Far Trader

[Captain Jonah]

In most past editions of Traveller a ship has to be at zero speed to jump, I haven't read yet if that's been changed. I'm hoping that it's also clarified as to what zero speed means, as speed is relative. Is it zero speed relative to the planet you just left or the one you're about to jump to? Is it zero speed relative to the galaxy's spin or the galaxy's movement? Or all of the above?

All of the above. If you aren't at a dead stop relative to the starting planet you won't be stopped relative to the destination planet, which could cause some serious problems (both traffic and legal)when you leave hyperspace.

Dead stop relative to the jumping world does not make you dead stop at the destination which may have a different orbital position, differing rotational speeds etc. It's the job of the Astrogator to sort things out so you arrive on the right vector for the destination, use the M drive to reach that vector then coast and jump.

Arriving on the wrong vector is likely to be more of a problem since you could be going off at a tangent to the other traffic.

 

[phavoc]

In most past editions of Traveller a ship has to be at zero speed to jump, I haven't read yet if that's been changed. I'm hoping that it's also clarified as to what zero speed means, as speed is relative. Is it zero speed relative to the planet you just left or the one you're about to jump to? Is it zero speed relative to the galaxy's spin or the galaxy's movement? Or all of the above?

All of the above. If you aren't at a dead stop relative to the starting planet you won't be stopped relative to the destination planet, which could cause some serious problems (both traffic and legal)when you leave hyperspace.

Dead stop relative to the jumping world does not make you dead stop at the destination which may have a different orbital position, differing rotational speeds etc. It's the job of the Astrogator to sort things out so you arrive on the right vector for the destination, use the M drive to reach that vector then coast and jump.

Arriving on the wrong vector is likely to be more of a problem since you could be going off at a tangent to the other traffic.

This would also affect the path you take when departing a world. It gets messy mechanics wise if you take all this into consideration. If your destination lies opposite the sun, you'd have to go to a jump departure point 100D above/below/side of the star in your way. Which means you may be travelling for a day or two to get there.

It's interesting information, but a pain to handle within the game. Easier to just go out to a generic 100D and press the jump key.

 

[vladthemad]

In most past editions of Traveller a ship has to be at zero speed to jump, I haven't read yet if that's been changed. I'm hoping that it's also clarified as to what zero speed means, as speed is relative. Is it zero speed relative to the planet you just left or the one you're about to jump to? Is it zero speed relative to the galaxy's spin or the galaxy's movement? Or all of the above?

All of the above. If you aren't at a dead stop relative to the starting planet you won't be stopped relative to the destination planet, which could cause some serious problems (both traffic and legal)when you leave hyperspace.

Dead stop relative to the jumping world does not make you dead stop at the destination which may have a different orbital position, differing rotational speeds etc. It's the job of the Astrogator to sort things out so you arrive on the right vector for the destination, use the M drive to reach that vector then coast and jump.

Arriving on the wrong vector is likely to be more of a problem since you could be going off at a tangent to the other traffic.

Everyone knows the far future doesn't have orbital mechanics! Seriously, some stuff has to be thrown out to make the game playable. You move trust half way to the 100d limit, then turn around and thrust to a stop, jump and repeat in reverse. That's what I've seen in the majority of the explanations in print. Unrealistic, but playable and easy for most people to understand.

 

[phavoc]

The rules don't even say that, just that you go to the 100 diameter limit and you jump. No need to stop.

Yeah, along with inflation and interest they have addressed the problem with orbital mechanics as well. Groovy!

 

[Rikki Tikki Traveller]

The Far Trader only has listed fuel for Jump-1 while it has a Jump-2 range. I believe this is a typo, but haven't counted the boxes. Also, this assumes that the jump fuel is still 10% per jump number.

The Far Trader should have 41 tons of fuel, reducing the cargo to 44 tons.

 

[hdan]

The Far Trader only has listed fuel for Jump-1 while it has a Jump-2 range. I believe this is a typo, but haven't counted the boxes. Also, this assumes that the jump fuel is still 10% per jump number.

The Far Trader should have 41 tons of fuel, reducing the cargo to 44 tons.

Yep. That's the post that started this thread off.

 

[Rikki Tikki Traveller]

Sorry, just going through my 7 pages of notes and trying to make sure that everything I caught was posted. Sorry to circularize the discussion.

 

[AndrewW]

Also, this assumes that the jump fuel is still 10% per jump number.

Yes, jump fuel remains the same.

 

[MongooseMatt]

Fixing the Fuel, double checking Cargo.

Oh, and this has cropped up elsewhere but yes, it is intentional that you cannot run everything and jump on some ships - the lights will literally dim when you engage the jump drive!

 

[-Daniel-]

Oh, and this has cropped up elsewhere but yes, it is intentional that you cannot run everything and jump on some ships - the lights will literally dim when you engage the jump drive!

What a cool image to think about.

This feels very Star Trekish. Drop shields so we can fire phasers kind of thing.

 

[Rikki Tikki Traveller]

It was something that was always mentioned in the fluff part of the OTU history, but never actually shown... I like it too; especially with the older (TL9 and 10) designs.

Of course it is also a good way to suck up Traveller cash as the first upgrade most groups make is to add weapons, now they also need to upgrade the Power Plant!

 

[AndrewW]

This feels very Star Trekish. Drop shields so we can fire phasers kind of thing.

Just use the prefix code.

 

[vladthemad]

The rules don't even say that, just that you go to the 100 diameter limit and you jump. No need to stop.

Yeah, along with inflation and interest they have addressed the problem with orbital mechanics as well. Groovy!

Hmm. You know you're right, the new rules don't. It was something that came out with some of the supplements in the other Mongoose addition and was considered "common" knowledge in most of the other versions. Oddly the Jump Limit Transit Tables given by Mongoose doesn't seem to conserve momentum. You thrust from zero velocity at full acceleration to the jump limit, but when you make it back into real space it appears you start again at zero velocity again. That was most likely an oversight.

If you wanted to get a *little* more realistic, you could say the only ships that must come to a complete stop before jump would be dispersed hulls. Anything else could use a combination of deceleration and aerobraking. Hmm...come to think of it, I'm adding that as house rule!

And I'm suddenly feeling an urge to play Kerbal Space Program....

 

[grauenwolf]

Hmm. You know you're right, the new rules don't. It was something that came out with some of the supplements in the other Mongoose addition and was considered "common" knowledge in most of the other versions. Oddly the Jump Limit Transit Tables given by Mongoose doesn't seem to conserve momentum. You thrust from zero velocity at full acceleration to the jump limit, but when you make it back into real space it appears you start again at zero velocity again. That was most likely an oversight.

I don't believe that is true. I did my own calculations for "zero to full to zero" for my trade calculator and I got the same numbers as the book (allowing for rounding errors).

But in any event, I would like to see both "zero to full to zero" and "full speed all the way" in the chart. Cause some times you just gotta get out of town regardless of the consequences.

 

[phavoc]

If you don't want to deal with the conservation of momentum, but still have a negative effect for jumping at speed, one could add a multiplier of 1D6 for the accuracy of the jump emergence.

So your nifty free trader has to make a quick escape and doesn't have time to stop for an accurate jump, so the ships software adds a larger margin of error, say 100,000km. You could simply add in 100 kilometers for every G they are travelling, or for every G they are going roll 1D6 and add in 100 kilometers they are from their intended destination.

If you want to be more strict about that make it a million kilometers from their destination.

 

[NOLATrav]

In MGT v1 a successful jump was Effect 0 or greater, negative Effect was a misjump. I built a table where each point of negative effect precipitated you further and further from your intended destination, where -1 was +1M km (extra in-system travel time), -6 was the 6D6 parsecs in a random direction, -7 or greater was ship destroyed (never used that one though). Broadly speaking here, I don't remember the exact details although "Middle" and "Outer" system were there, which could mean weeks or months of sub-light travel if the ship couldn't immediately jump again.

As far as relative velocity, the mid-point turnover always just made sense. You could use the travel times tables provided and save some work and there was some verisimilitude to the universe. But of course players would say no and insist on constant acceleration to the jump point - and so their ship suffered a -DM equal to the ship's Thrust on Astrogation AND Engineering jump rolls prior to jump (military ships suffered too) and once exiting jump space suffered the same -DM on Sensor and Comms checks in the new system (military ships did too). No gain in time regarding reaching the destination world, they had to bleed off all that extra velocity relative to their destination... Though it sometimes in worked in their favor - if they were especially smart/thoughtful/desperate role (not roll) players...

House rules - can't live with 'em, can't live without 'em.

 

[Reynard]

One way to make traveling at speed at jump entry is making an encounter roll immediately at jump exit with all the proper modifiers. Range from the entering ship can be frighteningly close because you just appeared instantly in that area, referee's choice depending on circumstance and cruelty. Nothing like screaming in at 6gs with a Free Trader only 100 km dead ahead and your sensor operator still need to make a successful sensors check! They could treat you as hostile and open fire.

This is why scouts entering an unknown system does so from outside the ecliptic and in the Oort region.

 

[hdan]

In my games, part of the pre-jump sequence is getting your ship into the right inertial frame (that is, velocity) to match up with the world you're jumping to. (In the interest of not boring players to death, I assume worlds are at low relative velocities to each other, but there is variance.)

That also means that anyone observing you can (Navigation, Routine 10-60 seconds) guess which world you're jumping towards, given the listed jump rating of your ship's class and the known velocities of all neighboring worlds.

That doesn't mean you can't spoof by matching up with one world but jumping to another, but it does mean that you'll have quite a lot of "course correction" to do on the other side.

I also like the v1 navigation check that adds (or subtracts) time from your "emergence to surface" time. In my handwave, I explain that as how well you plot your pre-jump velocity relative to the world you're going towards. Also, the time of day/year/etc, and the "launch window" you've been given modify the difficulty of achieving proper intertial lock. Because of this, there are optimal departure times to each neighboring world which require the least thrust.

But players being players will often have to "wing it", and hope for a good framelock solution while dodging incoming fire, etc.

 

[FallingPhoenix]

Actually, if jumps conserve momentum, it would make more sense to point your ship straight at your destination world when leaving the departure world, and jump at full speed after thrusting to the 100d limit. Then you just use your whole trip on the far side of the jump to slow down. That would cut half (+ or -) time off your trips!

My first instinct is that the relative motion of the departure world and the destination world are small enough compared to the speed you can reach with a constant acceleration drive that they would be real easy to take into account.

This also gives you the nice option of having ideal 'jump lanes' that people come in on and leave out of when traveling to and from any two given systems, so you have a lot better chance of meeting up with someone. Although that does leave you zooming past each other at pretty ridiculous rates of speed...

 

[Reynard]

"That also means that anyone observing you can (Navigation, Routine 10-60 seconds) guess which world you're jumping towards, given the listed jump rating of your ship's class and the known velocities of all neighboring worlds."

I think it was in the Ship Operation Manual that said jump course is determined by the distortion of the jump field, essentially you're 'tilting' the ship in the direction of the destination. Sensors might be able to ascertain a ships course by observing shifts in the target's field. Definitely a sensor check and difficult because you don't hear pursuers regularly accomplishing this tactic so it's either a lot of luck or great skill (Very Difficult or even Formidable).

Vector and speed matching between launch point and destination with any special destination course deviations should be considered part of the Navigation check for Jumping. Those expensive computer programs contain a VAST database for every known system so vectoring is fairly transparent. If a sensor operator observes a ship preparing for jump and can't achieve destination by observing the J field, all they will know is speed and direction and that says very little unless you know where they will ultimately exit. Best information you can have is the maximum jump a particular ship can jump versus the systems in the vicinity.