Fuel Bladders

[Condottiere]

An author's work, in other words, does not have to be realistic, only believable and internally consistent (even the last requirement can be relieved to some extent). When the author pushes an audience beyond what they're willing to accept, the work fails in the eyes of that particular audience. As far as science fiction is concerned, viewers are usually willing to go along with creative explanations which is why people don't criticize your wormhole travel system or how a shrinking potion doesn't violate the laws of matter conservation, but even in the more fantastical genres, suspension of disbelief can be broken when a work breaks its own established laws or asks the audience to put up with too many things that come off as contrived.

 

[phavoc]

Please provide the source documentation that has the designers of Traveller claiming the rules are scientifically accurate?

- All changes should be rational, logical, and scientifically sound (after a!l, Traveller is a science fiction role-playing game).

LBB0, p34.

OVERVIEW OF TECHNOLOGY
Traveller makes certain assumptions about the nature of future technological developments. In addition to the pro- gressive refinement of existing equipment and methods, several areas of future technology have been postulated. Traveller bases its technology on a series of logically explainable developments even if they may be far beyond any present science.

MT Referee's Manual, p56

Apart from a few specified magical technologies, most things should be scientifically reasonable, I believe. The rules are of course very simplified, where the limit to too simplified is may lie in the eye of the beholder.

Fuel filtration has always been a bit magical, rather than technological. But like it says, it's a sci-fi RPG, NOT a hard-science RPG.

 

[-Daniel-]

An author's work, in other words, does not have to be realistic, only believable and internally consistent (even the last requirement can be relieved to some extent). When the author pushes an audience beyond what they're willing to accept, the work fails in the eyes of that particular audience. As far as science fiction is concerned, viewers are usually willing to go along with creative explanations which is why people don't criticize your wormhole travel system or how a shrinking potion doesn't violate the laws of matter conservation, but even in the more fantastical genres, suspension of disbelief can be broken when a work breaks its own established laws or asks the audience to put up with too many things that come off as contrived.

Amen Brother Condottiere.

 

[snrdg121408]

Hello vargr1,

I use demountable fuel tanks and muti-use liquid/gas cargo / fuel tanks, in MTU.

Never liked the idea of bladders that might leak or rupture :?

The US Army has air-droppable fuel bladders.

Given some high-tech materials, I'd assume that Traveller starship fuel bladders would be darn near impossible to rupture.

Unless the dice decide to make a bad roll for the party or some other event occurs. ;-)

 

[Condottiere]

If they can drop an elephant, they can drop anything.

 

[vargr1]

Fuel filtration has always been a bit magical, rather than technological. But like it says, it's a sci-fi RPG, NOT a hard-science RPG.

True, but change fuel from liquid H2 to water, and the magic of fuel purification plants turn into simple reverse osmosis technology.

Or whatever follow-on tech is developed in the next 3000 years that does the same thing.

 

[-Daniel-]

If they can drop an elephant, they can drop anything.

Yes, CGI in movies make anything possible.

 

[phavoc]

Fuel filtration has always been a bit magical, rather than technological. But like it says, it's a sci-fi RPG, NOT a hard-science RPG.

True, but change fuel from liquid H2 to water, and the magic of fuel purification plants turn into simple reverse osmosis technology.

Or whatever follow-on tech is developed in the next 3000 years that does the same thing.

One problem is that storing water vs. liquid hydrogen in the same tank. Plus the base rule has always been "unrefined" fuel can be used for jump, which to me says you can use the raw water instead of LHyd. So there's that magic.

And then there's the question, IS it LHyd, like what the shuttle uses, or is it compressed? I think more of the former, however that makes impurities in your lines and tanks which get exposed to plain water an issue. I'm assuming the super materials of the future to line the tanks and such wouldn't have an issue with storing various forms of hydrogen in both processed and unprocessed formats.

Because of all that I just let sleeping magical dogs nicknamed Handwavium lie there peacefully.

 

[Reynard]

I think what everybody keeps forgetting is water is NOT a fuel. It does not burn per se to create usable energy. It takes a lot of energy to convert it to it's basic oxygen and hydrogen before it can be recombined for energy but that is highly energy wasteful such as seen for our primitive overly huge rockets today. We're not concerned with the initial energy waste to create the components of hydrogen and oxygen today because we have the luxury of time and energy outside the actual vehicle. We only want a clean, relatively power fuel compared to other fuels to get the vehicle off the ground as clumsy as that still is. Hydrogen for it's liquefied volume has a very high specific energy and is considered a very clean fuel for a fusion reaction while any oxygen would be a wasteful pollutant better served by carrying more hydrogen.

The issue of hydrogen leakage is not such a problem. Hydrogen is so small it will get through any barrier not specifically treated. You never totally stop the permeability but reduction is done even today for our rocket fuel storage and hydrogen transport pipelines. It doesn't take much to assume future tech discovers better means to further refine reduced-flow hydrogen barrier materials that also prevent transfer of the intense cold explaining why Traveller ships and vehicles carry it with little danger. Those fuel bladders are wonders of a flexible material that form fits then stiffens and becomes highly impermeable when filled with liquid hydrogen. Fuel bladders obviously are far too fragile and unstable without a solid brace of a ship's hold so no hanging outside a ship like a balloon.

 

[vargr1]

Fuel filtration has always been a bit magical, rather than technological. But like it says, it's a sci-fi RPG, NOT a hard-science RPG.

True, but change fuel from liquid H2 to water, and the magic of fuel purification plants turn into simple reverse osmosis technology.

Or whatever follow-on tech is developed in the next 3000 years that does the same thing.

One problem is that storing water vs. liquid hydrogen in the same tank. Plus the base rule has always been "unrefined" fuel can be used for jump, which to me says you can use the raw water instead of LHyd. So there's that magic.

There is no need to store H2 in the same tank as the water at all. You crack the O from the H2 when and as you need it. That can be done quite easily, quickly, and on an industrial scale with electrolysis. You don't pump H2O into jump space. No magic involved at all.

 

[vargr1]

I think what everybody keeps forgetting is water is NOT a fuel. It does not burn per se to create usable energy. It takes a lot of energy to convert it to it's basic oxygen and hydrogen before it can be recombined for energy but that is highly energy wasteful such as seen for our primitive overly huge rockets today.

Untrue electrolysis of water into H2 is a fairly cheap thing to do energy wise. It's certainly a lot less energy than you get by fusing that liberated H2 - like by a factor of several thousand times more energy. It's not like Traveller reactors or thrusters are actually setting a flame to the H2 fuel and watching it burn.

any oxygen would be a wasteful pollutant better served by carrying more hydrogen.

That wasteful pollutant really helps your life support system.

The issue of hydrogen leakage is not such a problem. Hydrogen is so small it will get through any barrier not specifically treated. You never totally stop the permeability but reduction is done even today for our rocket fuel storage and hydrogen transport pipelines. It doesn't take much to assume future tech discovers better means to further refine reduced-flow hydrogen barrier materials that also prevent transfer of the intense cold explaining why Traveller ships and vehicles carry it with little danger. Those fuel bladders are wonders of a flexible material that form fits then stiffens and becomes highly impermeable when filled with liquid hydrogen. Fuel bladders obviously are far too fragile and unstable without a solid brace of a ship's hold so no hanging outside a ship like a balloon.

Yeah, H2 leakage isn't a problem.

Until your ship gets hit in space combat and that H2 gets vented into the crew area. That's not going to be nice at all. When that happens, I'd much rather have water vapor venting.

Also, carrying your H2 supply as water (or even better - ammonia) means you can carry more H2.

 

[phavoc]

There is no need to store H2 in the same tank as the water at all. You crack the O from the H2 when and as you need it. That can be done quite easily, quickly, and on an industrial scale with electrolysis. You don't pump H2O into jump space. No magic involved at all.

But that is exactly what happens when you do frontier refueling, or buy unrefined fuel. You aren't getting pure refined LHyd, you are getting water. It's not processed instantly as the tables for fuel purification requires time to crack the water.

You could use multiple tanks and process one into the other, but there's nothing to state that. When you pick up 40Dtons of fuel your tanks are fully full. So that means the magic of fuel purification must take place within the same tank.

A scout ship, which doesn't have fuel purifiers, does exactly that - pump water into space to form the jump bubble when it's tanks are full of water it just picked up from that planet's hydrosphere.

 

[vargr1]

There is no need to store H2 in the same tank as the water at all. You crack the O from the H2 when and as you need it. That can be done quite easily, quickly, and on an industrial scale with electrolysis. You don't pump H2O into jump space. No magic involved at all.

But that is exactly what happens when you do frontier refueling, or buy unrefined fuel. You aren't getting pure refined LHyd, you are getting water. It's not processed instantly as the tables for fuel purification requires time to crack the water.

You could use multiple tanks and process one into the other, but there's nothing to state that. When you pick up 40Dtons of fuel your tanks are fully full. So that means the magic of fuel purification must take place within the same tank.

A scout ship, which doesn't have fuel purifiers, does exactly that - pump water into space to form the jump bubble when it's tanks are full of water it just picked up from that planet's hydrosphere.

Of course water purification takes place in the same tank. Why would that be a problem? Ever hear of osmosis?

You don't need another tank to purify water. It's perfectly possible to purify all the water in one tank without moving out of the tank. Yes, it means that pure water and dirty water will be in the same tank, but that's not a problem.

Imagine a movable permeable membrane inside the tank that allows part of the tank to be filled with pure water and the other side unfiltered water. The membrane would be one way, and only allow water to go through in one direction. Fill the tank from the local swamp, add pressure to the side with dirty water, let it permeate the barrier, and you get a tank full of pure water, with all the non-water stuff left over on one side. Waste space (with some type of filter on the intake to filter out solids) would be a very small amount. Not enough to worry about in Traveller's resolution scale.

Occasionally (like when you fuel up from a starport) you flush the non-water leftovers from the tank (or send some crew member in to clean it manually as a form of punishment).

You only need one tank and no magic at all.

Then - as MT's Starship Operations Manual states, you crack the H20 and flush the H2 (not the water - that would cause a misjump) to inflate the the jump bubble.

 

[AnotherDilbert]

I think we must be able to handle both water and hydrogen. When we refuel in the atmosphere of a gas giant we get impure hydrogen, that the fuel processor has to purify.

I imagine a normal spacecraft has several smaller tanks and can pump fuel between them to trim the balance. We could pump unprocessed fuel from one tank to the fuel processor and deposit the processed fuel into another tank.

I agree with vargr1, I see no magic involved.

 

[Reynard]

The graphic diagram in the MegaTraveller Starship Operator's Manual shows the fuel scoop to the fuel processor with waste ejected before the pure product pumped to the tanks. Water is pumped in from the Aux In/Out at the pump to the fuel processor then back to the tanks. The Aux In/Out most likely also connects to the fuel bladder and/or dismountable tanks and possibly the drop tank fittings.

Oxygen from water processing isn't added to the ship's life support because water sources are the exception to the rule compared to skimming gas giants. That's why you're replacing those expensive life support modules so often, your removing spent air scrubbers that recycle oxygen in a closed system.

 

[phavoc]

Of course water purification takes place in the same tank. Why would that be a problem? Ever hear of osmosis?

As a matter of fact, I have. But have you heard of liquified hydrogen? You know, that stuff that in order to be a liquid has to be cooled to about -425F? And did you know that just plain old water kinda freezes at just 32F? So explain to me how osmosis can occur in a tank where one thing can't exist with the other? It is impossible to have liquid hydrogen co-existing with liquid water in the same container. If you could, now that WOULD be magic.

You don't need another tank to purify water. It's perfectly possible to purify all the water in one tank without moving out of the tank. Yes, it means that pure water and dirty water will be in the same tank, but that's not a problem.

You do realize that we aren't talking about drinking water here. We are talking about liquid hydrogen. And that's the stuff of Traveller. Unrefined fuel can be plain water, or hydrogen and other gases collected in a gas giant. Refined fuel is pure liquid hydrogen.

Imagine a movable permeable membrane inside the tank that allows part of the tank to be filled with pure water and the other side unfiltered water. The membrane would be one way, and only allow water to go through in one direction. Fill the tank from the local swamp, add pressure to the side with dirty water, let it permeate the barrier, and you get a tank full of pure water, with all the non-water stuff left over on one side. Waste space (with some type of filter on the intake to filter out solids) would be a very small amount. Not enough to worry about in Traveller's resolution scale.

Yes, that's called water filtration. And it's done today. However using the same exact machinery to purify swamp water and super-cool gaseous hydrogen into a liquid is a pretty nifty idea. Except the two types of filtration mechanisms aren't the same.

Then - as MT's Starship Operations Manual states, you crack the H20 and flush the H2 (not the water - that would cause a misjump) to inflate the the jump bubble.

I don't disagree there. As you purify the H20/GG gas you will be venting any excess materials. Venting 02 at a spaceport isn't a big deal, though it is a fire hazard. Venting ammonia and helium and other gases in space also isn't a big deal.

 

[vargr1]

You do realize that we aren't talking about drinking water here. We are talking about liquid hydrogen. And that's the stuff of Traveller. Unrefined fuel can be plain water, or hydrogen and other gases collected in a gas giant. Refined fuel is pure liquid hydrogen.

You do realize that my point was (and that I had said many postsa go) that if you go through the Traveller rules and replace 'starship fuel is liquid hydrogen' with 'starship fuel is water', the amount of magictech needed to justify purification goes away?

You did get that point, yes?

 

[AnotherDilbert]

'starship fuel is water'

Where do we get the oxygen when we skim a gas giant?

 

[vargr1]

'starship fuel is water'

Where do we get the oxygen when we skim a gas giant?

There's a lot of crap in a gg's atmospheres, including water vapor. Some ggs have a lot of water in higher layers, some of them are colder and have the water layer much deeper. Still, most of them have some water.

Besides, if you stumble upon a gg with no water, you can always use the ice from one of their many tiny moons. No doubt most ggs collect a passel of moons, and they're probably lousy with water ice. Honestly, I always thought gg refueling to be a dangerous waste of time. Just send some fuel cutters to the nearest icy moon.

Fuel as water solves so many problems.

 

[phavoc]

You do realize that we aren't talking about drinking water here. We are talking about liquid hydrogen. And that's the stuff of Traveller. Unrefined fuel can be plain water, or hydrogen and other gases collected in a gas giant. Refined fuel is pure liquid hydrogen.

You do realize that my point was (and that I had said many postsa go) that if you go through the Traveller rules and replace 'starship fuel is liquid hydrogen' with 'starship fuel is water', the amount of magictech needed to justify purification goes away?

You did get that point, yes?

Unrefined fuel is water. Refined fuel is liquid hydrogen.

Traveller posits both forms. Fuel purification converts it.