Oolite Bulletins

Wildeblood wrote:

Alex wrote:

Why all the thought?
A sphere is the ideal shape for anything moving through space.
Look out side. A rain drop is round not tear shaped. Planets, suns, even galaxies try to be spherical.

Construction:
Blow a bubble in space, It'll be round.

No brainer.

Yeah, I said upthread geodesic spheres were the go. But spherical is the shape of things just floating about, accelerating things are elongated. The best shape for something really fast is a line: the smallest possible cross-section to minimize interaction with the environment, and miles and miles of shielding. I imagine an interstellar spacecraft being hundreds of kilometres long and maybe a few centimetres in diameter.

However, the most efficient combination of volume/surface-area and aerodynamics, and probably some more naturally important factors, is that what came before the chicken.

aerodynamics? in space? lol

dont forget the psychology of the inhabitants of these spacecraft.

humans tend to prefer square corners, vertical walls and flat ceilings.... which brings us back to some form of box. cubic rectangular whatever...

Smivs wrote:

Wildeblood wrote:

I imagine an interstellar spacecraft being hundreds of kilometres long and maybe a few centimetres in diameter.

Crewed by giant space worms?

Crewed? A crew opens a whole other can of worms.

spud42 wrote:

aerodynamics? in space?

Like I mentioned earlier, it depends on how fast you go. The drag produced by the Earth's atmosphere is negligible, at low speed: you only have to worry about aerodynamics in air if you want to go fast. The same is true for the interstellar medium: if you want to go significantly fast, then 1 hydrogen atom per cubic centimetre will start to cause significant drag. And they may be very, very thin on the ground out there, but you really don't want to collide with something the size of, say, a grain of sand when travelling at e.g. one-tenth of the speed of light.

Edited to add: using some online calculators, a bit of wikipedia and my own patented dim grasp of numbers, I estimate that colliding with a chunky grain of sand (small granule of quartz, 2 mm diameter, 11 milligrams) in a 20-tonne spaceship (quite light, all things considered) at a relative speed of 30,000km/s (one-tenth of the speed of light, give or take) would yield roughly the same energy as 100kg of TNT - or this, for short:
https://www.youtube.com/watch?v=G1W-LPkiyUA

Edited again to add: or it might be 1kg TNT ... not quite so impressive, but still enough to spoil your day!

yes i get 1.18Kg TNT.... not something to sneeze at...

https://www.youtube.com/watch?v=QUSff_JGyqw

a bit of googling for armour needed to survive 1Kg TNT didnt really give a direct answer but this site describes armoured toyota landcruiser able to survive 15Kg TNT from side 1M off ground and 2M away...... so maybe this isnt such a big problem in armour plating a spaceship?

http://www.aurum-security.de/en/our-car ... -vr10.html

spud42 wrote:

maybe this isnt such a big problem in armour plating a spaceship?

Ablative armour would be the way to go, although this adds mass - and, of course, the energy from any collision would directly impact the ship: no 2m air-gap ... Alistair Reynolds's lighthuggers are wrapped in ice, to absorb damage from micrometeorite impacts (amongst other things).

Ye very thin worms at that

Disembodied wrote:

Edited again to add: or it might be 1kg TNT ... not quite so impressive, but still enough to spoil your day!

Most certain I wouldn't want it in my pocket. Now that would spoil a day.

Some good words and interesting images:

"Wanderers": a short film by Erik Wernquist

Disembodied wrote:

Some good words and interesting images:

"Wanderers": a short film by Erik Wernquist

Ah yes.. I think that's been posted here before, but it's always worth another look.

One of my favourite short films.. I'll admit to having even put it on loop, and played it over and over again a dozen times or so in a row.

Beautiful

You can't say how space ships will look like if you don't know the technology that will power them. But I think, no technology will ever lead to fragile designs like the original Enterprise or the Andromeda!

With today's technology, a ship going, let's say, to Mars probably won't look much different than the ISS. Cylinders are the best way to build sturdy pressure vessels with little weight. Spheres are even better from a mathematical viewpoint but are much more expensive to build - perhaps this will be different if carbon fibre materials are used instead of aluminium plates. Many small cylinders (or spheres) are safer as a single big one and can be transported to orbit in one piece. Apart from the cylinders, a Mars ship will need solar panels and radioisotope thermoelectric generators for powering the whole thing (perhaps including ion thrusters). And it will need rocket engines and big tanks for chemical fuel for launching from Earth orbit, entering Mars orbit and relaunching from there (ion thrusters are to weak for this).

And of course it will need at least one landing vessel. This would probably resemble the Apollo Lunar landers, but perhaps with a disposable heat shield for atmospheric braking and with only one stage instead of two to be reusable (to make more than one trip from mother ship to surface and back). The rockets of these landing vessels could also be used to power the main ship, to save weight, but this could turn into a problem if one of the landers has to be left behind...

More realistically, most of a ship like this will be left behind to reduce the weight that has to be brought back to earth as much as possible.

The most realistic science fiction ship I can remember is the one in Kubrick's 2001 Space Odyssey. It is made up of many small components fitted alongside a central backbone, and that seems a sensible way to build something like a "propelled space station".

Without some complete new technology and physics, humans will never go much farther than Mars or perhaps the Jupiter moons. There are basic laws like the Tsiolkovsky rocket equation that can't be circumvented, and it can be calculated that even with the most powerful rockets that can theoretically be imagined (using annihilation of matter and antimatter!) interstellar travel wouldn't be possible in reasonable time scales.

Interstellar travel would need engines that aren't limited by the Tsiolkovsky equation, like the standard engines in Elite. And for engines like this we need to discover new physical phenomenons and principles! Perhaps there is some way to propel a ship through a sea of dark matter by using some kind of electro-magnetic propeller? But this is science fiction already...

Back to the idea of using a concrete like substance, spheres are simply 'bubbles' which you then second fit (add oxygen and the internals etc), and what I was originally thinking of.

The ship used in the opening sequence to Avatar had the feel of a 'real' ship.

I can't remember the film but one ship I've seen which looked like it had had some thought was one where by during the cruise section of the journey the 'living' accommodation was strapped to the spine. Once the destination had been reached the accommodation was spun out on tethers and slowly sped up to produce some G with the spine becoming the axle for 0G work.

How about a  Bussard Ramjet ?

For interstellar travel, you don't really need high acceleration , but a small steady acceleration.

a bit more details : http://hyperspace.wikia.com/wiki/Bussard_ramjet

As I understand it, they don't work. Basically, it intrinsically costs more energy to collect the hydrogen than you get from it as fuel. They're now being touted as brakes for starships, assuming you have some other way to get the ship up to speed.