Working on a futuristic supercavitating-hypersonic Submarine for a game made in the UDK, thus the aircraft look. It's the first time I properly model something for a project that isn't an RTS mod. It's for a 3rd Person Arcade, a bit like Crimson Skies under water. It's for two players: A pilot who drives the sub and fires torpedoes, and a gunner who operates the rear turret which can be fitted with a bunch of different weapons, but by default comes as a quad gauss turret. It's not based on a concept art, but instead I made it up as I was modeling it. Now I don't really know anything more to add to the low-poly model that I couldn't do as well on the normalmap.
Edit: Rear-view render: