Problem of math

[Catavarie]

Or you could take the Andromeda/Babylon 5 road and hyperspace is only mapped out for teh region you want to keep them in, outside of that area you risk being lost in hypersapce forever.

 

[pawsplay]

For the longest of times I have wanted to start a campaign in space. The idea is that some thousand or so years in the future mankind has ventured to a nearby system, for reasons that are campaign based (I have Players that post and read here so please, lets not spoil it for anyone) the FTL drives are gone, no longer accessible to anyone.

My problem is however that the system is 2 LY across (2 light years in diameter), but I want the characters ship to be able to venture from the core planets (1+ or – AU) to the outer space stations (1 LY out) in a reasonable amount of time- perhaps a few weeks or even as much as two months.

If you do not use FTL drives, the minimum amount of time it can take to travel two light years is two years, at nearly the speed of light.

 

[Ed_Laprade]

If you do not use FTL drives, the minimum amount of time it can take to travel two light years is two years, at nearly the speed of light.

QFT. If you want your characters to cross a system one light year in diameter in a few weeks or months they are travelling FTL. If they are travelling FTL then other systems are within reach. Unless the system is way out(side) on the rim and the closest other systems are tens of lightyears away. If not you have to make your system smaller. Those are pretty much your only choices if you don't want your players telling you you're crazy.

 

[Rabelais]

/ geek check

Space Shuttle enters the homeworld's upper atmosphere at around Mach 25 or so. According to one thing I read the Challenger was going around 18,000mph when the unspeakable happened. (Via Con Dios amigos)

 

[Harmon]

The Kuiper Belt is out at 30 AU to 50 AU, and the Oort is out to a 100,000 AUs if I recall my Discovery Channel science correctly.

A Light Year is about 63,000 AUs if memory serves, so by my understanding our system- while Pluto is only out 50 AUs I was kinda thinking that some of the adventures would take place on mining stations in the outer cloud around this mythical system.

Perhaps I should consider travel time for 50 AUs and not worry so much about the 100,000 and consider placing a Kuiper like belt within the system, though that kinda of restricts some of the campaign ideas it does not take out the whole campaign.

The understanding that this is a Firefly like campaign is indeed true. I have wanted to run this campaign sense the early to mid ‘90s, when Firefly came out I really wanted to do it and it changed a lot of what I was thinking, but for the most part its still a space smugglers/mercenaries campaign that takes place in a solar system not of our own (not Sol).

I thank you all for your thoughts; it’s helping me get some ideas. Hopefully I will get this off the ground before another decade passes.

 

[sjmiller]

The Kuiper Belt is out at 30 AU to 50 AU, and the Oort is out to a 100,000 AUs if I recall my Discovery Channel science correctly.

A Light Year is about 63,000 AUs if memory serves, so by my understanding our system- while Pluto is only out 50 AUs I was kinda thinking that some of the adventures would take place on mining stations in the outer cloud around this mythical system.

Your numbers are pretty accurate from memory! 1 light year (ly) = 9.4607 x 10^12 km or 63,240 Astronomical Units (AUs) or 0.3066 parsecs. An AU is, as you will recall, the average distance from the Sol to Sol-3 (aka the Sun to the Earth). Neptune is 30.06 AU from the Sun, and Pluto averages about 39 AU. The Kuiper Belt should be about 30 AU to over 50 AU. Pluto's orbit, being elliptical, is as little as 29.7 AU and as great as 49.7 AU. Gee, sometimes it is fun being an astronomy geek!

As for your system problem, like many others have said, it should be vastly smaller than 2 ly across. A distance of 24 light hours would make a good system. You could go as big as 36 light hours and still have a huge system with lots of planets. If you have some planets that don't orbit on the same elliptical plane as the rest, you can have more planets. At that point you have to start worrying about orbital "wobble" due to the plants coming in at odd angles, but it should not be too bad.

 

[Umbran]

I want no interstellar travel, but the speeds at which I would like to operate at place interstellar within reach, and that is what is confounding me.

Well, here's a few thoughts for you to consider -

You say you want no interstellar travel, but your system is a couple light-years across? That's a conflict right there. More than a few light-hours is pretty much "interstellar distances". Unless you express a need for the system to be so large, the simple answer is to shrink the system.

Which makes a lot of sense - in general, a star doesn't provide enough light to be what we'd call "life giving" more than a few light-hours out anyway. So there's little point for anyone to be farther out from a star, in the general case. So, if you have only one star (thus no "interstellar" travel), then why do you need the system to be so large?

Also, you are confusing speed and range. Interstellar travel isn't about how fast you can go, so much as how far you can go. If no current ship can hold enough fuel (or is otherwise resticted), you can have them go as fast as you like, but with limited range.

There are drive systems in development right now that you'd not want to use within an atmosphere - ion drives and "Orion" drives are decent examples. They won't do superluminal flight, but they do require that the things you use for atmosphere and space be separate.

 

[DJCupboard]

My math isn't good enough to give you any good ideas about inter- vs intra-stellar travel, but I'll just go ahead and second the good ideas already mentioned anyway. In terms of the stellar vs. atmospheric travel dichotomy...

The energy expulsion needed for any kind of stellar propulsion system could be such that, while still using the same drive, anything approaching extra-orbital speeds within the orbit of a planet is not at all safe in terms of the planets continued existance. Sure, you could go from the US-equivalent to the Spain-equivalent in the blink of an eye, but sSpain, the US, and the rest of the planet wouldn't be much more than debris clogging your drive system by the time you got there, which isn't a very efficient transit system, if you ask me.

 

[Slife]

The energy expulsion needed for any kind of stellar propulsion system could be such that, while still using the same drive, anything approaching extra-orbital speeds within the orbit of a planet is not at all safe in terms of the planets continued existance. Sure, you could go from the US-equivalent to the Spain-equivalent in the blink of an eye, but sSpain, the US, and the rest of the planet wouldn't be much more than debris clogging your drive system by the time you got there, which isn't a very efficient transit system, if you ask me.

Great! Now the PCs can destroy the campaign setting just by pressing the wrong button!

 

[DJCupboard]

Great! Now the PCs can destroy the campaign setting just by pressing the wrong button!

To quote the best uncle any web-slinger ever knew: "With great power comes great responsibility."