Bob Kuykendall wrote:
On Dec 12, 7:36 pm, jcarlyle wrote:
...is there some way for getting them into the same frame of reference?

I'd recommend that you come to terms with MAC. As they say in Make
Magazine, if you can't open it, you don't really own it.

This article describes a graphical method for determining the MAC of a
double-taper wing such as that of your LS8:

http://www.djaerotech.com/dj_askjd/d...s/canard1.html

There are also calculators available on the Web for determining the
MAC of a multi-tapered wing numerically.

Once you determine the length of the MAC, locating it with reference
to the aircraft longitudinal axis is a matter of simple surveying that
you can do with a yard stick and some strings and plumb bobs.

Sensible remainder snipped...

I'm not really intending to argue w. Bob K.'s position or reasoning,
just offering a slightly differing view...at least insofar as 'real
world' determination of CG is concerned.

For lots of sensible - if occasionally murky-at-first-glance - reasons,
the aerodynamic field has a love affair with mathematically elegant
approaches. While calculation of CG is arguably 'merely' a W&B
arithmetic exercise, the aerodynamic implications are obvious to anyone
who's ever flown models. That noted...

When it comes to *Joe Owner* verifying a ship's CG position, I've long
thought designers'/factories' use of MAC just a touch lazy. Since the
designer has obviously already done the math, IMHO Joe Designer should
take the next step and translate their (useful to those in the
aerodynamic field) MAC datum to some trivially-easy-to-locate fuselage
datum: less chance for user error, arguably reduced liability (sigh), etc.

Why have Joe Owner 're-design the wheel' every single time for every
single ship? If we assume CG-calc-accuracy is the goal, then failing to
make it straightforward to owners/others to perform, is (ruminatively):
thoughtless, lazy, obtuse, arrogantly didactic, etc. Personally, I don't
like RE-messing with plumb bobs when someone else already has...

Regards,
Bob - lazy, degreed AE sort - W.

P.S I blame my whine of a week+ of below 0 (F) temps prior to the onset
of winter. Where's Global Warming when you want it?!?