Accuracy of Jump

[malloyd]

Originally Posted by Anaraxes

That's only true if you imagine that you jump to a fixed point in an absolute coordinate scale, so that being late means your planet has moved on.

That's actually yet another pretty strong indication jumps can't be tied to real universe directions and hence that jump masking makes no sense at all. You could imagine jumping to something in a fast enough orbit that whether or not the 100D limit of primary is in the way depends on what the roll is for the time variance. Even at more typical orbital speeds for habitable planets, there's no overlap at all between the 100D spheres for smaller worlds with higher variance rolls - it takes Earth a little less than a day to move 100D.

[Anaraxes]

Originally Posted by malloyd

That's actually yet another pretty strong indication jumps can't be tied to real universe directions and hence that jump masking makes no sense at all.

Not to exhume this particular dead horse, but yes -- at least in realspace geometry. On the other hand, that might be exactly how it works in jumpspace coordinates. You might stop at the first sufficiently steep gradient you hit in jumpspace. But even if true, if the two spaces don't correspond that point still tells you nothing useful about whether any particular object is "in the way" in jumpspace. Just a handwave / GM fiat when you need that plot point.

[Hans Rancke-Madsen]

Originally Posted by malloyd

That's actually yet another pretty strong indication jumps can't be tied to real universe directions and hence that jump masking makes no sense at all. You could imagine jumping to something in a fast enough orbit that whether or not the 100D limit of primary is in the way depends on what the roll is for the time variance. Even at more typical orbital speeds for habitable planets, there's no overlap at all between the 100D spheres for smaller worlds with higher variance rolls - it takes Earth a little less than a day to move 100D.

23 hours? I thought it was less.

Anyway, just assume that the game rules for jump are simplified. If you want to jump to Earth, you aim for where it will be in 168 hours. If you arrive 17 hours ahead of shedule, you'll hit Earth's 100D limit and be precipitated out ahead of Earth. If you arrive 17 hours late, you'll hit the jump limit and be precipitated out at the limit. If you arrive at any time in between those two extremes, you'll be precipitated out somewhere along the jump limit. Just as the rules has it.

But what if you're aiming for a world that moves 100D in, say, 15 hours? That's where the simplification comes in. Since jump duration follows a bell curve, we can assume that you will usually arrive within the +/- 15 hour window and ignore the possibility of arriving more than 15 hours before or after.


Hans

[Drifter]

Well, I see that there is no widely held opinion :)

I despaired about the Marc Miller's article until I searched JTAS for it, and lo and behold!

Among other things it says you come out within 3000 km of your desired exit, for a jump 1, with other factors combining to possibly make that distance worse 'by a factor of 10'.

So it is a function of timey-wimey, jumpy-wumpy physics. To me that does not necessarily exlude jump masking, as seen in Far Trader (not sure if anywhere else). That does seem to imply that you don't absolutely have to end your jump at a 100D limit area. Although I've always taken it as a given you can jump to anywhere you want, such as deep space, just no inside a 100D of a substantial body.

If your destination is masked, you exit jump in deep space, 3000km give or take from the spot you've calculated as the closest you can get from a straight line from your departure point.

The whole point of this being - this adds a tremendous amount of time to a trader's time in a system. Days in some cases - a fully loaded freighter can take over 3 DAYS to reach a port at a G star system. AND anothere 3 days to get back to a jump point.

All this discussion of trade rules got me wondering just how fast freighters can be processed in a system. Its seems to me that just jumping into a star system, landing at the starport, doing tradey stuff, then launching and jumping again is actually rare. That is, the way I envisioned it in the Classic Traveller books. You spend nearly as much time in deep space as in jump space (depending on the stars you visit and the luck of the dice).

Astography is a very real consideration, deciding which ports to visit or avoid. Freighter liners and X boats would want to avoid ports where you need to spend days getting to maintinance and refueling facilities.

[Malenfant]

Originally Posted by Drifter

If your destination is masked, you exit jump in deep space, 3000km give or take from the spot you've calculated as the closest you can get from a straight line from your departure point.

The whole point of this being - this adds a tremendous amount of time to a trader's time in a system. Days in some cases - a fully loaded freighter can take over 3 DAYS to reach a port at a G star system. AND anothere 3 days to get back to a jump point.

You think that's bad? Spare a thought for Antares - its 100D limit is 1000 AU in radius!

[Fred Brackin]

Originally Posted by Malenfant

You think that's bad? Spare a thought for Antares - its 100D limit is 1000 AU in radius!

Antares is unlikely to even have GGs inside its' 100D limit so it doesn't matter very much.

Besides I'd always be afraid that light speed lag would keep me from finding out that Antares had gone supernova before I jumped in. :)

[Malenfant]

Originally Posted by Fred Brackin

Antares is unlikely to even have GGs inside its' 100D limit so it doesn't matter very much.

It's a subsector capital, an asteroid belt with pop A. Even if you assume that the asteroid belt orbits a distant companion, if the companion is masked by Antares from the direction you're arriving from, you have a very long trip to get there ahead of you.

[Hans Rancke-Madsen]

Originally Posted by Malenfant

It's a subsector capital, an asteroid belt with pop A. Even if you assume that the asteroid belt orbits a distant companion, if the companion is masked by Antares from the direction you're arriving from, you have a very long trip to get there ahead of you.

As Wil (Aramis) has pointed out, as long as the target is outside a jump shadow, the greatest additional delay would be one additional jump to get to somewhere with an unobstructed line of sight to the target. By no means insignificant, economically, but scarcely crippling.

Also, Antares lies on the edge of a minor rift, so there's an 180 degree arc to and from which no traffic will come. Perhaps the capital is moving so that it always stays on one side of the star within line of sight of all its neighboring systems.


Hans

[Fred Brackin]

Originally Posted by Malenfant

It's a subsector capital, an asteroid belt with pop A..

If Antares has an unrealistic asteroid belt why should it have a realistic 100D limit?.

http://en.wikipedia.org/wiki/Antares

Look here for the parts about the star's age and the way it's probably donated significant amounts of mass to its' type B companion.

Even if it didn't blow away all the pre-planetary dust when it ignited 12 million years ago and even if possible asteroids have (just barely) had time to form their orbits got scrubbed during one of more expansion phases.

All those orbits had their basic parameters shifted by the star's changing mass too.

So I wouldn't invest a lot of energy in selective realism. I'd go all or none. So if it is canonically a Sector capitol it's astrography probably doesn't interfere with that significantly.

[Anthony]

Originally Posted by Fred Brackin

Antares is unlikely to even have GGs inside its' 100D limit so it doesn't matter very much.

Eh, it could perfectly well have some space crud in that area, though the orbital interactions of A and B probably cleared most of it out.

Originally Posted by Fred Brackin

Besides I'd always be afraid that light speed lag would keep me from finding out that Antares had gone supernova before I jumped in. :)

Heh. Actually, you could partially resolve the Antares issue by saying that Antares A has already gone supernova, and 'Antares' in the 3I is actually Antares B. Not sure how destructive a supernova of A would be to something orbiting B, though.