FTL Assumptions [Space]

[copeab]

Originally Posted by Rupert

You don't need 0.1c. Sure it's nice and all, but you don't need that much speed.[/ Quote]

What fraction do you need? 0.01c? 0.001c?

[quotes]There are plenty of side-systems that are linked to the main branches, but uninhabited and unused. The hardest part would be hiding the high real velocity whilst you're dumping warp charge, but as most system have gas giants in their outer systems you could probably get away with it, especially if you weren't over-ambitious about how many systems you moved through.

There may be a few side-systems, but they rarely only in 7.7 ly of one or two inhabited systems. Piracy is just enough of a concern to warrant a military patrol craft popping in every now and looking around.

I don't think you could involve more than two systems, the one you play planetary yo-yo in, and the one with the target. Otherwise you will have stop for 40 hours to discharge the static accumulating on the stutterwarp drive to go more than 7.7 ly.

Oh, and I think it is safe to say that governments understand the weapon potential of a nuclear stutterwarp ship and *will* look for a missing one.

FWIW, in Ships of the French Arm, there are about 30 ships (not counting fighters and missiles). Only four have nuclear power plants: a German battlecruiser, a French battleship, a hundred year-old Chinese freighter, and an English mining vessel. Terrorists aren't getting their hands on the first two. Add to this all are unstreamlined and the game lacks contragravity, so plowing into a planetary atmosphere at very high speed has a high chance of the ship disintegrating in the upper atmosphere (of course, the freighter could stuff it's hold with steel bowling balls and pepper the planet).

[AlexanderHowl]

I really doubt that there is going to be any money gained from interstellar commerce. I see societies investing in terraforming and colonization in order to have an ark for what they consider important. The cost of space travel is just too much for trade.

GURPS tends to forget about the replacement costs that business people would charge. If a spacecraft possesses an average life expectedly of 40 years, mechants will probably increase their costs by 5% per year to account for the cost of replacement (the doubling takes in account the risks involved with interstellar travel). On a $150 million spacecraft that is capable of moving 5,000 metric tons, that ends up being an extra $1,500 per metric ton per year (around $30 per metric ton per week). This is in addition to any other costs associated with running the spacecraft.

[Verjigorm]

Originally Posted by Fred Brackin

The "realism of outer system travel" is that it takes years. If every trip to another star requires going through the outer system of each star each way nobody will be able to make money doing it.

It takes delta-v. IF you have enough of it, you can zip around pretty quickly. For example, the Jupiter class from Spaceships, which picks up hydrogen from a gas giant approximately like Saturn, and hauls it out to say pluto's orbit. It has 120 delta v, and a 50mps burn would let it make that trip in about 660 days, hauling 19,500 tons of hydrogen, which sells for about $39M. Now, the Jupiter costs close to $600M, so you need like 15 trips to pay for it, which is something like 27 years to pay for itself.

But wait, it's hauling almost 20,000 tons of hydrogen that it's fusion rocket can burn. So what if you burned some of that as reaction mass? Well, at double fuel, you're making the trip in 251 days(120mps burn), for 33M a trip, allowing you to pay off the ship in twelve and a half years. With four times the delta V, you can do a trip in 91 days, cutting the time to pay for the ship down to 7 years.

For a commercial venture, that's not exactly horrible terms, but it does have implications. Reaching the inner system isn't trivial, and not every system has habitable planets(I'm using garden planet as the standard for "habitable"), so the outer system is much more easily exploited. While it might be wild open space out there, it's where "civilization" and the authority of the "empire" will be located. The inner planets in a system, if settled or inhabited, tend towards the "wild" side.

[AlexanderHowl]

Hauling hydrogen from Saturn to the Kuiper Belt is a bit like trying to sell ice cubes on a glacier, why would anyone buy hydrogen scooped from a gas giant when they could have it by cracking ammonia ices? An SM+10 refinary is capable of processing 150 tons of ammonia ice per hour, which would produce 26 tons of hydrogen and 124 tons of nitrogen per hour. At TL10, two can operate off a single fusion reactor, producing 52 tons per hour.

At a cost $750M, you could have a facility producing 260 tons per hour anchored to a KBO. If we assume costs of 30% per year (capital, insurance, labor, O&M, etc.), the facility can produce hydrogen for a cost of around $100 per ton. It could sell hydrogen for a wholesale price of $500 per ton and make a fantastic profit. Anyone trying to compete by scooping a gas giant would go bankrupt within a year.

[Rupert]

Originally Posted by AlexanderHowl

Hauling hydrogen from Saturn to the Kuiper Belt is a bit like trying to sell ice cubes on a glacier, why would anyone buy hydrogen scooped from a gas giant when they could have it by cracking ammonia ices? An SM+10 refinary is capable of processing 150 tons of ammonia ice per hour, which would produce 26 tons of hydrogen and 124 tons of nitrogen per hour. At TL10, two can operate off a single fusion reactor, producing 52 tons per hour.

At a cost $750M, you could have a facility producing 260 tons per hour anchored to a KBO. If we assume costs of 30% per year (capital, insurance, labor, O&M, etc.), the facility can produce hydrogen for a cost of around $100 per ton. It could sell hydrogen for a wholesale price of $500 per ton and make a fantastic profit. Anyone trying to compete by scooping a gas giant would go bankrupt within a year.

Given that the ammonia (or water) is in the form of ice, you'd probably need three mining systems feeding each refinery, but it'll still beat the pants off shipping hydrogen from a gas giant 'down' in the 'inner outer system'.

[AlexanderHowl]

Originally Posted by Rupert

Given that the ammonia (or water) is in the form of ice, you'd probably need three mining systems feeding each refinery, but it'll still beat the pants off shipping hydrogen from a gas giant 'down' in the 'inner outer system'.

Not really, mining turns rock into ore and/or mass driver reaction mass while chemical refinaries turn ice or water into its component elements (Spaceships, p. 19). A single android could shovel 20 lbs of ammonia per turn into a hopper, so forty-two of them could keep the refinaries going (though eighty-four would be better). Of course, the androids would only need NAIs.

[Rupert]

Originally Posted by AlexanderHowl

Not really, mining turns rock into ore and/or mass driver reaction mass while chemical refinaries turn ice or water into its component elements (Spaceships, p. 19). A single android could shovel 20 lbs of ammonia per turn into a hopper, so forty-two of them could keep the refinaries going (though eighty-four would be better). Of course, the androids would only need NAIs.

The ice is likely to be very hard, so unless it's already fine gravel it'll need to be extracted and broken up. Also, once you've been running the refinery for a bit you'll have to move the extraction end to a new site, if not the whole factory.

For an effective industrial-scale operation I think you'd need mining systems to extract, break up, and move the ice to the refinery.

[D10]

I find it very odd to conceive a physics in which FTL travel is possible but FTL communication is not, or even one being easier and the other one being harder

I can understand you not wanting it to enable things, but wouldnt it be more sensible to add features that make it unreliable instead of inexistant ?

[Daigoro]

Originally Posted by D10

I find it very odd to conceive a physics in which FTL travel is possible but FTL communication is not, or even one being easier and the other one being harder

Generally it's because your FTL-drive needs to go along with the thing it's transporting.

[AlexanderHowl]

There are actually very few possible FTL schemes under our current understanding of physics that allow FTL travel with FTL communications and/or FTL sensors. FTL travel might actually be possible, depending on if we can create a negative matter effect, but FTL communications and FTL sensors are probably magic. Since any possible FTL scheme generally changes the frame centered around the drive to disconnect it from the Universe, either through a hyper drive (frame disconnected by leaving the Universe) or a warp drive (frame disconnected while staying in the Universe), it is impossible to pierce the frame while traveling.

Of course, you could potentially use wormholes for communication and sensors, but the communications and sensors are not FTL. In that case, you would create a wormhole small enough to extend a communication antenna or sensor probe. When you were done, you would extract the probe and close the wormhole.

An interesting possible version of that technology would be to have it only being able to function beyond the Outer Limit of a star system (due to instabilities caused by gravitational vibrations or the like). I would have them be high energy systems with a minimum size of SM+12 for one wormhole, SM+13 for three, SM+14 for ten, SM+15 for thirty, etc. In that case, the wormhole base would function much as a telegraph, as communications to and from the wormhole base would take nearly six hours each way in the Sol System. Of course, such bases would also be the first target during any conflict, so they would be fiercely defended.