ORIGINAL: RCKen
When you build the fuselage make sure that you put the sides so that the bow in the pieces DO NOT go in the same direction.
If you're talking about a die cut fuse I don't see how you have much choice how to align the bow. It's not like you could put one backwards or upside down. If they're both bowed in the same direction there's not much you can do, but I have no doubt the top and bottom of the fuse will straighten it out.