Wooble

[Daren]

Hi all
I am new to this list and just built an ECO8 I have removed the head and balanced it twice once to check but I still get a wooble on!

It hoovers great for about 5 -10 secs then the whole air frame gets a kind of resonance on, slow but big movements.

The tail starts to go up and down (not side to side like gyro) its as though the main shaft is bent, the disk is smooth and the heli is woobling from it.

Any ideas please?

[giheli]

I initially had lots of problems as you described.
Here are the possible sources:
(1) Bent blade bearing shaft.
(2) Bent main shaft- not likely if you aren't detect vibration while rotating on ground
(3) Blade tracking: see lite machines web site for a good adjustment algorithym.
(4) Improper heighth adjustment of the motor pinion. This problem occurs in certain motors with a vertical "floating" shaft. The solution is easy. Remove the main blades and slightly ( very slightly ) loosen the motor pinion. Run the mechanics slowly. The pinion will self adjust to the proper height. Without moving the pinion's new position tighten down the locking screw and your done. Note: Prior to making this adjustment be sure to have the proper gap between ALL gears per the Ikarus manual directions.
You can check for this problem by watching the motor shaft (canopy off) if you see it ocillating up and down it probably needs a height adjustment.
(5) Improperly balanced blades or bell/hiller fly bars and paddles. I balance both independently, flybars first. I am assuming from you decription that this is not the problem. Everything should be real smooth.
(6) Friction on the links of the cyclic to the blades and paddles. This causes vibration when cyclic is applied, but often not when the cyclic is level. As a result it often goes undetected until flight evaluation.
(7) If all of these check out. Check your rotor blade speed for the proper minimum speed. Too low of a speed for whatever reason, can cause your symptoms.

Good luck