How do jump drives really work?

[whartung]

I've never seen any reference, pretty much anywhere (but I have not read every shred of Trav material), that mentions any need for a Jumped ship to readjust their clocks upon entry (vs say setting it to local time like when you fly from the west coast to east coast), nor any relativity effects on folks in "normal" space vs "jump" space. No mention of aging or non-aging affects, no mention of age discrepancies, players manipulating J-Space with money in interest bearing accounts, zip nada.

So, after applying a thick layer of handwavium cream to the Jump vs Normal space, I'd argue that there is no relativistic effect. When you're in J-Space for a week, it's the same week as those who are out of J-Space.

And, finally, if you want to reconcile fuel usage, you need to reconcile it with the fact that it's ALL consumed PRIOR to jump, otherwise drop tanks "don't work".

 

[shadowcat20]

So for drop tanks to work All the fuel must be used in the process of opening the jump point and entering it......fair enough.....We are back to the fuel is either used for power or cooling....or forming a bubble in jump space for the ship to enter.


Hmm...maybe the jump drive takes the H2 and spits it out at almost C to open the jump point. Or sends it out FASTER than C to start the process. The bigger the ship and the further it goes then more you need to excite the boundry between Normal space and Jump space to enter. The week time frame is how long the ship will stay in jump space before being kicked out and gravity wells just attract the mass of the ship more.

 

[Dragoner]

I've never seen any reference, pretty much anywhere (but I have not read every shred of Trav material), that mentions any need for a Jumped ship to readjust their clocks upon entry (vs say setting it to local time like when you fly from the west coast to east coast), nor any relativity effects on folks in "normal" space vs "jump" space. No mention of aging or non-aging affects, no mention of age discrepancies, players manipulating J-Space with money in interest bearing accounts, zip nada.

So, after applying a thick layer of handwavium cream to the Jump vs Normal space, I'd argue that there is no relativistic effect. When you're in J-Space for a week, it's the same week as those who are out of J-Space.

And, finally, if you want to reconcile fuel usage, you need to reconcile it with the fact that it's ALL consumed PRIOR to jump, otherwise drop tanks "don't work".

Of course there would be time dilation with normal G drives, but this isn't discussed in the rules. I am trying to fill in the blanks with real (or theoretical) physics. I have an aversion to too much handwavium if at all possible. Maybe it is like OCD, but I even think of ships having a mini-repulsor field extendind from the ship a few cm to ward off dust and micrometeorites in normal G acceleration.

That normal week could be a buffer, in which the drive synchronizes the ship's jump bubble with normal space, no need to adjust the clocks, the drive is doing it. Though in the double bubble theory, it would make sense that the bubble of normal space held within the False Vacuum bubble, would be sync'd back in with normal space as before the nucleation of the "jump bubble", just in case the normal space the ship was in had somehow become out of sync before re-entry.

The fuel usage could be explained in that all the fuel is used to create the False Vacuum Jump Bubble at a higher energy state. Maybe the j-drive does it in realtime or maybe the drive has some quantum phase (don't touch it or your hand will be shredded into 10cm pieces like a drop tank).

I have a question: once jump is initiated, can it be aborted? If yes, at what stage?

 

[mike wightman]

There is no hydrogen jump bubble ever mentioned in CT canon - ever.

And every time someone says that hydrogen is necessary in some way to actually open the jump point/survive jump space I will remind them that the Annic Nova class of ship can do both without using hydrogen.

 

[Dragoner]

I'm working off the wikia:

The Jump Drive opens a transition to jumpspace. Every ship stays in jump for around one week before entering normal space again. Ships in jump are isolated, and can not detect or communicate anything; they are totally isolated in a small bubble of space until they reemerge into out universe again.

and not supposing a hydrogen bubble.

 

[shadowcat20]

The Annic Nove was a unique ship from what I have seen. It was a unique design in the game so it would have a unique way of working.

We are heading full circle back to it is done on Capacitors only. Unfortunatly that is way too easy to break in game. Great for power gamers but not realistic for a made up game... We get back to filling the hold with spare caps and turning the tankage into cargo. Then the characters get a 400 ton ship with jump 2 or more and 300 tons of cargo. Can we say game breaker? At that rate just give them a Anti Matter drive for the same effect.

My goal is to find a reasonable way for the system to work that fits in with cannon but makes sense. I am also looking for a way to break power gaming tricks the characters may try. The entire capacitor mess was started with black globes from HG and never fully explained in the LBB version. It worked well for combat but left too many questions.

Ok rant over, this thread is still very interesting and I am glad you guys are throwing around so may ideas.

 

[aramis]

I've never seen any reference, pretty much anywhere (but I have not read every shred of Trav material), that mentions any need for a Jumped ship to readjust their clocks upon entry (vs say setting it to local time like when you fly from the west coast to east coast), nor any relativity effects on folks in "normal" space vs "jump" space. No mention of aging or non-aging affects, no mention of age discrepancies, players manipulating J-Space with money in interest bearing accounts, zip nada.

See the sections on jump mishaps in TNE and MT core rules.

T:TNE p.227
MT-IE p.93

Both use the term "Jump Relativity Error" (JRE)- it affects how long you stay in jump. SSOM mentions temporal misjumps.

Neither mentions it causing clocks to be reset, but some GM's interpreted it to be perceived onboard time (POT) is affected but not actual galatic reference time (GRT); others took it to be adjusting GRT but not POT, and a few roll for both. (SSOM implies fairly clearly that POT and GRT are the same... but many of us had our house rules in place before that came out.)

 

[rancke]

And every time someone says that hydrogen is necessary in some way to actually open the jump point/survive jump space I will remind them that the Annic Nova class of ship can do both without using hydrogen.

And every time someone brings up the Annic Nova, I will remind them that it's a very early reference that can be either ignored (like the early CT fusion torch maneuver drives)[*] or explained away ("The Annic Nova is built around an Ancient artifact that provides the fuel it needs").

[*]If jump drives could be explained without violating some piece of canon, there wouldn't be a controversy in the first place. And if the only bit that needed to be ignored was the Annic Nova, I think it would have happened years and years ago.​

Hans

 

[rancke]

See the sections on jump mishaps in TNE and MT core rules.

T:TNE p.227
MT-IE p.93

Both use the term "Jump Relativity Error" (JRE)- it affects how long you stay in jump. SSOM mentions temporal misjumps.

True, but those are for when the jump drive misbehaves. There is no evidence that it happens when the drive works correctly.


Hans

 

[Xerxeskingofking]

as far as i know, modern physics hit a singularity at light speed, so what happens at that point is unkown.

however, i must point out that a ship travelling though J-space, as near as i can understand never has a velocity greater than that of light. it accelerates up to the 100D limit, and then, travelling at sub C speeds, disappears. a week later, as near as makes no difference, the ship appears agian, still travelling at sub-C speeds.

in J-space, thier is no way of mesuring your speed, or even if you are moving. you never ger close to c, so you never experience time dialation.

 

[mike wightman]

And every time someone brings up the Annic Nova, I will remind them that it's a very early reference that can be either ignored (like the early CT fusion torch maneuver drives)[*] or explained away ("The Annic Nova is built around an Ancient artifact that provides the fuel it needs").

Except that HG then reintroduced the idea of jump capacitors, and the original JTAS version makes it clear that this isn't relic ancient technology - that's just a fan based coop out rather than trying ti explain it properly.

[*]If jump drives could be explained without violating some piece of canon, there wouldn't be a controversy in the first place. And if the only bit that needed to be ignored was the Annic Nova, I think it would have happened years and years ago.​

Hans

Yup I agree, the jump drive write ups are often contradictory.

And if any set of authors pick up one small piece of MWM's article and re-write the jump paradigm according to their interpretation it just muddies the waters further.

 

[rancke]

Except that HG then reintroduced the idea of jump capacitors,

Capacitors that do not perform like the ones in the Annic Nova, so that's moot.

...and the original JTAS version makes it clear that this isn't relic ancient technology -

It specifically states that there is no relic Ancient technology involved? I think not.

But that's not the point, really. The point is that if it's a fact that ships can't jump without fuel, then something about the original JTAS version is wrong, since it contradicts that fact. Contrariwise, if the Annic Nova can jump without fuel, then the rules that require ships to have fuel are wrong. They are mutually exclusive. You have to pick one. And if you pick the one about fuel being necessary, then that original JTAS article doesn't prove anything anymore, because it's been superceded.

...that's just a fan based coop out rather than trying to explain it properly.

Fan-based, yes. But it's not a cop-out. It's an attempt to reconcile two mutually exclusive bits of canon in a way that causes the least amount of disruption. The alternative is to say that the Annic Nova doesn't exist at all. Because there IS no way to "explain it properly".

"Ships need fuel to jump" or "the Annic Nova can jump without fuel". Pick one. (Though, actually, I'd argue that TPTB picked option one long ago, so none of us actually gets to pick (Except in our own TUs, of course)).


Hans

 

[hdan]

We also need to accommodate the fact that unrefined fuel can cause misjumps.

The "coolant" theory doesn't really work too well under those circumstances, since would not all Hydrogen isotopes work equally well?

The "blow up a pocket universe bubble" theory of later Travellers matches, since impure Hydrogen could skew the necessary mass transfer calculations slightly.

The rest is entirely IMTU, and added just for the fun of discussion:

The bubble is not spherical - in fact its shape is held to a convex hull surrounding the starship's hull by the lanthanum grid, which is why a starship needs a power plant even if it doesn't have M-drives. The earliest starships had very simple shapes for this reason - it takes more advanced gravity manipulation technology to "clothe" a complex hull shape, and local gravity fields skew the shape at J-space insertion time. I imagine that the "Jump Bubble" slowly evaporates during the 168 hours until all that's left is the ship, which is dumped back into our universe. It's ok to pump more hydrogen in, but less would mean that you would run out of "bubble" before J-space evicts you, which means parts of your ship start evaporating. Standard jump procedures give you a small but sufficient margin of error in the fuel used, and more fuel burned just means more "waste" at precipitation point.

(As another aside, the "evaporating" hydrogen makes a cool, streaky-blue light show like "hyperspace" does in various SciFi shows, and any left over "flashes" during precipitation. High-tech stealth jump drives can minimize this excess flare-off by manipulating the jump grid field during precipitation)

 

[HG_B]

We also need to accommodate the fact that unrefined fuel can cause misjumps.

I already covered that in my earlier post.

 

[mike wightman]

Capacitors that do not perform like the ones in the Annic Nova, so that's moot.

They store energy to initiate a jump, pretty similar to me.

The difference is the HG jump engine still requires hydrogen as well as the capacitors.

But then LBB2 jump drives are much bigger than HG jump drives...

and originally a LBB2 jump drive didn't require a power plant as well.

It specifically states that there is no relic Ancient technology involved? I think not.

It specifically states that you can register it with the Imperium for 100kCr - for an ancient relic - I think not.

Also in the final paragraphs more uses for the Annic Nova class are given:
a pirate operated Annic Nova
a shipwreck
a free trader the characters work passage on
mercenary escape route

all of which suggests there are lots of annic novas out there - or at least in the early days there were.

What if we try and explain the Annic Nova class as being produced by a world beyond the Imperial border instead of writing it off as ancient technology.

But that's not the point, really. The point is that if it's a fact that ships can't jump without fuel, then something about the original JTAS version is wrong, since it contradicts that fact. Contrariwise, if the Annic Nova can jump without fuel, then the rules that require ships to have fuel are wrong. They are mutually exclusive. You have to pick one. And if you pick the one about fuel being necessary, then that original JTAS article doesn't prove anything anymore, because it's been superceded.

Go check who wrote Annic Nova...

and as I've said many times the good folks at GDW didn't bother using their own rules much, nor did they stick to one version of the OTU, nor did they seek to mitigate the impact of radical new rules - it was their sandbox.

Fan-based, yes. But it's not a cop-out. It's an attempt to reconcile two mutually exclusive bits of canon in a way that causes the least amount of disruption. The alternative is to say that the Annic Nova doesn't exist at all. Because there IS no way to "explain it properly".

Of course there is a way to explain it - it's pretty obvious and it doesn't break the game at all.
How much space do you think all that solar energy collection machinery would take up if there were design rules for it? (hint - the ship plans account for about 430 of its 600t - 170 tons of collection machinery)
Collection machinery that takes 1-6 weeks to fully charge I may add.

"Ships need fuel to jump" or "the Annic Nova can jump without fuel". Pick one. (Though, actually, I'd argue that TPTB picked option one long ago, so none of us actually gets to pick (Except in our own TUs, of course)).


Hans

The prime power is the one who wrote the adventure in the first place

 

[rancke]

They store energy to initiate a jump, pretty similar to me.

The amount of energy they store and the time frames involved are completely dissimilar.

What if we try and explain the Annic Nova class as being produced by a world beyond the Imperial border instead of writing it off as ancient technology.

Won't work, because the technology involved is incompatible with that of the OTU.

Go check who wrote Annic Nova...

Irrelevant.

...and as I've said many times the good folks at GDW didn't bother using their own rules much, nor did they stick to one version of the OTU, nor did they seek to mitigate the impact of radical new rules - it was their sandbox.

That's the reason why the Annic Nova is incompatible with the universe that has evolved over the 30 years that has gone by since JTAS#1 was published. And that's why articles from JTAS #1 are inferior canon.

Of course there is a way to explain it - it's pretty obvious and it doesn't break the game at all.

How much space do you think all that solar energy collection machinery would take up if there were design rules for it? (hint - the ship plans account for about 430 of its 600t - 170 tons of collection machinery)
Collection machinery that takes 1-6 weeks to fully charge I may add.

What's the maximum amount of energy that can be collected by the Annic Nova's solar sails in six weeks, let alone one? If we accept the Annic Nova as a viable design, it follows that the amount of energy you actually need to initiate a jump is equal to or less than this amount. How much of a power plant would you need to equal that? I suspect you would be able to equal it with a small steam engine, but I may be wrong there. Be that as it may, you most certainly don't need 170T worth of machinery to do so. There must be far smaller alternatives. Just because the Annic Nova is a very impractical design doesn't mean more practical ones aren't possible -- if the implications are true.

The prime power is the one who wrote the adventure in the first place

I still don't see what relevance that has.


Hans

 

[HRLMT]

How the Jump Drive Works?

Greetings !

You should get a copy of Digest Group Publication's Starship Operator's Manual. The book provides some well very thought-out descriptions of how key starship systems function, including the Jump drive.
The book is slanted toward civilian ships, as the ship given as an example is the Far Trader. There is some basic information regarding military ship systems.

That is all.
H. Leidner

 

[shadowcat20]

Part of the problem is writers in the old days did not follow cannon.

The Annic Nove for one.
Calling a Kinunir a Battle Cruiser at 1200 tons
A lot of the FASA Adventure class ships had weapons bays while weighing in at under 1000 tons. I could almost see a 500 ton ship getting a 50 ton bay but they still included a full compliment of hard points.

Writers were throwing all sorts of odd things at us for years, many before High Guard and Trillion Cred Squadron.

Cannon is trying to make sense out of all these tidbits. Not much can be resolved without SOME conflict.

As a aside, Maybe Annic Novas collectors also act as a hydrogen scoop when the ship is going into jump. A ramjet so to speak. It would explain all the extra tonnage. The entire ship feels like a prototype Battletech Jump ship before the game took off. It was the first double adventure so the timing is about right.

 

[Ishmael]

What's the maximum amount of energy that can be collected by the Annic Nova's solar sails in six weeks, let alone one? If we accept the Annic Nova as a viable design, it follows that the amount of energy you actually need to initiate a jump is equal to or less than this amount.

at 1AU from a star with lum=1, , incident solar energy is ~1370 w/m2
at ~18% efficiency for the photvoltaics( we already do better than that now ), let's assume we can get 250w per square meter.
250 w/sec
15,000 w/min
900,000 w/hr
21.6 mw/day
151.2 mw/week

for each and every square meter of solar collector

so, if we assume the Annic Nova had 100m2 of collector, energy ranges from
15.12 Gw to 90.72Gw ( 1 wk to 6 wks )

someone please doublecheck my numbers

 

[rancke]

at 1AU from a star with lum=1, , incident solar energy is ~1370 w/m2
at ~18% efficiency for the photvoltaics( we already do better than that now ), let's assume we can get 250w per square meter.
250 w/sec
15,000 w/min
900,000 w/hr
21.6 mw/day
151.2 mw/week

for each and every square meter of solar collector

so, if we assume the Annic Nova had 100m2 of collector, energy ranges from
15.12 Gw to 90.72Gw ( 1 wk to 6 wks )

someone please doublecheck my numbers

Acording to MT:Referee's Manual[*], a 20 kiloliter (roughly 1½ dTon) power plant has an output of 25 Mw and a fuel consumption of 0.0125 kiloliter per hour. That would be enough to match the performance of that 100m2 solar collector.

[*] If I've managed to work out the sums correctly, which may not be the case.​

I really don't think it would be a good idea to establish this technology as viable for the OTU.


Hans