Originally Posted by rtbates
3 degree or so down and right is correct for just about all rc planes. It counters motor torque and the tendency to climb under power. I do have a few gliders with no down/ right and under full power they will loop IF you don't add lots of down elev..
Most models benefit from some right thrust (assuming standard prop rotation) but far from all planes need downthrust. Mid and low wing aerobatic type model generally do without. I've got several aerobatic models and none of them have down thrust, nor do they need it. Trainer type planes with high wings and lots of stability usually need lots of downthrust. There is no 'one size fits all' solution.