cfircav8R and eddieC, Of course the principals are the same however the models have a fraction of the wing loading and a ton more power to weight. That changes the whole ballgame. I have competitivly flown both Pattern and IMAC. In IMAC the rules state that the airplane must be a scale aerobatic airplane with 10% or less deviation from scale outline. We get them to fly very true by careful setup. One has to look at every force that applies to the airplane and make adjustments to work in unison with one another. One of those adjustments is engine thrust line. We do a vertical climb and the goal is a strait upline that extends 150-300 ft depending on airplane size. As the airspeed decays and the prop gets into a higher loading, the airplane will start to yaw left. When one hits the sweet spot of right thrust it helps with the whole flight envelope including take offs. Pattern airpanes do have fewer bad habits as they do not have to resemble a full scale airplane. Both disiplines require that the airplane be set up to fly as true as possible. For me this usually takes 50 or so flights making small adjustments and one adjustment at a time until the airplane flys through a sequence with as little pilot workload as possible. Successful R/C pattern and IMAC pilots do not just " Fly with their thumbs " they do exactly the same as described above. For the record, a Chipmunk is not an aerobatic model, in full scale trim it is a trainer. Yes Art Scholl did an amazing show with his Super Chipmunk however the airplane was not intended nor was it capable of precision aerobatics. So my remaining question for the OP, does your model have any right thrust?