Hi Bill,
Surprised that you did not get more responce to this.
I probably developed the first R/C biplane and from there played for the best with numerous Bipe designs.
Locating the C.G is rather simple but finding the needs to do it
can be a problem.
For example your Christan has sweep back top wing, both?
You umderstand how to locate the MEAN CENTER OF LIFT on a wing? Especially a swept one?
If you do we are in business>
Locate the mean C/L on all 4 panels. The mean points will be out
on the panels. On each wing draw a line connecting the mean points. With the wings mounted mark where these lines intersect
the fuselage side. There will be an upper and lower mark. Connect
these marks with a straight line.
Assuming both wings are identical in size, find the center of the
fuselage line, This is the aircraft wing's C/L, aircraft's C/L will
probably be a bit behind this, thus it is safe to set the desired
balance point in relation to the wings C/L.
Aircraft C/L is known as the neutral point.
Further: often the Bipe's lower wing is smaller than the upper.
For this the same proceedure is followed until dividing the fuselage line is needed.
Associated with this is each wing's area. What percentage is the
smaller wing area of the larger one? Say 2/3?
If so. instead of the C.G, point being half way on the fuselage line i twould be 2/3 UP from the bottom. The larger wing has more
authority thus it's lift is greater and balance must consider that.
Hope I have not made a simple proceedure seem complex, in
practise it really is not.
Good luck!