QAV ZMR 250 build

I’ve always been interested in RC planes and copters although I’ve never done anything with it. In this post I will share the process I went trough to build a QAV250 quadcopter. Some two years ago I bought a QAV250 kit from Aliexpress (https://nl.aliexpress.com/item/Carbon-Fiber-Mini-QAV250-H250-C250-Quadcopter-1806-Brushless-Motor-12A-ESC-CC3D-Control-Board-5030/32285772418.html). 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.

http://www.dronetrest.com/t/qav-zmr-250-assembly-build-guide/1244

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).

IMG_0979
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.

ToDo:

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

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