Dear Stephen,
Your artwork is shaping up
I have a comment, but it's a minor one and totally based on my own taste. When you posted first WIP grayscale at 6:12 AM the smoke from the ship behind looked like two things: tornadoes and creature's claws. I like that very much, it's a detail, but it adds so much to the piece. And then you converted to the standard well executed smoke.
As I said, if you don't see it the way I do or you have more realistic plan for it, then do you own thing, it's pretty damn good. Unfortunately I cannot critic the color, as I am green in this field and will be struggling with my own entry when the coloring time comes.