I just got my first plane!!! It's a Superstar 40 trainer, and I'm so pumped. I bought it used from a friend who trained on it, and has moved n to his second plane. I went to the field and saw him fly it, and put it through some work before I gave him the money, but I did have one question to ask you guys. He told me the plane was already balanced and trimmed, and not to touch anything, but as he would fly the plane without touching the controls, the plane would gradually climb. Is that normal. He told me that a perfectly trimmed plane will always make some type of subtle movement, be it to wind, or other things. I was wondering should I retrim the plane, or leave it as it is. Like I said the plane didn't climb dramatically, but it did climb. Thanks for your help. Oh yeah. After a plane has been trimmed once, do you have to do it again, or every so often???

Thanks....Noir

He's right. The different wind conditions will change climb rate. You simply move the elevator trim tab up a couple of clicks.

Most trainers will climb a little at full throttle, it's natural. ANd once a plane's been trimmed, you shouldn't have to re-trim it unless you crash it and have to repair it, or change engines or servos or something.
Dennis-

Most folks that I know trim out the trainer so that it will fly straight and level at about 1/4 throttle and most other planes at about 1/2 throttle. If the plane will fly level at 1/4 throttle you can bring it to a crawl on landings. Great for beginners!!!

I trained on a superstar 40 and it is a good flyer, but had to retrim every day. If you have an instructor let him or her trim it untill you can safely fly it and then trim it for the way you fly so you are comfortable. Without instructor, good luck!

I generally re-trim on every flight. It all depends on how you like to fly. But changes in wind speed and direction may be a reason to re-trim. Also, I generaly like to fly at full or nearly full throttle, so when cutting the throttle for landing will cause the nose to drop. Sometimes I will then add a few clicks of up trim to compensate. Another thing is that as you burn off fuel from your tank, the trim will change slightly. Some people like to keep adjusting the trim to maintain a more neutral balanced plane.

I have always trimmed my planes on relatively calm days. I never trim them for wind conditions, I simply fly the plane. In my opinion, trimming for wind can't really be done, because if you trim it to handle flying into a 15 mph wind, it will perform differently when you turn downwind.
Dennis-

Try this some time... on a calm day, trim the model for maintaining level but in a slight turn.

Now on a day with appx 10 mph wind, take the plane up to 200 to 250 ft and let go (throttle the same as it was trimmed for level above) Watch it do the circles and just drift with the wind.

The airplane doesn't care about the wind! It just thinks the ground is moving under the air.