RE: CG for Vailly 90.5 FW 190
Actually, if anyone is interested in how designers figure out the acceptable CG range for a new design, look at the notation to the right on that calculator page at geistware.com. Those formulas are used by the entire industry. Fullscale and model designers, and by those of us who know about them.
The pitch stability of any layout depends primarily on only a few things. There are a BUNCH of modifiers to those things, but they seldom affect the CG location significantly. So if you look at the formulas and study how they're used you'll basically see what's taught in Aero Design, Pitch Stability 101.
And you'll see that the major players are the area of the wing, it's chord, the area of the horizontal tail, it's chord, and how far back the tail is from the wing. Everybody and anybody who wants to figure out a safe range of locations for the CG can work out those values for his model or new design (be it a new Boeing or an existing model) and plug them into the formulas and come up with reliable numbers. Or he could plug the measurements into the Geistware application and hit the button.
Ain't no guesses or opinions in them thar formulii. Just the aerodynamic principles that're in use today.