ZMR-250 buildlog

In this post I will share my experiences with building a budget quadcopter I bought from AliExpress. This is by no means a tutorial and I advise you to look in the links section of this post if you are looking for a one.

So let’s begin.

It came without instructions, I messaged the seller and he/she replied that there are enough build instructions available

One problem though it came without instructions. I messaged the seller and got a reply similar to use google and RTFM. Not knowing where to go from there I shelved the project. Two weeks ago I decided to get over my self doubt and continue the project. After all how hard could it be right?

I started looking for tutorials online and found one which suited my needs.

Although the overall proces seems simple the tutorial managed to confuse me quite a bit. The topics I got confused about:

  • Which length srew to use for the motors
  • How to connect the wires for the motors
  • How to orientate the cc3d board computer
  • How to connect the receiver to the cc3d

Motor screw length

This will probably vary on the types of motors but I ended up using 6 mm screws which I thought would be to long and might damage the motors. I tested it with one motor which continued to work. I decided what worked for one will work for all and fitted the 6mm screws on all motors. Please note that this does not mean 6 mm is the right fit for your motors.

How to connect the motor wires

According to the tutorial the wires for motors that turn clockwise have to be switched and the wires for the CCW motors do not need switching. Further along the tutorial it says the wire for the CCW motor needs to be switched. To be clear only the first statement is true (although this issue could probably be fixed in the firmware).


Build almost completed.

Orientation of the cc3d board.

The tutorial tells you to place the cc3d board with the arrow to the side (left) but instead this needs to point at the front of the copter. Putting the cc3d arrow to the left will make the computer think the side is the front of the copter which causes the copter to flip immediatly on takeoff.

After fixing these issues I was able to get my quad of the ground.

I’ve included the maiden flight below:

Note2Self #1:

buy a small drone and learn how to fly it.

Tried to fly the drone outside and crashed it :(.

Also one of the motor wires came loose and when testing for damage the ESC fried.

Fried ESC

Note2self #2: 

Do not remove shrink wrap from ESC’s or re apply if removed. Plus isolate the power pads on the power distribution board. The frame of the QAV250 is conductive and will create shorting causing all tons of fun like mini fires :D.


  1. Get 4 new ESC + motor
  2. Get a new smaller drone to fly indoors
  3. Get a strap to fasten the battery

Saturday the 14th of october:

Got my replacement motors plus ESC’s in the mail. Also got my mini drone the day before. Those things are awesome and a good tool to learn how to fly a quad.

28th of January

So I rebuilt my quad just to find out one of my motors stutters. When searching for a solution I found several other people had this problem in combination with the cc3d and librepilot. One suggestion was to update the firmware on my simonk Esc (which of course are cheap ripoffs of the real thing). I looked at the pcb to find a fis 330 chip was there waiting for me. Supposedly these can be flashed with an arduino nano and blheli suite. So that’s where we are going next.

3 thoughts on “ZMR-250 buildlog”

  1. Here are some things to possibly help you out
    Replace the CC3D with a Naze32
    Install Cleanflight onto the Naze32

    Check out YouTube channels like Flite Test, Joshua Bardwell, and Painless 360. They’ll have A LOT of tutorials. (Especially Paineless 360)

    The only real con of the Naze32 for beginners, is that since it’s old, future versions of Cleanflight won’t be supported.
    It’ll still work of course. You just wouldn’t be able to get any future features.

    1. There will be a bit of a learning curve, but it’s way more intuitive than Libre Pilot. Also since a lot of people use Cleanflight, there’s a bunch of tutorials and help out there.

      These have been my favorite ESCs so far. They work just fine with the motors I’m using (Emax RS2205s), and with Cleanflight / BLheli Suite.
      Slightly cheaper option if you’re using lower powered motors

    2. Thanks! I actually temporarily gave up on this project because I got demotivated. The last thing I did was to flash the cheap knockoff “SimonK” ESC with Blheli firmware in the hope of fixing the issues but still. I was hoping this project would be easy but I guess it requires some more time and effort. 😀

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