Lots of dihedral is what makes the rudder effective in turning the plane and is common in trainers. Ther bad news is that the high angle of the wing makes the plane easier to get pushed around in windy conditions. Higher performance planes have little or no dihedral and can handle the wind better. Planes with no dihedral can not be turned with just the rudder. The idea of trimming a plane is to have the plane fly straight and level without needing to move the sticks. Bear in mind that on a trainer you will want to check this at 1/2 throttle. Reason being that trainers are designed to climb at full throttle, fly level at 1/2 throttle and lose altitude at under 1/2 throttle. If the plane gains or loses altitude at 1/2 throttle then you will need to adjust for that as well as if the plane turns left or right. [8D]