If you only need to get sorta close to the true CG then his method is workable. But if it is your butt on the line you probably want something a wee bit more precise than that.
On models I used something like shown in this link:
Shows a hanging method
Or for the modern generation that prefers video (this is the *exact* setup/procedure I used):
I could see this being scalable up to an ultralight and probably more precise than using multiple scales. At least to establish a baseline for W&B. Once you have the baseline you can add in stuff like fuel and pilot to verify the envelope.
That's a really good old school method that us old timers have used on on R/C models. It works. However, in the real world,
I would prefer to not gamble and load my Eagle's wing roots on such small contact points. I can just now imagine hearing the ropes or cable ripping through leading edge ply! Doh!
No thanks, As an experienced full scale airplane builder who has
put his butt on the line, I will continue to use the tried and true 3 scale method and
Leonard's knowledge for locating the true CG and adjust afterward.
Still, the Demon driver video is interesting for quickly estimating or eyeballing a CG though...