Hey,
Lately I modeled this Spaceship/Spaceplane/shuttle (whatever you want to call it). I now hope you can help me to improve it, it’s supposed to be in a little short film when it’s finished.
i already noticed the repetitive dirt texture 
the grime map could use some more attention, imo. it should be more streaky, less spotty.
I think you could use a little attention on the wings and tail sections. Both seem very thick to me. The whole reason that the Space Shuttle’s were the way they were was because of the glide scope of it. In unpowered flight, i.e. after reentry, it had the glide scope of a rock. In fact, here is a glide scope image:
You notice that the glide scope is 39 degrees. That’s VERY steep.
With your wings, the glide scope should be very much shallower, like that of a plane.
The only reason I bring it up is that you state that it’s realistic…which…it’s close. But, not with those wings and tail. 
The style is cool,but need a better angle to show more details I think.
Maybe some models in Planes would be helpful,they are awesome.
