Solved! Strange tail problem

Hi,

what an odyssey so far :-/

I doubt it's the wiring, and the TelMe, but you could just disconnect the TelMe and try (at both ends, for good measure).

I also doubt it's the ESC, if you get a drift from it it's usually like a ticking wag, the tail moves ever so slightly at intervals, if the governor and the tail control loop interact. You could try and re-progam the ESC to a non-governed mode without brake, and try with a simple throttle curve. Simplest thing probably, set Nitro Governor and the spool up bank, so you can just hover it and see, without any governing.
Of course, if the drift there is very little, it's difficult, if you can see a considerable drift in a hover, it can help ruling this or that out.

Vibration analysis in the visible range looks clean, but that's hardly the range any more which can affect the VBar unless vibration is really bad.
And high frequencies (the highest rpm) come from the motor, and then it would probably be harmonics, not the actual rpm ... also not very likely.

This is really strange.

Kind regards

Eddi

Born to fly ...
forced to work.

Well today's trip to the field has seen some progress.

Things that didn't work:
New main blades
New tail blades
No Telme
New wiring from Kosmik to Neo
Strap around Neo

Then I changed Neo again, it's literally done in 5 minutes with VBC (Touch). Suddenly the drift has slowed right down. It's still there, I'd say around 20% of what it was before. This is an older V1 VLink if that matters.

Hi,

a third NEO, same setup?

Best,

Eddi

Born to fly ...
forced to work.

Are you sure that there is no yaw signal given? Maybe bad "mid-signal"? If there is a Servomonitor is should be easy to check if yaw is 0%.

Or do you have accidentially done a subtrim?

MfG
Tobias

This was the same second Neo from my 800, but the drift was still there.

There is no input, this heli can hover hands off forever. I'm watching the monitor and nothing happens.. I've also tried two different vbc.

Over the last week I've changed all bearings, main gear, pinion, secondary shaft.. no use.

One thing that surprises me is that sub trim doesn't help much. When I do a trim flight the tail correction value is -12. I just assigned tail trim to a poti, and tried every value from end to end. The drift doesn't change.. why is that? Why doesn't a "wrong" sub trim value give an input to the tail?

The national f3c competition is this weekend.. I'm screwed

I just felt this thread deserved to be summed up as I found the error.

The national f3c championships went great even with the tail drift and I managed to win the Sport class. The setup I currently use makes the Urukay so calm and predictable in hover and in acrobatics the Vbar is perfect.

After this I really went after the problem and after everything it all came down to the fastest rotating object in the helicopter, the motor. I changed the bearings and shaft along with the support bearing, and the heli was transformer. Much calmer sound, no drift, no vibrations through the boom. These vibrations couldn't be seen in the analyzer, but were strong enough to fool the sensors into a drift. I also think the autotrim was fooled into trimming the wrong direction.

Well done! Thanks for the report!

Would be interessting: How is the gear ratio and HS / Motor RPM?

regards (EN) / Gruss (DE)

Rainer Vetter

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