Running a #36 with 1800mAh LiPo, brushless motor and metal head conversion.
Finding vertical stability a problem. Small rudder input causes a sudden drop or lift a fraction of a second later depending on left or right.
Nose right causes a drop and nose left causes a jump up.
This is also worse because trying to bring the heli back down causes a sudden drop with almost no input at all on the collective.
I have the similar rudder sensitivity in a stock #36 but not the erratic control in collective.
I was wondering if its slop in the linkages causing a "flipping" effect in at the main blades.
Any body have this before?

Cheers
ViciousHeli

My guess is that your pitch is set wrongly. Try to set move your pitch settings at the servo a bit more upwards, just a tooth or so on the servo . Keep on trying until the problem settles. Good luck I had the same trouble - took me a while to figure it out.

Yes well I thought that at first but I've been playing with the trim through quite a range. If I dial in more positive then it reduces the jumpiness but has a greater sensitivity to rudder input. However it also loads the motor down more through the whole pitch. You can hear the RPM are lower.
If I reduce the pitch then the revs come up more through zero pitch and then load out to become more level and stable through the pitch curve. With the higher RPM the tail becomes more stable but the heli becomes more vertically sensitive. I'm assuming this is because the increased rotor inertia can be more easily converted in to lift and then it takes longer to spool back up once its dropping down making it more oscillatory as the delayed power comes back on..
With more pitch dialed in the linkages have more load in just one direction so don't allow the rotors to flap around through the neutral position.
This is my theory but was hoping it was simpler as this will need me to make new linkages. I will keep trying a bit more with the pitch trim but I've got over 2hrs of flying time on it now and not dialed it in yet.
One thing when it goes vertical its got a lot of acceleration in it. Problem with that is I'm fling under a 2.4m ceiling
Thanks for your help.
Cheers
Viciousheli

Hi me again

Just try the following with your current pitch settings when you increase throttle to 50% does your pitch also move about 50% of its movement range? I have found that just 50% of both throttle and pitch I get easily manageable vertical movement. I still use this as an indication of how well my blades are set up

I really hope you get it sorted as the heli is really fun to fly with 1800 lipo batteries and brushless motor.

Hope to hear from you soon that all is well and working

HP