As I mentioned in my original post, I use a profile fuselage made of 4MM coro spaced 1/4" apart, with two .157 diameter carbon fiber rods thru the flutes of each of the two sides for stiffness. I have been disappointed that the fuselage did not stiffen up as much as I expected. I use three "bulkheads" between the two coro sides plus I tie in the long carbon rods to these bulkheads for further stiffening. After many days of thinking about it I decided that the carbon fiber rods had to be slipping in the coro flutes as the fuselage was being twisted. The movement would be very small, and I could not detect it visually. Well, after about 6 flights and not liking the wimpy fuselage, I dripped some Gap Filling CA glue into each flute that had a carbon fiber rod until some leaked out the other end. The fuselage is MUCH stiffer now. In the future the CA glue must be added before using string to tie the rods down in order that the CA glue can flow the full length of the rod in the flute. I was forced to drip it in from both ends of the rods.