# Are there existing Earthly body plans that make trapezoid or hexagonal spacecraft volume efficient?

Volume efficiency is extremely important when it comes to minimising the targettable cross-section of a warship in space. Humans make pretty efficient use of spaces that are generally square or rectangular in vertical cross-section. I want a legitimate argument to have starships that are in the form of trapezoid or hexagonal prisms but those shapes don't make a lot of sense for human crews, too much wasted space, so I wondered if there are creatures on Earth that can take full advantage of such spaces and on which an alien species could be based?

As MorrisTheCat pointed out I need to specify that these are ships with artificial gravity creating a fixed up-down orientation, otherwise the question is kind of moot as three dimensional use of the space will render its shape less important.

I have thought about wasp and bee hives but their apparently hexagonal form is actually a solution to efficiently stacking circles in 2D sheets and doesn't, to my mind, (I'm happy to be convinced otherwise) make sense in longitudinal forms.

• Are we assuming artificial gravity here? Because if we're not, you don't need alternate body plans. Hexagonal spaces would be more efficient for humans too, the only thing preventing it is the leftover desire to have a clearly oriented Up and Down. Humans that spent a lot of time in space and were more comfortable with Zero-G living would likely gravitate to hexagonal rather than rectangular spaces just for efficiency's sake. Jul 15, 2019 at 18:13
• @MorrisTheCat Hmm I hadn't considered that, we'll go with yes because otherwise hexagonal prisms sense for all ships. I'll edit accordingly.
– Ash
Jul 15, 2019 at 18:19
• What sized warship are you talking about? For a single-person fighter, I don't know a single human fighterjet with a rectangular cross section. For larger ships like bombers, they have circular cross sections. For larger ships, the outside environment dictates the ships' shape. Jul 15, 2019 at 20:22
• @CortAmmon You're talking about aircraft, aircraft have to be aerodynamically efficient round is good for that, and for fuselage strength:weight ratio when the hull material thickness is measured in millimeters. Spacecraft don't have to be aerodynamic and warships won't have thin hulls so I don't believe that thinking tracks across.
– Ash
Jul 16, 2019 at 10:25
• The vertices in most actual honeycomb that I've seen are chunky enough to call the hexagonal pattern an optical illusion. It's just stacked circles. Jul 16, 2019 at 13:31

Sextually Dimorphic Spiders

This will cause some additional oddities in your ship design that you may or may not want, but I think it talks more to the biological element of the question you are asking.

Female spiders are often much larger than male spiders. This means for a gender equal society of sextually dimorphic spiders to work together, the ship will need to be made to accommodate both genders, but the spaces they use will need to be at two different scales. Since spider legs have a wide profile, the males could travel safely in the narrow lower part of the tunnel to avoid being stepped on while the females walk along the walls. Small rooms will branch off at floor level, and bigger rooms will be higher up.

Technically, it still makes more sense to just make two separate tunnels, but there may be cultural factors here as well. These mixed gender tunnels may be perceived as an expression of gender inclusion that has resulted from generations of equal rights movements and failed separate but equal initiatives.

• I was afraid someone would bring up spiders because I hate spiders, but this is a good answer in terms of physical form.
– Ash
Jul 16, 2019 at 15:38
• you could make them crab people... Jul 16, 2019 at 15:40
• Definitely better but still a little creepy.
– Ash
Jul 16, 2019 at 15:42
• Many reptiles and amphibians also have splayed leg patterns that might work . They tend to not be sextually dimorphic like spiders, but if you specifically want a non-threatening alien race here, I'd go with something frog like. Jul 16, 2019 at 17:11
• I had a nasty thought about this, if the dimorphism involved creates a really large difference, like human vs horse then the males would have been used as cannon fodder in the age of atmospheric fighter craft.
– Ash
Jul 18, 2019 at 17:18

As for biology, this may be the wrong approach to think about it. We don't make rooms rectangular because we fit in them better, we make them that way because our stuff fits in them better. As long as you have 1-directional gravity, a flat floor and ceiling connected by vertical walls will be best for storage efficiency no matter what your organism looks like.

"I have thought about wasp and bee hives but their apparently hexagonal form is actually a solution to efficiently stacking circles in 2D sheets and doesn't, to my mind, (I'm happy to be convinced otherwise) make sense in longitudinal forms."

However, here you are on the right track. If the ship is filled with honeycomb shaped rooms instead of square rooms, damage from enemy weapons is more easily contained and dispersed. Instead of just thinking about the stacking strength of a bee hive, consider that those hexagons will buckle without breaking much more so than square rooms. Vertically hexagonal spaces can be filled just as efficiently with hexagonal boxes as a square room is with squares; so, there is no major loss in efficiency if you use top-down hexagonal shapes.

Horizontal hexes or trapezoids will limit space efficiency under gravity no matter how you add it up, because they impede stackability (a key aspect of storage efficiency when gravity is a factor). However, there may be given parts of the ship where a hex makes more since for the purpose it serves. For example, if it is meant to be a minimally small crawlspace, a hexagonal form may be intended to allow a little extra shoulder room while maximizing the amount of serviceable wires and conduits you can fit around it. Or you might have angled parts of the ship's exterior that are just better to fit the room's shape to than trying fit the ship to the room.