Traditional Vilani ships are angular in nature, due to the original design constraints of hull plates only coming in flat pieces. With much of the Third Imperium being a Vilani-Solomani fusion, curves are more prevalent than they were before, but that mainly serves to round the edges on what are, essentially, simple geometric shapes like cones, cylinders, and wedges. On the whole, Imperial ships still have that blocky, made-from-Lego look.
Solomani ships are purpose-built and exemplify function over form. They are typically referred to as "fugly". Their exteriors often bristle with sensors, weapons, and other greebles: WYSIWYG design at its finest with no pretension at elegance.
|Notice how it looks like a gun? That's how you know it's a warship.|
Other than the Sulaco, above, other excellent examples of Solomani ships would be both the Firefly class mid-bulk transport, and most of the Earth Force ships from Babylon 5.
Zhodani philosophy, on the gripping hand, emphasizes sleekness and elegance over simple shapes or brute design. Their ships look graceful, perhaps even fragile, with spars and winglets perhaps even flying buttresses.
|A Shivva-class patrol frigate, perhaps.|
Minbari ships from Babylon 5 are excellent examples of the design (but not the technology).
Aslan ships look similarly organic in design, but whereas the Zhodani appear sleek, the Aslan are rounded: ovals and hemispheres are predominant. It is believed that this hearkens back to hunting instincts, where a gentle curve would blend in with the terrain more than a stark line or perfectly round shape. Clan markings reminiscent of camouflage are common.
Droyne ships are... weird. Instead of being mass-produced like the starships of the other major races, they are hand-crafted by Droyne Workers under the direction of Technicians (who are themselves directed by a Leader). Because of this, no two Droyne ships look alike. This gives them an oddly anachronistic feel, perhaps in a steampunk or pulp science fashion.
Hiver ships are even blockier than those of the Imperium. At a guess, this is because Hivers seem to lack any sense of aesthetics whatsoever, but it could all be a massive Manipulation (or a joke). Who knows with them?
|Upper left is not a Hiver ship.|
K'kree, being claustrophobic herd animals, refuse to use any ships smaller than 1000 dtons. Their ships are either saucer or sphere shaped, in order to give the greatest approximation of flat plains under an open sky.
Vargr ships just look mean, full of spikes and protrusions and fins and weapons. They also look fast.
|Kind of a cross in design between Solomani and Zhodani, interestingly enough.|
Even a simple Vargr merchant vessel has enough armor and armament to serve well as a commerce raider.
(As an aside: the chief difference between Vargr and Aslan ships is essentially the same as the difference between wolves and lions. The former says "I will chase you down and rip you apart when you fall," and the other says "If you get in my way I'll murder you, but as long as you acknowledge I'm a badass you
may will probably live. If I'm not hungry.")