And now a Tricopter!

After playing around with the quad for a while, reading blogs and forums I decided to make a tricopter. It’s largely based on Davids build, but with some changes here and there based on what parts I had on hand and what parts I wanted.

Build details

I went with a 4mm brass tube for the yaw mechanism, mainly because that’s all I could find at my hardware store. It works fine and is light enough. More details on yaw mechanism.

I made the motor mounting plate from a scrap photosensitive single sided PCB I had around. A 1-2mm carbon plate would have been even prettier, but this is all I had and works just as well. Zip ties are used throughout the build for fastening things, mainly because I want those to break in stead of motor shafts bending or other parts breaking in hard crashses.

Here I have fastened all motors with zip ties. Because the aluminum arms are a bit more slippery for zip ties than wood, I decided to drill holes in the end of the arms for fastening the motors properly. Yaw is also ziptied, and ziptied to the yaw mechanism.

Here I’m starting to thread the arms with power wiring. I decided to keep the servos on the ends of the arms because supposedly keeping the 3 wires for the motor too long may cause issues.

Here’s what the arms look like wired up. I decided not to use servo extensions for the ESC (or servo) signal wires, but in stead desoldered the signal and BEC wires from the ESC and replaced it with just one signal wire, the blue one in this picture. The other end of the blue wire is connected to my kk2 control board. Pro tip: Don’t have the wires stick out like this, you’ll cut them in a crash. Drill a hole or dremel out some material in the arms to route the wires through.

It’s easier to see here how my ESCs are wired. I desoldered the old power wires from the ESC and soldered mine on. I also removed the servo connector from the ESC, replaced it with my signal wire and the power wires for the yaw servo for a little less wiring mess.

I flashed my ESCs with simonk firmware for extra stability. You probably want to do the same, especially if you get the cheap servos I recommended. Google simonk firmware for a guide on how to flash ESCs.

Here’s what it looks like complete. I fastened the kk2 board to the frame with a couple of layers of double tape, making sure no part of the board could touch the metal screws. The receiver is also held on with double tape. The kk2 is powered with a 3A BEC I had laying around. The BEC is connected straight to the battery and the output from it goes to the receiver, and the receiver powers the kk2 board.

Folds together nicely, which is a big plus that tricopters have over other multirotors! Even with the 40mm arm length it’s much more compact when packed down than my quadcopter.

Note the direction of the props – You need right hand rotation for back and left motor and left hand for right motor.

Parts list

I used 10x10x1mm aluminum square tubing for the arms which I got from my hardware store. They are reasonably cheap and rigid.

Total cost: $192.46. Excluding shipping.

Most of these parts aren’t set in stone. You could for example use smaller motors and smaller props or whatever you feel like doing. What’s also missing is a transmitter (remote) and a receiver. Also a battery charger and a power supply for the charger.

For flashing the ESCs you need this: