Jump Bubbles

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GypsyComet
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Re: Jump Bubbles

Postby GypsyComet » Sat May 03, 2014 5:49 pm

Mostly because fissionables are not a standard assumption, so they too are a handwave.

A common PP handwave that can handle this is the presence of a "starter motor" in all power plants. It only generates a small percentage of the powerplant's total output, but also burns a similarly small percentage of the fuel.

Another, seen in MT, is the idea of a low power mode. Late MT is where the idea that would later become the segmented plants of T20 and T4 came from; you don't have one PP, but several, either conceptually or as actual components. If you get into a bad spot, you turn off all but the emergency beacon, a little temperature control (so the ship will be visible in IR, if nothing else), a few lights, and the cold berths, and run on your smallest sub-plant (possibly in its lowest mode). The computer might run an automated scan for rogue planets or icy bodies occasionally.

If your available duration is at least two years and your beacon loud enough (and/or pointed at the right system), rescue is pretty likely. Not all systems are listening, but most settled systems probably have some sort of beacon listening box floating in solar orbit, since they are going to be cheap for any world above Space Family Robinson levels of population and any level of contact with the neighbors.

Of course, if you are outside of polity space in unknown territory, giving yourself a boost toward something likely to have hydrogen is probably a good idea, because there is no one out there to hear you...
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Re: Jump Bubbles

Postby sideranautae » Sat May 03, 2014 7:57 pm

GypsyComet wrote:Mostly because fissionables are not a standard assumption, so they too are a handwave.
No. There are PP's that are fission. Fission has ALWAYS been part of Trav. From '77 on.
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Reynard
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Re: Jump Bubbles

Postby Reynard » Sun May 04, 2014 1:05 am

I just looked through the five MT books featuring space and starships and only the Galileo research vessel has emergency low berths with no explanation as it doesn't match the crew compliment. Not every vessel carries low berths. Trade ships use them for passengers not life boats the safari ship stores live trophies, security vessels, the bounty hunter and pirates use them for prisoners, the hospital ship keeps seriously ill or injured patients 'on ice' and military ships carry frozen watches which get rotated out during missions. That means no one really wastes space with ELBs or even LBs for life boat purposes even though they exist.

As a life boat again, they fail once a ship runs out of fuel. Not very useful. Using them for such purposes usually might involve an unwritten game mechanic that powers the ship to minimal so the transponder (there's your beacon) and low berth function. Unless your paranoid though, your LBs are already carrying people. This would be more for a mild misjump putting you at extended range for the amount of fuel you carry.

Again, dropping out of jump space early or a bad misjump is a death sentence. The first would be a conscious decision due to circumstance while the later can be rare but unfortunate die roll.
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Re: Jump Bubbles

Postby hdan » Sun May 04, 2014 1:28 am

Condottiere wrote:The way I see it, if for any reason you are prematurely ejected from hyperspace the crew only experiences the time passed until that event; what happens in realspace could be anything, from time passed matching that of the crew's experience, to some point in the future, but never into the past.

Distance travelled could match time divided by jump factor, or could be subject to some warped physics within hyperspace that can pitch them all over the place, with dimensional crosswinds, blackholes and who knows what.
The reason that can't work in the OTU is that it would allow J-2 ships to make a J-1 in 1/2 of a week. That's a popular house rule (I've used it myself), but it *is* inconsistent.

In MTU, I view a jump as sort of a hyper-ballistic trajectory. You set yourself going on a course, and the sophistication and power of your jump bubble generator controls what path you take. The drive has to stay running to prevent the pocket universe from collapsing on you, but the moment of the jump is when the 'die is cast', so to speak.

(I've actually played around with the idea that once initiated, but bubble naturally decays in about 168 hours, and you are truly just along for the ride. The decay of the bubble is what propels you through J-space, like a balloon with an open nozzle, and the drive holds the bubble's shape to permit a predictable trajectory. Though it's a fun idea, I think it might cause more problems than it solves.)
/hdan
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Re: Jump Bubbles

Postby AndrewW » Sun May 04, 2014 3:24 am

Reynard wrote:I just looked through the five MT books featuring space and starships and only the Galileo research vessel has emergency low berths with no explanation as it doesn't match the crew compliment.
20 staterooms.
5 low berths, which each holding up to 4. So that's 20.

Staterooms can hold up to 2, but amount of researchers on board will vary.
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Re: Jump Bubbles

Postby GypsyComet » Sun May 04, 2014 7:05 am

sideranautae wrote:
GypsyComet wrote:Mostly because fissionables are not a standard assumption, so they too are a handwave.
No. There are PP's that are fission. Fission has ALWAYS been part of Trav. From '77 on.
Cite pages in the 77 edition that are not just trade goods, please.

Also keep in mind that the 77 edition is prior to the setting in any form.
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Reynard
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Re: Jump Bubbles

Postby Reynard » Sun May 04, 2014 11:20 am

I must not write so late at night when my internal math calculator is on low batteries. I somehow was thinking double bunking for a stateroom. Still, why is the Galileo the only ship to carry emergency low berths? Long naps between research projects? Even the safari ship uses low berths, not emergency berths. for preserving live trophies as well as the hospital ship for patients.

Emergency low berths seem to be a good idea only for paranoid adventurers with cash and cargo space. Then again, they are the last best hope in a bad situation. I notice the MT rules don't differentiate the mechanics of the two types except the ELBs are more compact and cheaper. Other editions say all four berths make one survival roll; not good odds. Yeah, the dealer never tells you that part at the sales pitch. I've never considered them when designing a ship.
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Re: Jump Bubbles

Postby AndrewW » Sun May 04, 2014 2:26 pm

Reynard wrote:I must not write so late at night when my internal math calculator is on low batteries. I somehow was thinking double bunking for a stateroom. Still, why is the Galileo the only ship to carry emergency low berths? Long naps between research projects? Even the safari ship uses low berths, not emergency berths. for preserving live trophies as well as the hospital ship for patients.
It's a research ship, possibility of something happening out there. Maybe they are observing something that sudenly emits a burst that knocks out most of the ships systems or something. With emergency low berths rather then the regular low berths that leaves more space for research equipment and the like.
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Re: Jump Bubbles

Postby Wil Mireu » Sun May 04, 2014 9:01 pm

GypsyComet wrote:
sideranautae wrote:
GypsyComet wrote:Mostly because fissionables are not a standard assumption, so they too are a handwave.
No. There are PP's that are fission. Fission has ALWAYS been part of Trav. From '77 on.
Cite pages in the 77 edition that are not just trade goods, please.

Also keep in mind that the 77 edition is prior to the setting in any form.
Is the 77 edition really relevant to any discussion of Traveller anymore? Fission reactors have been in Traveller since at least MegaTraveller, and were probably in CT somewhere too.
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Re: Jump Bubbles

Postby Reynard » Sun May 04, 2014 11:32 pm

I'm looking through my well worn 1977 boxed set Traveller including all the supplements. I haven't gone through every issue of JTAS or Far Traveller or High Passage or Traveller's Digest that may have an article concerning low tech fission plants. So far a 'power plant' is the power plant to power the lights and maneuver drive.

Also, there was no fission power plants as cargo back then. There were no individual manifest description except the single unit 'cargo' so the plants weren't mentioned there. For the thirty years of Traveller material, I don't remember fission power for starships except MegaTraveller. MegaTraveller was the minutia expert edition.

Seriously, don't justify fission over fusion by citing MegaTraveller. For each dton of plant:
TL 6 Nuclear fission 14 Mwt 100Kcr 0.028 Kl/hour fuel rate radioactives at 12 kg and 75 Kcr/Kl
TL 9 Fusion 28 Mwt 200Kcr 0.042 Kl/hour fuel rate hydrogen at 1 Kg and .035 Kcr/Kl

Leave MT power plants as safe and very efficient fusion. KISS.
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Re: Jump Bubbles

Postby Condottiere » Tue May 06, 2014 6:20 pm

Coming back to sudden/unexpected transitional re-entry, probably one of the reasons passengers tend to select ships with good reputations and known maintenance record, preferably a large spaceline with regular service.
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Re: Jump Bubbles

Postby Bardicheart » Wed May 07, 2014 11:45 pm

Wow, I get busy for a few days an you guys take off without me! lol
sideranautae wrote:
Bardicheart wrote: At this point, for me anyway, the essential remaining question is... how long does it take to form the jump bubble and fill it with hydrogen? Or put another way, "How long do the players-characters have to sweat while being pursued/shot at before they can jump away?"
The time increment for the Engineer's skill check to initiate jump may offer a clue...
So from CR, p54
Making a Jump: Intelligence, 10–60 minutes, Routine (+2).

First reaction... OUCH! That would pretty much make a ship a sitting duck for up to an hour. Even 10 min would seem like an eternity if someone is after you. But, then I recalled this...

CR, p 50
Going Faster or Slower
You can choose, before you roll, to move up or down one or two
rows on the Time Frames table. Moving up (reducing the time
increment) gives you a –1 DM for every row you move; moving
down and increasing the time taken gives you a +1 DM for every
row you move.


So one row up would reduce the time to 1-6 minutes, not bad... could still be bad though and a -1 DM.

Two rows up would reduce time to 10-60 seconds, pretty quick and a -2 DM.

To that point I don't have a problem with it. But the third row up is 1-6 seconds at a -3 DM. At this point I find believability being busted. I can't see a jump field being formed, filled with hydrogen, and then it and the ship entering jump space in all of 6 seconds, possibly only 1. So I'm thinking 10-60 seconds would be an absolute minimum.

Regarding what maintains the "jump bubble" during transit. My take on that is that the hydrogen maintains the bubble (why it does this I couldn't tell you, I'm guessing its "the cosmic creators decreed it so because it seemed like a good idea at the time") and there is no need to use power to maintain the field. That does raise the question though, how exactly does one re-enter "real" space? Do you "burst" the bubble and "pop" you're back or do you have to trigger some other gizmo or are you just stuck until it degrades and collapses on your own and "pushes" you out into real space? What about this reference from CR p141

This new universe is short-lived, and will eventually collapse,
precipitating the ship back into normal space several light-years
from its original position.


And this one from a little further down on the same page...
Gravity can cause a Jump bubble to collapse
prematurely, bringing a ship back into normal space early (so if a
ship tried to Jump from Earth to Mars when the Sun was between
the two, the vessel would fall out of Jump space as soon as it came
within one hundred diameters of the Sun.

Condottiere wrote:You turn off the power or the jump drive hiccups, you re-enter (hopefully) realspace.

Th probable reason no one does that voluntarily, is because it stresses out the equipment and the hull. And re-entry could be catastrophic.
Given the above references I don't think turning the jump drive off would have any effect, I think in fact its already shut down. If there was some way to deliberately trigger a premature return to normal space I'd treat it as a misjump, meaning maybe it kills you, you jump some where far away, you come out right where you started (maybe EXACTLY where you started), and you might be missing a week, a year, or a century.

What I would also include with misjumps, and this is a house rule on my part, is that given that gravity seems to affect the jump bubble any misjump dumps you out near some gravity field. That could be a star system, a gas giant, a rogue planet wandering though deep space, a black hole (oops), etc. But you wouldn't come out in the middle of no where.

Why are emergency low birth's so rare?
My guess, editing oversight on the part of Mongoose.

So now I've got two questions.

First question:
Assuming that forming the jump bubble and making the transition to hyperspace takes 10-60 minutes (adjusted for time as per rules on p50), how difficult would it be for someone to disrupt that jump field or disperse enough hydrogen to prevent a jump (or cause a misjump)? For example, you see ship A preparing to jump. Ship B fires a barrage of missiles at the ship. Some of these missles impact the ship or near it and the explosions disperse some of the hydrogen filling the jump field. Given that jump drives seem sensitive to volume wouldn't loss of some of they hydrogen cause the jump to fail, come up short, or misjump? (If you're 1 dT over your drive limit the range is degraded a full parsec, by that logic if you displaced 0.5% of the hydrogen, wouldn't that have a similar effect?) What other ways might the jump bubble be disrupted by a hostile attacker? If this is fairly easy, would this not seriously affect jump travel and combat tactics?

Second question:
Theories on how a ship re-enters normal space. It seems like, from the two quotes from p141, you're pretty much stuck for roughly a week (148+6d6 hours) until the bubble collapses on its own, you can't get out deliberately. What happens if an uncharted comet, rogue planet, etc. crosses your path during transit? Do you exit but a full week has still passed, do you pro-rate the amount of time based on distance traveled, or do you make the amount of time that has passed in the real universe random (you might have been in jump space for 3 days, in the real universe 1 day or 1 year may have passed)?

CR = Mongoose Core Rules
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Re: Jump Bubbles

Postby sideranautae » Thu May 08, 2014 1:16 am

Bardicheart wrote: Second question:
Theories on how a ship re-enters normal space. It seems like, from the two quotes from p141, you're pretty much stuck for roughly a week (148+6d6 hours) until the bubble collapses on its own, you can't get out deliberately. What happens if an uncharted comet, rogue planet, etc. crosses your path during transit? Do you exit but a full week has still passed, do you pro-rate the amount of time based on distance traveled, or do you make the amount of time that has passed in the real universe random (you might have been in jump space for 3 days, in the real universe 1 day or 1 year may have passed)?

This one is easy. If you aim for a planet but hit its 100D mark before you reach the planet how long are you in jump? 148+6d6 hours. Leaving jump because you reach a gravity well is considered a "normal" exit. No danger. Just use the same time period because a micro-jump uses the same time period. Deliberately ending a jump by sucking the hydrogen back into the ship (or whatever other creative means one uses) is a mis-jump situation. Roll on a table or let the GM take out his pent up aggression... :twisted:
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Re: Jump Bubbles

Postby Condottiere » Thu May 08, 2014 12:52 pm

One problem with vague descriptions, is that it's a lot harder to find (or perhaps, more precisely, justify) loopholes.
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Re: Jump Bubbles

Postby Bardicheart » Sat May 10, 2014 11:31 am

sideranautae wrote: This one is easy. If you aim for a planet but hit its 100D mark before you reach the planet how long are you in jump? 148+6d6 hours. Leaving jump because you reach a gravity well is considered a "normal" exit. No danger. Just use the same time period because a micro-jump uses the same time period. Deliberately ending a jump by sucking the hydrogen back into the ship (or whatever other creative means one uses) is a mis-jump situation. Roll on a table or let the GM take out his pent up aggression... :twisted:
Hmmm, not so sure I would agree. I do agree the time that passed for the crew would seem like 148+6d6 hours, that part of the rules is pretty clear. But, how much time passed in real space? Could be the same but then again, maybe not. I would be tempted to treat it as a type of misjump, except in this case where you come out is known, its just a question of when. But then when I consider the question of how much time passed in real space I start getting headaches. On the one hand, say in your transit an uncharted comet passes 3 days in and forces you to precipitate out of jump space. For the crew 148+6d6 hours has passed, but in real space only 3 days has passed... I can deal with that. But, its when I start considering the possibility that maybe more than 7 days has passed, several weeks, a year, etc. that I start getting relativity / time-travel headaches. Probably just over thinking it. For the sake of sanity, ship experience 148+6d6 hours, real time is whatever point GM decides the source of the gravity well crossed the ships path. Should be a very rare event but its one of those arbitrary things that could be fun to do once, maybe twice in a campaign as part of an unexpected adventure.
So you suddenly find yourself back in real space, something doesn't feel right. Sensors confirm you're not where you are supposed to be, damn, misjump. Oh no... there's no star, nothing just, wait... there's something there, gravity signature... its big, a planet. A rogue planet, a frozen world. Good news is you can crack the ice for hydrogen and refuel. Landing goes well, you set down on this strange world and get the equipment going to start cracking ice when you see something strange in the distance...
And you're off on another exciting Traveller adventure where in something tries to kill you and you wonder yet again why the Universe seems to have a grudge against you...

I would not allow them to deliberately collapse the bubble early. If they did, and I'd strongly discourage it, would automatically be a misjump and probably with really bad results... like... "so, how does it feel to be a sudden gamma ray bursts?"
Condottiere wrote:One problem with vague descriptions, is that it's a lot harder to find (or perhaps, more precisely, justify) loopholes.
True... but I got faith in you guys! 8)

What about this? Making an educated guess, a missile detonating inside the filling jump bubble will displace enough hydrogen to either force the jump to be aborted or if its a rapid jump (10-60 sec) the computer cut outs don't have time to kick in and you jump with an automatic misjump (roll for random exit point and maybe a time warp with a slight chance of gamma ray burst). Makes jumping during combat somewhere between stupid and suicidal.
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Re: Jump Bubbles

Postby Reynard » Sat May 10, 2014 11:44 am

From what I gather in the thirty plus years of the game, time is the same both in real space and within that bubble of real space you brought with you but jumpspace compacts distance with each layer of jumpspace. You don't travel faster per se just farther.

I'm sure there's a chief engineer out there saying "I hate jump paradoxes!"
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Re: Jump Bubbles

Postby sideranautae » Sat May 10, 2014 1:53 pm

Bardicheart wrote:
Hmmm, not so sure I would agree. I do agree the time that passed for the crew would seem like 148+6d6 hours, that part of the rules is pretty clear.
The rule is, Jump only 6 inches (in system jump) and it takes 148+6d6 hours. Jump 1 parsec and it takes 148+6d6 hours.

You need to restudy the rules.
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Re: Jump Bubbles

Postby Reynard » Sat May 10, 2014 4:50 pm

Yeah, get rid of microjumping. Who really uses it anyhow and assume the drives are optimized for interstellar distances rather than inter solar.
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Re: Jump Bubbles

Postby sideranautae » Sat May 10, 2014 5:06 pm

Reynard wrote:Yeah, get rid of microjumping. Who really uses it anyhow and assume the drives are optimized for interstellar distances rather than inter solar.
Has nothing to do with drive configuration. It is how jump space works. Microjumping is needed for long distance travel in solar systems.
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Re: Jump Bubbles

Postby sideranautae » Sat May 10, 2014 5:44 pm

GypsyComet wrote: No. There are PP's that are fission. Fission has ALWAYS been part of Trav. From '77 on.

Cite pages in the 77 edition that are not just trade goods, please.

Also keep in mind that the 77 edition is prior to the setting in any form.
Sorry, I missed this post. Um, for those who are new to Traveller. (didn't play the original version or weren't born yet) I believe that you'll find that FISSION PP's will most likely be listed in the LBB #3 under world generation, TL descriptions column for power sources by TL.

I haven't cracked that particular book in over 20 years though so don't know the page number...

Of course this datum was obviously in the game from the beginning as Marc had in mind back then that Earth history was going to be part of the game...
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