Alright, sci-fi nerd to the rescue, let me check my archives. Ok, here's one I just cooked up, I mixed a hull plate texture I downloaded from somewhere a long time ago with some mild scorch marks and a moderate bump map. The thing is, it sometimes makes the model look somewhat unsmooth; as you can see the four quadrants of the texture even though it is applied to a flat plane (plain?). Maybe this gave you some ideas.