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Spacescifi

Starship Design... a broad look

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Any shape can be used, but optimal shaped spaceships are more likely to be used than not if engineers in verse care about expense and effort.

Sphere: Best at holding air in. No pressure cracks that would occur if you had air pressure inside a blocky shaped ship. Really any streamlining is better than a hard edge when it comes to holding pressure. In that sense, spaceships are really like glorified balloons that house crew that need to live in the balloon.

Saucer: It is good for spin gravity. Although you could also do the same with a spaceship shaped like the letter H. Only with a LONG bridge between the sides.

Blocky: Pressure cracks at corners will stress hull sooner or later if you put air pressure within the blocky hull. If you ony put air pressure in spherical or cylinderal roons inside the blocky ship you avoid that problem. Thus blocky ships would be great for drones or robot ships that do not need air to breath and thus won't have lots of air inside.

Cylinder: You get most of the benefits of the sphere plus it is better for bulk storage of plenty things.

Inside the ship: Although the captain and chairs on the bridge is popular, spanning many imitators, it is is really a sub-optimal design.

They could likely save the energy they put into gravity generators by simply accelerating up instead of sideways. I know weightlessness is bad, and for times the ship is not accelerating the saucer is optimal for centrifuge spinning for 1g. It would be cheaper even if gravity generators were possible, since anything we already have a. grasp of is not considered very advanced in a scifi setting and should be thus easier to come by if advanced tech like gravity generators are available.

Ship purpose: What a spaceship is made to do also has a bearing on optimal designs. Astetoid mining ships, if they do any processing of their own, practically beg for a shape that will allow spin gravity. Since processing and refining ore is easier with gravity than without.

For ships that are SSTO's, compact designs have less drag, but if fuel is not a concern because the setting has super tech propulsion, suboptimal designs would have other reasons for existing.

Sure the ship creates more drag than it needs to, but if it has antigravity to fall up, then it could reach space in about 2 min just falling upward from earth at 1g. Which is a huge improvement. The ship would still need to use some other propulsion to maintain an orbit, but at least there would be little to no air resistance in LEO, thus increasing fuel efficiency of rockets. And that is if rockets are even used as a main source of sublight propulsion in a scifi setting. They certainly do not have to be, as the only limitations are the ones a writer imposes on their work and self.

 

Personally, I love saucer spaceship design, because antigravity makes it at least practical,  and while it may never be as optimal as a cylinder or a sphere for holding pressure, it is optimal for spin gravity at least.

 

 

 

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Interesting topic here. Personally, in terms of spaceship design, I prefer functionality over aesthetic. A research ship might be nothing more than centrifugal habitation pod with sensors and gizmos sticking out of the hull. An interplanetary relay is nothing more than a radar dish with thrusters, a space gun is literally just a gun with thrusters around it. It seems appealing to me when the spaceship is nothing more than a necessary life support components, habitation pods, thrusters and a variety of junk bolted around it

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Posted (edited)

A true Starship, as in a vessel that crosses the distance between stars in a reasonable timespan, will most likely be extremely thin, almost pencil-like as to hide its structure behind a long whipple-shield.

Also i don't think the ability to best hold pressure will ever dictate how a spacecraft will look overall, since there is no need for the whole structure to be pressurized.

Edited by Canopus

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It isn't new idea at all. Back in 1950's British Interplanetary Society thought the same.

orbital.jpg

See those two connected spheres? That's their project of an interplanetary transporter. Reactor and fuel tanks in one sphere, cargo and crew quarters in the other - as far away from reactor as possible, to minimise radiation exposure and need for shielding. Winged rocket is basically Space Shuttle equivalent - it transports people, cargo and fuel between surface of Earth and LEO. Lowermost is the lunar transporter, capable of TLI after being refuelled in LEO.

70 years since thet, and only now we're making steps along the same lines as those oldtimers envisioned the exploration of space :)

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1 hour ago, Canopus said:

Also i don't think the ability to best hold pressure will ever dictate how a spacecraft will look overall, since there is no need for the whole structure to be pressurized.

That and the fact that atmospheric pressure isn't really that much. Not like what a submarine has to deal with where the equivalent pressure delta is only 10 meters below the surface. Pressure is non-trivial in spacecraft design but not so much that it will override most other design criteria.

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35 minutes ago, Racescort666 said:

Not like what a submarine has to deal with

This seemed relevant:

 

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Keep in mind that spacecraft are likely to be double-hulled. So the external shape can be vastly different from the interior.

FNptg9p_d.jpg?maxwidth=640&shape=thumb&f

Spoiler

 

 

Edited by DDE

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A starship is likely to be 99+% propulsion system and propellant. But to minimize exposure a small cross section is desirable.

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22 hours ago, kerbiloid said:
  Hide contents

1-thisphotorel.jpg

 

Way to slow to be an starship, anybody would want to get up to some percentage of lightspeed. 
If alien It could be derbies however, some sort of sun shield or fairing or an tank, think the shuttle drop tank. Low chance of it being an dead ship, than on top of the low chance of being alien. 
 

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56 minutes ago, magnemoe said:

Way to slow to be an starship, anybody would want to get up to some percentage of lightspeed. 

They have 100 TB of DVD rips, and don't hurry.

56 minutes ago, magnemoe said:

If alien It could be derbies however, some sort of sun shield or fairing or an tank, think the shuttle drop tank. Low chance of it being an dead ship, than on top of the low chance of being alien. 

Actually, I guess the actual advanced starship would look like

Spoiler

image01311.jpg

, and look like a torus when disengaged.

This combines multiple physics at once: gas consuming, active front shield, active rad protection, artificial gravity (along the rotating inner torus), and so on

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13 hours ago, kerbiloid said:

They have 100 TB of DVD rips

Santabarbaratitle.jpg

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The choice of engine and power also vastly influence the design. Anything nuclear will tend to have long booms, or long cables, between the hab and the reactor.

More importantly than a sphere's ability to hold air is its surface area to volume ratio. When it comes to spaceships, surface area is bad (pressure hulls are heavy, comparatively speaking) and volume is good (holds more stuff). The reason to pick a cylinder is that cylinders are easier to build and launch than spheres. A torus would be equivalent to a cylinder in terms of surface area to volume, but more expensive to build, so it would really only be useful if you're going for spin gravity. Of course, you could also make something that's only mostly spherical, and actually is a lot of flat panels, or make the sphere part out of kevlar or the like with an easier to construct internal frame.

The choice of whether to spin the whole ship or just part of it also depends on the purpose. If it needs to dock frequently or perform observations, spinning the whole ship is a no-go. But spinning just part of the ship is bad for other reasons, mostly that it's hard to make an airtight joint that permits rotation, so it would be avoided unless necessary.

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On 5/16/2019 at 5:52 AM, Canopus said:

A true Starship, as in a vessel that crosses the distance between stars in a reasonable timespan, will most likely be extremely thin, almost pencil-like as to hide its structure behind a long whipple-shield.

Also i don't think the ability to best hold pressure will ever dictate how a spacecraft will look overall, since there is no need for the whole structure to be pressurized.

Songs_of_distant_earth.jpg

 

The premise of this, is their ship has a giant ice ablator on the front of their ship.  While ice has everything you need for life support and propulsion, they mostly use it for shielding and must stop to rebuild it on route.  

Most of the shielding needs to be in front.  But damage to the sides of the starship are possible also.  Ships systems need to be redundant and easy to repair in space.  Many rooms built of flat panels, with doors and airlocks on flat surfaces are the easiest to repair.  

Therefore a hexagonal rod has some advantages over a cylinder.  Lots of graphite and ferromagnetic material on the ends would help too.  

 

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(The torus above is about much farther techlevel, so this is about a closer low-tech)

A fractal structure.
No "one big hull" design, many smaller pressurized bubbles of modules inside the external envelope.
Less important/more redundant modules surrounding the inhabited ones - as rad shields and additional hit protection.
Imagine a bigger Mir with four wider cylindric modules at every end, packed into a big external cylinder. With auxilliary structures (trusses, etc) in between.

No spheres or big cones: they are technologically weird.
A cylinder with L~D is almost as fine as a sphere, and much better in any sense.

A longer cylinder = several L~D cylinders attached one by one. You anyway need inner walls.

An artificial gravity. Otheriwse they become boneless worms, as the starflight lasts for years or decades.
A faster ship? A hypernation chamber? Doesn't matter at all, they anyway will spend years at the destination star.

No rotating ship, but a set of centrifuges.
Not a torus (technologically weird), not a cylinder (a lot of unused space inside). Also both can be hardly kept being balanced. At least because a crowd of people suddenly running along a torus is bad.
A bunch of parallel cylinders rotating around an axis inside a cylindric protective hull. Weights between them, moving radially to dynamically balance the system.

An even number of such counter-rotating centrifuges (1 or 2 pairs).

A layer of auxilliary thingies around the external hull of the block of centrifuges. As an additional protection.

As the rotation radius is limited by the human biology, the habitat block is huge, several hundred meters wide and long.
So, for several hundred humans inside, maybe even a thousand.
Though, unlikely one sends a sixpack of humans to another star.

***

Some front active shield. Probably not just a solid plate, but a cloud of dust, to restore its shape after hits.
Probably not a big cloud, but enough thick to prevent radiation damages after the hit flashes.

***

The most important part: the purpose of a star ship.
No lone riders, no brave pathfinders.
A barge with passengers, not a star cruiser. And not from the beginning of the star exploration.

They don't fly to find moons and planets. They are a sci&aux crew delivered to the existing laboratory.

***

You can't fly to every star you see.
First of all you will anyway explore it with orbital telescopes at 550 AU in the opposite point from the Sun fro decades.
So, long before you fly there, you already know its planets, moons, asteroids, and continents much better than you wish to know the Solar System nowaday.

You select a star with something specifically interesting.
You anyway choose the nearest star.

Almost any basic research needs no human on board.
You send not a probe, not a ship, but a whole uncrewed fleet.

A bunch of orbital telescopes which automatically explore the celestial bodies from closer distance.
A bunch of telescopes into the counter-Sun gravitational focal point, to be observing the Solar system from that star.
A bunch of telescopes into several such points to look at other close stars and get a 4 l.y. wide stereopicture.

Clouds of simple but numerous stationary ground probes with seismo-, meteo-, and other sensors.
Clouds of tungsten impactors to hit the bodies and map their internal structure, using the former ones as sensors.
Clouds of orbiters, making multispectral photos of the bodies.

Several orbital data centers with radio relay concentrators, connecting the fleet to the Earth, sending the data back to you.
Equipped with complicated expert systems, redistributing the probes to the new targets.
(When it sees some significant data anomaly, it considers the place as a point of interest, and adds it to the research list).

Probably several microwave emitters to power the numerous probes.

***

A decade later you send the second wave, to repair the losses.
And uncrewed orbital labs, to wait for the crew near the star.

Then you know the system better than currently the Earth. You clearly see what exactly do you want to explore by hands.

You send the lab crew. They arrive and start labbing. They will probably spent there decades, and probably many of them never return.
The academic career is the salary. And you anyway send there a return ship. Though a true scientist would anyway stay there as long as possible.

The physicists and astronomers do the long-base experiments. They are needed because they can do their own conclusions and perform the experiments from the other side.
Their main aim - to invent/discover hyperdrive and/or hyperlink, using such distance as an experiment base.

Chemists/biologists/geologists do what they do.

Others are caretaking and cheerleading.

When the active exploration is over, the crew returns, while you are keeping sending new bots on demand.

Telescopes stay in their places, so you keep endlessly expanding you interstellar telescope network.

Edited by kerbiloid

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