ANY trainer should always be balanced right on the main spar. That will give stable performance.

I still fly my old LT-40 for giggles now and then. It's highly modified, so can't be used as a trainer anymore. I have my CG set about 1/2" behind the main spar. It's quite............ nimble. (tail heavy as hell) I wouldn't recommend that for inexperienced pilots or on any plane you are using to train new students.

Mine has 2.25" cord barndoor ailerons and flaps. TH .75 engine. Taildragger gear. Elevator is about 1/2" longer cord than stock. I'm planning to add a rudder counterbalance soon. It still won't hold a knife edge very well, but I'm hoping a counterbalance on the rudder will add that little extra umph I need for a decent knife edge. I think some of the guys at the field probably laugh at me for flying a trainer even though I've been in the hobby 10yrs and mostly fly gasser giants now. Who cares? It's a blast to wring out a trainer and show those guys that I can do rolling circles and outside snaps with a trainer. I fly it low and fast.......... 40' off the deck at full throttle.........cut the throttle and toss all the sticks to the right and full down elevator. It's hilarious to see a Kadet doing outside snaps 40' off the deck. As soon as it rotates back to level flight I hammer the throttle again.

It's so funny to watch, I got to laughing with one of my buddies and almost fell down while flying.

It's ESPECIALLY fun to take that plane out on Thursday night (Student Training night) and show those guys what a "trainer" can really do. Soooooooooooooo many modelers rush to jump into that 2nd plane without ever flying their trainer to it's full potential. A shame really. Basic recovery and aerobatic skills can be learned on a trainer. They really WILL do all the aerobatic maneuvers, just not that pretty. But they will do it. Snaps, both inside and outside. Hammerheads. Harriers. Rolling circles. Flat Spins. Slow and dirty. Fast and furious. The LT-40 will do it all if you just give it a chance.

Having too much HP and larger control surfaces helps. But the stock LT-40 will do it all. Just slower.