Hi quore,

You may find this site of assistance in providing info on how to trim your model.

FWIW I generally trim my models out at the throttle setting that I will fly the manouvers at, usually 1/2 to 3/4 throttle. If you don't learn throttle control, particularly on the "down lines" and you are flying an ARF the sound you hear immediately before impact is "flutter"[&o].

http://www.palosrc.com/instructors/trim-chrt.htm

Cheers,

Colin