Updated: 10 Ton Small craft
- Thread starter DFW
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atpollard said:
In a multi-world system (Earth to Mars can be > than 2 AU's, to asteroid mining operation, to industrial complex on a moon orbiting a GG. The possibilities are almost endless. Look at the travel times for a 2G ship and you'll see that 2 weeks only gives a safety margin.
As far as small craft needing "refined fuel", MGT doesn't say. Although, no fusion PP can burn water, methane or ammonia. Fuel scoops come standard with a streamlined hull.
captrooper
Mongoose
I like the design, and implied function, but you imply what I regard as luxuries in the stateroom.
What's your opinion on luxuries?
What's your opinion on luxuries?
Unrefined fuel only affects jump in MGT, same as classic. Makes sense - the odd impurity shouldn't affect normal operation of a fusion plant.
Nice idea, DFW. As you say, plenty of scope for a long duration boat in many systems. Could be considered a basic "car" for a belter
Nice idea, DFW. As you say, plenty of scope for a long duration boat in many systems. Could be considered a basic "car" for a belter
Cross-Dressing Aslan
Mongoose
Sounds useful as a sort of "Space Transit Van".
rinku said:Unrefined fuel only affects jump in MGT, same as classic. Makes sense - the odd impurity shouldn't affect normal operation of a fusion plant.
Nice idea, DFW. As you say, plenty of scope for a long duration boat in many systems. Could be considered a basic "car" for a belter
Unfortunately, in a P-P Fusion plant you can't really have anything in the chamber but H2. What you skim from a GG won't work. H2O also couldn't be used so, I figured some filtering would be used.
Ya, I always figured there was a place for a vehicle of this type. I really made it just to play with the small craft rules in HG. I found they are in need of fleshing out in the area of medium level accommodations. Think of a sleeper train of old. Bunks for trips that are ~2 days.
DFW said:
Well, there has to be some basic process built in to the ship to allow extraction of Hydrogen from skimming or water, or it couldn't work. That would be part of the fuel scoops upgrade; a combination filter (for skimming - a nanomesh that only lets H2 and smaller molecules through should work fine) and electrolysis equipment (for water), or something similar. The refining plant takes it to a higher level of purity required for jump fuel (for whatever reason this requires). Conceivably this could be reducing imputities from 1 part per million to 1 part per 10 million or something.
Scoops would be all you need for this boat, unless you also want a capacity for it to act as a fuel purifier for another craft.
Well, how the jump drive actually works has had various explanations over the years, as you well know.
All that matters is that for some reason, jump fuel has less tolerance for impurities than normal fusion fuel. It's a given that any fusion plant will need high purity H2, but as with any process what matters is quality sufficient for the job. A few ppm of oxygen or other molecules would be expected but not likely to cause problems in the power plant, but for reasons to do with inserting the ship into jump space (and thus not really subject to reality checking) this can be an issue with jump fuel on occasion. The old explanation was very small power fluctuations; if an impurity caused a drop of a milliwatt at the wrong time, it wouldn't cause any appreciable performance issue for a laser or M-Drive, but potetentially could for an interstellar jump.
Worth noting that even so, unrefined fuel is usually quite safe to use as jump fuel anyway in MGT - taking extra time to prep for jump with reasonable skill and stats give enough +DMs to make routine jumps safe.
"Unrefined" fuel is a misnomer - it's *all* refined from raw sources. It would be better to call the two grades "regular" and "high grade". Possibly the terms used are a marketing strategy by the fuel companies...
"Yew don't want ter be usin' that there dirty un-refined fuel there, son! Come over h'yar and let me set yew up with some premium re-fined juice!"
All that matters is that for some reason, jump fuel has less tolerance for impurities than normal fusion fuel. It's a given that any fusion plant will need high purity H2, but as with any process what matters is quality sufficient for the job. A few ppm of oxygen or other molecules would be expected but not likely to cause problems in the power plant, but for reasons to do with inserting the ship into jump space (and thus not really subject to reality checking) this can be an issue with jump fuel on occasion. The old explanation was very small power fluctuations; if an impurity caused a drop of a milliwatt at the wrong time, it wouldn't cause any appreciable performance issue for a laser or M-Drive, but potetentially could for an interstellar jump.
Worth noting that even so, unrefined fuel is usually quite safe to use as jump fuel anyway in MGT - taking extra time to prep for jump with reasonable skill and stats give enough +DMs to make routine jumps safe.
"Unrefined" fuel is a misnomer - it's *all* refined from raw sources. It would be better to call the two grades "regular" and "high grade". Possibly the terms used are a marketing strategy by the fuel companies...
"Yew don't want ter be usin' that there dirty un-refined fuel there, son! Come over h'yar and let me set yew up with some premium re-fined juice!"
captrooper
Mongoose
I've never been clear on this in CT even, and always thought I'd missed something in the rules...
If you are using unrefined fuel for anything, how can you do it? If hydrogen is the fuel, how can water at the same tonnage be used for anything other than 2/3 efficiency (if that)?
If the fuel in MgT is unrefined, it is not pure H2 - is it just gas or liquid containing hydrogen (if you don't purify it, what else is it)?
How can anything fueled by an element be as efficient on the same fuel tonnage of a multi-element-molecule formed fuel?
If you are using unrefined fuel for anything, how can you do it? If hydrogen is the fuel, how can water at the same tonnage be used for anything other than 2/3 efficiency (if that)?
If the fuel in MgT is unrefined, it is not pure H2 - is it just gas or liquid containing hydrogen (if you don't purify it, what else is it)?
How can anything fueled by an element be as efficient on the same fuel tonnage of a multi-element-molecule formed fuel?
Yeah, a lot of confusion on this.
Basically, the raw source of the hydrogen fuel is usually either water or a GG atmosphere. A ship with fuel scoops can skim hydrogen from a GG or electrolyse it from water to obtain "unrefined fuel", which is liquid hydrogen plus low levels of other molecules. Refined fuel is unrefined fuel that has undergone *further* processing to remove the impurities (or more accurately, to reduce the levels).
As a thought, it's also possible that the impurities being removed might include hydrogen isotopes - deuterium and tritium would electrolyse into the same tank as normal hydrogen.
Basically, the raw source of the hydrogen fuel is usually either water or a GG atmosphere. A ship with fuel scoops can skim hydrogen from a GG or electrolyse it from water to obtain "unrefined fuel", which is liquid hydrogen plus low levels of other molecules. Refined fuel is unrefined fuel that has undergone *further* processing to remove the impurities (or more accurately, to reduce the levels).
As a thought, it's also possible that the impurities being removed might include hydrogen isotopes - deuterium and tritium would electrolyse into the same tank as normal hydrogen.
DFW said:
Yup, 1.6 times as much.
LH2 = 68 grams of Hydrogen per litre
H2O = 1000 grams per litre with 2/18 of the water being hydrogen,
so water contains 111 grams of Hydrogen per litre (1000*2/18 ).
Ammonia is another good source of Hydrogen.
NH3 = 682 grams per litre (liquid) with 3/17 being hydrogen,
so liquid ammonia contains 120 grams of Hydrogen per litre.
NH3 = 817 grams per litre (frozen solid) with 3/17 being hydrogen,
so solid ammonia contains 144 grams of Hydrogen per litre.
For comparison, solid H2 (<14 degK) = 88 grams of Hydrogen per litre (lighter than marshmallow).
[as an aside, 1g/L = 1 kg/m3]
atpollard said:
Yep, about as good as ammonia. In the MGT rules you can't store and use H2O or ammonia directly without purifying 1st (otherwise you could have smaller tanks for a small craft) but with a purif plant you could design a ship with smaller tanks. Unlike jump usage, you can purif as you go because of the usage rate.
With the ship I designed I wanted to keep normal sized tank but, I could have reduced the volume to .62 tons and gained tonnage even with a purif plant.
Zero, take note. Chemistry is a wonderful thing.
:wink: :wink: :wink:
captrooper
Mongoose
LOL... 
While I am fully in accord with DFW about the advantages of storing water or some other hydrogen compound then extracting the H2 later on, I don't agree with his interpretation regading what a fuel processor does. Core rules, p.110:
"Fuel processors convert unrefined fuel into refined fuel. One ton of fuel processors can convert 20 tons of unrefined hydrogen into refined fuel per day."
"Fuel" in Traveller has always meant liquid hydrogen, whether refined or unrefined. Fuel scoops, not fuel processors, are the basic equipment that gathers fuel - the processors are used to produce H2 of higher purity required for safe jump operations. Core pp140-1 supports this.
But as discussed above and in a previous thread on this topic, hauling tanks of water around to be converted into H2 later is a very valid concept, since it takes up less volume than the H2 that can be extracted from it, it's easy to store and cheap (usually free) to obtain*. Normal cargo space can be used, either by converting it or just by carrying big tanks of it as cargo. Turning off the heating and carrying it as ice is also an option - though this would add another level of processing (i.e. melting it and feeding it into the electrolysing chamber. I just had a vision of ice-fuelled spaceships, with "wet gang" crew members shovelling ice into a furnace, where the steam is then passed through a chamber to crack it. Steampunk, indeed...).
* Ammonia has its points, but is more difficult to store, is much more toxic, less easy to obtain and has less use for life support purposes. Plus it smells.
"Fuel processors convert unrefined fuel into refined fuel. One ton of fuel processors can convert 20 tons of unrefined hydrogen into refined fuel per day."
"Fuel" in Traveller has always meant liquid hydrogen, whether refined or unrefined. Fuel scoops, not fuel processors, are the basic equipment that gathers fuel - the processors are used to produce H2 of higher purity required for safe jump operations. Core pp140-1 supports this.
But as discussed above and in a previous thread on this topic, hauling tanks of water around to be converted into H2 later is a very valid concept, since it takes up less volume than the H2 that can be extracted from it, it's easy to store and cheap (usually free) to obtain*. Normal cargo space can be used, either by converting it or just by carrying big tanks of it as cargo. Turning off the heating and carrying it as ice is also an option - though this would add another level of processing (i.e. melting it and feeding it into the electrolysing chamber. I just had a vision of ice-fuelled spaceships, with "wet gang" crew members shovelling ice into a furnace, where the steam is then passed through a chamber to crack it. Steampunk, indeed...).
* Ammonia has its points, but is more difficult to store, is much more toxic, less easy to obtain and has less use for life support purposes. Plus it smells.
