Hi guys,

I have been flying a lot and it works well. At higher rotor RPM it goes well but at lower rpm at hover I get oscillations. or rather like the heli is dangeling back and forth. If I make stick input the helicopter goes to the new position and then dangels back and forth. If I up the cyclic gain to 70 it gets a bit worse and if I lower the gain to 25% is't still there. Is it safe to go lower at the cyclic gain?

As with my tail problems I never saw a clear change when doing quite big adjustments on the settings.

Might this be from another setting being wrong?

Hi,

could you send me your settings file and all details about the model, please?
Then I can tell you what could be wrong.

Do you know head speed with high and low RPM?

Is the behavior occuring on aileron or elevator axis?

_________________
Spirit System developer

I can get you the files this evening.(need computer and dongle to save right? not via jeti Tx directly?) I fly with VTX 557 blades now and are testing 1550-2300rpm where I mostly fly 2100 as that's the designed rpm for the blades, but I also tried 1800 and 1550 where 1550 gives this wobbling looks like it's both roll and elevator. Also when inverted.

No stalling of the blades and the heli got pretty good oumfp still at this RPM. Wouldl ike to try lower too but need to know why it acts up first.

Thanks!

Some helicopters with DFC heads or bad dampening are oscillating at low DFC. This is not caused by any settings in the unit, but the mechanics does not allow to use such low RPM - if oscillations are rather slow.
For this any settings will very likely not help, but possibly changing head dampeners can solve the problem.

With Spirit there are very rarely some problem with swashplate oscillations due to settings, so I am afraid that it could be only mechanical issue.
Theoretically it could happen if Geometry 6° is not configured precisely, but it should occur with higher RPM as well and there are usually very fast aileron oscillations in that case.

Yes, configuration from computer is needed.

Slow oscillations in aileron and elevator at the same time are also caused by bent main shaft or some asymetry in the rotor head.

_________________
Spirit System developer

As I best understand it, harder head dampers and/or DFC style heads offer the advantage of more crisp and precise mechanical reaction to electronic inputs, but commit you to flying at higher head speeds when compared to softer head dampeners and/or traditional style heads with mechanical follower arms. The result of a relatively low head speed for a given head damping and/or head style is elevator bounce/shakes (very little if any aileron bounce/shakes). All heads will give you elevator bounce/shakes if the head speed is low enough, but lower head damping and/or traditional style heads with follower arms will allow you lower the head speed lower when compared to harder dampening and/or DFC style heads before encountering elevator bounce/shakes. This is a mechanical issue, not a FBL unit issue.

Since the OP is discussing VTX 557 blades, I'll share my a experience with a 550 size heli I no longer have. For a 2010 original T-Rex 550E with a traditional style head swinging Align 550mm blades (stock blades where Align 520's), one could not spin much lower than 1900rpm with the harder durometer black head dampers before encountering elevator bounce. With the softer durometer red dampers, one could spin much lower than 1900rpm.

Thank you! The dampers are stiff delrin, I could try with softer ones too. I will how ever share my settings.