Originally posted by Montague
Here's a short hand way to do it (assuming constant taper and sweep, no funky curved surfaces). Take the tip and center chord measurements and average them. So a 10" root and 6" tip would give you 8". Then find the location on the wing that has an 8" chord line. That's your MAC. If you take that point on both the left and right wing. Then go back from the leading edge 10-15% and make a mark. That's your CG. Connect the marks, and you can see where the CG is at the center of the wing for easier balancing.
Never had it explained that way before. I like it cause it seems simple. Thanks Montague.