# Spaceship design?



## BetaWolf (Apr 15, 2013)

I am thinking about spaceship designs for my space opera stories. The focus is on the characters, but I want the technology to be at least plausible. So I ask for help, specifically in designing parameters for spacecraft:

- no faster-than-light travel. Propulsion is by solar sails, magnetic sails (especially in Jupiter's very large magnetosphere), ion engines.
- artificial gravity for living quarters. I've considered different kinds of cyllinders. I know that the larger the cyllinder's diameter, the more efficient the system, but I am thinking of craft that can comfortably house six to ten people.
- The cargo and hydroponic bays would not need to be gravitated (is that the right term? ). The crew should be growing most of its own food. I had thought of throwing in some chickens and goats for extra protein (I started writing a cooking scene and threw in milk and eggs. . . .).

So does that seem plausible? Or if there are any other ideas that I'm missing?

Thanks.


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## Abernovo (Apr 15, 2013)

We've had similar discussions in the past. Even if slight, remember there will be inertia, so when the propulsion is active, the objects in the cylinder (or torus, if you consider that a possibility) will be subject to it - I think one of the solutions suggested was to curve the edges of tables upwards to prevent things rolling off.

If the hydroponics are in zero G, make sure the system's fully contained. Even water vapour is messy, plus it makes for a clammy environment.

For extra proteins, have you considered algal solutions? Grow them in containers, with light, harvest the algae and process it. It's actually an old idea - seaweed has been harvested and cultured for centuries - converted to a factory process. I suggest it, because goats and chickens make a mess, and someone has to clean them out.


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## Vertigo (Apr 15, 2013)

It's not just the mess, in general terms all meat eating is highly inefficient; energy in way too high for energy out. I think you would rely on plant based proteins in the same way a modern vegetarian does.

Aber: I see you've been getting into O'Neill Cylinders!


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## nightdreamer (Apr 15, 2013)

I've wondered about how small you can practically make a centrifuge.  Too small, and the coriolis effect will be a problem: stand up suddenly and you get knocked over.  I know it can drive your sense of balance nuts on those playground merry-go-rounds when you get them spinning fast, but I have no idea where the practical threshold would be.


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## Ursa major (Apr 15, 2013)

nightdreamer said:


> I've wondered about how small you can practically make a centrifuge.  Too small, and the coriolis effect will be a problem: stand up suddenly and you get knocked over.  I know it can drive your sense of balance nuts on those playground merry-go-rounds when you get them spinning fast, but I have no idea where the practical threshold would be.


There's a mention of that here.



By the way, in my WiPs, my ships either rotate (slowly: these ships are quite large) or leave the occupants weightless (smaller vessels).


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## Verse (Apr 15, 2013)

What about using constant acceleration/deceleration of 1g? Is that viable/achievable within the Solar system?

Example journey from A to B: Get up to and accelerate at 1g until halfway. Flip the ship around (a period of weightlessness in free-fall) then burn to decelerate at 1g. Gravity nearly all the way.

I guess it can't work otherwise every other space opera would use this technique.


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## Verse (Apr 15, 2013)

Oh look, found a link. Turns out constant acceleration is impractical for other reasons.

http://io9.com/5904565/how-could-you-create-artificial-gravity


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## Ursa major (Apr 15, 2013)

Verse said:


> What about using constant acceleration/deceleration of 1g? Is that viable/achievable within the Solar system?
> 
> Example journey from A to B: Get up to and accelerate at 1g until halfway. Flip the ship around (a period of weightlessness in free-fall) then burn to decelerate at 1g. Gravity nearly all the way.
> 
> I guess it can't work otherwise every other space opera would use this technique.


The lighthuggers in Reynolds's Revelation Space universe do this. I'm sure there must be many other examples.


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## nightdreamer (Apr 15, 2013)

Ursa major said:


> The lighthuggers in Reynolds's Revelation Space universe do this. I'm sure there must be many other examples.



Yeah, I've used that technique, too, but it assumes propulsion systems that just don't exist yet.  Chemical rockets provide enough thrust, but not for very long, and ion engines, solar sails, etc., run for a long time but just don't provide enough thrust.  Unless it was a very, very big solar sail!


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## BetaWolf (Apr 15, 2013)

Magnetic sails seem a viable option in Jupiter's magnetosphere, if you have enough power to adjust polarity properly--Ganymede and Callisto are locations I'm thinking of.

Some other kind of thrusters would have to be employed when closer to your destination. I like ion engines, but it would have to be a design much more advanced than current tech allows. http://dawn.jpl.nasa.gov/mission/ion_engine_interactive/

And then I got hit with the problem of artificial gravity. With engines like these, I think that ships would have to be self-sufficient, closed systems. A torus seems a good solution, with simulated gravity and room for whatever I need my characters to do: sleep, cook, eat, exercise, entertain themselves. From what I understand, a rotating disk would solve this problem, with some need for adjustment (you're living on the inside of a donut instead of the surface of a sphere after all).

But this design seems better for an orbiting space station, because moving a torus would shake up whatever the artificial gravity is holding in place. Unless the acceleration is very smooth.


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## Mirannan (Apr 15, 2013)

It is fairly likely that the hydroponics section would need at least some gravity; it appears to turn out that most plants need an up/down distinction to grow properly.

Part of the artificial gravity solution might be that some of the drives you mention actually produce very little acceleration and hence wouldn't disturb the artificial centrifugal gravity much. For higher-thrust engines, it ought to be possible to simply de-spin the living spaces while under thrust. Preparation, in the form of lashing stuff down and moving some stuff around, might be necessary here. Failure in that procedure being a plot point, perhaps?


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## chrispenycate (Apr 15, 2013)

If you're talking about ion drive type acceleration, more likely to be a hundredth of a g than a tenth, then the difference in 'down' between starting and stopping or just cruising is almost negligible; you can have a swimming pool, and it won't even slop.

But thinking of the kinetic energy requirements for any practical interstellar drive, has anyone thought about how devastating one would be in the wrong place? If you think that an Orion drive (pottering around by goosing yourself with H-bombs) is on the low end of what would be necessary, so we're looking at tens of megatons per hour. All these starships seem to boost directly away from Earth, with no thought of what their drive exhaust would do to unprotected populations; even my graviotronic drive woud cause tsunamis, earthquakes and probably volcanoes if used within a few light minutes of the planet, and that's not emitting any high-energy particles at all.

Spinning the thing up is _the_ way to go with present day physics, and a toroid's fine; no need to make it aerodynamic. After all, you're not going to try and land it, are you?


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## Ursa major (Apr 15, 2013)

chrispenycate said:


> But thinking of the kinetic energy requirements for any practical interstellar drive, has anyone thought about how devastating one would be in the wrong place? If you think that an Orion drive (pottering around by goosing yourself with H-bombs) is on the low end of what would be necessary, so we're looking at tens of megatons per hour. All these starships seem to boost directly away from Earth, with no thought of what their drive exhaust would do to unprotected populations....


Yes cool. My most "safety-conscious" PoV character is, in his second narrated scene in WiP1, very much concerned with where the highly accelerated ions are going when a small fleet of ships is accelerating and decelerating while manoeuvring. And the MC mentions, in chapter 5, what happened when an (enemy) ship tried to use full ion power when inadvertently disoriented in low orbit.



chrispenycate said:


> Spinning the thing up is _the_ way to go with present day physics, and a toroid's fine; no need to make it aerodynamic. After all, you're not going to try and land it, are you?


Definitely not. (Well, not on purpose, anyway; not that "land" would ever be the correct verb.)


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## BetaWolf (Apr 16, 2013)

@Mirannan: Yeah, that's a good idea.  When your world's a giant hamster wheel, it could be unpleasant if some nasty writer made your cage shake.

@chrispenycate: thanks for the info on ion drives, and the stuff that comes out of them. I've heard of space flatulence, but this stuff is deadly. 

Okay, this has all got my mind going. Back to writing.


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## Mirannan (Apr 16, 2013)

The business about high-performance reaction drives being dangerous has been called the Kzinti Lesson, after Niven's warrior cats who learned that lesson to their detriment.

Ion drives aren't the only type of drive with dangerous exhaust, either. One type of reaction engine posited for near-future space exploration is a mass driver, using waste material from asteroid mining perhaps, with an exhaust velocity of maybe 5km/s. Needless to say, a spray of dust and gravel at meteoric speeds isn't likely to be good for the health of anything in the way!

Fusion motors and Orion drives are pretty obviously dangerous.


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## BetaWolf (Apr 16, 2013)

Mass drivers sound interesting. 

I thought on the Orion Project. My first sci fi scene involved preparing to go to Ganymede aboard one of that project's ships. The thinking was that it would launch from Los Alamos (already pretty contaminated by that point of course) and that in space nuclear fallout would diffuse pretty widely. 

Here's Dyson's son talking about growing up while the project was going on: blog.*ted*.com/2008/02/14/george_dyson/


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## BetaWolf (Apr 19, 2013)

I spent the afternoon plotting out Lagrangian points and where I'd put a couple of Bernal spheres for my characters to stumble upon.


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