Hopefully this will be moved to another section soon..
About stiffness- forget about stiffness. Bow building is all about compression and tension. Sinew has no stiffness, yet it is used on the back because it resists tension. The bow's belly is under compression- so use a material that resists compression (wood, horn, FG). Fiberglass is very resistant to compression, while sinew is quite stretchy- therefore if you put on a FG belly, the sinew will stretch way more than the FG compresses (this is what's meant by "overpowering the back).
The reason wood is used between FG laminations is that it's lighter than FG. Whatever material you have in the center of a bow does almost nothing- it's just there to hold the back and belly apart- FG would work for this, but the added mass would slow the bow.
The reason your FG lam doesn't feel stiff is because it's thin. If you could slice it into two strips that are even thinner and then put a wood core between them, it would feel very stiff. Even if this core was made of dry pasta, it would still feel the same.
You ask- "would wood work for the belly? Yes, of course- bows have been made this way for thousands of years.
If you want the best and fastest bow, it doesn't matter if you build it from wood, horn, sinew or FG- it's all about design. The best FG bows outperform wood bows by only a tiny amount.
If I were you, I'd try to laminate a hickory or osage strip to the belly- this will be quite difficult to achieve a good glue line because the bow is mostly built already.
Next time, I recommend using a method and design that has been proven successful. Once you get a few bows under your belt, you can try something radical.
