Servo connection issues with "VTOL Duo Tailsitter"

Hi all,
if connecting the motors and servos according to the “Airframe Reference” for a VTOL Duo Tailsitter (elevon left --> MAIN6 and elevon right --> MAIN5), then both in acro- and in stabilize-mode, elevon deflections are in wrong direction. By swapping “PWM_MAIN_REV*” you can either set a correct elevator behavior or a correct aileron behavior, but either of both is always wrong.

I swapped the servo-connection (now: elevon left connects to MAIN5 and elevon right connects to MAIN6), and not the servo direction is correct.

Could it be that there is an error in the documentation?

@sfuhrer you can probably help here.

I could be that this has to do with how the servos are oriented. If we want to improve the documentation then I guess also some clarification on that part would be necessary. Contributions on the documentation side are always especially welcome!

For banking to the left or for pitching up, the left elevon has to deflect to the same direction (upwards). There is no possibility to generate this behavior with the help of system-parameters such as PWM_MAIN_REV. The inputs for those two types of movement always leads to opposite elevon-deflections. The only way to solve this is to swap the left and the right servo port (MAIN5/MAIN6).
Once I understand the system and I get the wing airborne it will be a pleaseure for me to correct and extend the documentation but for now I am not sure if this works reliably.

By connecting Elevon Left to MAIN5 and Elevon Right to MAIN6, everything works well. Error in documentation corrected on 14.05.2020.


I think the original document was 50% correct, 50% wrong, maybe you wired the servo in a different orientation, this is my 2nd prototype. since the wires are obviously a mess, it’s hard to see in the actual picture. however, my motor and servo connection is wired like the 2nd picture. I think if you mount the servo arms towards the fuselage your case is correct.

VTOL tailsitter servo outputs 5-6 swap

Hi Sven, same problem here, and same solution of swapping 5-6 servo outputs

I wasn’t able to find any solution by reversing servo arms/directions, only by swaping the servo outputs of 5 and 6

Yeah, same.
Plus in new firmware version 1.11.0 (beta, rc and stable release) yaw direction was reversed, so we had to make changes to the main mixer.

You should enter an issue on github.