I haven’t wrote about this yet, but I’ve spent the past half year or so learning about and getting involved in multicopters. I have a full size UAV (a 3D Robotics X8) which I have been building into an airborne videography machine, but I wanted to practice my flying more often and the big quad requires a lot of preparation and outdoor space.

I recently bought a Turnigy Micro-X Quadcopter Kit from Hobby King to practice flying at home. The flight dynamics on a tiny quad are really similar to the big ones, so I could actually improve my flying without having to deal with weather and other complexities. I wanted to be able to use the same transmitter that I use with the X8 with the micro so I wasn’t wasting money on that part of the setup. The Micro-X kit seemed like the perfect choice. It comes with two batteries, the body is the board, and it runs on MultiWii which is hackable and relatively similar to ArduCopter which is what the X8 runs.

The box came on Wednesday. I had practiced soldering for the first time on Tuesday night in preparation. I’ve never dealt with building hardware very much and it makes me nervous when I can’t just ‘undo’ something.

The kit was straightforward and bare bones. The body/board, 4 motors, 2 batteries, 8 props, usb charger, usb bridge to program the quad, 2 rubberbands to hold the batteries, and a piece of carbon to help lock the legs in place.

I was overwhelmed at how small it was. The kit came with no instructions at all, so it was pure logic and internet research. I was quite scared I was going to screw something up. The legs are meant to be cut off, but the nubs should remain in place for the motors to sit on. I picked that up from this video. The carbon rod is cut to fill in the holes that hold the legs in place. I used thin CA glue on the leg joints and medium CA glue on the motors.

This was the first time I was soldering something I really cared about, so this was the most nerve-wracking part. The wires were too thin for my wire cutters, so I heated up the end of the wires with a lighter to pull the rubber back (protip from Joey Hagedorn). Seemed like it worked. I read in the RC Groups forum the wiring is reversed on the image from the Hobby King site, so this was the image I followed for my connections.

My first solder point pushed the wire out of the hole and I filled it with solder. Panic. Luckily I had bought a solder sucker and resolved it quickly. I heated the solder from one side of the board and sucked from the other. (Another Joey soldering protip.) The rest of the solder points went pretty well. Here is some evidence of my success and mistakes:

All the props easily slid into place on motors except one. I’m not sure if it’s a manufacturing defect but the orange props for the front right wouldn’t slide all the way down. I eventually ended up using all black ones just to get it to work for the time being.

I plugged in the battery and a green LED was flashing rapidly. I attempted to bind the quad with my Spektrum DX7s. For whatever reason, it took many attempts for this to work. I have no idea why it did eventually bind, because I didn’t do anything different.

The quad automatically goes into a bind mode when it can’t find a transmitter. Start up your DX7s holding the bind button and at some point it will catch. I also set up a profile just for the Micro-X on the DX7s. To do this you hold both the back and clear buttons and you get to a high level menu which allows you to set up multiple profiles.

When I first spun up the motors, I noticed the back right motor was not idling the same as the others. I tried to get it airborne and it immediately crashed. Turns out it needed to be calibrated. Helpful video. Basically you get the quad on a level surface, connect it to MultiWii and click CALIB_ACC.

Here is what it looks like in MultiWii Config when you successfully connect to the quad:

I had to do two things to the DX7s to make it controllable. First, both the roll and yaw were reversed, so I flipped them in the transmitter. Second, I turned the throttle up at 125% instead of 100% to make it less twitchy. Here’s a video of my first outdoor flight:

It is flying pretty good, but it has been rotating slightly in the air. I’ve been trying to adjust the values in MultiWii to fix that. It’s gotten better but it’s not perfect yet. It flies outdoors better than expected. It’s really fun. If you are interested in quads and are feeling patient, I would definitely recommend this kit.

There is a great forum for this quad on RC Groups where you can find most everything else you need. One thing I wasn’t sure of was how to charge the batteries. The black wire goes to the minus symbol on the USB charger. The light turns off when it’s done charging.

I am going to continue to tune this little quad and maybe eventually add FPV if it seems like it’s the right move.