[Space] Technobabble for my new campaign.

[AlexanderHowl]

It would take 9.5 years for a 0.1g spacecraft to reach 0.98c (though time dilation would probably fiddle with the numbers).

[cvannrederode]

Originally Posted by AlexanderHowl

It would take 9.5 years for a 0.1g spacecraft to reach 0.98c (though time dilation would probably fiddle with the numbers).

That's according to someone watching them from a "stationary" point. From someone on the spacecraft, every second is five seconds in stationary space when going .98c.

[ericthered]

Originally Posted by AlexanderHowl

It would take 9.5 years for a 0.1g spacecraft to reach 0.98c (though time dilation would probably fiddle with the numbers).

According to this site (you have to put in distances, look at the max speed, and halve the time) 9.5 years only gives you .75 of c. for .98 of c you need 45 years. Which is not to say that .75 of C isn't scary. Its just no .98 c.

But .75 C gives you a fair amount of time to respond and protect yourself, especially if you've got FTL. And WWI, which was lost when national economies broke down, would be fought and the resulting civil wars over between launching your weapon and it arriving.

[cvannrederode]

Originally Posted by cvannrederode

That's according to someone watching them from a "stationary" point. From someone on the spacecraft, every second is five seconds in stationary space when going .98c.

Hold on...I think I got that backwards...

<shakes angry fist at Einstein's grave>

[vicky_molokh]

Think carefully about whether 0.1g/5% is sufficient for your needs of in-system travel times. It's very possible that it may be found lacking once you try mapping out the timings of individual adventures you plan to throw at the PCs. In which case you may want to consider pseudovelocity as a way to get faster travel without the kinetic kills.

[Lord Azagthoth]

A Star Trek The Next Generation RPG system (form Last Unicorn Games) had a table on which you could roll and it would give you some random technobabble (in case you're out of ideas to make something up when the PCs have done something unexpected again).

[cvannrederode]

Originally Posted by vicky_molokh

Think carefully about whether 0.1g/5% is sufficient for your needs of in-system travel times. It's very possible that it may be found lacking once you try mapping out the timings of individual adventures you plan to throw at the PCs. In which case you may want to consider pseudovelocity as a way to get faster travel without the kinetic kills.

With hyperdrive widespread, long in-system travel isn't as big a deal. Even with a minimum time in hyperspace of 10 seconds, that's 23 AU and change. Longer trips can be done by using the star drive to go out about 100 AU or so, let if reset, and shunt back to where you want to be. (Military ships carry multiple star drive systems to quicken turn around to just the plotting time...)

So it comes down to how long it takes a ship to get to "flat space"...100 planetary radii is 400,000 miles for the earth...not too long even at 0.1 g if you don't worry about slowing down when you get there.

[vicky_molokh]

Originally Posted by cvannrederode

With hyperdrive widespread, long in-system travel isn't as big a deal. Even with a minimum time in hyperspace of 10 seconds, that's 23 AU and change. Longer trips can be done by using the star drive to go out about 100 AU or so, let if reset, and shunt back to where you want to be. (Military ships carry multiple star drive systems to quicken turn around to just the plotting time...)

So it comes down to how long it takes a ship to get to "flat space"...100 planetary radii is 400,000 miles for the earth...not too long even at 0.1 g if you don't worry about slowing down when you get there.

You may want to consider things other than radii for space flatness. A simplistic thing would be the locally-felt real gravity.

Also, do consider the troubles of lifting off with a mere 0.1g drive. Works with winged launch, but not with wingless. And you can't meaningfully use wings for planets with a trace atmosphere, and your runway requirements will be huge with low thrust/low air density in general.

[cvannrederode]

Originally Posted by vicky_molokh

You may want to consider things other than radii for space flatness. A simplistic thing would be the locally-felt real gravity.

Also, do consider the troubles of lifting off with a mere 0.1g drive. Works with winged launch, but not with wingless. And you can't meaningfully use wings for planets with a trace atmosphere, and your runway requirements will be huge with low thrust/low air density in general.

The actual requirement is "gravitational flux" or how much gravity changes over distance. Between myself (Comp Sci/Software Engineer) and my one player(PhD Astrophysicist and collage physics prof) we'll probably work up a little app that gives you the proper distance. Most in game work will be handwaved, however. True grav flux is a mutli-body problem.

As far as take offs, that's already been thought of at length. Campaign is starting on an Arcology farm on a Ceres analog, with 0.03g at the surface. They'll have winged shuttles for most large inhabited planets, when they get there. They don't actually have their own ship yet. Yet.