> The problem is that while it is true when applied to similar structures
> (if you double the wood you double the glass also) it is not helpful if
> you seek to maintain the same weight (decrease the wood and increase the
> glass or vice versa).

If we decide to double the core thickness and leave the layup the same, then we could expect the panel strength to double. Ignoring things such as the modular ratio and assuming that the layup due to its higher modulus of elasticity takes most of the tension and compression forces in a stressed panel and that the core (the wood) transfers only shear stresses then the layups have equal and opposite forces and together form a couple (a pair of point loads separated by the core thickness plus a layup thickness). Thus if one doubles the core thickness the couple forces also nearly doubled and so for a given load layup stresses are cut in half and if layup stresses remain the same then the load can double.