have my fatshark goggles and a black pearl monitor.
This is the FPV camera you wire to your VTX. It’s the camera that you basically fly with. There’s so many different camera’s on the market now for these. Some of the things to consider is power. 5v or 12v. AOV (angle of view) also your lense.
A Lot of the cameras the lenses can be changed some people like the flying with a close up kind of look (smaller field of view) and others like having a far away kind of look (larger field of view).
HD Camera for Recording
With this you can use almost anything you can find. But keep in mind. Weight you don't want anything to heavy. I know a lot of people like to use their GoPro. Which is fine and all good. I use a Mobius Camera. The lense are changeable, its smaller and more compact and it doesn't cost 500 dollars. It’s also pretty indestructable with the right type of case of it.
With a battery strap. Really any velcro battery strap will work. The trick I do with my batteries is I put a piece of foam the length of the battery where the battery will sit. That way it will help the battery stay in place. If you put the battery just on the frame it has a tendency to slide.
HOW TO BUILD A RACING DRONE
250 FPV Quadcopter Game Plan
Ok now that we’ve gone over the items we’ll be using in our build and you're now familiar with what they do. Lets dive into this build. First let's make sure all parts and tools are laid out and ready.
I myself like to put the quad somewhat together so that I can put together a plan in my head or on paper whichever you feel comfortable with. On how I want my quad to look and where i’m going to put everything.
So here’s a prime example of why I do this. Here’s my VTX.
I know I still have to put my receiver and camera in there.
Which its going to be tight. But it lets you know this ahead of being in the middle of the build and stumble upon it and then have to rethink some things. So we have our game plan in our head and have a vision for our racing beast.
The next step is to solder the pads and setup the power distribution board (PDB). So I have to explain I’m doing this QAV250 slightly different. The stock PDB is this
It comes with the PDB and two LED’s. First off we’re flying FPV. So no need to put on the LED’s. Yes they look nice but they draw power. More power being drawn less power for flight times. Now the bummer with this stock PDB is that it has no BEC’s so the power you plug in is the power you get out. Our flight battery is a 3s 11.1V battery. So that 11.1v we put into the PDB is what we’re going to get coming out at anyone of these pads.
Now the problem with that is. Our Flight controller and possibly our camera and VTX depending on the hardware you get. Run off of 5.5V. So if you put 11.1V to it you’ll likely get what we call magic smoke. (hehe). That is bad!! So I’m changing the way I build this QAV250 and going to use one of these Diatone V7 PDB’s.
This PDB has built in BEC’s for not only your Flight controller but also your Camera and VTX. So here we have the pads tinned.
I know, not the greatest but it gets the job done. Like anything the more you do something the better you get.
Flight Controller Setup
Our next step should be to setup your flight controller. Just flash it and make sure it works. Cause once soldered most places won’t allow returns. I’m not going to dive into how to do all that as there are plenty of videos on youtube for flashing your flight controller. On this build I will be using Beta flight firmware.
Ok firmware is flashed so let’s continue.
Motors mounting and ESC preparation
Next let’s mount the motors.
After motors are mounted time to prep the ESC’s. Because of using the different PDB. I’ll be mounting the ESC’s on the arms. Where typically with a QAV250 you mount them on the stock PDB underneath the craft.
So here’s our 20A Littlebee ESC’s that we’re using. Again I love these. They are flashable with any up to date version of BLHELI firmware. I’m going to flash these with v14.3 I've never had a problem with them and have used them on several builds.
You're going to want to cut away the shrink wrap and pop off the motor wires and the signal wire (which is the black and white). Like such.
Keep the signal wire (white). I like running a single wire setup. It makes for a much cleaner look. I’m a little OCD when it comes to this. So let's solder up the ESC output pins on the flight controller. I’m only soldering one pin, for the ESC signal wire like so.
A little trick that helps is marking the wires so you know which one needs to go to which ESC.
I do it at both ends. Ok, let's mount up this ESC. So another prime reason why to have a game plan. As I was setting up the first ESC I realized I had forgot to pay attention to my firewall while coming up with my game plan. I wanted to mount the ESC’s on top of the arms. As I was putting everything together on the first ESC.
I realized I wouldn't be able to do that because of my firewall. The firewall is this 3D printed part that protects the Flight controller from the battery sliding up and hitting it during a crash.
So I decided to change things up and mount the ESC’s on the bottom. Putting a spacer on the landing gear to extend it. So to give enough space for the ESC.
Which this is ok to do. Actually you can mount your ESC's anywhere you're comfortable with. Just keep in mind the balance. You don't want to put too much weight in any one place. So now with the fact of the firewall, I'm going to continue mounting each of the ESC's this way.
Also I want to point out. You can pretty much not worry about what motor wires go where. Cause with Cleanflight and BlHeli Suite you can go in and change motor direction if your motors are spinning in the wrong direction.
I also recently learned that Beta Flight now supports SimonK bootloaders. Which prior to this you could only change the settings of ESC's that had a Blheli bootloader through cleanflight and Blheli suite.
But now with the latest beta flight update you can change any ESC with either blheli or simonK bootloaders. Again there’s different videos out there on how to do this process as well. How to use BLheli passthrough.
Boom, our ESC's are all mounted and connected.
Let’s work on connecting our xt60. Grab some red and black 16GA wire. Tin the ends like so.
Grab a battery if needed, make sure you put positive into positive and negative into negative. Also, solder them up and put some shrink wrap onto the ends. Cut to length and you’re ready to go.
So I put my battery cables underneath and up into the battery bay. I feel it's just a cleaner look, and it keeps it inside. I know some people run it on the outside. Again it’s personal preference.
So next up I cut and connected the positive and negative cable for the flight controller to the 5v on the PDB.
Mounting Quadcopter Camera, Receiver and VTX
Next, let’s mount the camera, I’m just using a 3d printed 15-degree angle mount.
Now at this point I’m going to put on the standoffs. That way I can see what space I have to work with for mounting my Receiver and VTX.
So here’s our little beast. It’s coming along but as you can see. Still have a few pieces to fit in here. The receiver, LC filter and our VTX. I have the VTX just sitting in there with some double sided sticky tape. But I will mount it with hot glue.
Ok, I have a vision, so let’s get to it… I wrapped the ends of my lc filter with electrical tape since it’s sitting on the frame. And Carbon Fiber is very conducive, so I just want to make sure there’s no way any of the power from it touches the frame.
So with the Lc Filter it’s pretty basic. It goes in line with your camera power. Power in, power out. So the 5v power supply or 12v whichever you use for your camera. It just goes in line at wherever your choosing.
Now take the yellow wire and connect it to the yellow wire from the VTX. I removed all the other wires from the harness. The two white ones are for audio which we don't need, and the power and ground are for if you're going to power your camera from the VTX.
Since I'm not doing that there's no need for these wires. So I’m left with this.
Solder the yellow from the camera to this one and we’re good to go. Now let’s take the power and ground wires from the VTX and connect them to the PDB.
Next, we want to take the group of cables for the receiver that has the red, black and white in one connector. Like this.
Connect it to the side port of the flight controller on the right side like so.
And then plug it into the SBUS of the X4R receiver.
Plug in the video and power wires to the VTX.
Put the top plate together and our little beast is done.
So here’s one of the great things about this hobby… Customization!! I love these skins.
Tuning and Configuration
So now that our little beast is built. We now have some tuning and configuring to do with the flight controller and ESC’s. Then making sure all of our motors spin in the right direction.
Now let's connect the flight controller to Cleanflight and upload the latest firmware.
Flight controller updated. The next thing to do is connect to Blheli suite and update the ESC’s and make sure the motors are spinning in the right direction.
What i like to do while in cleanflight with a battery connected. See which direction the motors are spinning so you know in Blheli which to change.
This is why I love the cleanflight Blheli passthrough. I had three motors spinning in the wrong direction. Was able to go into Blheli suite, change directions and all is good.. Also, while in Blheli suite. Make sure all ESC’s are synced. Meaning each one’s setting are identical to the next. This is different then doing the ESC’s in the motor menu in cleanflight.
Tips and Tricks
These are just some things that I’ve come to realize after the build that I should’ve mentioned during the build. First right from the start before putting anything together.
- Sand the edges. Especially with carbon fiber frames. Be sure to wear a protective mask. But this will help your wires from being cut if rubbed up against any edge of the frame.
- Make sure you have an adjustable soldering iron and clean tips. It’ll save a lot of headache in the long run. 540F-600F is a good range. I know some people do 750F but you have to be quick.
- Having extra parts on hand is never a bad thing. It’ll cut down on wait and downtime if you mess something up
Build, Fly, Crash, Repeat