T20 Optional Jump Fuel Calculation

[far-trader]

This started in the T20 Q and A - "Refined vs unrefined fuel" but my reply seems more appropriate here as a new topic...

Originally posted by Liam Devlin:

There are several ways to tweak this:

<snip>

d) Make refined fuel more efficient IYTU- better gas mileage? my modern equivalent is what I'm saying.

I'd suggest if anyone is considering the T20 books optional rule of 50% less jump fuel this might be the way to implement it. Unrefined fuel is at the listed (100%) calculated rates while refining it allows you to use only half as much. This would justify the cost difference and everything else. You could continue to use basic T20 ships as designed to run (inefficiently) on unrefined fuel or if using refined fuel they double the number of jumps between refuelling.

Hmm, ponder ponder, new house rule?

What if unrefined fuel is what you get after it goes through the listed cheap and small fuel purifiers (not just scoops) while refined fuel requires yet a further step and much more equipment and time (i.e. prohibitive for ships but not for big starports). If you don't have at least an onboard fuel purifier you can't do wilderness refueling at all. If you spend the extra creds for refined fuel you avoid the problems (misjump chance) and only need half as much to get where you're going. Or you can buy or scoop and purify, run a small risk, and need to fill the tank to get where you're going.

Comments? Is anyone using/considering this optional rule for their game? I know I wasn't but now I'm not sure, this could justify it for my game though I prefer to play canon.

 

[lightsenshi]

Personally, I've always scratched my head at the 10% tonnage per parsec jumped rule. That's an awful lot of power.

 

[Father Fletch]

Looks interesting, and it will make the characters think twice about what fuel options they choose. I may even run with it. My only concern as a GM would be that perhaps that is something that should happen in the background when running players who are not of a mercantile bent. Not every player wants to play paperwork and paychecks, which I have seen some Traveller games devolve to. YMMV

 

[far-trader]

Absolutely FatherFletch, a detail if the players want it but easy to gloss if its someone else's problem, like if they are just mercs for hire on a patron's cruiser.

 

[far-trader]

Originally posted by lightsenshi:
Personally, I've always scratched my head at the 10% tonnage per parsec jumped rule. That's an awful lot of power.

Yeah I can hear what you're saying, but what's always bugged me more (course it wasn't CT, only later as things got more gear-headed) is to power the electronics in a small starship requires the energy equivalent of a small town's needs, not counting the drives! As far as how much energy is required to tear a hole in the fabric of space to another dimension, well I'll accept whatever the game says till someone does it in RL

 

[lightsenshi]

Originally posted by far-trader:
</font><blockquote>quote:</font><hr />Originally posted by lightsenshi:
Personally, I've always scratched my head at the 10% tonnage per parsec jumped rule. That's an awful lot of power.

Yeah I can hear what you're saying, but what's always bugged me more (course it wasn't CT, only later as things got more gear-headed) is to power the electronics in a small starship requires the energy equivalent of a small town's needs, not counting the drives! As far as how much energy is required to tear a hole in the fabric of space to another dimension, well I'll accept whatever the game says till someone does it in RL </font>[/QUOTE]Hence we use Harrington style gravatonic drives.

 

[Liam Devlin]

Originally posted by far-trader:
Absolutely FatherFletch, a detail if the players want it but easy to gloss if its someone else's problem, like if they are just mercs for hire on a patron's cruiser.

__________________________________________________
Or a patron's Q-ship?!

Uh huh! Hmmm, methinks Mike may have a chat with the skipper next time..Ensign Burrunsu! Flip these pancakes-I'll be right back [exits to command deck!].....

 

[womble]

Hi Far Trader

You said:
"...What if unrefined fuel is what you get after it goes through the listed cheap and small fuel purifiers (not just scoops) while refined fuel requires yet a further step and much more equipment and time (i.e. prohibitive for ships but not for big starports). If you don't have at least an onboard fuel purifier you can't do wilderness refueling at all. If you spend the extra creds for refined fuel you avoid the problems (misjump chance) and only need half as much to get where you're going. Or you can buy or scoop and purify, run a small risk, and need to fill the tank to get where you're going.

Comments..."

I don't like the idea, m'self. Moving from "Unrefined for free or a 100 bucks and refined for 500 unless you have a refiner" to "No free fuel unless you've got a refiner and no free refined ever" is a move in the wrong direction. It would seem to explain why refined is so expensive, but at that sort of margin, there'd still be a competitive market to drive the price down. Maybe the process of refining is hideously expensive, but even if you double the efficiency of refined fuel, you're driving the "Free Trader" (archetype, rather than ship) closer to the margins of viability.

 

[jfwking]

Many years ago I seem to recall something called super-refined fuel which was twice as effective as refined. I think this came from either one of those little pocket booklet adventures or from a white dwarf traveller adventure.

This gives us un-refined, missjump chance and it clogs the drives. Refined fuel, as spec. Super refined, requires half the volume and costs a lot more.

Bear in mind that super refined fuel adds a vast change to what has gone before and the way things could be done. Warhips using super refined can pull 2 jump 6s on internal fuel, the rifts and vasts become far less of a problem when you can cross them with a single fuel load. Drop tanks become less usefull etc etc.

One point to consider also is that the whole traveller universe is an organic entity, it has grown up and out over the years from its core concepts. One of those concepts is the jump restriction which has shaped the universe around it. The effect at the PC level is less, a few tons more cargo with a smaller fuel load on the trader. The effect at a higher level is greater. Less tonage on fuel is more cargo/weapons/secondary systems. A 10000 ton cargo hauler doing jump 2 gets an extra 1000 tons of cargo, a 10000 ton warship doing jump 4 gets an extra 2000 tons of space presuming they stay at one jump of onboard fuel.

Cutting down on the ammount of fuel used allows more room for usefull stuff on board ship but it does change one of the baseline concepts of the universe so care must be taken when doing this.

 

[Liam Devlin]

Then again, if the fuel is resolved, there's this (from Jeff Zeitlin, maestro of Freelance Site):
http://www.freelancetraveller.com/features/rules/tech/lymanjd.html

that gets you a different tweak on adding more room with a higher efficiency engine...(and uses refined fuel only)

 

[far-trader]

Originally posted by womble:
Hi Far Trader

I don't like the idea, m'self. Moving from "Unrefined for free or a 100 bucks and refined for 500 unless you have a refiner" to "No free fuel unless you've got a refiner and no free refined ever" is a move in the wrong direction. It would seem to explain why refined is so expensive, but at that sort of margin, there'd still be a competitive market to drive the price down. Maybe the process of refining is hideously expensive, but even if you double the efficiency of refined fuel, you're driving the "Free Trader" (archetype, rather than ship) closer to the margins of viability.

Yes it could make it tougher for the little guy, I didn't do any calculations for that side of the equation but went with my gut for the way it explained the 500% cost difference and why not every starport has refined fuel. As a bonus it offers a small limitation and rationale for the non canon optional fuel rule in the book. By the way I was unclear there, when I asked if anyone was using this rule, I meant the 50% fuel rule in the book (p 265) not "this" idea of mine.

Anyway its definitely a strictly free choice to adopt, alter or ignore, its just a little MTU idea after all

and still in development. More thinking aloud follows.

In answer to the no free fuel part, I guess what I'm going for in MTU is if you want 'free' fuel you need a purifier. There has to be a reason the refined fuel costs so much and is only available at better starports.

This also justifies the need for military fuel supply via tankers. The fact that you can rift jump (using the optional 50% j fuel rule) if you fill up with refined fuel won't guarntee you can come back. There will have to be refined fuel on the other side to do that. In fact I can see this creating more strategic value for rift border systems with refined fuel capability.

Further it creates two different dynamics. The core with its high tech well developed starports will have refined fuel (common and perhaps cheaper). This is where you'd find ships designed exclusivly for refined efficient fuel use. Out on the border (by far the better setting for travellers) ships would be built to allow for the contingency of using unrefined fuel (i.e. the standard rules). If some fancy pants noble comes slumming with her TL-F Yacht and ends up tanks dry in some backwater system with only unrefined fuel who oh who will help her and bring her a load of refined fuel for her baby? She would be oh so grateful, and daddy would just be forever indebted

I think part of what always bothered me a little about fuel use in traveller is driving this. That is your tanks (a specific volume) filled with 'unrefined' fuel (sea water, swamp water, polar ice melt, or mixed gasses from gg's) or 'refined' fuel (either purified on board or bought, liquid H) give you the same energy when fed into the drives.

Then there is the bit about 'refining' on board. You fill your tanks with whatever and then remove the impurities and change it to liquid H and (almost magically) you end up with the same volume of pure liquid H from the muddy pond water (or whatever).

It works better for me if the J drive (mostly a fast hot reactor) and the power plant (a slower reactor) are set up to use 'unrefined' at the listed performance with the chance to misjump because of impurities. Better still if that has to go through the available purifiers first (which perhaps reduces the volume significantly in the process). Or, if the tanks are filled with pure liquid H, you only need half the volume for the same performance.

Granted, as pointed out, this has ramifictions. However if, as I intend to do if I use it, the Imperial (et al) design philosophy is that ships are built around the assumption that unrefined fuel may have to be used (i.e. the standard J fuel calculation). That means all canon ships are still valid. There may of course be a few custom produced ships that take advantage of the refined fuel efficiency but they would always have to use refined fuel and therefore be limited to operating out of starports with the capability to supply it.

Well, I got a little long winded. I'll hush a bit and see if I won or lost anyone to the cause. Thanks for the sounding board and feedback (prior and incoming)

 

[marginaleye]

Personally, I've always scratched my head at the 10% tonnage per parsec jumped rule. That's an awful lot of power.

That's why I prefer to believe that "jump fuel" plays a role vaguely akin to the hydrogen consumed by a fission-pile rocket. It's not a source of energy, it's more like "reaction mass," passively consumed in the process of dropping the starship into hyperspace pushing it in the right direction. After being reduced to energetic plasma by the ship's power plant, and passing through the jump drive, the "fuel" gets vented out into hyperspace. Eventually, it "misjumps" back into our universe, as widely-scattered individual particles.

 

[womble]

Hi Far-trader

I hear what you're saying... One comment/response:
"...the bit about 'refining' on board. You fill your tanks with whatever and then remove the impurities and change it to liquid H and (almost magically) you end up with the same volume of pure liquid H from the muddy pond water (or whatever)..."
I see the canon as two stages:
1) Either: crack the H2 out of the goop you pipe out of the pond, using elecctrolysis, then liquefy it. This requires a much larger volume of crude H-source - you'd need to leave the hoses in the liquid because a tankful of the uncracked stuff is no where near enough L-Hyd for a jump. This is something any power plant can do. It results in fuel which is impure because the electrolysis breaks down impurities in the water into a gaseous phase, too.
Or: scoop a mix of Hydrogen, Helium, methane and water from the upper reaches of a GG atmosphere and filter out the non-Hydrogen using filters built into the scoops. This produces impure fuel because the filters are imperfect (though as good as they can be made).

2) run the resultant fuel through a refiner which takes out maybe 1% of the volume by removing "impurities" generated one way or another.

If you filled your tanks with seawater, orbitted and began to process fuel out of it you'd get a small amount of drive-quality fuel.

Thank you all for your thoughts on this. I think I'm going to just drop the price of refined to a competitive level, so that fuel refiners are not a "gimme" fit. Makes adventure hooks too - especially if the owner decides not to install one: take the time to repair the starport refiner, or risk misjump. I think I'll have spacelanes rumour exaggerate the risk of a misjump when using unrefined fuel...

 

[Liam Devlin]

there's anew angle, one that Lisa brought up, Mr Womble, fits in with yer merchant campaign too: A Price War say in refined fuel between the starport-and some wildcatters! Or two habitable worlds in same system trying to draw a crowd of revenue! Boggles the mind, why I haven't thought of it sooner! Top of the day to ye tho!
Slainte!

 

[Spinward Scout]

I've done something similar in my game with the fuel. Emperor Strephon (using the GURPS timeline) has been working on about 10 different projects during his reign. One of which is Super-refined and Ultra-refined fuel (75% and 50% of fuel volume needed, respectively). Basically running on the same principles as above. A Star Tranciever (space communicator) was a really good one. Stellar communication traveled almost as fast as starships (then only the really important stuff and time-sensitive stuff went by x-boat and courier). Another was a jump multi-inductor to propel the ships once they are in jump-space to a secondary level (or even a third) thereby multiplying the distance traveled for the same amount of jump fuel. The only drawback, was that I made it draw almost as much normal (non-jump fuel related) energy as the ship needed for an entire month. If you didn't figure things out correctly, you couldn't even call for help once you made it out of jump-space.

And not all of these projects were completed. And some of them never could be. But the Emperor's Fleet (a small groups of ships that escort the Emperor around) were outfitted with the best of these finished or even unfinished projects. And the Emperor began to appear in places in the Imperium that was impossible with the CT type of jumps. And the Zhodani, the Solomani, and the Hivers are all trying to get ahold of the project specs.

Basically, if you make something really hard to get ahold of, make it really expensive (or hard to steal), or make it hurt you if you don't use it right, it doesn't matter if it exists in the universe.

Later,

Scout

 

[legate_legion]

Hello fellow Travellers,

For the 50% break on fuel, I have the standard fuel rates for TL 9 to TL 15 ships, at TL 16 & above I give them the break as by that time a better understanding of Jump Space has to be around...