Alternative Jump Drive

[alex_greene]

I found myself working out an alternative Jump drive to the standard one presented in High Guard. Hear me out.

Alternate Jump Drives are rated Jump-1 to Jump-6, as one would expect, and turn up at the same tech levels as found in the standard ship's design rules. Here are the two main ways in which these alternates differ from regular Jump drives.

One, Alternate Jump drives use the same principle as the ones you are familiar with - the drive consumes fuel, the Jump point forms, and the ship steps out of Einsteinian space for a while - but the duration of Jump can be for one or more weeks, though always a whole multiple of the basic 148 + 6D hours.

During that time, the ship will be travelling in a sort of hyperspace conduit, and the distance travelled depends on the Jump rating - a Jump-1 drive can only limp along at 1 parsec per week of travel, and a Jump-4 drive can manage up to 4 parsecs per week. One Jump always means at least one week of travel, and if a Jump-4 ship wanted to make a Jump to a world just two parsecs away it has to load Jump-2 into the astrogation computer or it literally will overshoot the mark, exactly like a Misjump.

Ships equipped with these alternates can travel across any gap or Rift, though for most ships the journey could take absolute weeks for the crew, probably forcing many or all of them into low berths during the trip. Crew can take turns staying out of the pods, maintaining the ship for a week or two at a time before being relieved and taking up a week or a fortnight in the low berths until it is their next turn to be thawed out for rota duties.

A Rift of ten parsecs between worlds could still be crossed by a Jump-1 ship, but it would take ten weeks of travel. A long time for the crew to be bottled up in confined quarters. Most passengers would book Low berths, if they knew that their journeys were going to take more than a fortnight in Jump.

And then there is the second thing that makes these alternates different. The fuel consumption. Each Jump consumes the fuel at two stages: half at the beginning of the Jump to open up the hyperspace conduit, and half at the end of the Jump to open up back to normal space and collapse the conduit behind the ship.

And the amount of fuel consumed is equal to 10% of the mass of the Jump drives per Jump rating ... not the mass of the ship.

Example: A Jump-4 ship might need to make a 16-parsec journey (four weeks at Jump-4), but it would consume hydrogen fuel equal to 40% of the mass of the Jump drive, 20% to open the conduit and 20% to return to normal space after the four week voyage. Or it might want to make a single Jump-2 to a planet two parsecs away, and consume fuel equal to just 20% of the mass of the Jump drive, 10% at the start and 10% to return to normal space, one week later and two parsecs away.

I can't imagine any but the stingiest of Captains who'd want to throttle back his Jump-4 ship to make the 16 parsec journey at Jump-2 or even Jump-1, but he could do it - and his ship would only consume the fuel needed to make such a slow Jump, condemning his crew and passengers to an unnecessary 8-week or 16-week voyage through a featureless hyperspace conduit.

Anyhow, that was the thing I was working on this morning. Thoughts?

 

[phavoc]

I found myself working out an alternative Jump drive to the standard one presented in High Guard. Hear me out.

Alternate Jump Drives are rated Jump-1 to Jump-6, as one would expect, and turn up at the same tech levels as found in the standard ship's design rules. Here are the two main ways in which these alternates differ from regular Jump drives.

One, Alternate Jump drives use the same principle as the ones you are familiar with - the drive consumes fuel, the Jump point forms, and the ship steps out of Einsteinian space for a while - but the duration of Jump can be for one or more weeks, though always a whole multiple of the basic 148 + 6D hours.

During that time, the ship will be travelling in a sort of hyperspace conduit, and the distance travelled depends on the Jump rating - a Jump-1 drive can only limp along at 1 parsec per week of travel, and a Jump-4 drive can manage up to 4 parsecs per week. One Jump always means at least one week of travel, and if a Jump-4 ship wanted to make a Jump to a world just two parsecs away it has to load Jump-2 into the astrogation computer or it literally will overshoot the mark, exactly like a Misjump.

Ships equipped with these alternates can travel across any gap or Rift, though for most ships the journey could take absolute weeks for the crew, probably forcing many or all of them into low berths during the trip. Crew can take turns staying out of the pods, maintaining the ship for a week or two at a time before being relieved and taking up a week or a fortnight in the low berths until it is their next turn to be thawed out for rota duties.

A Rift of ten parsecs between worlds could still be crossed by a Jump-1 ship, but it would take ten weeks of travel. A long time for the crew to be bottled up in confined quarters. Most passengers would book Low berths, if they knew that their journeys were going to take more than a fortnight in Jump.

And then there is the second thing that makes these alternates different. The fuel consumption. Each Jump consumes the fuel at two stages: half at the beginning of the Jump to open up the hyperspace conduit, and half at the end of the Jump to open up back to normal space and collapse the conduit behind the ship.

And the amount of fuel consumed is equal to 10% of the mass of the Jump drives per Jump rating ... not the mass of the ship.

Example: A Jump-4 ship might need to make a 16-parsec journey (four weeks at Jump-4), but it would consume hydrogen fuel equal to 40% of the mass of the Jump drive, 20% to open the conduit and 20% to return to normal space after the four week voyage. Or it might want to make a single Jump-2 to a planet two parsecs away, and consume fuel equal to just 20% of the mass of the Jump drive, 10% at the start and 10% to return to normal space, one week later and two parsecs away.

I can't imagine any but the stingiest of Captains who'd want to throttle back his Jump-4 ship to make the 16 parsec journey at Jump-2 or even Jump-1, but he could do it - and his ship would only consume the fuel needed to make such a slow Jump, condemning his crew and passengers to an unnecessary 8-week or 16-week voyage through a featureless hyperspace conduit.

Anyhow, that was the thing I was working on this morning. Thoughts?

There's nothing wrong with this at all. It essentially takes the concept of jump space and applies it to the normal method that is used today for travel.

Though the idea that people would need to go into low berths during a longer trip would be outside the norm. Today you have vessels (submarines) that travel for months without surfacing and crew don't go into pods. For passengers, boredom would be the issue, thus you'd have to have a number of places/things for them to while away their time during the transit. I would suspect that crews would be treated the same (hopefully). But even during the age of sail you had no choice but to find something to while away your travel time. With the inherent risk of low berths I don't think that most people would take the risk just to stave off boredom.

If you have read the old H Beam Piper books that the Sword Worlds are based off of, you'll find in there that the ships had to travel for weeks, sometimes months to get to their destinations. Travel to Poictesme (Cosmic Computer) took nearly a year (six months if you could travel direct). In Space Vikings, the Sword Worlders had to travel six months or more just to reach the old Federation to start raiding (which is why Trask set up a forward base of his own, due to the distances involved).

Something to think about would be for jump drives being powered, period. There would be the initial power requirement (maybe) to initiate jump, and then maybe some power required to maintain the bubble. Or you could adopt a more Bablyon 5 style jump issue, where most any ship was capable of travelling in jump space, but only the larger ones created their own jump portals. Thus you power requirements may simply be life support and drives.

And most likely a ship would never throttle back their drives to save fuel, unless of course saving the fuel was of paramount importance. Maybe they are doing it because where they are going no refueling is possible? Naval vessels today have a cruising radius based on a much slower speed than their normal full capabilities.

 

[rust2]

I see no problem with your alternate jump drive.

The ships of my Thalassa setting use a somewhat similar hyperspace drive. The ship enters a "hyperspace corridor", but moves through it at the inherent speed of the "corridor", not of the ship's drives. It basically "falls" through hyperspace towards its destination, and long voyages of 30 days or more are common.

 

[Condottiere]

1. Commercially, time is money.

2. Assuming normal maintenance cycles, you probably have to add crew to compensate for that extra time spent in Neverland.

3. Militarily, the Solomani could hit every communications node in the Imperium, between Sol and the Spinward Marches.

4. Our canine friends will be raiding Core.

5. At least, piracy is now viable.

6. Going by Dumarest, Fast Drug is an option.

7. No one really thinks about the full implications of Star Viking.

 

[rust2]

3. Militarily, the Solomani could hit every communications node in the Imperium, between Sol and the Spinward Marches.
4. Our canine friends will be raiding Core.
5. At least, piracy is now viable.

But, but ... these are not problems, these are excellent opportunities ... :twisted:

 

[Tom Kalbfus]

How about a wormhole drive, the ship comes in two parts, each part holds an end of a wormhole, one of the parts stretches the other does not. The stretchy part gets sent ahead, it accelerates as fast as it can, the part that stays behind fires its engines through its end of the wormhole accelerating the stretchy part of the ship, the stay behind end gulps as much fuel as it need to keep on firing its engine and accelerating the stretchy end, And then when the stretchy end reaches its destination, stretches to allow passage of the rest of the ship through the wormhole, closing the wormhole as it passes through. The two ends dock and become one starship and then the whole starship proceeds to its destination.

 

[Rikki Tikki Traveller]

With longer times in JumpSpace, it is likely that the average ship would be larger too. If a ship is going to be spending 2+ weeks in JumpSpace, then there will need to be more entertainment etc.

This alternate method would make space travel much more similar to the Age of Sail or Age of Steam trans-Atlantic journeys. Only if Low Passage is much safer than standard Traveller would people really opt for that on longer voyages. The current MGT2 "standard passage" would be quite common, but the use of extra space/luxuries for entertainment would be a must.

As a Referee, I would think that a lot more adventures that occur in JumpSpace would be used since so much time could be spent there.

I very much like the idea of keeping the 1 week limit. That is something that is often dropped when going to this "velocity" based alternate Jump Drive. By keeping the 1 week intervals, you don't break the 3I setting (assuming you are using that) and the "loose interstellar governments due to travel times" stay in place.

Like it a lot actually.

 

[Condottiere]

This is new.

 

[Tom Kalbfus]

One could have an alternative to the Jump Drive, such as putting the habitable planets close together in an unusual situation such as my Cyrannus example.

 

[Condottiere]

Doesn't Firefly operate on a similar concept?

 

[Tom Kalbfus]

Doesn't Firefly operate on a similar concept?

For all we know Caprica might operate the same, we don't know when their jump drive was invented, it could have been during the First Cylon War. The nearest neighbors to Caprica are Picon, Gemenon, and Tauron. Each of these can be reached with a sublight spaceship in a reasonable amount of time, if fact all the planets can be reached by sublight starship in less than a year.The furthest components are 0.16 light years apart, this means a communications time delay of 3.9 months for two way communication, sending out a message and getting a response. If we have a Traveller like maneuver drive tech level 8.
Maximum 0.16 LY
T=2√(D/A) Velocity Distance Acceleration
1-G 24,843,448 seconds 287.5399088 days 121,857 km/sec 1.51368E+15 m 9.81 m/s²
2-G 17,566,971 seconds 203.3214193 days 172,332 km/sec 1.51368E+15 m 19.62 m/s²
3-G 14,343,371 seconds 166.0112437 days 211,063 km/sec 1.51368E+15 m 29.43 m/s²
4-G 12,421,724 seconds 143.7699544 days 243,714 km/sec 1.51368E+15 m 39.24 m/s²
For 5-G and 6-G maneuver drives you need to use a relativistic acceleration equation, and you get two results, time as experienced by the crew and passengers and time it takes externally for the ship to arrive at its destination.

 

[alex_greene]

Nah, I think I'd prefer this version of the drives, and worlds which are orbiting stars in different systems.

That way, I can throw in the occasional surprise which could throw them for a loop, such as an accident which sends them into the Pegasus Galaxy, which would be teeming with lifeforms that would never be encountered through standard Jump drives.

(Of course, the crew's main problem would be getting back again, but it'd be worth giving them a few adventures in the Pegasus Galaxy first before they find their golden ticket home ...)

 

[Tenacious-Techhunter]

To be fair, a Hard Science Fiction approach would have wider diversity of lifeforms than the OTU. And it shouldn’t be too unreasonable for the Ancients to have preserved some of those races for the sake of allowing them to continue to develop uninterrupted. Of course, if you need an entire other starfaring civilization, even other parts of the same Galaxy would do, and would be considerably less of a game-breaking physics hassle.

 

[Epicenter]

I found myself working out an alternative Jump drive to the standard one presented in High Guard.

Your drive would profoundly change the nature of Traveller.

As other posters have noted, you couldn't use the OTU anymore - space warfare and economics would be pretty profoundly different. Obviously, if you have no intention of playing in something resembling the OTU, then I think your system is as good as another.

Unless my reading of your examples are incorrect, the amount of fuel consumed by a jump remains the same, regardless of distance traveled. This has a massive implication and would basically preclude the OTU from really existing. There's nothing that prevents any Navy from tucking a massive strike fleet into Jump, even with Jump-1 drives, waiting months, then the fleet de-jumps right by the enemy capital and proceeds to bomb them into oblivion. From your description it seems like you have a safer low berth system than the "canon" traveller death lottery low berth, so supplies aren't a big deal - pretty much everyone goes into cold sleep for the months duration between leaving from mustering point in their home nation to the enemy capital.

For fairness sake, I should acknowledge since the idea of Calibration Points was introduced, I think around MT/TNE, the 500-pound gorilla that should destroy the Traveller canon has been around, unacknowledged. (in fact, I think the way was paved when they started letting ships jump to empty hexes.) Seriously - it's decades between Frontier Wars - why couldn't the Zhodani slowly set up a bunch of fuel-stocked CPs so they could "stealth Jump" all the way to Mora or Rhylanor and simply bomb those places flat, at the beginning of a war, decapitating the Imperial response? Yes, it'd be tedious, time-consuming, and likely expensive to forward-deploy all that fuel. However, CPs are apparently (somehow) basically undetectable (don't ask me how) in the OTU, so this should have destroyed Traveller history long ago.

I think jumps like this would likely change the "stellar geography" of the Traveller universe even economically. Mains wouldn't be quite as important as before, though still important. Low priority cargoes, especially bulk goods with a constant demand, might be shipped in huge Jump-1 vessels Nostromo-style with weeks-long trips (things such as, say, grain or steel). Time is money, but air freight hasn't 100% replaced ocean freight on our own 21st century Earth, despite the fact that air freight is many times faster - if the economic cost is great enough people will deal with slower but cheaper methods to move goods around.

Again, for fairness sake, this is mostly a moot point. OTU is still using that decades old 2d6 generated map where world TLs and so on have no bearing to if they're on mains or not or relation to neighboring high TL worlds. If the OTU doesn't care, maybe you shouldn't, either.

If you want something approaching the TU existing in a world with a revised Jump drive mechanic like this:

* Ships must be detectable in Jump.

* A reasonable way for empires to protect their borders from people just doing stealth strikes.

* Some other limit on Jump drive range preventing hugelong jumps with the only cost being time.

Of the three, I think the third point is the easiest to do. Putting a cap on distance

 

[Condottiere]

Interception in hyperspace would probably need to be an option.

 

[Reynard]

It sounds more and more like the Star Wars hyperspace. Move anywhere in the galaxy at the speed of the need of the story, detectable and there is a means to precipitate a detected ship out of hyperspace. This will also allow starships the size of fighters.

 

[alex_greene]

It sounds more and more like the Star Wars hyperspace. Move anywhere in the galaxy at the speed of the need of the story, detectable and there is a means to precipitate a detected ship out of hyperspace. This will also allow starships the size of fighters.

Which is why, at the start, I explicitly pointed out that the hyperspace corridor is just that - in hyperspace, outside of the normal universe. Interception and detection are impossible, just the same as they are for the default Jump drives, and I never said anything about Jump drives being tiny - only that fuel consumption is based on the size of the drives, not the ship.
Here's the thing - the less the need for fuel capacity, the larger the available space for cargo, crew, ground troops, auxiliary vehicles, fighters or weapons.

 

[phavoc]

It sounds more and more like the Star Wars hyperspace. Move anywhere in the galaxy at the speed of the need of the story, detectable and there is a means to precipitate a detected ship out of hyperspace. This will also allow starships the size of fighters.

Which is why, at the start, I explicitly pointed out that the hyperspace corridor is just that - in hyperspace, outside of the normal universe. Interception and detection are impossible, just the same as they are for the default Jump drives, and I never said anything about Jump drives being tiny - only that fuel consumption is based on the size of the drives, not the ship.
Here's the thing - the less the need for fuel capacity, the larger the available space for cargo, crew, ground troops, auxiliary vehicles, fighters or weapons.

As far as I can tell, the Star Wars hyperdrives and Traveller jump drives operate along the same fashion - they jump along a straight line and encountering a large gravitational object (or appropriately equipped Star Destroyer) will yank your vessel out of jump/hyperspace. SW drives do seem to be far smaller and consume much less fuel, though it seems nearly all SW tech is smaller and more efficient than Traveller tech. But other than that they are pretty similar.

 

[alex_greene]

It sounds more and more like the Star Wars hyperspace. Move anywhere in the galaxy at the speed of the need of the story, detectable and there is a means to precipitate a detected ship out of hyperspace. This will also allow starships the size of fighters.

Which is why, at the start, I explicitly pointed out that the hyperspace corridor is just that - in hyperspace, outside of the normal universe. Interception and detection are impossible, just the same as they are for the default Jump drives, and I never said anything about Jump drives being tiny - only that fuel consumption is based on the size of the drives, not the ship.
Here's the thing - the less the need for fuel capacity, the larger the available space for cargo, crew, ground troops, auxiliary vehicles, fighters or weapons.

As far as I can tell, the Star Wars hyperdrives and Traveller jump drives operate along the same fashion - they jump along a straight line and encountering a large gravitational object (or appropriately equipped Star Destroyer) will yank your vessel out of jump/hyperspace. SW drives do seem to be far smaller and consume much less fuel, though it seems nearly all SW tech is smaller and more efficient than Traveller tech. But other than that they are pretty similar.

Yeah.

I'm definitely going with the HG2 rule that the minimum Jump drive size is 10 tons. Maybe a TL 19 Jump drive could be built that's the size of a briefcase - but for everyone who has no access to the Ancients, your minimum Jump drive size is going to be a huge chunk of machinery, requiring housing inside a vessel of minimum tonnage 100 tons.

 

[Reynard]

Also remember there is something >similar< to Alex's idea as an alternative drive in 1e and most likely 2e, the warp drive. It allows a ship to operate in (warped) real space and move a distance and time similar to jump measurements except it a faster than light velocity, Warp 1 is travelling one parsec in seven days and you can start, stop and maneuver as desired and that includes micro-jumps distances. Much like Alex's concepts , fuel is the important new factor. You burn fuel constantly through the power plant at twice the PP's burn rate to run the Warp engine rather than all at once at the jump rate. You also can move any distance as long as you have enough carried fuel. Rift travel made easier.