Velocity and Jump Space

[FallingPhoenix]

It will, once I figure out how to minimize power output in relation to transitional requirement.

If you want to minimize power output, you apparently don't want to mention T5.

 

[Nerhesi]

Hah -zing.

It has occurred to me, before as well, that ruling that space vehicles come out of jump with 0 momentum is perfectly fine. Technically, with no clear explanation as to Jump-space, you can easily deduce that when you jump, you are accelerated to some multiple of c, then you de accelerate on exit. Inertia, structural integrity, etc - all may not apply due to the "black box" nature of jump space.

So really, it is a Traveller legacy thing, not a realism or that other word that refuse to type... ok fine, versmiliciscitude (pls fix)

 

[Reynard]

Not a 'realism'? Do you know something about jumpspace not on the books? Marc and the gang created jumpspace and for forty years, from Classic to T5, have described how it works. Realism and the real world has no bearing on the mechanics of jumpspace. Conservation of momentum has always been there.

 

[Nerhesi]

Not a 'realism'? Do you know something about jumpspace not on the books? Marc and the gang created jumpspace and for forty years, from Classic to T5, have described how it works. Realism and the real world has no bearing on the mechanics of jumpspace.

That is what I stated just above... It is not a realism, as in the real-world thing. Glad we both agree.

Conservation of momentum has always been there.

That I did not see - despite owning those books. So it's been expressly stated that velocity prior to jump = velocity after jump?

 

[Reynard]

Nerhesi, sorry about my wording concerning realism. I look again and realize I wrote it incorrectly. A bit of confuzzilation at the time. Here are all references I found so far.

Traveller: The New Era - "When a ship leaves orbit and accelerate to the safe jump distance (100 diameters), they do not usually decelerate When they arrive. Instead they jump out-system while still traveling at a high rate of speed. This vector is retained when it jumps in-system at its destination and this is called residual velocity."

MegaTraveller Starship Operation Manual - "Further, the normal laws of conservation of mass and energy apply to a craft entering or leaving jumpspace. Thus a craft which is travelling at 150 kilometers per second when it jumps will be moving at the same velocity and direction when it reenters our universe."

"In cases where the origin and the destination stars have a great proper motion with respect to each other, the navigation computer automatically compensates for it in the jump vector computations. If factors such as this were not considered, the ship may find itself hurtling through space at an undesirable speed and direction in the new system and be unable to counter with its remaining fuel supply."

Marc Miller's Traveller - "Although jumps are usually made at low velocities, the speed and direction that the ship held prior to jump is retained when it returns to normal space."

Traveller20 - "Astrogators attempt to arrive as close as possible to the 100 diameter Jump limit, with residual momentum towards an orbital position (not the planet itself, just in case...),"

"Achieving [perfect Jump] it would be something of a fluke and most Astrogators never get within 5% of all three factors (duration, exit point and vector) at the same time.

Traveller5 - "...gravity-based drives are generally ineffective [to change speed and direction in Jump space]."

"Vectors are preserved. The law of conservation of momentum applies to ships as they enter and exit jump space."

"Absent any changes made in jump space [with a non-gravitic drive], a ship arrives at its destination with the same vector (speed and direction)as when it left. Speed and direction are expressed within a constant frame of reference which encompasses both the start and destination (that is, probably relative to the galactic core)."

It would take a while to go through every Journal of the Traveller's Aid Society which was where Classic added details to their version of the game.

 

[phavoc]

Nerhesi - Yeah, Reynard schooled me in those examples too. It's not in every version, and it's not always put in a place you'd expect to read it.

So the concept is more or less canon for Traveller as a whole. However, none of the rule systems have anything (that I'm aware of) to deal with the concept. It's one of the many irritating parts of the game mechanics system in that they don't always mesh well together. As I said upthread, if you do something like this, you are able to essentially arrive on the edge of the 100D limit at high speeds, thus making it impossible for a lurking ship to intercept you.

Plus if you take this into account, you have to track the number of G-hours, or G-minutes the ship spent accelerating to jump. That same time period must be applied upon exit. Which is something none of the versions talk about (again, that I'm aware of). It's always been how long does it take a ship to travel from 100D to orbit (the reverse of the travel tables).

N-space travel has always been 50% acceleration, 50% deceleration. The rest was more or less ignored as a game mechanic as the intent was to make it more of an RPG rather than a ship-to-ship sort of thing. Which is ok, but also leaves a big hole in the game mechanics if you want to have fun with ship-to-ship encounters.

 

[Reynard]

By the same extent being described here, there is no rule or game mechanic saying you can get away with screaming out of J-space and just waltz past any opposition. The rules do say once an encounter occurs all participants start at sighting range, either V. long range or Short to Medium near a planet and commence combat.

 

[hdan]

"In cases where the origin and the destination stars have a great proper motion with respect to each other, the navigation computer automatically compensates for it in the jump vector computations. If factors such as this were not considered, the ship may find itself hurtling through space at an undesirable speed and direction in the new system and be unable to counter with its remaining fuel supply."

How is this not a contradiction of the idea that velocity is preserved?

I guess it implies that "relative to your gravity framework" or something vague like that, but there's no reason then that a jump couldn't just cancel out any unwanted momentum.

From a gaming perspective, this at least allows the astrogation roll to give you a "how close to matched up were we?" result, which of course really just randomizes how long it takes to get to the mainworld once you precipitate. That sort of rule is good, in my opinion.

 

[phavoc]

By the same extent being described here, there is no rule or game mechanic saying you can get away with screaming out of J-space and just waltz past any opposition. The rules do say once an encounter occurs all participants start at sighting range, either V. long range or Short to Medium near a planet and commence combat.

Yeah, but that is diametrically opposed to the concept of retaining momentum coming out of jump space. You can't have both rules - or at least not with a straight face. That is a complete rules miss, which I think is why this discussion is happening.

It would be better to revise the retention of momentum coming out of jump space into a rule that says regardless of your velocity when you enter jump space, when you exit your velocity is always zero. This aligns the rules AND makes far more sense. Your heading, at zero velocity becomes a non-issue, even for spinal-mounted weapons because you can always point towards your enemy in your combat turn.

 

[Reynard]

Maybe then there needs to be that rule for automatic Zero Vector due to Jump space physics as a particular Mongoose rule to fit with Mongoose space combat. It will be a first in forty years. It will also be the first ridiculous rule I ignore since I can grasp the game implication of vector conservation without going munchkin abuse on it's use still have a fun game play as I've done for forty years.

 

[phavoc]

Maybe then there needs to be that rule for automatic Zero Vector due to Jump space physics as a particular Mongoose rule to fit with Mongoose space combat. It will be a first in forty years. It will also be the first ridiculous rule I ignore since I can grasp the game implication of vector conservation without going munchkin abuse on it's use still have a fun game play as I've done for forty years.

Maybe. Munchkins can be dangerous. You probably owe SJG a dollar for using "munchkin abuse".

But more to the point, I don't see why you have issue when you are presented with two rules that contradict one another. So if you think it's "ridiculous" to point out the contradiction, how do you reconcile a ship that accelerated non-stop for 4hrs at 1G, jumps, then emerges and can be caught from a ship that has been sitting still?

What exactly is the issue with aligning the rules so that they, I dunno, don't contradict one another? It seems to me, who also has been playing since the introductory LBB's, that any time you can fix the rules so that they flow well together it's a win for everyone. People do buy rulesets for games not because they are going to toss everything out but because they are willing to pay for someone else to come up with rules they don't have to make up on their own.

So I'm very interested to here in why you can defend an error when it's easy to fix. Or else adjust the other rules to account for the ability to emerge from jump space at high speeds and zip past any ship. I don't see a good argument that defends retaining the two opposing views except with a defense of "don't change anything". And if you use that logic, why would you be interested in the MGT2 gaming system in the first place? It's all about change!

 

[Nerhesi]

I see now.

We are all on the same page now I think.

a) Velocity pre-jump is maintained post jump.
b) The rules do say you begin at X-distance with no presupposition of speed/velocity though...
c) How do A and B not contradict then? Assuming you, as the jumper/aggressor, wanted to jump with a pretty high velocity...

Yes we can definitely house rule it or make small modifications and so on, however, I do not think anyone would want to jump with any existing/initial velocity

Considering Jump Time is random, no matter how well you roll, you will therefore never be heading anywhere you intended to. The only exception to this would be stationary space-objects/stations that are not orbiting anything...

Otherwise, that 30 seconds difference (let alone several days), due to planetary orbital speeds can suddenly have your military force shooting off in a completely incorrect direction. Or worse, it can have you heading into some other planet, satellite, asteroid belt or what have you...

But thanks for all those links Reynard

 

[Nerhesi]

By the same extent being described here, there is no rule or game mechanic saying you can get away with screaming out of J-space and just waltz past any opposition. The rules do say once an encounter occurs all participants start at sighting range, either V. long range or Short to Medium near a planet and commence combat.

Yeah, but that is diametrically opposed to the concept of retaining momentum coming out of jump space. You can't have both rules - or at least not with a straight face. That is a complete rules miss, which I think is why this discussion is happening.

It would be better to revise the retention of momentum coming out of jump space into a rule that says regardless of your velocity when you enter jump space, when you exit your velocity is always zero. This aligns the rules AND makes far more sense. Your heading, at zero velocity becomes a non-issue, even for spinal-mounted weapons because you can always point towards your enemy in your combat turn.

That would be good and I'm totally fine with that. But, as others have pointed out.. thats not very.. legacy travellerish? Granted - neither is 9G Thrust but now we have it as cannon direction from above anyways - as well as Jump 7 at TL16 and so on

So really - Cannon isnt synonymous with "has always been thus"

 

[phavoc]

That would be good and I'm totally fine with that. But, as others have pointed out.. thats not very.. legacy travellerish? Granted - neither is 9G Thrust but now we have it as cannon direction from above anyways - as well as Jump 7 at TL16 and so on

So really - Cannon isnt synonymous with "has always been thus"

Meh. Canonical info is good, but I don't see the need to keep buying the same exact version of Traveller over and over again. So I expect changes and tweaks to the rules and additional contributions over time. What is bothersome is when a problem gets identified and nothing gets done to fix said problem. Canon mistakes abound and some get fixed, while others do not. Now THAT is annoying.

And you are quite right - if canon can be "broken" for going beyond 6Gs, why can't other things be "broken" too? Especially if they are fixing something by doing so.

 

[AndrewW]

That would be good and I'm totally fine with that. But, as others have pointed out.. thats not very.. legacy travellerish? Granted - neither is 9G Thrust but now we have it as cannon direction from above anyways - as well as Jump 7 at TL16 and so on

Had up to 16G before, was just limited to small craft. More along the lines of some limits expanding then anything new.

 

[phavoc]

That would be good and I'm totally fine with that. But, as others have pointed out.. thats not very.. legacy travellerish? Granted - neither is 9G Thrust but now we have it as cannon direction from above anyways - as well as Jump 7 at TL16 and so on

Had up to 16G before, was just limited to small craft. More along the lines of some limits expanding then anything new.

We've been talking about jump capable ships, though it's never been well understood why ships topped out at 6G. But things like fleshing out the maneuver ratings are fine with me. As is something like making 500 to ships that don't get treated like 600 ton ones. Some arbitrary rules are just fine (100 ton minimum for jump ship) but others seem capricious, like the hull tonnage chart, that don't make sense and come off as simply arbitrary - in a bad way. Games often have arbitrary things because they are games. But they should at least follow some sort of internal rule set that stays true to itself.

 

[Reynard]

Problem is I don't believe Mongoose ever planned to make their Traveller as complex and detailed as MegaTraveller or even Marc Miller's Traveller ship systems. They were sticking with the simplicity of Classic. Simplicity doesn't always create the minutia of rules for design such as hulls of every conceivable size or complicated power systems that need calculating (and recalculating) with electronic devices. Simplicity doesn't define every possible rule for every possible situation that playtesters can imagine. Same thing drove Robocop to a mental breakdown. That's why I like Mongoose, simple and therefore fun to play.

 

[phavoc]

But that still doesn't address your point. If you like simple, then you should approve of the idea that ships emerge from jump space with zero velocity. That fits in better with the encounter chart and it keeps play simple. What more could you ask for?

I like simple rules too. I don't like seemingly arbitrary holes in the rules that make no sense. Classic Traveller is the way it is because D6 was the chosen die and so many tables are based on 2D6 rolls. Not a bad think, but they impose specific limits that sometimes can be tweaked to both ADD and keep things simple. Those two issues aren't mutually exclusive.

 

[FallingPhoenix]

If retaining velocity through a jump is (ahem) retained in the rules, we really need a note in addition to the current travel times table to show how fast you can get to and from the 100D limit if you're only speeding up on the way out, and only slowing down on the way in.

 

[Condottiere]

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