V911 Cannot sustain fast forward flight problem. Help appreciated - Page 2 - RC Groups
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Oct 16, 2012, 04:19 PM
Cranky old fart
Balr14's Avatar
Tightening the flybar intentionally would be very unusual. It would impede head movement. I'm not sure how TBE got into the discussion, but basically it's a change in the air flow between the flybar and rotor head, it occurs once every rotation and it only occurs with 45 flybar helis. Since it only occurs, with a 45 flybar, that would impy that it's related to mixing the out-of-phase condition, which makes sense. So, either there's a momentary change in phasing or in the values being mixed. That seems to suggest something is too tight, too loose, or worn, in either the flybar or the rotor head, or the linkage. Good luck finding it! Of course, this theory is only good until somebody proves it wrong... but it's held up for a few years now.
Last edited by Balr14; Oct 16, 2012 at 05:14 PM.
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Oct 16, 2012, 05:37 PM
Sir Crashalot
stonecutter's Avatar
I'm not saying it's a good thing, but tightening the flybar does indeed make the flybar less effective in self stabilization, which is one way to make the heli go faster. You can verifiy easily for yourself, you can even make it so tight as to immobilize it (but make sure it is horizontal), the heli would be almost impossible to fly w/ the stock tx like that, but possible w/ a programmable tx (kkddmm has modded and flown flybarless v911's, however, he takes out the flybar completely though, making the process non-reversible). With the flybar immobilized, the swash tilt translate into blade pitch w/o any damping, so unless you have super fast thumbs, a programmable tx is a must.

Making the flybar tighter but still movable introduces delayed pitch commands to the blades, which is what I theorize to cause the pendulum, and perhaps TBE (I tend to think of TBE as a 2-d pendulum).
Last edited by stonecutter; Oct 16, 2012 at 07:02 PM.
Oct 16, 2012, 06:21 PM
Registered User
In my limited helicopter experience. When I have used Xtreme head parts on my Solo Pro 328, I have ended up with TBE, rolling over during turns, and total loss of self correction, when the flybar has been to tight. Not even to tight that I can't move it easily, just enough that you can feel the drag. On both the metal head, and the plastic head, I have had to install the screws until they began to induce drag, then unscrew the until there was 0 drag.
Oct 17, 2012, 10:38 AM
Registered User
Air Vaca's Avatar
I've noticed with 45` flybars, you need to "re-assert" your command for FFF. A 90`head/flybar will keep going, until you stop it. A 45` stops on it's own.
Oct 21, 2012, 09:38 AM
Get to the choppa!
RFDelie's Avatar
I think the heli flies better with a tighter flybar. I like it to be tight enough that it does not roll around when holding the heli and doing a slow sway, but moves when you sway quickly. It just seems to fly and stop better, I know my flybar is loose when I start getting the rocking when I I stop.
Oct 21, 2012, 11:39 AM
Cranky old fart
Balr14's Avatar
Originally Posted by Air Vaca
I've noticed with 45` flybars, you need to "re-assert" your command for FFF. A 90`head/flybar will keep going, until you stop it. A 45` stops on it's own.
Absolutely! The purpose of a 45 flybar is to damp movement. Since it effectively reduces remaining movement by 1/2 (depending on linkage) every rotation, it will stop soon enough. The V911 flybar has lots of latency, too.

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