Bobble at low HS

[richardmills]

Im using the new head with black inserts and black orings. Radix 710 standard V1.
Ive got 1400, 1600 and 1850 HS
Vbar is set pretty much default. 80 gain.
Ive not flown it that much and when i have its mostly been at 1600 and 1850 for faster FF.

Doing some hovering yesterday i noticed 1400 induced a slight bobble in the heli. (like it does on other helis with harder dampers and too low HS)

I havent had time to play with settings but can increasing gain fix that? or uping headspeed to say 1450?

Is it me but 1400 is soo quiet and doesnt seem like it should even hover. I really wanted to fly at 1400 all the time bit it just feels wrong. (and i like slow / smooth flying)

[marcosp]

Up it to 1450, more gain won't change anything or even worsen it. You can try red o-ring on the inside, I am flying that and don't have bobble and feels great at high head speed doing 3D too.

[richardmills]

are the red softer?

[ZuvieleTeile]

Originally Posted by richardmills

are the red softer?

Yes there are. . .

[marcosp]

Only confusion is you are using black bushings, you shouldn't have bobble even with double black o-rings at low rpm. Are you sure you moved the blade holders to center the spindle before tightening the set screw on the center hub? You might have the spindle slightly off center.

[jointer]

I had the heli chassis "wobbling" under the rotor when i hovered at low RPM and used small sharp control inputs.
Try it and try to look for that.
The reason was black head inserts of course, if you notice something like that and do not like it, the white inserts is the solution.
You gain agility, precision, but the TDR is less "forgiving and relaxed" with the white ones.

[ZuvieleTeile]

+1 Jointer.

I would like to add that a change of HS might be in order.
You can clearly see it on the bench, when the tail struts start oscillating.
50 points up or down might do the trick.

[marcosp]

ZT, do you test on the bench with blades on??!!??

Otherwise you might not notice the oscillation.

[worldofmaya]

I had some kind of wobble between 1000 and 1050rpm with 2011 head with two black dampers and white bushing. Cruising around at 950 or lower wasn't a problem at all.
-klaus

[ZuvieleTeile]

Originally Posted by marcosp

ZT, do you test on the bench with blades on??!!??

Otherwise you might not notice the oscillation.

No blades on the bench except tail blades and rod disconnected.
I was referring to the vibrations which in turn can cause also a wobble.
It is different with the mains on, I know, but at least you find an RpM on the bench where the tail does not induce vibrations.

[richardmills]

Originally Posted by jointer

I had the heli chassis "wobbling" under the rotor when i hovered at low RPM and used small sharp control inputs.
Try it and try to look for that.

yep tried again today. and its the little sharp inputs the induce the wobble.

i tried lots of HS's and its only around the 1400 spot i get the wobble. I presume this is due to vibes / resonance.

1200-1350 and > 1450 above no wobble. Didnt try too many above 1650 as im more interested in the lower ones. 1850 was fine though.

Wow 1200 is so subdued and gentle. I was only hovering mind.

Whats the lowest HS people actually fly with? and does battery weight make much differnce? Im using some 5000's from another heli but will probably get some 4000's for my TDR. Save about 300g.

[richardmills]

Originally Posted by marcosp

Are you sure you moved the blade holders to center the spindle before tightening the set screw on the center hub? You might have the spindle slightly off center.

I assemble the head and shimmed it, gave it a wobble and then tightened down the set screw. It may well be slightly off.