lol ARGHHHHH i had to stare at this thing for a YEAR! if you want to know anything about the real model (from the film) just ask!! 
What I would say to you is to separate the engines from the main body. models dont have to be one continous mesh they are split into separate components. that way you can model more detail into the separate parts.
You've got the general shape pretty accurate though well done 

Alan
Technical Director - Framestore
Currently working on: Your Highness
IMDB