Fuel Bubbles

[markus_d]

Last session my players needed fuel bubbles to cover a 4 parsecs jump with a ship only capable of a jump 2.
The question that came up is how to get the fuel from the bubbles into the tank of the ship.
They have a far trader which can refine its own fuel. The question is if somebody needs to leave the ship in a vacc suit to connect a hose to the ship?
Or are ships normally prepared to do that from within the cargo compartment?

 

[AnotherDilbert]

We have no specific rules, so it's up to you.

Carrying extra fuel in the cargo hold have always been possible. Worst case I would allow rigging an internal hose to the fuel processor.

 

[Condottiere]

I doubt it's mentioned, though you probably have to assume that the pumps and hoses will have an ad hoc nature to them; there might be an air vent through which you can push through a hose and link it up either to the main fuel tank, or take a detour through the fuel processor.

 

[phavoc]

I guess it depends on if you are using water as your stored fuel, or hydrogen. If it's water, then it would be very easy to simply run a hose from your cargo bay to a fuel tank and pump the water in, refine it, dump the O2 into space and go from there. If it's Lhyd, you would need to be a bit more cautious about it.

Also, if you had the fuel in pods, you could simply float them out of the hold and connect them to your external fuel filling location. Or, if you wanted to make it a bit more permanent, you would set up in your cargo bay a fuel attachment (LHyd and water) so that you could pump directly into the fuel tanks any time you wanted to do this again in the future.

Come to think of it, I'm wondering if such fittings might not be optional for free traders when they were built? Since they are considered the tramp freighters of the future and their owners would do things like this, it seems reasonable.

For a straight water connection to the tanks it shouldn't be any more than say 50k. Opinions?

 

[markus_d]

Great idea to carry water in the bubbles instead of hydrogen as one should not enter the cargo bay when carrying hydrogen as its not safe.
I read they are leaking constantly so you even have to carry more of it that you have enough to jump again.
Wondering how much hydrogen I get out of water. Is it like 1 litre of water gives me 0.5 litre of hydrogen? Suggestions?

 

[AnotherDilbert]

Liquid Hydrogen has a density of 0,07. Water has a density of 1,0. The hydrogen in water is ~2/(2+16) ≈ 0,11 of the mass of water.

1 m³ of water should ideally give you 0,11/0,07 = 1,58 m³ of liquid hydrogen.

 

[PsiTraveller]

The handwaving magic of fuel processors rears it head here I think. Carrying 20 tons of water will give 20 tons of L-Hydrogen after processing correct? It makes collapsible bladders in the cargo bay more like waterbed balloons instead of cryonic bags.

Or am I missing something again?

 

[Grazelander]

The first thing to remember is make the initial jump using the reserve fuel then rely on your internal tankage. That way the processing connections can be established planet-side without dangerous space walking and afterwards disposable tanks can be jettisoned or reusable tanks recovered on board easily and not impact your maneuverability on arrival at your midway point.

 

[Jeraa]

The first thing to remember is make the initial jump using the reserve fuel then rely on your internal tankage. That way the processing connections can be established planet-side without dangerous space walking and afterwards disposable tanks can be jettisoned or reusable tanks recovered on board easily and not impact your maneuverability on arrival at your midway point.

Fuel in an internal fuel bladder (what I assume the OP means when he says "fuel bubble") can not be used to jump - it has to be pumped into the regular tanks first.

Collapsible fuel tanks (also called fuel bladders) are large flexible bladders which expand when filled with hydrogen fuel. They take up cargo space in a ship and are used to extend range without the need to fit demountable tanks. Fuel cannot be pumped directly from these tanks to the jump drive, and so a ship must complete a jump before it can use fuel stored in collapsible tanks.

 

[Condottiere]

You can use it to drip feed the fusion reactor; jump fueling is a moot point, since it's all used at the time of transition.

Arguably, you could use it to power the reaction rockets, after passing it through the kidneys.

 

[phavoc]

Liquid Hydrogen has a density of 0,07. Water has a density of 1,0. The hydrogen in water is ~2/(2+16) ≈ 0,11 of the mass of water.

1 m³ of water should ideally give you 0,11/0,07 = 1,58 m³ of liquid hydrogen.

Yeah.... unfortunately the game doesn't play well with this part of science. If you think of all the problems you could run into by pumping water from a lake or ocean into a tank designed to hold liquid hydrogen, then somehow purify all of it into liquid hydrogen without having two distinct tanks. Lol!

I try not to go down that path because it was broke the day Traveller was written. It's not really hand-wavium, more hand-over-eyes-um.

It's 1 for 1, magic purification included!

 

[PsiTraveller]

The fuel processor is a fission splitting ractor that splits everything down to Hydrogen.
H2O now gives 10 units of Hydrogen.

 

[AnotherDilbert]

Yeah.... unfortunately the game doesn't play well with this part of science.

That is not too bad... There's no magic involved, just some very good engineering.

If you think of all the problems you could run into by pumping water from a lake or ocean into a tank designed to hold liquid hydrogen, then somehow purify all of it into liquid hydrogen without having two distinct tanks. Lol!

I assume a normal spacecraft has several tanks and can pump between them. How else could we trim the balance of the craft?

 

[AnotherDilbert]

The fuel processor is a fission splitting ractor that splits everything down to Hydrogen.
H2O now gives 10 units of Hydrogen.

Nice idea, but that would take more energy to split the oxygen nuclei than we get back by combining them back again...

 

[Condottiere]

I like to think it's reverse osmosis.

In theory, there should also be an oxygen tank onboard.

 

[vargr1]

I've always figured that starship designers are pretty smart and put the requisite valves and pumps to allow fuel to be moved from storage containers to the ships tanks in the cargo bay as standard equipment. It can't be that hard or that expensive.

After all, the Vilani have been moving starship fuel for 10,000 years. They've probably figured it all out by now. No need to rig up anything.

MT had collapsible fuel bladders that you could build into the cargo hold. They collapsed to 10% of volume when not loaded with fuel.

/IMTU starship fuel is plain H2O. Liquid hydrogen is dangerous, and replacing it with H2O doesn't lose that much energy at Traveller's resolution.
//Refined fuel is pure ammonia. Ick, but still safer than liquid H2.

 

[Condottiere]

I wonder if fuel bladders may actually be a Solomani invention.