You are welcome Mlw, Some thoughts on the trims and I believe you are talking about the pitch trim (elevator). What many folks do not realize is that with a power plane is that pitch trim changes with every little small power change. Increase the power and the nose will want to rise and reduce the power it will want to drop.

I suspect that this is what you are experiencing from flight to flight and simply not aware you are flying with a slightly different power setting. This is one reason that all who I mentor I give homework yup homework and that is while they are watching TV to practice finding both the aileron and elevator trim with their left thumb all without looking.

Back to the pitch/power trim thing, the idea is to establish a reduced power for level flight and not blasting along at full power all the time (SRT is quite right when he suggest the use of the rudder is a mark of someone that flys with more skill but also throttle control is another very important and obvious mark of better airmanship) Once this power setting is established then the pitch trim is reset.

Oh by the way your Goldberg tiger is a superb next type airplane and likely will become your favorite, Suggestion build it reasonably stock and do not get carried away with big engines.

John