CG is a term that is used for a hypothetical range in which the airplane will fly comfortably.

Let's say a plane gives you a 1/2" CG range. If you balance the plane at the forward end of the range it will be heavier in the nose than it would if it balanced at the rear end of the CG range. At this setting, the plane will be more stable and less maneuverable.

If you balance near the rear end of the range, the plane will be more maneuverable, but less stable.

They both have their good and bad points, but what is worse is when you go too far outside of the range in either direction.

If a plane is too nose heavy it will become very sluggish and stall speed can increase to unacceptable levels (Won't slow down to land).

If the plane is too tail heavy it will rarely make it home in one piece. The reason for this is simple: Think of a dart. Now take the lead weight off the front and make the fins out of lead instead of feathers. If you throw it, the fins will flip around and go first.

A tail heavy airplane will do the same thing - the tail will try to go out in front. It's not pretty.

So where is the best place for the CG? That's totally up to you.

Balance the plane in the center of the CG and fly it. Do you like it? If you like it, leave it. If you want to experiment with other settings, move the battery pack back a bit and fly it again. Is it better? Worse?

You will usually find that the rear-half of the CG range will give you a better flying plane. Then again, you may prefer the way it flies when it's on the nose-heavy side.

So you see, it's totally up to you where the plane balances best.