We're apparently both in the same boat here. I'm not at all sure if my design will be dependent on delta lift or not. I have not settled on an airfoil yet and I guess that's a vital part of the equation. However, whatever I choose, the internal structure needs to have some 'form' in my mind. Although I started with the D.D. as a basis, it's wing design does suit my needs, it barely has a spar of any sort. I've spent some time today making a simplified model of what I have in mind. My question would be, will spars of this configuration be able to prevent any twisting? bearing mind that the outer wing is removable. I'm thinking of wooden spars and foam ribs on 3-400 centers. The spars will won't be as high as in my model and will be boxed where they enter the stub wings.