Tricopter tail servo behaves weird at bench test
Guys any idea why this can happen?
I'm doing bench tests of my new tricopter a la D. Windestal.
KK 2.1.5 with Steveis KK2.1 V1.15S1 FW.
Tail rotor goes clockwise.
No mixes on radio so far.
Stick moves cause servo deflection in correct direction.
Problem:
- On turning on the motors tail servo slowly goes to either side (most often to the left if seen from the tail side).
- It doesn't go all the way; usually to some 30 degrees tilt, and then stops.
- If copter is turned around, servo works to compensate for the turn in correct direction.
- Tilt speed or angle or side to which servo tilts the motor do not depend on motor revs.
- While servo drifts slowly, it springs back in upright position immediately at throttle off.
- Increasing servo filter value from default 50 to ~75 hardly has any impact at all, after 75 servo starts reacting to stick input slowly and reluctantly while drift decreases only slightly. At 100 drift stops, but so does the servo itself - it ceases to react to stick input altogether.
- When servo drift reaches its end point it is possible to return it to upright position with trim on the radio, HOWEVER it is hard to do as servo tends to go past the trimmed in value (i.e., if it drifted to the left, and I trim it to the right, then it goes way too far to the right, then I trim it back to the left, and so after several minutes trying I finally make it vertical). Trims do NOT retain it from drifting again on next throttle up.
Small video about it is here
Please come down with your advice and suggestions. This is my very first copter (I have flown planes for some time though). I'm pretty sure there are no serious assembly flaws or wrong mixes (as I said there are no mixes at all on radio side).
Thanks a lot.
- Mark -
I promise my questions will be more sophisticated next time 
