I have made a new model but when I try to unwrap it, Chilli fails to unwrap the upper portion of the body. It comes up with two messages which say 'Object xx will be distorted if unfolded. Force Unfold?' or something like that. The turrets and missile launchers may unwrap properly, I just left them in to make it clearer which part is the problem. It doesn't unwrap when they are hidden either. The two pictures illustrating this are here:
http://www.freewebs.com/djrowley/images.htm