Hello,
Im having a problem with the tail on my 700 sport, the servo is a 7007HV Kyle Stacy edition. I am getting a violent wag when flying into wind, the gain multiplyer is set to 1.0 and the gain in the radio is set to only 25 and im still getting wag, if i lower the gain any more the tail gets sloppy.
I have tried rudder delay at 0 with no effect, all mechanics are smooth, belt is at the right tension the end points are all set correctly and the servo has the correct settings in the spirit, the heli flys well in most maneuvers but i cant get it really locked in and tight. Is the BK servo the issue? i have read other posts using the BK servo and their problems went away when they swapped it out.

Any suggestions are most welcome

Many Thanks
Jay

Hello,

I recommend to start the model without blades and observe the tail servo carefully.
You can increase the Gain and see if there are some unexpected movements.

I guess that the servo will be moving or jittering on its own causing the oscillations.

Possibly it could be also due to Spirit unit mounting - wrong double sided tape or something is touching the unit (for example free servo connector).

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Spirit System developer

Thankyou for the suggestions, the unit is mounted properly. I spun up the heli without blades and moved the pushrod by hand and it felt smooth with no binding, next i went through the tail setup again in the software and i found i needed to reset the subtrim as i had lengthened the tail slightly because the belt had stretched (its a new kit), upon adjusting the the subtrim slider in the software the servo "jittered" as i took it through the range of movement, this was repeatable but it never "jittered" in exactly the same place when moving the slider in the software.....could this be my problem, a bad servo perhaps? The jittering never happens when i'm giving rudder input with the TX

Anyway i re-setup the subtrim and end points. I also noticed the metal bar that is glued into the carbon control rod had become loose, i was able to spin it in the rod but i couldn't pull it out without using alot of force, maybe this was also moving slightly and putting the tail out?

Everything is now setup as best it can be but i wont be able to test it until this coming weekend, i will report further once i have test flown the heli.

Thankyou
Jay

i have built 6 Goblins and have tried 3 different BK servos . I have had no luck using them i always had tail wag dont waste your time install another tail servos . Also do the recomended 3-4 degrees of counter torque on the tail blades.

Quick update......

Non of my alterations make any difference, i did the 3 degrees of counter on the tail blades too. Next i'm going to swap out the servo for a DS 825 that's on my 550x and see what happens.

Jay