Jump distance details

[Madmax]

Here is something I've added to MTU to make Jumping a little more challenging and hopefully interesting. It requires extra calculations and bookkeeping, so is maybe mostly of interest to gear heads, but others might like it too.

Jump Distances.

The distances between stars on Traveller maps is always in Parsecs. Jump Drive ratings are in parsecs. Very useful for keeping things simple. But simple can be boring, and not very realistic.

So, I was implementing the Primitive and Advanced Spacecraft rules from Chapter 4 of Mongoose Traveller 2nd Ed. when it occurred to me that it would make sense for the Jump Drives to gain a small distance increase at higher tech. For example J2 drives become available at tech 11, but wouldn't a tech 14 J2 have a slightly better range than a tech 11 J2?
As I said, this is just a detail for those that like details.
Say the tech 14 J2 drive's actual range is 2.3 parsecs. That fits the idea, but the map still only shows jump distances as absolute Parsecs. So, for this idea to be meaningful, one must have jump distances between systems vary a bit from the simple Parsec model.
What I do is when someone wants to decide on whether to jump somewhere I roll dice for the accuracy of the map distance. The actual distance can be up to 0.5 Parsecs off compared to the distance shown on the map. Roll 2 dice, subtract 7, use the result as tenth of parsec distance adjustment for the distance between those two stars. Once you roll for the specific distance between a particular pair of stars write it down and use that same distance going forward for all jumps between those stars.
For example: The distance from Regina to Yori is 2 Parsecs according to the map. Roll two dice with the result of 10, minus 7 = 3, the actual distance is 2.3 Parsecs. (If the roll is less than 7 you have a negative adjustment to the distance, so a roll of 5 results in the distance between Regina and Yori being 1.8 Parsecs.)
Now you need a ship with a J2.3 drive to make that trip. Still, you want to allow other J2 ships to be able to make such a jump or the whole game gets distorted. Simple. If the distance exceeds the ships rating by 0.1 or 0.2 Parsecs then the difficulty of the Jump is increased one level. If the distance exceeds the rating by 0.3 0r 0.4 Parsecs then increase the difficulty two levels etc.
This way a ship with a J2 drive can still go to all the same places as before, but some Jumps may involve a bit of a risk.
Now there is a real advantage to having a Tech 14 J2 (J2.3) over a Tech 11 J2.
Note that if one wants to buy a ship with a Budget Jump Drive the drive might be rated as J2, but in actuality only be J1.8. Save money, but trade off is that some Jumps are a bit more dangerous.
The specific rule is: add "Increase Jump Range by 0.1" to the Jump Drive Advantages list, and "Decrease Jump Range by 0.2" to the Jump Drive Disadvantages list.

 

[Condottiere]

The actual hurdle to utilizing sub parsec distances is lack of astrocharts to precisely calculate distances.

Or avoid gravity wells.

And of course, everything continues to move.

 

[Madmax]

The actual hurdle to utilizing sub parsec distances is lack of astrocharts to precisely calculate distances.

Or avoid gravity wells.

And of course, everything continues to move.

Not sure I understand what you mean. Even today we can determine the distances to nearby stars with a high degree of precision, by which I mean much more precisely than a 10th of a parsec, with little difficulty. Yes things move, but the movement is also very much less than a 10th of parsec except on very very long time scales.

 

[Condottiere]

The short take would be that someone would have to write a computer application that can place every interstellar object in Traveller precisely in time and space.

The longer one involves me trying to figure out how to squeeze out every scrap of performance from factors zero and one jump drives, and realizing it doesn' t matter, unless I know where everything relevant actually was, in relationship to the starship.

 

[kilemall]

The short take would be that someone would have to write a computer application that can place every interstellar object in Traveller precisely in time and space.

The longer one involves me trying to figure out how to squeeze out every scrap of performance from factors zero and one jump drives, and realizing it doesn' t matter, unless I know where everything relevant actually was, in relationship to the starship.

IMTU you get misjump chances going to a system that doesn't have PRECISE gravitic/EM/subspace charted.



So jumping into the unknown really is dangerous, there are known/safe jump areas most commerce uses, accurate charting is a military secret for certain areas, pirates function in part because it's tough for the navies to jump-surprise corsair bases, and smugglers prize little known jump patches for illicit rendezvous.



Those low-end jump-tapes? Could be BIG money for some important ones at certain times.


IMTU that is a BIG function of the Scout Service, charting all those safe jump zones, out there plodding around with sensors configured for gravitic and EM detection, year after year. Much like oceanographic work navies do now on wet seas.

 

[Madmax]

Those are interesting ideas too, but I don't think they exclude, or are really relevant, to my idea, unless I am just misunderstanding what you mean.

 

[kilemall]

Those are interesting ideas too, but I don't think they exclude, or are really relevant, to my idea, unless I am just misunderstanding what you mean.

Not trying to persuade you to my preferences, just that others have thought along 'think different' lines and extending/prompting even more different takes.


And more about Condot's take then yours, anyway.

 

[Condottiere]

I actually meant in real life practicality.

I was wondering if I could game the system, assuming the jump numbers can be rounded up, which means factor one would 1.49 parsecs, factor two 2.49, factor three 3.49, which meant that with an additional eight days, I could traverse 2.98 parsecs, 4.98 parsecs, and so on, which would be close enough to the aspired destination, even if short of 0.02 parsecs.

Instellar Wars introduced factor zero jump drive with a quarter parsec range: this sort of shrank total distance to factor plus a quarter.

It's then I realized you (that is, the player) need a chart (showing distances at that particular time point) to know if your aspired to destination was within range of the jump drive, in the sense that if you can make it so precise, you need to more precisely identify the exit point.

 

[kilemall]

I actually meant in real life practicality.

I was wondering if I could game the system, assuming the jump numbers can be rounded up, which means factor one would 1.49 parsecs, factor two 2.49, factor three 3.49, which meant that with an additional eight days, I could traverse 2.98 parsecs, 4.98 parsecs, and so on, which would be close enough to the aspired destination, even if short of 0.02 parsecs.

Instellar Wars introduced factor zero jump drive with a quarter parsec range: this sort of shrank total distance to factor plus a quarter.

It's then I realized you (that is, the player) need a chart (showing distances at that particular time point) to know if your aspired to destination was within range of the jump drive, in the sense that if you can make it so precise, you need to more precisely identify the exit point.

Ummm. I never really wondered that but then again I'm not exactly a RAW type anyway. It's inherent in the act of jumping, you HAVE to have a well-defined exit point, just for making sure you can hit a J-1/J-2/J-3 distance AND where you want to come out relative to the planet or other destination.


If you can program in a 2LY destination vs. a 3.1 LY destination in the wriggle room J-1 has to have to be functional in a non-evenly spaced universe, a 200 AU jump should be a snap.



Also, reading between the lines of jump tech, a lot of being able to hit those higher 'distances' in one jump HAS to be in part about that much better an understanding of jumpspace and making a CONTROLLED exit. Misjump is easy, reliable longer/'faster' jumps aren't. Example, virtually all editions of Traveller involve more powerful computing resources to get those better jumps.

 

[Condottiere]

Think of it this way: you have a jump factor one equipped starship.

You can jump from the southern most point of a parsec, to the northern most point of a connected hex, which let's assume is above the hex you're presently in.

This would be about six light years, probably more.

You could, then, when positioned a little off centre of a hex, jump two parsecs, over the connecting hex, to the following hex, exiting somewhat off centre of that hex.

That's why, in my opinion, additional minor fractions do not matter, unless you know where you are, and where you're getting off.

We could construct models of our solar system, that probably would be accurate three millenia down the road, but for every other hex, someone would have to simulate all that planetary motion in order to take advantage of the additional fractions, of a movement that abstractly already allows you to to jump from any point within one hex, and exit at any point in another, as long as the jump factor matches the distance.

 

[whartung]

Think of it this way: you have a jump factor one equipped starship.

You can jump from the southern most point of a parsec, to the northern most point of a connected hex, which let's assume is above the hex you're presently in.

Jump-1 is 1 parsec. That's it. Not 1.1. Up to 1 parsec.

One of the most interesting characteristics of the Traveller Universe, is not only is it FLAT, all of the systems live in the center of their hexes. Just what are the odds of that, but it shows it's just another one of the great mysteries that reflects on the power of the Ancients and their OCD nature. They squashed the galaxy flat while scattering Man across the stars.

If you want to map the J drive in to a more realistic astrographic situation, then J1 drives can STILL only jump 1 parsec. Need 1.1 parsec? Then either jump twice, or get a J2 drive.

The ships designs will adapt to such a universe, not the J drive. If most systems are 2-3 parsecs apart, then you'll have a bunch of J1 ships with a lot of fuel to make the extra jumps. Just the way it is.

 

[Condottiere]

So, a starship with a factor one jump drive does not have the range to transit from the far southern end of a hex and exit from the far northern end of an adjacent hex?

 

[mike wightman]

Technically no.

In practice it doesn't matter because the hex grid is an abstraction.

 

[Condottiere]

That's my realization when I read Interstellar Wars.

Because if it was calculated on actual distance, jump factor one starships, if correctly positioned, can skip over an intervening hex.

 

[Grav_Moped]

Jump-1 is 1 parsec. That's it. Not 1.1. Up to 1 parsec.

One of the most interesting characteristics of the Traveller Universe, is not only is it FLAT, all of the systems live in the center of their hexes. Just what are the odds of that, but it shows it's just another one of the great mysteries that reflects on the power of the Ancients and their OCD nature. They squashed the galaxy flat while scattering Man across the stars.

If you want to map the J drive in to a more realistic astrographic situation, then J1 drives can STILL only jump 1 parsec. Need 1.1 parsec? Then either jump twice, or get a J2 drive.

The ships designs will adapt to such a universe, not the J drive. If most systems are 2-3 parsecs apart, then you'll have a bunch of J1 ships with a lot of fuel to make the extra jumps. Just the way it is.

Or if you're going with real-world spacing between stars, set the distance of Jump-1 to approximate the shortest distance between nearby stars. That way J-1 gets you to the next star over. This is a "change the hex grid scale" approach rather than "change the number of hexes a Jump Drive can go" approach.

 

[Madmax]

Hmmm, well let me explain my view of what the star maps are representing, and thus why I suggested this addition to the jump drive model for those interested. The maps are fitting the 'real' galaxy into a hex grid for convenience. IMHO that means they are rounding all distances to the nearest whole Parsec. So if two stars are 2.34572 Parsecs apart they are shown as 2 Parsecs apart on the map.
Actual distance 2.5 Parsecs? Map shows 3 Parsecs. Etc.
It then seems logical that the Jump Drives rarely have exactly whole number Parsec maximum jump either. The actual Maximum Jump would then depend on the Jump Dimension used (1 through 6), as indicated by the Drive type (J1 - J6) AND the technology level, i.e. the maximum range creeps up with higher tech level.
As I said, my whole goal was to allow (for example) a Tech 14 J2 drive to have a useful advantage over Tech 11 J2 drive. Otherwise all J2 ships have exactly the same jump abilities, regardless of tech level, instead of the variety that makes having a higher tech JDrive an advantage to strive for. For example, it allows the ship owner to have more options of where to go without risk, when transporting cargo, than a competitor who has a less advanced J2 Drive.
It seems to me these differences could provide some interesting story hooks, for example a Patron asks the players to steal a Type J Seeker ship that has a prototype Tech 15 J2 drive that is capable of up to a 2.6 Parsec jump (perhaps with a slight misjump risk), because in the cutthroat competitive world of prospectors even a small jump increase can make the difference in scoring claims first.

 

[Grav_Moped]

In point of fact, you can build a Type S at TL13 that can do Jump-3: Replace the LBB2 drives with LBB5 ones. Drives total out to the same 15Td. It needs 33Td fuel instead of 40Td. Of the 7Td freed up by unneeded fuel, 1Td goes to upgrade the computer to Mod/2bis, 5Td go to the fuel purifier, and the last 1Td can be cargo.

At TL15, it could even be Jump-4 if you're willing to give up 1.5 staterooms, or the Air/Raft and 2 Td cargo space.

In both cases it's still 2G maneuver.

The big space savings is in power plant fuel, but at TL15 the power plant and fuel processor are smaller too.

 

[Madmax]

In point of fact, you can build a Type S at TL13 that can do Jump-3: Replace the LBB2 drives with LBB5 ones. Drives total out to the same 15Td. It needs 33Td fuel instead of 40Td. Of the 7Td freed up by unneeded fuel, 1Td goes to upgrade the computer to Mod/2bis, 5Td go to the fuel purifier, and the last 1Td can be cargo.

At TL15, it could even be Jump-4 if you're willing to give up 1.5 staterooms, or the Air/Raft and 2 Td cargo space.

In both cases it's still 2G maneuver.

The big space savings is in power plant fuel, but at TL15 the power plant and fuel processor are smaller too.

Which version of the rules are you using for this?

 

[Madmax]

Which version of the rules are you using for this?

Never mind. I see you said LBB5, so CT. No, I never liked LBB5 for this very reason, it made things too easy (and was inconsistent) IMHO.

 

[Condottiere]

If you want to make it more granular.

Divide the hex into seven sub hexes; the subdivide the sub hexes into seven mini hexes.

That ought to give you about nine or ten mini hexes to cross a hex.

Of course, now you need to place everything within the hex into where they'd be in the mini hexes.

That would kinda fit into my supposition that it's jump factor plus a quarter, or you can be generous and say ten mini hexes per jump factor, plus three.

And you can squeeze a jump factor four out of a hundred tonne hull.