No HeliTailRSC and ESC calibration on pixhawk


After moving my traditional Heli project to pixhawk I am close to operation. Main rotor works with all FC functionality applied. One problem seems to be an issue.
After Imdid away with the brushed tail motor and modified to a brushless 5100kv motor with a 10A ESC it looked good. The problem of the HeliTailRSC setting is still there. But I got the motor4 setting to work. But when I try to calibrate the tail ESC using any of the proposed methods I get nowhere. The ESC beeps but there is no change in behavior. It runs once and is controllable but then winds down and can‘t be controlled anymore. Turning off Engine-Run-Enable and Arm does have no effect. Motor still moves.
Any errors on my side should be pointed out or any suggestions for improvement are welcome.

Thanks very much.



if you are using a DDFP (direct drive fixed pitch) tail then it does not use the HeliTailRSC function for the servo output. You would use motor 4 as the servo function for the tail ESC connection. But you have to set H_TAIL_TYPE to DDFP for it to function correctly. Please post you parameters and a log if you can provide one.


Hi Bill,

Thanks! Takes care of the HeliTaiRSC mystery…
Will send you log and parms.

Thanks again


20200813 pixhawk.param (18.1 KB)

Hello Bill, as my efforts to get the ESC for the tail rotor to work were not successful I switched the hardware to another frame with a variable pitch through a servo. But my fight with motor4 continues. The only setting for the servo4 that works is motor4. Is that correct? HeliTailRSC does not work with „servo only“ on the tail. Rudder is also not working. RC4IN works well. But as I don‘t know the algorithm behind the firmware I just want to make sure it is all set right.
Attached you find the last parms file. If you need the logs I need to zip them.

Thanks again.



@RoMe82 here is the run down.
Tail rotor driven by shaft from main gear uses a servo to change tail rotor pitch. This uses Tail type of servo only.

DDVP uses the tail type of DDVP. You have to set one servo output to helitailRSC and another servo output to motor 4. The ESC is connected to the servo output designated as helitailRSC. The servo that changes the tail pitch is connected to the servo output that is designated as motor 4.

For DDFP, you will connect the esc to the servo output designated as motor 4. You will set the tail type to DDFP_CW for main rotors that turn clockwise when viewed from above. You will set the tail type to DDFP_CCW for main rotors that turn counter clockwise when viewed from above.

Hi Bill,

Thanks for the info.
Figured the issue out now.
My current frame is a belt drive tail rotor from the main shaft. The pitch is done by a servo. My setting is „Servo only“. And I use motor4 for that. Keeps coming up after each boot anyway.
The issue was a faulty wire with intermittent problems.
Will integrate all in the frame now and hope to fly this weekend.
Thanks again