Spaceship Design: What makes sense, and what's nonsense?

[Frost]

Originally Posted by Varyon

An interesting consideration when it comes to gravity is for spacecraft that are meant to operate planetside as well as in space. Planetside, a layout like a modern airplane (long and short) makes sense, whereas in space, a layout like a tall tower (tall and skinny) makes sense, provided constant - or at least frequent - thrust. The Savage Chicken from the webcomic Freefall has an interesting compromise - many of the amenities rotate or are otherwise setup to work under either situation. For example, the tables have booth-style seating, and the seats are setup so that the seat and back are functionally interchangeable, while the table can rotate for either orientation. That example can be see here.

You make a good point aircraft style belly landing would actually be more convenient for managing cargo amongst other things.

But I think it would make more sense to put the main engine in the 'belly' so that gravity and main engine thrust were on the same axis rather than placing the main engine in the 'tail' and having build everything to handle loads in two directions and to reconfigure the ship every time you land or take off.

[Varyon]

Originally Posted by Frost

You make a good point aircraft style belly landing would actually be more convenient for managing cargo amongst other things.

But I think it would make more sense to put the main engine in the 'belly' so that gravity and main engine thrust were on the same axis rather than placing the main engine in the 'tail' and having build everything to handle loads in two directions and to reconfigure the ship every time you land or take off.

An interface craft (that is, one that is designed both for planetary and space travel) that deals exclusively with airless worlds could pull that off, but typically you'd want something more aerodynamic for travel through atmosphere. If you can vector your thrust, switching it to be in the belly while in space would let you generally maintain the same "down" direction, but I suspect the mass cost associated with doing that isn't worth the convenience. Really, I think just designing the living/working areas so that they can work with either orientation would be less problematic (and humans adapt to things well enough that doing the switch would be, at worst, a momentary problem for someone unused to travel in an interface craft) - but I could be mistaken.

[FenrisLoki]

If you have fun things like a reaction less drive, a sphere is probably the best design with the engine at the center of the sphere and mounted on gimbals. You could then thrust in any direction, just dependent on how fast your can rotate the drive unit.

[FF_Ninja]

Originally Posted by Frost

You make a good point aircraft style belly landing would actually be more convenient for managing cargo amongst other things.

But I think it would make more sense to put the main engine in the 'belly' so that gravity and main engine thrust were on the same axis rather than placing the main engine in the 'tail' and having build everything to handle loads in two directions and to reconfigure the ship every time you land or take off.

So, Firefly's Serenity did handle this issue fairly well. It had a massive rear engine, but it also had two sizable engines (one on either side) that could be rotated downward to provide downward thrust for landing/take-off or rearward to provide additional forward thrust. Or, I guess, rotated forward to provide rearward thrust.

It mimicked VTOL craft that we have in real life, such as the V-22 Osprey that the marines use. Multi-vector thrust makes sense even when you hit higher TLs.

[Fred Brackin]

Originally Posted by FF_Ninja

So, Firefly's Serenity did handle this issue fairly well. It had a massive rear engine, but it also had two sizable engines (one on either side) that could be rotated downward to provide downward thrust for landing/take-off or rearward to provide additional forward thrust. Or, I guess, rotated forward to provide rearward thrust.

The swivel engines were the atmospheric propulsion system. they could be turned all the way to the front. You see this done (for one engine only) in the "Crazy Ivan" maneuver in (ISTR) the pilot. They shut off when you hit orbit.

Guesses at how they work mostly center around what's usually called a "grav-ram" that pulls air (and the occaissional human body) through the engine with intense artificial gravity. It obviously has no internal fans or blades.

The big engine at the back is for space propulsion only and its' mode of function is utterly mysterious. It does appear to involve that spinning _thing_ in Kaylee's engine room (but it uses no fuel). Rotary motion is important to many forms of spece travel.

Possibly a Rotary Reactionless in Spaceships terms.

[Phil Masters]

Originally Posted by FF_Ninja

To give you a point of reference: I don't see any functional or physical inconsistencies or design flaws with the typical Star Trek and Star Wars faire.

If you're going to be using media references and are trying for some kind of approximate plausibility, The Expanse is a much, much better bet than Trek or SW. That merely has insanely powerful and efficient reaction drives and no radiators, which is a miracle of plausibility by media SF standards.

Originally Posted by FF_Ninja

My plan is to design an entire hierarchy of new ships for futuristic Earth, starting from the earliest space-fairing vessels, gradually incorporating FTL into the design (haven't settled on what FTL actually looks like in this setting), and building on that form factor over time.

FTL is usually a magic black box that gets you between locations. A much more important question is usually whether you're going to have magic reactionless thrusters and artificial gravity. Ladle enough miracle-tech on and quietly forget that space has a third dimension and you can have spaceships impersonating WWII battleships and fighters, and your spaceships will look nothing like anything built with current tech.

[Ulzgoroth]

Originally Posted by Phil Masters

FTL is usually a magic black box that gets you between locations. A much more important question is usually whether you're going to have magic reactionless thrusters and artificial gravity. Ladle enough miracle-tech on and quietly forget that space has a third dimension and you can have spaceships impersonating WWII battleships and fighters, and your spaceships will look nothing like anything built with current tech.

FTL is usually a conceptual magic black box to a large extent, but it's not uncommon for it to have distinctive architectural/aesthetic implications. Examples include:
-Star Trek warp nacelles
-The 'ship-in-a-hoop' designs you can see in a number of properties but for an easy visual Sword of the Stars human ships have this.

[Johnny1A.2]

Originally Posted by FF_Ninja

I'm going to be spending some time in Inkscape and GIMP over the next few days working on some custom top-down spaceship layouts for use in a campaign later. In preparation for this, I started looking today for reference models (starting with my old stomping grounds, CGSociety).

It then ocurred to me that I'm highly influenced by sensational, flashy, exotic designs - and I don't have a clue what's more functional and realistic versus what might be highly improbably or unlikely a design feature to be incorporated.

To give you a point of reference: I don't see any functional or physical inconsistencies or design flaws with the typical Star Trek and Star Wars faire.

My plan is to design an entire hierarchy of new ships for futuristic Earth, starting from the earliest space-fairing vessels, gradually incorporating FTL into the design (haven't settled on what FTL actually looks like in this setting), and building on that form factor over time.

I would very much prefer to approach my designs with a practical understanding of what "would" and "wouldn't" make sense, rather than throwing elements together in an arbitrary fashion.

For those of you who consider yourselves more of an authority on "space-y" things, I would appreciate any insight into what would make sense in terms of spaceship design and form, and I appreciate any commentary on examples in media that stand out in one way or another.

Thank you all very kindly.

As others have pointed out repeatedly on-thread, what 'makes sense' depends on what the technology assumptions are, and also on the purpose of the ships and how rich the society is.

If you're looking for basics:

1. If the ship is rocket-propelled, 'down' is the direction toward the engine. The ship will be laid out internally more like a skyscraper than seaship. Except that 'down' is only that way while the rocket is firing. Then, unless you have artificial gravity tech, the interior is either weightless or you're spinning it, in which case 'down' is toward the outer wall.

2. If the ship is rocket propelled, then the designers will try to make it as light as humanly possible. Literally every milligram of mass they can shave off helps.

3. You mention media examples, and the problem is that in visual media there just aren't many. The reason is that a spaceship built with technology we can envision right now, under our current understanding of physics, looks fragile and clumsy and actually is going to tend to be fragile. Battle means that either you get hit and are destroyed, or they missed and you're fine. Not much in between, and very little margin to maneuver or do much else except hope your weapon gets him before he gets you, and the battle will be at distances where your unaided eyes won't matter.

Which is why Star Trek is perversely in some ways more believable than the Expanse. At first glance the latter show uses tech more grounded in the physics we think is real, while ST uses a lot of what we think is impossible magical tech (but keep in mind that nuclear bombs, radios, X-ray machines, spectrographs, etc. are impossible magical tech, too, by the physics of 1822).

But the problem is that given the more 'realistic' tech, it's highly improbable that the situations described in The Expanse will come about in the first place. Whereas once you posit the superscience, some of the Trek setting suddenly becomes plausible.

What makes for a believable space ship depends on the setting and the intentions of the creator.