I've decided to dedicate a blog section to the tail vibration problem for obvious reasons.
Getting these tails vibration free seems to be one of those things that many of us have problems with, including yours truly. It also seems to be an inherent problem with these small Heli's in general. Part of the reason is that the tail blades are spinning 3.4 times faster than the main rotor. So if the main blades are going 4000 RPM's the tail blades are at 13,600 RPM's.
You know how the tail fin buzzes back and forth and it's difficult to hold onto without it buzzing your fingers off? If you're lucky you don't have this problem "very unlikely" or it's not very bad "mild buzzing" that is about where I'm at now. Dynamic balancing helps but doesn't get rid of the tail buzzing completely.
This was recently referred to as the holy grail of small heli fixes. You can tune out part of the problem by dynamically balancing the blades using clear tape but I think there is more to the problem than this.
I believe a major part of the problem is that the bearings do not fit snug enough into the plastic bearing retainer's which tend to stretch out over time. Using higher quality precision bearings should also help.
Ideally the bearing retainer should be C/Aed into position and held firm so it can't vibrate or move at all...more »