Jump Bubbles

[Reynard]

You are correct! So much to keep track of from the info in the current book as well as referencing other books that tweak the rules. It does seem they fire up the PP reactor to energize the jump bunny.

They mention some plants can't handle the strain when energizing and caused power drains elsewhere while superior designs (and Engineers) do not. That means the Plant is meant to be overpowered BRIEFLY while maintaining normal output. The plant, however isn't built to do this frequently. I'm sure that's part of the regular maintenance schedule.

As to bubble and grid, semantics, both produce a field enveloping the ship in jumpspace filled with hydrogen with a slight difference in physics. Considering how often Traveller editions flip back and forth, it's a name.

 

[sideranautae]

Besides the fact this variant uses a grid rather than the bubble, if the jump drive had it's own dedicated fusion plant to energize it, rather than draw on the ship's power plant why would you need the ship's power plant's factor to match that of the jump drive, as it would only be required to produce juice for all other ship's functions and could be reduced to factor one?

The Starship Op Manual is from MT. In MT the jump drive was also a hi yield fusion PP. The normal ship's PP didn't supply it power. Your PP did not have to match your Jump Drive. The Jump fuel was not used to form a bubble.

 

[hdan]

Though I'm aware of the "jump drive is a high-yield fusion plant" background in other Travellers, I have to say I prefer Mongoose's "Jump Bubble" to all of them. Not only does it provide a more plausible to me reason for needing so much hydrogen, but it also explains why you can't just turn off your J-drive and precipitate back into realspace at any point. It also explains why you need enough Power Plant to power the J-Drive. If the J-Drive were self-powering, then that would not be the case. (Yes, I also know about early X-boat designs that only had J-drives - we're talking about MgT, right?)

In fact, IMTU I consider the hyperdimensional *shape* of the jump bubble to be related to its jump performance, and the TL of the drive determines how sophisticated a shape it can control. You need higher TL math and science to even discuss higher jumps, and the size of the drive and hull together are not the final word on ship performance. That's why installing a large drive built at a lower TL won't help you make higher jumps. (Not RAW, but it's the way I see it - even a Type-S with drives built below TL-11 wouldn't make J-2, regardless of the table.)

This echoes the "Age of Sail" meme - a clipper is just faster than a cog, and harder to build. Jump bubbles are your rigging and sails. And have your ship built at the lowest TL that will do the job, so you can still service it out on the frontier.

 

[sideranautae]

Jump bubbles are your rigging and sails.

OMG, that's how I described it (paraphrased) to my players!

I use the bubble (to account for all that H2) but have the JD also supply power to itself. That way you can have a J-3 drive with a PP-1 ship.

 

[dragoner]

I just show my players this graphic from MIT:

 

[Condottiere]

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.

 

[Reynard]

You come out of jump space too soon and you're probably well outside any system with no jump fuel to try again. There are probably untold numbers of derelict ships between stars which, if they're lucky, will pass through a system in tens to hundreds of thousands of years. Remember, your ship's vector will not be the same as the jump vector.

 

[sideranautae]

There are probably untold numbers of derelict ships between stars which, if they're lucky, will pass through a system in tens to hundreds of thousands of years. Remember, your ship's vector will not be the same as the jump vector.

That's HIGHLY doubtful. Most would be in the vicinity of heavily used jump lanes. A simple distress beacon would easily be picked up by planetary receivers (within a few years) and salvage would be all the rage.

 

[Reynard]

Let's see... you have a few weeks fuel when you jumped. Something causes your ship to exit jump too early. You are not in a system. It will take forever to reach a system on your fuel minus one week. Why did you install a beacon whose light speed message will take years to be received?

Seriously, do NOT push the off button.

 

[hdan]

You can turn off your jump drive if you want, but your pocket universe doesn't reconnect with the real universe until the week is up, no matter what. Your engine's control of the jump bubble is the only thing that prevents you from returning as a gamma ray burst though, so you might want to keep it running.

 

[Condottiere]

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.

 

[Reynard]

It seems simple enough the time and distance are relative. Divide the time traveled by seven then take that fraction to determine the fraction of the distance travelled. Dropping out of a Jump 1 after one day will put you 28,918 AUs from your start or the same if you exits a day early at the destination. Still not a winning number.

 

[Condottiere]

Less time than if you initiated a microjump; however, the consequences for pulling the plug early probably don't make it worth it.

 

[sideranautae]

Let's see... you have a few weeks fuel when you jumped. Something causes your ship to exit jump too early. You are not in a system. It will take forever to reach a system on your fuel minus one week. Why did you install a beacon whose light speed message will take years to be received?

BECAUSE, if this was the major problem that you paint; 1) there would be emergency LB's with years of endurance for all crew & passengers. 2) If you THEN didn't send a signal, you wouldn't be rescued.

Come on, that is obvious. :wink:

 

[Reynard]

Try building a lifeboat with years of endurance, it would be much bigger and far more expensive than the ship. Remember also they have the low berth lottery because even that technology is slightly unreliable; your lifeboats won't be Khan's Botany Bay. Look how today we can't find a single plane with all our tech in a vast stretch of ocean knowing a lot about it's original location and course and that's a drop in the bucket compared to even a one parsec distance and not knowing if the ship misjumped or blew up or aborted or any number of issues. The unlucky ones die on a vessel when the lights finally go out in a very, very short time. That's why you don't see and special built search and rescue ships.

In Traveller, you take a chance when you step on to a starship or sometimes even a spaceship). It's that Age of Sail flavor again not Star Trek or Star Wars.

 

[sideranautae]

Try building a lifeboat with years of endurance, it would be much bigger and far more expensive than the ship.

MRB: "Most ships carry emergency low berths where the crew can freeze
themselves and wait for rescue."

This has been a standard in Trav versions for decades. Nuc batteries make this easy at our current TL.

Sorry, no reasonable argument to be made against this.

 

[AndrewW]

Try building a lifeboat with years of endurance, it would be much bigger and far more expensive than the ship.

MRB: "Most ships carry emergency low berths where the crew can freeze
themselves and wait for rescue."

If you look at the ship specs this is pretty rare.

 

[sideranautae]

Try building a lifeboat with years of endurance, it would be much bigger and far more expensive than the ship.

MRB: "Most ships carry emergency low berths where the crew can freeze
themselves and wait for rescue."

If you look at the ship specs this is pretty rare.

Right. Because unless you try to jump within 100D and/or don't do maintenance Trav starships don't stop working. They don't malfunction.

 

[GypsyComet]

The "high fuel burn" model of most editions makes years of duration difficult without some other powerplant handwaving (such as T20 or T4's segmented plants), while the "efficient burn" model used in GT and TNE can get years of powerplant duration fairly easily.

 

[sideranautae]

The "high fuel burn" model of most editions makes years of duration difficult without some other powerplant handwaving

For something like LB's? Not at all. Current technology can handle. Why mess with handwaivium?