Blackhawk - what a beauty! this is just my brainstorm on the structure of the belly, but i am an architect, so i'd like to think that i might be onto something. you've essentially created an arch, which is of course one of the best shapes to carry a compression load, so in theory if you're able to keep the thickness tillered correctly, you could have less material doing more efficient work. the more i think about it, the more it makes a lot of sense to design a bow this way.