Pulling Left on Vertical?
 

I have a plane with about four flights. The lateral balance is off right slightly if anything. The rudder trim appears great in loops and straight, level flight. On vertical it pulls left pretty hard. Any suggestions? I've had a lot of planes and none have had this tendency.

does it want to yaw left when you pull up HARD? (like during the pull)
or does it more wander off to the left on any upline?
if the latter, it sounds like it may need right thrust... and if you're saying the right wing is slightly heavy, that could mask the lack of right thrust issue in other maneuvers.

other possibilities: elevator mis trim /misalignment (although you'd probably notice in normal loops... unless the misalignment doesn't manifest until the elevators get near their end of travel....)

+1 what airplane is it, what's you engine/prop combo and how much right thrust does it have?

The plane is a Japanese kit from the eighties called a Barnstormer 25L. It's basic design looks very much like a 25 sized Sig Four Star. I am running a Saito .30 on it. It had zero right thrust. I adjusted the mounting to give it three degrees. I think you guys hit the nail on the head. I'll know tomorrow.

Thanks a lot. Amazing how much that changed the way this plane flies. Much more enjoyable. I do appreciate it!

Here is a tip. Most aircraft need a touch of right rudder when pulling up elevator like in an inside loop to track well. They also need a touch of left rudder when doing outside loops or when using down elevator to change pitch. With just a little practice, it becomes automatic. Slower aircraft with larger diameter props tend to need this more than fast airplanes with small props.

The 4* planes do need a bit more right thrust than is built into the fuse, so if its a copy of one, it probably has the same firewall angles. Both the ARF and the kit built 120 I have needed at least 2 washers of right thrust to correct issues I had with taking off, and doing maneuvers.