[solved] Yaw stick has no effect (octocopter)

I’m using Copter 3.5.5 on a big octocopter.
All setups done (accel, compass, radio, ESC calibration, motor test, etc), default PIDs

Hardware :

  • Tarot X8 (1050mm)
  • Dropix v2 upside down (AHRS_ORIENTATION=4)
  • Hobbywing Xrotor 40A
  • Tarot 4114 KV 320
  • Tarot foldable 15x5.5
  • FrSky X8R
  • FrSky X9D+ (profile copied from another working quad)

Symptom :
Absolutely no response to Yaw command
RCIN C4 shows stick actions
Takeoff in Loiter is ok, roll & pitch response seems to be good
Vibrations are below 15

Log file :

I quickly read other similar topics but none seems to have the answer to my problem.
I certainly missed something but unable to find what.

It seems that your copter is yawing in circle without your input.

Try removing all trim and re-calibrate RC input. When you completed the max min input make sure your stick is center then click OK.

You’re flying on 4 motors.1,3,5,7 all produce thrust.2,4,6 and 8 lose sync or bottom out otherwise.As 1,3,5,7 are the front four motors the octo should flip as soon as you give it throttle.The fact that it’s flying means that your set up is incorrect.And other problems that stem from that.Photos of set up ? Videos of it flying ?

Thanks, I confirm there’s strange things about motor order, I followed motor test order where A, B, C, D, E, F, G and H are in CW sequence but I’m probably wrong as it’s not the same order than the copter motor order documentation (http://ardupilot.org/copter/docs/connect-escs-and-motors.html).

Thanks for analysis, I’ll try it as soon as the weather become kind.


Do not fly until changing your settings: your frame is defined as OCTA_QUAD in your configuration… Should be Octo-X for your flat Octocopter.


Thanks Marc, very good remark, parameter is changed (FRAME_TYPE=3).
I think this was my mistake.

Nice one Marc.I didn’t go into the parameters and spot that.Explains a lot. :grinning:

Motor order fixed and motor test give expected results. Thank you guys I think the problem is solved.
Happy easter.

By design, the motor sequence (A,B,C,…) used in Motor Test DOES NOT FOLLOW MOTOR LAYOUT NUMBERING.

Thanks Marc, problem solved, the misconfiguration of frame type was the issue.
Thanks all for your help.

The octo now flies smoothly with all working commands.