R/C Helicopter Balance question...

[Disastrous]

I got given an 'Extreme Fliers Robocopter GST' for Christmas and after a few days of it being great fun and quite easy to control, it started behaving strangely.

It developed what I can only describe as a sort of unbalanced rotation in flight or when hovering that starts as a small circular oscillation and gradually gets worse and worse until it literally shakes itself out of the air, with the rotors colliding (imagine an unbalanced carwheel, if that makes sense)...

My only guess is that somehow, the main rotor shaft has a very slight bend in it but it looks ok.

Does anyone have any idea what could be causing it and if so, whether it's repairable? Naturally, it took a few crashes whilst I was learning to get the hang of it so I suspect I've done *something* to it...Any ideas appreciated!

[Paulbav]

TBE or toilet bowl effect, usually caused by out of balance rotors or binding swash plate or swash plate link arms. Make sure everything runs smooth link wise and balnce the blades (off the chopper) by using cellotape to equal them out, also check top and bottom sets of blades are mounted in the correct locations.

[GhostDriver]

A bent flybar might do that?

[Disastrous]

Thanks both. I've done a bit of reading and investigation into TBE and balance issues and have ordered a new top rotor and balance bar so will see if that clears things up!