[Space/Spaceships] Getting the velocity/Delta V I want with the tech I want

[Humabout]

As promised, Numbers! For lack of better data, I used an initial orbit of 1 AU and a final orbit of 400 AU. If you give me more exact figures, I can give you better information back.

Assuming you achieve a top speed of 300 mps, as you stipulate, you will need about 600 mps worth of delta-V and be capable of about 0.0004 g acceleration. The trip will take you about 8 years - not 4.

Various launch windows will occur about once an earth year, assuming the primary is about one solar mass.

[Vaevictis Asmadi]

I expect realistic, reasonable interstellar trade between similar civilizations* to be information, live people, and very valuable biological materials. Biological substances can probably be cultivated in artificial environments cheaper than shipping. Even genetic data may be cheaper to ship as raw info rather than samples, if their biotech is high-tech enough to build living systems from genetic blueprints. If that isn't possible, cell lines, biological samples, and even (non-synthetic) drugs might be physically traded.

Bulk raw materials are very unlikely to be shipped, unless they are produced by some bizarre natural condition unique to one system, or by an organism that has never been successfully cultivated off of its homeworld (like Arrakeen sandworms). If the 6 star systems all formed together in the same open cluster from the same nebula, they should have similar enough composition that whatever you can mine in one system, you can mine just as easily in the neighboring systems too.

However, unreasonable trade might involve manufacturing secrets guarded by jealous corporations, allowing corp. A to manufacture/grow whatever and then charge out the nose to ship it. Not sure how they can prevent corp. B from re-engineering it on the other side, or finding cheaper alternatives, though. Even if it's a drug produced by an organism that can't be cultivated in artificial environments, expect people to search for a synthetic formula or alternative, or even brute-force a GMO one codon at a time to produce the stuff.


* If the civilizations are not similar, especially if they have separate origins, then there may well be things one can make that the other can't.



EDIT: Alright I thought up a few odd cases in which people might ship large quantities of stuff between the stars:

1. One star system has ruins of an alien civilization. Some artifacts can be repaired enough to make them useful, but nobody can recreate them.

2. One star system contains a bizarre, apparently unique source of exotic matter that can be mined.

3. People build a gigantic particle accelerator in space, or an exotic matter factory, or even discover an abandoned alien factory and manage to sort of get it going without understanding how it works. Essentially, a manufacturing 1 or more TLs higher than the rest of the civilization. It produces exotic matter, stable superheavy elements, or other weird things in significant quantities. It may be cheaper to ship this stuff rather than build a second hyper-expensive factory in another star system, or perhaps they are building a second factory but it will take a long time and isn't done yet.

4. Not relevant to your setting, but I could imagine a setting in which FTL travel is possible, but FTL communication isn't (or is very unsecure). In this case even data itself may be physically shipped between stars on ye olde data storage devices.

[David Johnston2]

Originally Posted by scc

OK, I'm working on a so far hard Sci-fi setting and I've got two planets that are 400 AU apart, +/- 44 AU. Now according to my math that means that at a velocity of ~300 mps it will take a ship 4 years to move between the two planets.

My problem is that I want there to be somewhat regular trade between them (In fact one's supposed to be settled from the other).

The logical thing to do is to either dispense with the apes in cans or use FTL.

[Flyndaran]

Originally Posted by David Johnston2

The logical thing to do is to either dispense with the apes in cans or use FTL.

A.I. ships means background color not center stage gaming. And FTL obviously breaks OP's attempt at hard science fiction.

[jacobmuller]

If it's any help, TL's aren't set in stone - unless you're seeking to publish a generic article, ie getting paid by SJG. Even then, RAW covers you having different TLs for different technologies. Basically, if the drive you want doesn't work at the settings baseline TL, use a better one.

I wanted an FTL and subwarp that didn't work well with spaceships; realistic TL10 systems actually made more sense. However, strict adherence to the spaceships stats also didn't fit. So I have a hyperdrive and a realistic sublight but the sublight stats are from TL11.

[Anthony]

Originally Posted by Flyndaran

A.I. ships means background color not center stage gaming.

Who needs AI ships? This is firmly TL 8 stuff, we routinely manage comparable stuff with interplanetary probes.

[Flyndaran]

Originally Posted by Anthony

Who needs AI ships? This is firmly TL 8 stuff, we routinely manage comparable stuff with interplanetary probes.

With quite a few mistakes that might not have happened with on board A.I. Not to mention the expense of having such a tense paid ground control.

But I meant as in no humans on board makes the whole trade background color.

[Anthony]

Originally Posted by Flyndaran

But I meant as in no humans on board makes the whole trade background color.

Is there any reason to think it's not intended to be background color?

The other problem is that realistically, it's hard to think of much in the way of goods that justify expending several hundred gigajoules per kilogram, there's really not much that you can't synthesize for less. Other than information, which doesn't need a ship at all to trade.

[adimar]

Originally Posted by scc

Boosters/upper-stage's are just sort of wrong for the setting, there's supposed to be a lot of traffic so it doesn't work out

Originally Posted by scc

I specifically stated in the OP that staging was not really a viable option

The reason I mentioned staging was the reason you wrote for rejecting it.
You stated that staging wouldn't work because there was a lot of traffic. (presumably a cost issue and not the cluttering of outer space).
I suggested a design where the cost of a single use craft would lower shipment costs to less than a million $ per ton.
The notion of reusable being cheaper than single use is not necessarily true.
If the reason for the rejection of staging is not a cost issue, but an aesthetic setting consideration than no probs. But on a purely functional basis...

This holds especially true if shipments are unbalanced (weight wise, i.e. one side sends the other a lot more tonnage than he gets.)
For example earth ships the colonies oxygen and other consumables (a lot of stuff) but gets back an equally valuable cargo that weights only a fraction. (helium-3) .
This means that any spacecraft would make one way full and the other way practically empty. The spacecraft itself isn't worth the cost of refueling it and sending it home for another round trip.

Adi

[scc]

Originally Posted by adimar

The reason I mentioned staging was the reason you wrote for rejecting it.
You stated that staging wouldn't work because there was a lot of traffic. (presumably a cost issue and not the cluttering of outer space).
I suggested a design where the cost of a single use craft would lower shipment costs to less than a million $ per ton.
The notion of reusable being cheaper than single use is not necessarily true.
If the reason for the rejection of staging is not a cost issue, but an aesthetic setting consideration than no probs. But on a purely functional basis...

This holds especially true if shipments are unbalanced (weight wise, i.e. one side sends the other a lot more tonnage than he gets.)
For example earth ships the colonies oxygen and other consumables (a lot of stuff) but gets back an equally valuable cargo that weights only a fraction. (helium-3) .
This means that any spacecraft would make one way full and the other way practically empty. The spacecraft itself isn't worth the cost of refueling it and sending it home for another round trip.

Adi

UM, possibly. But using external tanks might be a better solution, use the Equipment Packs from Pyramid 3/40