GURPS Space: Stardrives

[Agemegos]

Originally Posted by Diomedes

I happen to think Terra is a pretty interesting place, but it didn't even exist fourteen billion years ago.

Very little did. The Universe isn't that old.

[Anaraxes]

Hmphf. Maybe your universe isn't that old. You nouveau species always think you know it all, as though one trip through a bangcrunch cycle is all you get, and yours is the only universe in the Cosmos.

[Diomedes]

Originally Posted by Agemegos

Effective speed in what frame of reference?

Effective speed from the perspective of someone who stays at home.

The tougher part is picking a reference point to decide your realspace velocity at the time you jump. I just assume the planet of departure is stationary and hope no one calls me on it.

[Anthony]

Incidentally, I think this thread is going about the problem slightly backwards. We should start with discussing what features a plot-useful stardrive has, and then proceed from there. I would say that useful plot features for a stardrive include:

• Permits smuggling
• Permits piracy, preferably including boarding actions
• Is slow enough to keep events somewhat isolated -- PCs should be days or weeks from civilization, not minutes or hours.
• Conveniently available on inexpensive, PC-scale ships.
• On the opposite end of things, something keeps the interstellar population limited.

[Fred Brackin]

Originally Posted by Anthony

The advantage, here, is that any place that a ship can exit hyperspace must be interesting, because the presence of a gate implies something capable of creating a gate

A similar set up I've considered is called the Swirlway. It is an artificial network of portals which always come in pairs. Access to the network is obtained by playing the tones from CE3K (or at least something like them) on a radio specific frequency. Entry and exit are non-dramatic.

This pair of portals would be approx. 400,000 miles ahead and behind a planet of Earth's mass. Note that this does not consist of an orbit. Keeping a sensor always on the portal is relatively easy. keeping an interception fleet within range is certainly possible. Even keeping a weapon always within range might be doable but you can't just sit on top of a portal without a something like a reactionless drive.

When you enter a portal you're on an Alpha line. This appears to be something like the inside of a tornado made of energy (hence the name). The Alpha line will connect relatively soon to a Beta line and perhaps eventually to a Gamma line and so forth. Sometimes higher level lines may connect directly to an alpha. There's a legendary Omega line out there somewhere. If you can make it to the Omega line you can go _anywhere_

To control your movement within the swirlway you must have what's called a "Turbo". The Turbo spins (rotary movement is very important to interstellar flight, see many TV shows) and contains the stored energy that you use to maneuver in the swirlway. As your turbo winds down (or runs out of "revs" in the local jargon) you need to get out of the swirlway or start a rough ride to a random place.

Unpowered swirlway riders always get dumped out _somewhere_ (or at least such is the local article of faith). If their ship was small and sturdy they might even be in one piece.

Most swirlway portals lead to habitable planets. Others lead to resource sites, places of scientific interest or for the very smallest cases (asteroids c. 100 miles in diameter with correspondingly close portal pairs) what may be hyperspace bypasses.

With known levels of technology turbos can not be recharged while in use. These leads to a pattern of short trips. In one alpha, down the beta to the next alpha and out again to recharge your turbo.

Sometimes you go right back in and up the same beta and sometimes you go from a leading portal to a trailing portal (or vice-versa)

High performance turbos (greater ratio of of turbo size to ship mass) can enable longer trips. So can high quality piloting. Swirlway navigation is complex, based on passive sensor input only and even that has a chaotic uncertainty factor.

An A.I. that can even equal to performance of a trained human is a very high order machine and probably more expensive than a trained pilot. P.C level pilots with Luck, Intuition and similar Ads can usually exceed any A.I.'s results.

The swirlway has probably been in existence for a few billion years or so and whether Earth life has been transplanted to other places or taken from other places and transplanted to Earth so long ago that it's blended completely in is an exceedingly difficult question to answer. Combinations of both repeated over a very long time are also possible.

How recently the Builders were doing this and whether or not there are Homo Sapiens or closely-related species beyond Earth and it's colonies is left to the individual GM. There could be intelligent dinosaurs or anything else out there as well.

It can be easily established that portal exits that are close to one another in the swirlway are not close to one another in normal space. Also, portals that are close to one another in normal space (i.e the leading and trailing ones) are very rarely close to one another in the swirlway system.

Can it even be proven that different exits are even in the same galaxy, universe or time? Not so far.

If anyone wonders this all came out of a thought experiment of what would justify the life pod in UT. The 400-500,000 mile distance from a habitable planet is the key thing.

[Diomedes]

Originally Posted by Anthony

Incidentally, I think this thread is going about the problem slightly backwards. We should start with discussing what features a plot-useful stardrive has, and then proceed from there.

Indeed.

I would say that useful plot features for a stardrive include:[list][*]Permits smuggling[*]Permits piracy, preferably including boarding actions

Smuggling requires the ability to go "off the trail" on routes the Navy doesn't patrol – so no point-to-point. It also requires the ability to get contraband down to the planet without getting caught, which is the real bottleneck, no mater what stardrive you use.
Piracy requires that the legitimate trade use those same unpatrolled routes, or a navy that is seriously under-resourced. Boarding actions aren't really affected by stardrive, unless you want them to actually occur in FTL.

[list][*]Is slow enough to keep events somewhat isolated -- PCs should be days or weeks from civilization, not minutes or hours.[*]Conveniently available on inexpensive, PC-scale ships.

Both of these are very good to have.

• On the opposite end of things, something keeps the interstellar population limited.

Realistically, it takes an awfully long time to grow interstellar colonies, unless you assume population growth rates will be considerably larger than they are now. Do we really need a limit?

[Diomedes]

Originally Posted by Fred Brackin

When you enter a portal you're on an Alpha line. This appears to be something like the inside of a tornado made of energy (hence the name). The Alpha line will connect relatively soon to a Beta line and perhaps eventually to a Gamma line and so forth. Sometimes higher level lines may connect directly to an alpha. There's a legendary Omega line out there somewhere. If you can make it to the Omega line you can go _anywhere_

So you go through the portal and travel down the line until you reach the appropriate exit, or jump to a higher power line? Is there just one Alpha line that can theoretically take you anywhere if you can stay on long enough, or do you have to switch via a Beta or higher to a separate Alpha line?

[Agemegos]

Originally Posted by Diomedes

The tougher part is picking a reference point to decide your realspace velocity at the time you jump.

Yes, that is what I was asking about. You have so far specified a drive which, when you turn it on, moves you in every possible direction at all speeds up to 200,000 c.

I just assume the planet of departure is stationary and hope no one calls me on it.

"Too late!" she cried, and waved her wooden leg. I've called you on it already.

[Anthony]

Originally Posted by Diomedes

Smuggling requires the ability to go "off the trail" on routes the Navy doesn't patrol – so no point-to-point.

Well, sort of. It can be point to point as long as the points are very large.

Originally Posted by Diomedes

It also requires the ability to get contraband down to the planet without getting caught, which is the real bottleneck, no mater what stardrive you use.

If you have a stardrive that places you in low orbit (or even suborbital speeds) reaching the surface isn't too hard. It's when you have to start in deep space that reaching the ground is really hard.

Originally Posted by Diomedes

Piracy requires that the legitimate trade use those same unpatrolled routes, or a navy that is seriously under-resourced. Boarding actions aren't really affected by stardrive, unless you want them to actually occur in FTL.

I actually favor boarding actions in FTL, but the requirements for normal-space drives are determined by the stardrive, and also influence the practicality of close engagements.

Originally Posted by Diomedes

Realistically, it takes an awfully long time to grow interstellar colonies, unless you assume population growth rates will be considerably larger than they are now. Do we really need a limit?

I mean the number of people bopping around in spaceships should be fairly limited, not anything about the size of colonies, at least here.

[Diomedes]

Originally Posted by Anthony

Well, sort of. It can be point to point as long as the points are very large.

In space, "very large" will have to be measured in light-seconds.

If you have a stardrive that places you in low orbit (or even suborbital speeds) reaching the surface isn't too hard. It's when you have to start in deep space that reaching the ground is really hard.

Getting from orbit to land undetected will be a function of whether the government can afford to cover the surface with radar. You could sneak onto a colony, but a homeworld would be much tougher.

I mean the number of people bopping around in spaceships should be fairly limited, not anything about the size of colonies, at least here.

What precisely is the objective of lower scale space travel? If space travel is too limited, so to will be colonization.