I have an Aircore 40 that I am learning to fly on. I am having trouble keeping the model in trim.. Every time I start the days flying, I need to re-trim the elevator. I mean large changes in trim.. Could it be a problem with different wing seating each time I re-install the wing? Fred 123[&:]

First off I would like to say I can't beleive the moderator hasn't tried to help you with this question. Secondly
I think you may have posted this question in the wrong area, ARF post room may be where you want to be.

OK , I dont know anything about US Aircore planes, but I have had this problem before with an electric plane. Check to see if the servo tray is moving around. If it is moving even just a little bit then this will be the answer to your problem.

If it isn't moving then make sure the elevator is not moving , then check the servo to see if it is stripped.

Good luck.

I haven't had that problem with mine. My elevator trim has always been none.

You might check your:

Check for "play" or binding in the linkages.

Be sure everything (like the battery) is secure in the cabin.

Balancing on Center of Gravity. With PC in-place and ready to fly except the fuel. Be sure it's not tail-heavy.

Elevator throw rate. It should only be 3/8 - 1/2 inches.

The wing should always be installed in the same place... centered and all the way back against the rear lip. At it's flight-ready weight of 8 lbs. , mine takes 16 rubberbands to keep the wing on and in-place during flight. It should not be moving at all.

http://www.vlsdynamics.com/rc/planes/us_aircore40.htm

I don't have this plane but from experience I know there has to be some kind of play in the servo tray or the servo it self.

Good Luck.

A few years ago I had one of the Aircore Colts. I loved the plane but it was prone to elevator and rudder trim changes. I finally traced it to the long nyrods used in the kit. They will change length noticeably in hot/cold weather.

Matt