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Old 09-02-2012, 06:07 PM   #282 (permalink)
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Originally Posted by pgoelz View Post
The flybarless system is basically two heading hold gyros. They attempt to hold the last commanded position and interpret cyclic commands as attitude change requests. If the gyros see a non-zero aileron, they will attempt to roll the heli continuously.

Some heading hold gyros recognize the stick positions seen at power up as "neutral". The 3 in 1 does not... it looks for a hard coded position. If the stick position sent by the transmitter with the sticks neutralized does not agree with what the gyros are expecting when no attitude change is being requested (ie., neutral), they will attempt to move the heli continuously as you describe.

Normally, the transmitter and gyros are calibrated so that with zero trim and subtrim, the gyros see that as neutral. But it is possible that something changed and your transmitter isn't sending what the gyros expect for "neutral" (ie., no movement) or vice versa. Try trimming out the drift and see if that works. If not, then you may indeed have a 3 in 1 issue.

well...color me surprised...

I tried correcting for the roll using trim settings on my tx, and damned if it didn't work! I guess because the roll is so consistent (always to the same side, always with the same speed) my tx's aileron trim can compensate for it.

Thanks for the suggestion, Paul. I would have never tried that, as I thought it was a golden rule to not use any trim when dealing with a fbl heli.
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