WHY???

[mikey100]

Went to fly my Bee today at SC... threw it off the cliff and-DIVE- it needed 15 clicks of 'up trim' to fly level. Seems both of the servos have moved their centres; exactly the same amount. Why would this be? Am using a Spectrum DX6i. Checked the sub-trims and they are exactly where I put them! Any ideas???

[sean]

Could be that your pushrods expanded? Was it much colder last time you flew? Another possibility is that your CG has moved forward somehow, not unlikely if the last landing on your previous flight was hard, could have caused something to shift forward.

Sean.

[thevon]

Or there could be a switch that you haven't realized you had set, and you've knocked it on. Or you put your radio down switched on, and something was pressing against the elevator trim button.

[mikey100]

Good ideas.......
*Took 8 turns on the clevices to adjust so don't think it was a pushrod expansion problem.
*Elevator trim was showing in centre when 1st switched on...just the servos both off centered, tho sub-trims exactly where I programmed them.

[Hamburglar]

I had a similar thing happen. It turned out that battery had moved forward slightly on the previous landing/crash. I've heard that some servos will centre differently at different temperatures but never experienced it myself.

Jordan

[ding]

Did you play with the mixing between flights. My bet is some kind of mixing or subtrim changes within the radio.

[mikey100]

no.

[felix]

maybe your problem is mechanical in nature rather then electronic?
I had something similar happen to my bee recently….had a shelf collapse in my shed and dump some paint tins,glues,etc onto my wing.a quick look over showed no damage.next time at the slope and I had next no up pitch control resulting in flying straight through a tree and crushing an elevon!!! Turned out that the control horns themselves had been shifted in the avalanche
So maybe with flying loads,prangs,bad landings,etc the horns have shifted or loosened?

[callun]

Or even the servos themselves moving is pretty common.

[mikey100]

The prob with my Bee came,back, but in reverse. I needed 15 clicks of DOWN trim today. No idea! Nothing seems loose etc.

[felix]

Hey mate, just got to thinking about your problem….are the control surfaces actually moving between flights or simply just the trim you need for straight and level?

[mikey100]

You can see that the control surfaces are in a diff spot....so the servos are changin centre- both-same amount. I think I has got to be a transmitter prob, but dont know how.

[Pij]

Nov 2, 2008 20:38:02 GMT 10 felix said:

Hey mate, just got to thinking about your problem….are the control surfaces actually moving between flights or simply just the trim you need for straight and level?

Good question, Felix. I was thinking of how I re-trim for the changing conditions - with lots of difference between mostly horizontal wind compared to mostly vertical lift.

But this case has visibly different surface positions - weird. What about stripped teeth off servo gears?

[mikey100]

Metal gears....no stripping evident....both the same. Odd....

[ding]

Nov 2, 2008 20:15:29 GMT 10 mikey100 said:

The prob with my Bee came,back, but in reverse. I needed 15 clicks of DOWN trim today. No idea! Nothing seems loose etc.

Yep, it's the servos moving. They are held in by that double sided tape and after a while they come off and move up and down within the box.