Trading time for distance?

[Rooster Cogburn]

Would it be conceivable to have a jump drive that allowed you to jump twice its rating but at twice the time?

X-Jumpdrive1

1 pc = 1 week or 2 pc = 2 weeks

X-Jumpdrive6

6 pc = 1 week or 12 pc = 2 weeks

Has this been tried/discussed anywhere?

 

[far-trader]

Effectively doable under the rules as long as you have the fuel.

For example the Classic 200ton Yacht has Jump Drive 1 and fuel for 4 weeks of operation and 40tons of jump fuel. It can jump 1pc using 20tons of jump fuel and taking 1 week. Then when it comes out of jump after that week it jumps again using the rest of its jump fuel and taking another week. It arrives 2pc distant in 2 weeks with just 2 weeks of operational fuel left and will need to refuel and perhaps restock supplies before jumping again.

The problem with a Jump 6 ship making 2 successive jumps is the fuel. Needing 120% of the hull dedicated to jump fuel to make 12pc is difficult

...it can be done using drop tanks though

 

[Whipsnade]

Has this been tried/discussed anywhere?

Ever jump drive wrinkle, fiddle, and tweak you can think of, plus plenty of wrinkles, fiddles, and tweaks you've yet to think of, have been suggested, examined, toyed with, used, and enjoyed during Traveller's 35 years.

When examining an alt-jump drive the most important aspect is determining what effect there will be on communications. As is repeatedly pointed out in threads with topics as diverse as trade and extradition, the One Week Per Jump paradigm is fundamental to the OTU. Change that paradigm and the OTU simply will not exist as described in canon.

Here's a common jump drive tweak you may find interesting: What if drives with higher jump ratings could perform jumps smaller than their faster? ForEx: What if a J4 drive could perform a three parsec jump in 75% of the usual time, a two parsec jump in 50% of the usual time, etc.

 

[DangerousThing]

Here's a common jump drive tweak you may find interesting: What if drives with higher jump ratings could perform jumps smaller than their faster? ForEx: What if a J4 drive could perform a three parsec jump in 75% of the usual time, a two parsec jump in 50% of the usual time, etc.

That's a neat tweak. I could easily picture a ship with a J-4 drive but only fuel for a single jump.

I'm doing something like that in MTU by having a Hyperdrive. If it worked without acceleration than an H4 drive (4 parsecs per week) could get to a close planet (one parsec) in 1/4 a week. Unfortunately this is impractical because of acceleration, so it really takes about 3/4 a week to go 1 parsec with this drive. So therefore the mail stays the same. Because Jump Drives are much less expansive than Hyper Drives, the X-Boat system uses Jump Drives.

 

[Fritz_Brown]

It's a "neat tweak", but it does break the OTU paradigm.

Also, in the OTU paradigm, a J4 ship already only uses fuel for a J1 if it's going to do a J1.

 

[rancke]

When examining an alt-jump drive the most important aspect is determining what effect there will be on communications. As is repeatedly pointed out in threads with topics as diverse as trade and extradition, the One Week Per Jump paradigm is fundamental to the OTU. Change that paradigm and the OTU simply will not exist as described in canon.

Here's a common jump drive tweak you may find interesting: What if drives with higher jump ratings could perform jumps smaller than their faster? ForEx: What if a J4 drive could perform a three parsec jump in 75% of the usual time, a two parsec jump in 50% of the usual time, etc.

'One week per jump' is unquestionably one of the basic Traveller paradigms, but the OTU could actually survive reasonably intact if the paradigm was changed to 'speed of communication maximum 6 parsecs[*] per week'. So your suggestion would change the details of interstellar traffic considerably, but not the overall history much.

[*] Or rather, maximum the highest jump drive invented at the time.​

Indeed, I suspect (without having taken the time to analyse the figures) that one of the big discrepancies with the OTU, namely the importance of mains despite the fact that jump-2 and jump-3 are both more efficient than jump-1, would be fixed by it. The cost of interstellar travel would definitely be quite a bit lower.


Hans

 

[Ackehece]

'One week per jump' is unquestionably one of the basic Traveller paradigms, but the OTU could actually survive reasonably intact if the paradigm was changed to 'speed of communication maximum 6 parsecs[*] per week'. So your suggestion would change the details of interstellar traffic considerably, but not the overall history much.

[*] Or rather, maximum the highest jump drive invented at the time.​

Indeed, I suspect (without having taken the time to analyse the figures) that one of the big discrepancies with the OTU, namely the importance of mains despite the fact that jump-2 and jump-3 are both more efficient than jump-1, would be fixed by it. The cost of interstellar travel would definitely be quite a bit lower.


Hans

And it would create a definite rule related to misjumps. A J6 drive misjumping 36 parses would be in jump space 6 weeks but a jump 1 drive would be 36 weeks..... Oo

 

[Ackehece]

It's a "neat tweak", but it does break the OTU paradigm.

Also, in the OTU paradigm, a J4 ship already only uses fuel for a J1 if it's going to do a J1.

Think he was heading for more speed to j1 locations while having more cargo or space for accessories. Fuel tank tonnage redistributed to other purposes.

 

[DangerousThing]

Think he was heading for more speed to j1 locations while having more cargo or space for accessories. Fuel tank tonnage redistributed to other purposes.

Thank you, that's exactly it.

You could do a system-to-system jump in 1/4 week to speed information to adjacent systems.

IMTU, I have jump drives almost as stated, except they have to go further from the planet (actually usually the star) to get to a specific (but large and usually well-marked) jump-zone before jumping. Misjumps are *extremely* rare.

And a ship doesn't need a jump drive if it only intends to go on routes in the core worlds of my Empire, because jump gates will supply the power and shielding for a jump. Usually these are used by the really huge freighters that travel between the core worlds. They can be used by a free trader not wanting to use his jump power (IMTU they don't use fusion plants on ships, they use energy-cells).

The Hyper Drive (H-Drive) is more expensive, is a bit more dangerous, but it can go it's rating in parsecs each week. However, transitioning from realspace into H-Space is fairly easy (a 1D task), but it gets more difficult going from H1-Space to H2-Space (a 2D task). Essentially the ship needs armor and shields at least equal to the H-Space that they want to go into, because it shakes up the ship. And it's much better to have a good pilot because they can make it easier for the ship also. And it works the same way going down.

With a better pilot you can go a bit faster, because you can go closer to the upper end of your speed.

So, with a *really* good H-4 ship and a good pilot and a crew not minding the shaking, yes, IMTU it is *possible* to make a single parsec trip in about 2-3 days. However, most H-4 ships would make such a small trip in H1 or maybe H2 space, so I figure 4-5 days.

 

[77topaz]

And it would create a definite rule related to misjumps. A J6 drive misjumping 36 parses would be in jump space 6 weeks but a jump 1 drive would be 36 weeks..... Oo

The maximum misjump possible would likely be related to time, not distance - a misjump would be a maximum of 10 jumpspace weeks, for example. This is because there is a fixed normal jumpspace time, but not a fixed distance.

(Hey, there's a lot of x's in that paragraph... )

 

[Ackehece]

The maximum misjump possible would likely be related to time, not distance - a misjump would be a maximum of 10 jumpspace weeks, for example. This is because there is a fixed normal jumpspace time, but not a fixed distance.

(Hey, there's a lot of x's in that paragraph... )

actually my reply was to a suggestion that the time was not fixed... (read the thread in order )
eg: if you used a J4 drive and used it to travel 1 parsec it would take 1/4 the normal time, or 2 parsecs in 1/2 the standard time... extrapolated that out... if you mis-jumped 8 on a j4 drive it would take twice as long, 16 4x as long, and 32 8x as long.

 

[Carlobrand]

...Indeed, I suspect (without having taken the time to analyse the figures) that one of the big discrepancies with the OTU, namely the importance of mains despite the fact that jump-2 and jump-3 are both more efficient than jump-1, would be fixed by it. ...Hans

"More efficient" in terms of what? Under High Guard, a jump-2 ship spends 2 to 4 percent more of its internal space for the power plant and drives needed for the additional jump, at an added cost of MCr7 to MCr13 per hundred tons of ship. Then it has to allocate another 11% for the power plant fuel and jump fuel, and it needs to upgrade to a MCr4 Model 1-bis instead of the MCr2 Model 1 (unless it masses more than 600 tons, in which case it already has a Model 2). The ship costs more, therefore has a higher monthly payment to meet, but it has less space to make money with, yet it charges the same for cargo and passengers. Jump-3 is even worse.

Under the rules as written, the jump-1 ships are simply more profitable. If I'm a manufacturer trying to move product, I want jump-2/jump-3 ships to get my product to the more distant markets ... but if I'm a shipping line, I'm sinking every penny into jump-1 ships because they produce more income for less money invested. I won't explore jump-2 until the jump-1 market is thoroughly saturated and jump-2 is the only place left to go to make money, and then only if I'm very certain about filling my rooms and hold.

For the same financial reason, I wouldn't go to jump-3 until the jump-2 market was thoroughly saturated - and that depends on the ship being high enough in tech level to shrink the power plant and reduce the ship cost to something manageable. I don't think anyone but the Megas are going to be running jump-3 transport.

 

[rancke]

"More efficient" in terms of what?

In terms of costing less and being faster.

Under High Guard, a jump-2 ship spends 2 to 4 percent more of its internal space for the power plant and drives needed for the additional jump, at an added cost of MCr7 to MCr13 per hundred tons of ship. Then it has to allocate another 11% for the power plant fuel and jump fuel, and it needs to upgrade to a MCr4 Model 1-bis instead of the MCr2 Model 1 (unless it masses more than 600 tons, in which case it already has a Model 2).

But it only takes one jump to move the lesser amount of cargo two parsecs whereas the jump-1 ship has to make two jumps to do the same. Which means that if the jump-2 ship has 80% the cargo capacity of the jump-1 ship, it moves 160 T of cargo two parsecs every time the jump-1 ship moves 100 T two parsecs. And it does it twice as fast. That is more than enough to compensate for the higher investment cost.

The ship costs more, therefore has a higher monthly payment to meet, but it has less space to make money with, yet it charges the same for cargo and passengers. Jump-3 is even worse.

I'm talking about the true costs of moving cargo and passengers. Which is why per-jump payment is ridiculous. It requires heavy, market-distorting enforcement be a powerful government. The Imperium could do it, but if it did, there would be no jump-3 and jump-4 freighters and liners at all, since they would be unable to make a living. Merchants doing speculative trading could survive, they wouldn't be paying freight rates anyway (they would buy stuff at one end, ship it for the true costs, and sell it at the other end).

Under the rules as written, the jump-1 ships are simply more profitable.

Under the rules as written, and assuming for purposes of argument that canny businessmen won't find ways to circumvent those market-distorting regulations, jump-1 ships are more profitable if it can find someone willing to pay the freight. For one-parsec routes the cost is the same no matter what the jump capacity of the ship, but that matters little, because no jump-2 ship would be able to compete with jump-1 ships across one parsec. But for shipping something two parsecs, the cost of shipping it by jump-1 ship would be Cr20,000 as opposed to Cr10,000 by jump-2 ship. Under those circumstances no shipper is going to ship by jump-1.

Across three parsecs a jump-2 ship will charge Cr20,000 for the distance while a jump-1 ship would charge Cr30,000. I haven't done the math, so I don't know if a jump-2 ship can stay in the black with those freight rates, but if it can, it will outcompete jump-1 ships at that distance too, naturally.

But, of course, the original assumption that people wouldn't find ways to circumvent the regulations requires a degree of enforcement on behalf of the Imperium that certainly does not seem to be the Imperium I know of from every other piece of setting material that describes it.

For the same financial reason, I wouldn't go to jump-3 until the jump-2 market was thoroughly saturated - and that depends on the ship being high enough in tech level to shrink the power plant and reduce the ship cost to something manageable. I don't think anyone but the Megas are going to be running jump-3 transport.

You wouldn't go to jump-3 at all, since you'd be losing money on every trip. And yet, canonical jump-3 and jump-4 ships exists. Which I take as proof (not just evidence), that the rules as written are SUBAR (Stuffed Up Beyond All Redemption).

Or rather, that they are a game artifact that applies only to refereeing PC-crewed tramp ships, for which purpose they work quite well. But they don't work at all for regular freighters and liners.


Hans

 

[aramis]

Hans, bull.

CT Bk2 J2 and J3 can be made passenger profitable by simply cutting turn-around times from a week to 2 days. This gives a 9 day cycle (instead of 14). Cargo, not so much, but J2 cargo on the same routing makes money at the book rate of Cr1000/ton per jump.

And that's ignoring spec. Add your own broker 3+ and Trader 3+ (not of need the same guy) and you get the ability to decide whether or not to carry the cargo lot(s). Note that, since having said skills in CT implies Bk7, that also means allowing multiple spec lots for purchase.

All you need to do to make J2/J3 profitable under Bk7/MT is keep the differential at least KCr2 for J2 - KCr1 is built in to the MP trade system, and one bonus is good enough for the second - and KCr2.5 for J3. And thats with either Bk2 or Bk5 design systems (albeit Bk5 only at TL12+, since PP are the big problem).

So, Hans, your assertion of stuffedness is, itself, stuffed.

 

[rancke]

Hans, bull.

CT Bk2 J2 and J3 can be made passenger profitable by simply cutting turn-around times from a week to 2 days.

Yes, but the rules as written don't allow that, do they? So bull right back at you.

This gives a 9 day cycle (instead of 14). Cargo, not so much, but J2 cargo on the same routing makes money at the book rate of Cr1000/ton per jump.

And if they do, a jump-2 ship will carry its freight across two parsecs for 1000 credits per ton while jump-1 will carry it across two parsecs for 2000 credits per ton.

Incidentally, this 9 day cycle is possible only if you ignore jump shadowing (and jump masking, but I don't mind ignoring that, as it's very much not explicit in the rules as written).

And that's ignoring spec. Add your own broker 3+ and Trader 3+ (not of need the same guy) and you get the ability to decide whether or not to carry the cargo lot(s). Note that, since having said skills in CT implies Bk7, that also means allowing multiple spec lots for purchase.

No, I mentioned speculative trade. As I said, with speculative trade the shipper and the ship are the same people, so they carry the cargo for the true cost rather than for Cr1000 per jump.

So, Hans, your assertion of stuffedness is, itself, stuffed.

No, Wil, it's your assertation of the stuffedness of my assertation of stuffedness that is stuffed.


Hans

 

[aramis]

Actually, hans, you earn a Fail in rules reading.

CT book 2 indicates NO required down time. It notes that one can only roll for spec cargos once per week per trader (p.46) and that LS costs are per 2 weeks (p.8) and that a trip is no more than 2 weeks (p.8). The travel formulae put the 100diam limit at under a day for most worlds (those not orbiting GG's).

Commercial starships usually make two jumps per month. They spend one week in jump, followed by one week in the star system, travelling from the jump point to the local world, refuelling, marketing cargo, finding passengers, leaving the starport and proceeding to a jump point again. The week in the system usually provides some time for crew recreation and wandering around the planet.

It says nothing about delivery times... One could, based upon CT Bk2, land and take off in one day with a 1G ship from any mainworld with cargo in tow... and jump can be, per Bk2 "about one week." J3 and J4 traffic would not be the majority of traffic. Given the requirements to build J3 and J4 in Bk2, they're bloody rare, even tho they can be built at TL12...*

Jump drives are rated from 1 to 6: the
number of parsecs which can be travelled in one week. Actually, making any jump
takes about one week, regardless of the distance travelled.

So, we have, in Bk2 rules, at most 17 hours (size 10.5 world 16800km diam, 1G, 25923s {rounded up to next s}=432min=7.2h), plus allowing for both directions and trip to orbit , and one hour for load/unload. Truth be told, load and unload is an issue, which, realistically, needs to be accounted for. If we assume one container per minute, with 4Td/container, for high speed load and unload (not unlike the rates at a current freight port), we get 96/4=24 min load, and 24 min unload. Pax load is more likely to be an hour, anyway...

We have a "use of reason" limit of at least 2 days down, rather than the mathematical 1 day, simply to allow for "local business hours" to hit. But we have no hard Bk2 rules on it.

So, it's possible, RAW, to presume the J3 traffic running 9-10 day cycles, and simply not being "usual" traffic.

Then again, a pure Bk2 universe also has TL10 J4 ships, and TL 9 J3 ones.

 

[rancke]

Actually, Hans, you earn a Fail in rules reading.

While you earn a gold star for quibbling.

CT book 2 indicates NO required down time.

Wil, you actually quote the part where the rules says that commercial starships usually make two jumps per month. If regular liners and freighters are not commercial starships, then I've failed English in addition to rules reading.

But wait! Don't we have a canonical example of a shipping company that describes its operations? We do indeed. True, the description is also stuffed up, but it IS canonical. Al Morai's ships makes one jump per 14 days.

So it would appear that you're the one that has earned a fail in rules reading.

I also note that you failed to address my point about jump shadowing.

It notes that one can only roll for spec cargos once per week per trader (p.46)...

Right. So if there is one ship in port, there's one, and only one, lot of cargo available, but if another ship arrives a second lot suddenly and miraculously appear on the market, though the first ship is barred (by some exotic but universal regulation, no doubt) from trying to acquire it.

and that LS costs are per 2 weeks (p.8) and that a trip is no more than 2 weeks (p.8). The travel formulae put the 100diam limit at under a day for most worlds (those not orbiting GG's).

Those not orbiting gas giants or orbiting inside the jump limit of its star. Which is about half of them, I believe (GV III to MV). And let's not forget that some worlds orbit weeks worth of travel inside their star's jump limit. Try getting anyone to delive freight there for Cr1000 per ton.

If ignoring that doesn't qualify the trade system for stuffed up status, it will do until something that does comes along.

It says nothing about delivery times... One could, based upon CT Bk2, land and take off in one day with a 1G ship from any mainworld with cargo in tow...

But according to that very same Book 2 ships usually don't do that. And if a ship does that, then (according to the rules) it takes off without passengers and freight, because according to the rules it takes five days to collect passengers and freight. As for speculative cargo, I'm not sure if the rules specify how long it takes to examine the offers, buy a cargo, and have it loaded. Conceivably the RAW allows you to touch down, load up, and blast off in no time at all.

Then again, a pure Bk2 universe also has TL10 J4 ships, and TL 9 J3 ones.

A hit, a very palpable hit!

Yes, quite conceivable it can be proved that the Book 2 system works for Book 2 ship designs. I'm certainly not going to waste my time trying to prove otherwise.

If so, the trade system wasn't stuffed up originally (since we will presumably be ignoring jump shadowing too). It just became stuffed up when HG was published and TL9 J3 ships and TL10 J4 ships disappeared from the OTU.

It has still been stuffed up for over 30 years.


Hans

 

[aramis]

While you earn a gold star for quibbling.



Wil, you actually quote the part where the rules says that commercial starships usually make two jumps per month. If regular liners and freighters are not commercial starships, then I've failed English in addition to rules reading.

Indeed, you seem to have.

Usually does not mean "all". There is your ultimate failure. You read things for absolutes, and ignore the vast and wide shades of gray that English provides for.

The majority of traffic should be moving J1 under Bk2 and Bk5+Bk7 rules.

It has still been stuffed up for over 30 years.


Hans

No, I'd say you're just incapable of admission of being dead wrong about your conclusions.

Bk5 specifically allows Bk2 ships to continue in the OTU. So we have a situation where we have both Bk2 TL9 J3 200Td priority cargo units, and big ships being unable to to J3 until TL 12...

See:

DESIGN AND CONSTRUCTION
The ship design and construction system given in Book 2 must be considered to be a standard system for providing ships using off-the-shelf components. It is not superceded by any system given in this book; instead this book presents a system for construction of very large vessels, and includes provisions for use of the system with smaller ships.

 

[rancke]

Usually does not mean "all". There is your ultimate failure. You read things for absolutes, and ignore the vast and wide shades of gray that English provides for.

The majority of traffic should be moving J1 under Bk2 and Bk5+Bk7 rules.

Ah, so you're saying that the 'usual' only applies to J1 and J2 traffic but not to J3 and J4 traffic? (Except, that is, to Al Morai J3 and J4 traffic which it canonically do apply to).

You do realize that this does not make any commercial sense whatsoever, right? If the rules were meant to allow quick turnarounds, quick turnarounds would apply just as easily to J1 and J2 traffic as it applies to J3 and J4 traffic. And if quick turnarounds were profitable for J3 and J4 traffic, it would also be profitable for J1 and J2 traffic.

(Incidentally, the majority of traffic may be moving under J1, but if it is, it's only because traffic back and forth between systems lying one parsec apart would weigh heavily in the balance. Only an extremely miniscule amount of long-distance traffic would go by J1. Even under the trade-distorting fixed per jump prices J2 is cheaper than J1.)

No, I'd say you're just incapable of admission of being dead wrong about your conclusions.

That's the pot calling the kettle black with a vengeance. You are so bent on not admitting that you're wrong that you consistently refuse to address the points that prove you wrong. I'm referring specifically to two things: 1) the problem with getting freight and passengers (and, yes, even cargo) under the Book 2 rules if a ship engage in quick turnaround, and 2) the fact that Book 2 completely ignores jump shadowing.

Bk5 specifically allows Bk2 ships to continue in the OTU.

Yes, it does. But that's a huge mistake, because the two systems are mutually contradictory and can exist in the same universe only if one is willing to accept a logical impossibility.

So we have a situation where we have both Bk2 TL9 J3 200Td priority cargo units, and big ships being unable to to J3 until TL 12...

No, we have a completely broken system where we have Book 2 TL9 J3 ships or we have a slightly less broken system where only Book 2 designs that do not break the HG ban on making jump-3 drives at less than TL12 are grandfathered, or we have a almost not broken system where Book 2 designs do not actually exist in the OTU even though we pretend they do for game purposes.

Under no circumstances do we have a system where jump-3 ships built at TL9 are compatible with the history of the OTU.

See:

You don't have to prove that HG grandfathered Book 2 designs. I'm well aware that they did. What you have to prove to back up you claim is that the setting does not make it abundantly clear that jump-3 cannot be buit at tech levels below 12.

And since the setting material does make it abundantly clear that you can't build jump-3 at tech level below 12, you can't.


Hans

 

[aramis]

The setting doesn't, until MT, have any clear declaration that I've seen that J3 is unavailable prior to TL9.

CT has only one TL table that I've found - it lists drive letters, not J numbers, and it's canonical for CT (and by Bk5, the standard). (The irony that many missed that is not lost on me...)

The wording of Bk5 implies strongly that nothing smaller than 1000Td was supposed to use Bk5, but they realized some would do so, and so made provisions for doing so. In which case, Bk5 designs are only somwhat an issue.

Quick turnarounds are, by the way, possible in CT using Bk7... just up the cost of your spec goods by 40% for immediate delivery. (Not practical - but definitely possible, RAW.)

Taking the nominal turnarounds implied in Bk7, we can justify 4.25 day turnaround... tight, but doable, and a nominal 7 day trip... round up, that's 12 days, instead of the 14. 28/12 is 2.333... which is enough to make the op costs on J2 work with freight.

It's far easier to ignore a-morai than actual rules, BTW. Whomever did the writeup either presumed costs in Bk2 being per parsec or some form of other fudge; until I had good spreadsheets with fill commands, doing the math involved to find the profit margins was just too much work. I'm not in any way surprised that no one did it back in the 80's.†

As for "can't coexist" - well, Hans, the setting, until revised by MT, had Bk2 and Bk5 designs happily coexisting, using Bk5 for small craft and big ships. Bk2 designs must needs dominate small shipping - the costs per ton are lower for J1-J2. Longer runs are less incompatible. So, either there's two different kinds of J-drive and m-Drive (which may operate on similar but different principles) or one or the other was wrong. I prefer one to be wrong, but the rules clearly say both exist. And both continued to be used in canonical materials until MT was released. I agree that they are not truly compatible, but they do coexist in canon.

Canon also says that specific dates were involved in JDrive changes - without reference to TL changes.

-=-=-=-=-​

† Actually, some did. But their results weren't as obviously available.