these are prety good but i have a few ideas/ complaints
the 'Comand center' is more like a house and it usualy makes the builders, try make it longer and maby give it a stelite dish on the roof, or a few of ariels (to make it look comanish) and it also looks subed.
the land factory sub looks weird, too round. try put a roof area on it sorta like this http://i172.photobucket.com/albums/w37/aussiemadboy/factory-1.jpg
(for the cars to drive under, looks cooler)
the bomber looks cool, more like a futuristic space ship.
good work so far tho

keep it up and you'll get better.
http://www.afrokid-fps.co.nr