I have made and used the Vanessa jig for a few months now and find it works. It also served to get me interested in some kind of jig that I could just set a plane in and check the balance. I am probably being excessive. I first made a 2 "U" shaped pcs. from some 3/8's ply with one leg of the U about a 3rd of the other and then connected the two pcs with dowel and hung it from a string and set my electric model on it after balancing the jig and marking the cg of the jig. It appeared to work. So then I purchase some 3/4" pvc and some fittings and started cutting and glueing etc. etc. until I came up with this jig.
The first pic is of the jig on my mobile bench with the back legs and safety uprights on, the back uprights are removable and are to keep the plane from sliding off, they are removed to place the plane in the jig. I have marked the same point "cg" of suspension on both lower legs and for the purpose of trying it out one inch forward of this to accommodate my old bipe. The next pic is the jig by itself balanced by itself with the lower legs lined up with a level horizontal surface and then the third is with an old Aeromaster bipe with the front edge of the lower wing placed on the one inch mark and a string tied over the aft part of the fuse to hold it in proper flying attitude. The jig flexes, when suspended. as expected in the fourth picture but I think this is of little importance and something I could fix if it is. I originally determined to use larger dia. pvc to avoid this but it was not available. My intention is to put a leveling bubble on the horizontal leg for accuracy.
The whole thing with the plane installed and suspended seems very stable and appears to work although I question whether it is sensitive enough. It doesn't compare to the Vanessa rig for cost and ease of storage but the ability to place a plane in it and hang it and then add weight to see the results is interesting. I can see hanging a plumb bob for more accuracy from the upper support.
I'm really looking for feed back about the design and logic used. It has been fun and interesting so far and accommodates my one giant scale gas as well. The dimensions are approximately: width 15" height 20" without the legs [img][/img]and length 20".