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Roll Trim Problems

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Roll Trim Problems

Old 07-29-2003, 04:46 PM
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crotts
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Default Roll Trim Problems

I'm at my wits end (which isn't very far), so I thought I'd turn to you guys for some advice. here's the deal:

I'm flying a Dragon Lady 40 which I just finished about two months ago. It has dual aileron servos mounted in the wing. After the first couple of shake-out flights, the plane flew great. The trims never needed adjustment and it track straight and true.

Then, one day, it wants to roll right in a bad way. I moved the trims left (almost all the way) and it seemed to correct OK, but after a couple more laps, it rolling left like crazy. After trying to chase the trims back and forth and almost crashing in the process, I got it down in one piece.

I had a much more experienced builder and flyer take a look. He thought it might be some slop in the aileron linkage due to my poor z-bends. So, back to the shop. Got all that taken care of with clevices on both ends and made sure the hinges were all good. Double-checked the rudder linkage and hinges too.

Back to the field and it's still doing the exact same thing.

The only other thing I can see that's different, is that my battery was a bit loose and was able to shift a half inch or so. I have resecured that but haven't had a chance to test that.

So, my question (finally) is: is that much movement in the battery likely to cause such results? And if not, does anyone have any other ideas?

Thanks in advance for your help.

Neal
Old 07-29-2003, 04:56 PM
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krayzc-RCU
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Default Roll Trim Problems

what servos are you running on the wings?
how do the wings attach?
how are the ailerons fixed on landing?
are they cocked, one up and one down?
does the wings have any noticed flex to the eye or twist?
has any of the wires show any signs of the wire inside showing does the pull pull ofr thorottle cable rub any of your wiring?


its something other than a battery moving a little bit.

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Old 07-29-2003, 05:02 PM
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crotts
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Default Roll Trim Problems

"what servos are you running on the wings? "
Futaba 3004s


how do the wings attach?
single piece wing, dowels in front, bolts in rear. BTW, have tugged on the wing to see if it is loose, and it is seated firmly.


how are the ailerons fixed on landing are they cocked one up and one down?
Yes, but only in the amount that is trimmed in.


does the wings have any noticed flex to the eye or twist?
No, checked that already and had atwo others look at that as well.

has any of the wires show any signs of the wire inside showing does the pull pull ofr thorottle cable rub any of your wiring?
Throttle cable isn't rubbing, but I haven't done a thorough inspection of wires, will do that tonight.

Thanks,
Neal
Old 07-29-2003, 05:15 PM
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Default clevises

Some ARF's with metal clevises on threaded rods have the clevises fit so poorly that they occasionally slip over the threads on the rods. The symptoms are exactly what you describe. A sudden change in trim, and then later a sudden change back to the original trim if the clevis slips back.

You can solve it by CAing the clevises to the threaded rod.

Jim
Old 07-29-2003, 05:26 PM
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daveopam
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Default Roll Trim Problems

I had a bad Y harness on AILE that would not center. With the plane on the bench and the radio on. I could move one AILE and it would stay where I left it. After changing the servo it was still the same. Changed the Y harness and all is well.
One of the servos could also have a bad gear. later daveo

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