Hex trying to flip on takeoff, w/ log


Long time APM user, but am setting up a large hex with 3DR Pixhawk for the first time.

The hex is trying to flip on takeoff as soon as I spool up.

The log file shows that there is a significant desired roll:

Things I have tried:

  1. confirmed multiple times that the motors are in the right channels and spinning the right direction
  2. Reloaded the firmware (AC 3.2), confirmed Hexacopter ‘x’
  3. Redid accelerometer calibration
  4. Checked all radio calibration and radio reversing.

If I spool it up in my hands at a very low throttle, the motors respond in the correct fashion to stick inputs and if I twist the frame around.

I have attached a log file. Any help is greatly appreciated!

With log file

Have you done an ESC calibration? That usually fixes it.

copter.ardupilot.com/wiki/initia … esc-motor/

Yes, I have done ESC calibration. That is not the problem, as that would not result in the pixhawk giving a strong ‘desired roll’ command.

For some reason the Pixhawk is trying to roll right. I am stumped why.

Found the problem… I believe there is some bug when changing the channels in RCMAP.

I was running SBUS from an OrangeRX via Spektrum DX7s. I had to change the channels around to make it map correctly. Even though everything appeared correct in the radio calibration page of mission planner it was not…

To resolved I used the 3DR PPM encoder, removed the SBUS, and set the RCMAP assignments back to default. Now it works as it should!

I need to escalate this bug to the devs… I would really like to use SBUS from the OrangeRX.

Thanks for the help.

Great to hear that you solved it! Please do report the issue to the devs on the dev list:


From your log on DIYD you can see you have the channels mapped correctly using RCMAP.

I think the issue is that the OrangeRX receiver is also doing a remap. If you go to the Failsafe view you can see each channel in. By moving each stick you can confirm which channel is being mapped to. Can you check that with the normal mapping i.e… as A=Ch1,E=Ch2,T=Ch3,R=ch4. and lets us know what happens?



I had not checked this thread in a while because I have been flying successfully using the PPM encoder.

In the failsafe view, if memory serves me, with the default RCMAP, the channels went as follows from the orangeRX:

Chl 1-Throttle
Chl 2-Aileron
Chl 3-Elevator
Chl 4-Rudder
Chl 5-Gear
Chl 6-Flaps
Chl 7-Aux
Chl 8-Aux 2

I changed the RCMAP around until the outputs in the tx calibration page showed the correct responses. It appears that not everything mapped correctly in that process and it didn’t work when I went to fly (despite the Tx page showing all neutral sticks).

I will double check this weekend and report back what the failsafe page shows.