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		WEIGHTY MATTERS: CENTER OF GRAVITY FOR FLYING WINGS
		We've all had to deal with this question at one time or another.    If you have a bought flying wing, it usually comes with a manual, a drawing of some kind, and on either one of these (or both) is the "Center of Gravity" indicated.  More often then not in inches or centimeters measured from the nose, or center of the TE.  But what if you made modifications? Or even better, made your own wing? Why is this "Center of Gravity" (CG) so important? The flying wing does not have a fuse, so the weight distribution, instead of being spread out over a relatively long distance from tail to nose, is spread out over just the wing.  The smaller the wing, the more important the CG.  On my 48" Unicorn a centimeter here or there isn't going to break the bank.  But on my 26" Mini Weasel 1 millimeter can drasticly change the entire flying behaviour. Any RC'er will tell you that flight behaviour of a "tail heavy" plane is totally different from a "nose heavy" plane.  Too much of either, and you will have your hands full! How to balance? The smaller your plane, the smaller the balancing point.  Again for comparisson; my Unicorn I balance on my fingertips.  My Mini Weasel I balance on two sharp-ish pencil points.  There are also wonderfull contraptions on the market that take most of the guessing out of this balancing act.  One of the better known ones is the "Great Plane CG Machine".  (Why they call it a "machine" I don't know, there's nothing mechanical about it.  Maybe so they can charge you another $10 for the name?) Measure the wing for the CG and put a small mark there (on both the left and right wing ofcourse), and balance the wing on your fingers, or on two pencils impaled on a piece of foam, two dowels, your children's noses (as long as they can keep very, very still), whatever is handy. How about the "dive test"?  Let's assume you got safely up in the air, and have trimmed your plane for straight and level flight.  Take your plane 3-4 mistakes high on a fairly calm day, point her into the wind and put her in a 45* dive.  Let go of the sticks.  If your plane's nose comes up immediately: you're nose heavy.  If your plane continues the dive and/or start diving even steeper ("tucking under") you are tail heavy.  Confusing, right? It's realy simple.  You've trimmed your plane for straight & level.  So when you're in a dive and you are nose heavy, the trim settings will make the plane go up, and vice versa.  If your CG is spot on, the trim will be neutral and not affect the dive. For some more detailed (and knowledgeable) explanations about the dive test, click here. Here is a little drawing and formula that I shamelessly copied from someone on RCGroups about a year ago. (If you are that person, please contact me so I can give the proper credit) There is also an? Excel file with the formula, so you only need to enter the relevant measurements. Once you have found your CG, make a mark there.  Most of my planes are dark blue on the bottom, so I put a piece of white tape on the CG.  I've heard of others who glued a small piece of sanding paper on the spot (also easier to launch), made a small indentation in the foam (if it's a foam wing).  Whatever takes your fancy, as long as it doesn't add weight, it doesn't come of easily, and remains visible. Now go and fly...
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