ORIGINAL: Tom Antlfinger
Hi Craig:
Point I was trying to make was that if one is going to use the leading edge for C.G. on a swept wing, you have to balance preferably directly at the leading edge which can be mechanically difficult. As you move your finger aft of the apex of the leading edge, I think you can see in the photo that to maintain the same C.G. line, you have to move to a different location on the leading edge since the planform is not a rectangle, but 1/2 of a parallelogram.
Tom Cook's Firebird C.G. locater does a good job of placing the balance point right at the apex of the leading edge.
All of this is probably superfluous anyway since it seems that guys are flying anywhere from 12 1/2 out to 14 1/8 with good results as I have seen your excellent flights as well as David, Vern, and Phil's flights.
I usually go out and fly and see if it wants to tuck or snap and adjust the final C.G. accordingly like no doubt you do as well.
OK, that makes more sense. I guess the "box" everyone is referring to is the square
panel just aft of the LE at about the 14" point (on top). If Phil and DavidR are using their fingers to balance at that point I suspect their actual cg is very close to mine. It's also apparent the cg is not critical within a range in that area.
I would still like to see a photo of David Gladwin bending over and balancing a 45 lb jet with his fingers.....from the front only please!
Craig