I am building a TowerTrainer-40. I glued the two wing halves together and I then latter found out that one half of the wing is longer then the other half. Thus when I cut the aileorons to size one will be about 1/2 longer. What should I do???

One wing panel is longer than the other?!?!

You should call Tower and ask to have it replaced!

No, its not Towers fault. It was me cutting and snading and not thinking about measuring the wing halves. I just worried about making sure that the two fit good togther and didn't think about length till the epoxy was done.

I see... i was thinking it was an ARF.

Perhaps you should clip the tip of the longer wing. Just free the tip rib, and slide it in 1/2 inch.

It will no doubt fly with the extra half inch... you'll always need some rudder trim... you're better if you correct it.

As for what to do, it's usually easier to cut one wing shorter, than extend the other.

You can cut through the spars and skin sections just outboard of the root rib, at your 1/2" dimension, then grind and cut the remains from the root rib, or fabricate a fresh one.

The new root rib should then be inserted and epoxied into the prepared open end of the wing. Same for your aileron.

... come to think of it, a couple of sheets of 1/4 balsa slapped on the end and sanded flush would be simple.

You may need a small weight on the other top to balance it... but you'd probably need a small weight somewhere anyway
when you laterally balanced it.

Don't be silly. What's the wingspan? I figure at least 50". That means there's a 1% difference in the length of your wing panels. That's not significant. Leave it the way it is.

Perhaps the easiest fix would be to move the fuselage over 1/4", if that can be done...

On a pattern ship where the slight lift and weight difference will make an airplane not track through loops consistently then it can be worth correcting regardless of the building stage. Nothing is worse than having to correct for loop tracking. Contests are scarey enough without having a badly aligned airplane to make it worse.

On a trainer a 1/2 inch is not a big thing and having one aileron a little longer than the other will not effect rolls and similar maneuvers. However the differential span will still mess with loops a little. If you are still in the balsa stage, change it to be correct, it is just a good habit to get into. If you get enough little accidents adding up the wrong way then it can mess up the handling of the airplane. If it is covered and ready to fly don't change anything unless you or an experienced pilot notice something that could be a result of the inbalance.