My high wing trainer has too much up trim on the TX for the elevator. The trim is up to 82% on the TX. What do I need to do to the plane to remove that trim (balance the plane)?

Jack

Remove the servo horn, set elevator trim to zero, reinstall servo horn, then adjust linkage to so elevator is neutral when servo is neutral.

Without knowing what you have and why it is as it is, this is impossible to answer.

Jonnysplits is right for some cases. You have not given enough info though for me.

What airplane?
What radio?
What servos?
What kind of linkage and clevis's?
Is the plane currently flying balanced and flying hand-off? If so there is nothing wrong with it staying at 82% forever (no need to fix what ain't broke).

The plane is trimmed to fly straight and level. However, the elevator required a large amount of up in order to accomplish level flight. I'm wondering why it needs so much up to fly level.
The engine appears to have no positive or negative offset. The plane is balanced according to the plans. There seems to be no incidence difference between the horizontal stab and the flat bottom wing.

So, why does it require so much up trim?

You asked:
What airplane? Fuselage from one and a wing from another
What radio? Why would that matter? DX9 and AR400
What servos? Why would that matter? Hitec HS325HB
What kind of linkage and clevis's? Same old stuff

The airplane is nose heavy. Bring the CG back 3/8" and fly/re trim.

I'll try that.

Everything matters. Small electrics have no threaded clevis's so a reset involves bending the control rod.
Airplanes matter because some planes require built in incidences.
Radios matter because the way to center the trim is different brand and model one to another.
Servos matter because some small electrics are not rotational with removable horns that could be mechanically change for trim.

Now, what do you mean " Fuselage from one and wing from another" same plane and brand ARF?

After a maiden flight I land and look at the elevator not the number in the transmitter. Next flight I pull a 45* up line and go inverted then hands off to see where my CG is (note this is after trimming for hands off level flight). If I'm nose heavy the plane will quickly curve downward. If tail heavy it will curve upward. Learning what CG suits you is something important but personal. I prefer a CG a little biased toward the back ( I want to not have to make a quick down elevator push when inverted).

You might have a lot to do. or not.........

Flat bottom wing.... if it rubber bands on, then stick a shim under the leading edge and see if that lessens the trim needed. But the more important question is how that trim works at different speeds.

Did you get that trim at full throttle? Does the model fly level with that trim throughout the speed envelope?

"The plane is balanced according to the plans" Fuselage from one plane, wing from another........... Does your wing have the same chord as the original wing had? Does the wing have the same airfoil?

Engine mounted with no offset? Some right thrust never hurts. While shimming some in, give it some downthrust as well. But try the wing shim first.

What is really worth looking at right off is how square are the pushrod connections to the servo and elevator hinge line. Does it make a right angle at both ends? If not, screwing around with all the rest is just wasting time.

I'll try to elaborate.
I had a "Super Trainer 60" ARF that I bought, in the box, at a garage sale. I assembled it and installed an OS 61FX on it. Took it to the field and had our top instructor test fly it. He quickly got it trimmed and it was flying great. Really nice plane BTW. Too bad they don't have any more.

So far, so good. All of a sudden the instructor had no control at all and the plane crashed. The fuselage was OK, but the wing was trashed.

I had a spare wing for another 60 size trainer that has the same chord as the crashed one. The crashed one used bolts to hold the wing, but the spare wing used rubber bands. I traced the outline of the spare wing and modified the fuselage slightly to accept the spare wing. Then I installed a 3/4" by 1/4" thick x 6" long piece of birch plywood onto/into the front of the spare wing. That enabled the plywood to slide into the 1/4" wide slot in the bulkhead in the fuselage. It is the same way the crashed wing mounted. I also reinforced the trailing edge area of the spare wing to strengthen to for mounting bolts, drilled the holes, and mounted the wing. (Yes, I'm an experienced builder, just a beginner pilot). I then verified that the wing and horizontal stab are within one degree of each other in incidence. Now I have a "kludged up" trainer with a different wing that has the same chord and span as the original wing.

Again I went to field and my instructor flew the plane, trimmed it, and handed the TX to me. I flew for 5 or 6 minutes and landed it. I continued that day flying 3 more tank fulls. We never really exceeded about half throttle except for take off.

When I got home I noticed the elevator is pointing up quite bit and the DX9 TX has 82 clicks of up trim. I just think that's too much and I'm wondering what would cause that.

The clicks don't really matter, because you may have started with some down trim. What's important is the actual angle or measurement that the elevator is relative to the horizontal stabilizer. Assuming the CG really is correct and the flight characteristics are otherwise good, the problem is likely that your wing incidence is too low relative to the horizontal stabilizer. Shimming the front or lowering the back will fix it if that's the problem, but I wouldn't change anything until measuring it. If you have a good rapport with an instructor who has an incidence meter it would be easy enough to see where it is. If not, I'm local to you and would be willing to meet with you and work on it. Which club are you flying with? PM me if you want to get together.

I'm in the TexasWings club.

It the model flies with it's fuselage parallel to the ground, your horizontal stabilizer has too much positive incidence and the up elevator is producing canceling out what that produces: a nose down pitching moment.

If your model has no ill handling tricks that show up with changes in airspeed, live with it. The tail is producing what is needed for trim. It could be doing it a bit more efficiently, but improving the efficiency would require a fair amount of hacking to get a better AOI.

If the model is flying around with the fuselage nose high, the AOI of the wing is the culprit. To fix that could require hacking up your wing hold down setup so the wing AOI held the fuselage parallel to the ground when the wing AOA was correct for the load it was carrying.

It's a trainer..... and you already know how to build....

You probably don't live far from me. I'm in Lake Worth. I'm a member at Thunderbirds because I think it's worth the drive, but I'd definitely be up for helping you if you want.

Thanks Jester. I'm at Boat Club and Ten Mile Bridge.
I don't really think it's necessary to fix it since it flies pretty well. I'm just curious as to how TO fix it. If it's simple, I'll do it. If it requires moderate to heavy construction, I'll live with it. I'm currently working on two other wings.

Jack

Although the wing is the same shape, what is different is probably the airfoil. The cord line or centerline of an airfoil is from the center of the thickest part of the leading edge through the trailing edge. That is the neutral position. The flat bottom of the wing is not "level."