darticus:

Yes, ballancing a airplane is critical to the way the plane will fly, and not just the CG. Many do it with their fingers, some create strange looking devices, some purchase devices called CG machines such as the one sold by Great Planes. A short distance between CG locations can make a great difference in how the airplane will fly. The farther back you move it the more pitch sensitive it becomes. Too far forward, it becomes a snapper. Best to locate the CG per manufacturers recommendations and then modify to suit your flying. Lateral ballanceilng is also needed to make the bird a better flyer. Say you have a hevy wing. The plane will tend to fly toward the heavy wing so you use your radio trim to compensate. Now it will fly level as the ailerons compensate for the heavy wing. The pros will take it home and ballance the wings correctly. This way, the plane flys ballanced naturally and does not require corrections during a flight that is being judged, or at least not as many. Exhibition pros will change CG locatlions between flights to suit what type of routine they plan on doing the next flight. Ever see a airplane fly backwards. Yes, is part of a routine Chip Hyde does that seems impossible, but yet he flys his Doublevision backward about 15-20 feet, changes direction and continues, all within about 5-6' from the ground. This can be a long long subject. Best you get a GP CG machine and follow recommended CG localtions to start with. In short order you will find out how necessary a streight airframe is, and how to create a streight one. ENJOY