Jim T. and the others are correct. The Stunt Chimp needs no rudder offset. It does need 1° to 3° out thrust to the engine, however. Most slack lines on trainer type aircraft occur at a time when rudder offset is the least effective, i.e., when the plane is moving at slow speed. Engine out thrust works the same at all speeds when the engine is running. A little extra tip weight will also help keep your lines tight.