I really like the first image a lot. What program are you using to make these?
I've never been a fan of the star-trek style "wings" or whatever they are called that hang off to either side
I think in this case their shape doesn't match the main body at all.
The main body of the ship though, is quite nice. Great shape to it and overall I like the design.
I did notice that there aren't a lot of airlocks on your ship, which if the hull was breached would be an instant "OH SHI...!" moment for anyone in the main area.
The second image made me think to ask if there were only the forward facing guns equipped on the ship? If so, an enemy behind you could be an even bigger problem than it already is. You could have gunports at key spots on your ship (front, rear, sides) that could be manned from inside or from some other designated area. Overall it looks functional.
The last image I don't find all that pretty, but it gets the job done and if I were gaming and using this image I wouldn't mind a bit!
So I hope I didn't sound overly critical cause I do like the style.
Keep up the good work!!