whats the material list and dimensions for your twin-tip prototype?
The fuselage is 1" 6061-T6 square stock. I made it very strong because of the cantilever with the wings at the end but also wider than I like because the moment on the weld gets ridiculous with a small width (this is a weakness with this design). If the wing is placed with little to no cantilever, then a lighter square tube could be used.
The wings are 1/8" 7075-T6. They are way too big. 6" x 24"
The frame is made of 1/8" x 3" 5086. 24" tall. I think closer to 30" would be better except the frame would likely buckle at that height unless more draggy bracing was added. Also, if welding aluminum and not heat treating afterword, 5086 is nicer than 6061 because it has a much higher annealed strength.
I really think an extrusion riser, square tube fuselage, a wing under the riser, and bolted together would be better and easy.
Edit: originally wrote 5068 but meant 5086.
There is this FoilSim program you can download. (version 1.4b)
I have fiddled around with it a bit using an eclipse shape with camber underneath. You can vary the thickness/chord ratio and the angle of attack using sliders and it helps you find the highest lift/drag ratio as you just keep moving the sliders around until you find the optimum.