Tricopter V2.5 or so

by rslegge | April 28, 2013 | (6) Posted in Projects

This is my first multirotor build.  After building and flying fixed wing airplanes for 2 years I found this project to be an easy build and a very stable platform.

Parts List:

  • HK KK2 board flashed to firmware v1.5
  • DT700 motors
  • Turnigy Plush 18A ESCs (not reflashed)
  • Orange 6ch Rx
  • HK 10 x 4.5 SF props in blue and yellow
  • 3S 2200mAh 35C LiPo
  • 1/2" square basswood arms
  • 1/8" hobby plywood

The build closely follows David Windestål's tricopter v2.5 design with the following differences:

  • DT700s instead of DT750s
  • Extended the ESC wiring instead of replacing it at the board
  • Used clear tape to attach the wires to the arms for a cleaner look
  • Mounted the ESCs between the circular frames instead of on the arms
  • Devised my own yaw control mechanism
  • Swimming noodle chunks for landing gear
  • Toothpick shear pins through frame to keep front arms in position
Build video:

Here is a flight video (tricopter gets small several times): 

Closeup of the board's antivibration mounts:

and the yaw mechanism:

I have been slowly adjusting the KK2 board's settings and have been concentrating of the self leveling settings so far.  They are as follows:
  • P Gain 85
  • I Gain 85
These settings allow the tricopter to move very quickly in roll and pitch and return to level fast.
Yaw settings are not connected to self leveling so to get good yaw response I have them set to:
  • P Gain:  60
  • P Limit:  40
  • I Gain:  40
  • I Limit:  50 
These setting allow for a 1 rev per second yaw and an almost instant stop.


Gsouth on April 29, 2013
Nice job. Clean lines. Flies nicely.
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Strange1 on May 1, 2013
Looking good!
I'm doing pretty much the same, David has made it all too easy. How much flight time did you have before the video? I like your yaw mechanism, looks simple and robust. Does the clamp just ride on the round section? The yellow/blue color scheme looks like it will really help with orientation. Also, thank you for posting up your KK2.0 settings, those will come in really handy once my KK board actually ships and I can finish my beast!
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rslegge on May 1, 2013
I probably flew 8 times very carefully in my small yard to test the settings and gain confidence prior to the video. The two pipe clamps are glued to the 1/2" pvc pipe that rotates on the round arm section.
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Gsouth on May 2, 2013
How did you round the arm? Thanks.
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rslegge on May 2, 2013
carefully with a knife for the approximate shape and then slowly with a file.
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Sirglider on July 22, 2013

I have the same designed tricopter but I tried to go a bit faster than just moving around my hover position and after about 5min. of flight, my arms folded back in the air and my tricopter encounters Newton's law again...
How do you secure or hold your arms in opened configuration?
Thank you for your article
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rslegge on August 15, 2013
I extended the arms to their correct position and drilled one hole (the diameter of a round toothpick) through the top plate, arm, and bottom plate on each side. These act as shear pins and hold the arms securely, but break on a crash landing.
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Tricopter V2.5 or so