Archive for June, 2011
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 truely. 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 roter. So if the mainblades 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 your 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 too 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.
After looking closely at what happens to the outside part of the bearing while running the heli I realized that the bearing retainer &...Continue Reading
Getting these tails vibration free seems to be one of those things that many of us have problems with, including yours truely. 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 roter. So if the mainblades 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 your 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 too 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.
After looking closely at what happens to the outside part of the bearing while running the heli I realized that the bearing retainer &...Continue Reading
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Views: 403
Yellow arrow = clear scotch tape for balancing Blue arrow = -002 70 duro oring Red arrow = Bearing retainer that spins -
Views: 271
Xtreme tail box with original bearings removed. -
Views: 287
New tail using Xtreme tail box. Boca bearings are C/Aed into place "mandatory step" -
Views: 245
I also made new tail blades from 1/32" carbon fiber and tail fin from 1/16" carbon fiber. -
Views: 247
Blue arrow = New Boca 440C sealed high speed bearing C/Aed into position very carefully slide out bearings and use very small drop of C/A behind bearing. -
Views: 266
Let C/A set up using card board to secure bearings firmly while they set up.

