Velocity and Jump Space

[Reynard]

That's never been a game mechanic issue. Most descriptions put most movement concerns on the expected and unexpected at the other end of a successful Jump. Before that, you're trying to get the engine to reach the destination. Makes you realize how complicated and important the astrogation action is.

I've been looking at so many sources concerning vector movement and Jump I'm not sure which said stellar navies will place objects in frequently use exit regions to discourage enemy attempts at high velocity incursions.

 

[-Daniel-]

Maybe the slower you go in, the less likely you are to misjump.

I like that idea, it adds a level of concern for those who might try jumping at full speed but it does not stop them from doing so.

 

[NOLATrav]

Maybe the slower you go in, the less likely you are to misjump.

I like that idea, it adds a level of concern for those who might try jumping at full speed but it does not stop them from doing so.

I've mentioned this before. I use each point of Thrust as DM-1 against Astrogation and engineering jump rolls, with negative Effect dropping you out of jump further and further from your destination. So you go in at Thrust 2, you save time getting out of the system, suffer DM-2 on all your jump checks and will probably be a lot further out than 100 diameters when you get to where you're going.

 

[Dracous]

It's best if we don't overthink this one. I've always considered that the travel in jump allows for some sort of magical velocity change as part of travel. Because it does not take into account the following.

- The velocity of the planet as it moves around the around the star (Example, earth has a velocity of 30km/s as it moves around the sun.)
- The velocity of two star systems relative to each other. (Alpha Centauri and The Sun are moving at a speed of of about 20km/s towards each other)

To that end, if we are going to have rules about the velocity of a ship, we should have a few thoughts about the velocity of the objects they are relative to, and my thinking is that going that far is a level of micromanagement I do not want to inflict on my players.

So.. yes... our wonderful astrogators are using the jump drive to cancel out all the other vectors so that our ship emerges with the same speed relative to the target as it had to the planet we are leaving. Don't ask me how, it's a complex calculation, and they assure me that the math works out best this way, now who wants some space tang and foodsticks?

 

[Reynard]

The thing is, and I've mentioned it before here, Traveller has always had references to the Jump astrogation calculations taking into account the active positions and vectors of the start and destination systems and where the ship will be based on the optimal Jump plus the ship's vector at the beginning of the Jump to it's subsequent vector at exit.

It seems it would be in Mongoose's favor for the newbies to the game to put the standard Jump vectoring statement in the next book since it disturbs so many. We already know:

"When the ship exits jump space after an accurate jump, it tends to arrive close to the target world, but outside or on the verge of the hundred-diameter limit. Inaccurate jumps dump the ship somewhere in the inner system, requiring a long space flight." That statement says the calculations take into account for relative system motions.

So, as with past editions, they merely need to add one sentence: "A ship in jump space carries the velocity and direction at the moment of entry into jump space, which can not be changed in jump space, and is retained at exit." That should be enough for players and referees to judge the consequences and effects when exiting at speed.