new jump fuel
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far-trader
SOC-14 10K
Probably; this would reduce the volume of 1 ton of fuel from 14 cubic meters to 12.5 (0.89 dton) </font>[/QUOTE]Not much of a savings especially if you consider possibly needing to add equipment to handle the extra chilling and heating, I'd think maybe something on the order of a fuel purifier. Still it could be feasible for a large ship.
Or you could use T20's half-jump fuel rule as an example of this process taken to its most efficient extreme.
Hmm, 10%, pretty close to T20's 80/20 rule for jump fuel. It could be that drop tanks employ a slush fuel mixing with the regular liquid fuel. The result is an 80% burn and 20% saved and added to the liquid resulting in a partial slush of the carried fuel so that the 20% fits into the regular tank. That might explain why drop tanks have an increased chance of misjump. The jump drive is obviously tuned for liquid fuel use. So if you want to use slush fuel I think you could argue no added equipment is needed but you have the same chance of misjump as if using drop tanks and for the same reason it would be illegal for commercial ships. Of course it would be hard to catch someone doing it
far-trader
SOC-14 10K
False alarm on the chow bell, got a couple more minutes
Wow, 20% savings exactly, I like my theory even more
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EvilDrGanymede
Guest
I suspect you could also use up less volume if you compressed it (you'd need a lot of pressure, but it's possible). Or is it compressed already to make it liquid? I'd always assumed it was frozen to get it into that state.
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EvilDrGanymede
Guest
Sure. I think you need to apply a HUGE amount of pressure (and possibly temperature) to get to the metallic state though, so you should be able to increase the pressure a lot til you get to that point, which *should* decrease the volume and increase the density.
Unfortunately I can't seem to find any info on the compressibility of liquid hydrogen, though I did find some info about solid hydrogen which is quite interesting - apparently the solid form (Which you can get below temperatures of 14 K) is extremely compressible.
if you can decipher the technical info, take a look at
http://www.tvu.com/EngPropsSH2Web.htm
mad13142000
SOC-13
It's critical pressure is 13 Atmospheres of pressure...that and it's freezing point of 14 degrees KELVIN (That's like -400 something Farenheit)...
I agree that the machinery to maintain these conditions would negate any space savings until you get over TL 16...
-MADDog
I agree that the machinery to maintain these conditions would negate any space savings until you get over TL 16...
-MADDog
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EvilDrGanymede
Guest
Well, I'm not sure why the Hydrogen is liquid here. Either it's compressed or it's cooled into a liquid form from a gaseous state. Either way, it can't stay liquid without either being at a high pressure or a low temperature... I suspect the pressure required would be rather high, so either option probably requires a fair bit of mass and volume to handle anyway.
I'd imagine that the fuel scoops/fuel purification plants convert the stuff being scooped into the suitable liquid H2 form. It'd be interesting to see if we can find out exactly how compressible LHyd is.
There's an interesting article about storing hydrogen in various forms here:
http://www.fuelcellstore.com/information/hydrogen_storage.html
I'd imagine that the fuel scoops/fuel purification plants convert the stuff being scooped into the suitable liquid H2 form. It'd be interesting to see if we can find out exactly how compressible LHyd is.
There's an interesting article about storing hydrogen in various forms here:
http://www.fuelcellstore.com/information/hydrogen_storage.html
It's been considered by a number of people; picking your materials well, you can get one ton of hydrogen down to about 0.6 dtons (beryllium compounds, IIRC, I don't have my notes).
However, you may not be able to process hydrogen compounds fast enough to deliver pure hydrogen to the jump drive, and impure hydrogen is a misjump risk. It should be possible to process slush hydrogen fast enough.
mad13142000
SOC-13
I don't think so...Once it's been liquefied, It becomes easier to deal with. The experimental Hydrogen cars use a simple insulated pressure cylinder to keep it in...
I'm reminded of dealing with CO2 for my restaurant. Most today use a BIG tank that sits in the back. It has a refill station built into the back wall - When the tank gets low, a truck comes out...He blows out the remaining gas, then fills the tank with liquid CO2. Yes it's under pressure, and yes, it's cold. But it looks so EASY when the equipment is built to handle it, and the tank sits there at room temp, and slowly dribbles off gas from the liquid to power the Coke machine...
I view ship's tanks to be much the same. They operate at pressure to keep the H liquid...If you refill them, its using a refill station, or you have a big plant to purify and compress it down till it liquifies...But once it's inside the tank, then it requires almost no maintainence to keep it liquid.
-MADDog
Liquid hydrogen is not like liquid CO2. Unlike CO2, it has a critical temperature well below room temperature, and thus can't be kept liquid by pure pressure. Also, hydrogen in general is a notably unfriendly molecule, with a severe tendency to leak, the ability to migrate through many solid materials, and a tendency to make metals brittle by doing so.
Also, escaping hydrogen is an explosion risk, unlike escaping CO2, which is largely harmless.
Also, escaping hydrogen is an explosion risk, unlike escaping CO2, which is largely harmless.
mad13142000
SOC-13
I was using CO2 as a real life example of today's technology...I doubt 50 years ago they would have thought of a system like it...
We are talking about 3500 years in the future. If Air Products can drag semi-tankers full of liquid Hydrogen around today, surely my far trader can have a tank for it in the year 5400...
Yes, most of the fuel systems for cars contain metal hydryde sponges as tanks instead of pressure cylinders, but I still say that as far as Traveller goes, Liquid Hydrogen is still the way. Slush, or frozen would be as far above normal, everyday tech of the future as we are talking about liquid H for a fuel source today...
So, the tanks are insulated, and it takes some care in transferring fuel. If you have metal catalysts for capturing escaped H molecules, and translating them into water vapor, you cut down on the explosion risk..It IS all about the level of Oxygen in the escaping environment...
If the Saturn V could carry the stuff 30 years ago, I got no problem with my spaceship carrying it in the far future...
-MADDog
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EvilDrGanymede
Guest
Yes, but bear in mind that Saturn V only carried the fuel for a few minutes, and by the time it reached earth orbit it had used up all the LHyd that it carried. The tanks were also far away from the habitable parts of the rocket (i.e. the top)
The ships in Traveller have the tanks more fully integrated into the ship 0 in fact, it is usually in direct contact with the habitable sections, and sometimes even completely surrounding those sections. And also Traveller ships carry this fuel for much longer periods of time - weeks, months, or even years.
So it's not quite accurate to compare a Traveller ship to a Saturn V or the Space Shuttle fuel tank. AFAIK no manned spacecraft has ever had the fuel tanks right next to the habitable sections.
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