Greg, for a 16 inch chord, 27.5% works out to 4 3/8 inch, not 3.5 inch. I think your plane was probably quite nose heavy, not tail heavy, at 3.5 inch. Your Fox .78 would have handled it a little better if the CG had been in the right place.

Many years ago people flew quarter scales Cubs on .60s. Not much choice back then, but they flew, very scale-like, I'm sure. In fact, Bill Northrup flew his quarter scale Gypsy Moth on a Fox .59 at the Nationals...yeah, that was WAY back.