Skimming gas giants

[Blue Ghost]

1ft³ = 0.028317m³

A snow shovel (a rough guesstimation) holds 4/10s of a cubic foot.

=> 4/10 * 0.028317m³ => a snow shovel can move 0.0113268m³ of snow per shovel load.

1m³ / 0.0113268m³ = 88.28618851 => shovel loads to get one cubic meter of Europan snow into the tanks.

360m³ => 31783 shovel loads for a full tank.

That's an awful lot of labor to fill your tanks. Presumably you're filling an airraft or wheel barrow, then moving that to some access hatch of somekind. I think one man stranded by himself would be hard pressed to get enough fuel in his ship to lift off and jump home, but I think it doable. I think a crew of four could definitely pull it off, and a crew of 6 to 8 players certainly could get a enough fuel (again, perhaps not a full tank), but enough to get off and get home.

*edit* if the fuel source is liquid, then I'm thinking a starship probably has an old fashioned hand pump to help fill the tanks. I can see snow being vacuumed up into the tanks, and then the power plant doing its work to keep the ship toasty, working, and to keep the tanks full.

Ergo, if you can't refuel on a gas giant, you can always shovel snow. It won't be easy or pleasant, but it can be done.

 

[Magnus von Thornwood]

EIE Mining Buggy!

See, this is why all Daarnulud Design Bureaux starships come equipped with both Fuel Bins and an EIE Mining Buggy. No pick and shovel work for your crews, some quick lasering, grab and go.

 

[Vladika]

1ft³ = 0.028317m³

A snow shovel (a rough guesstimation) holds 4/10s of a cubic foot.

=> 4/10 * 0.028317m³ => a snow shovel can move 0.0113268m³ of snow per shovel load.

1m³ / 0.0113268m³ = 88.28618851 => shovel loads to get one cubic meter of Europan snow into the tanks.

360m³ => 31783 shovel loads for a full tank.

That's an awful lot of labor to fill your tanks. Presumably you're filling an airraft or wheel barrow, then moving that to some access hatch of somekind. I think one man stranded by himself would be hard pressed to get enough fuel in his ship to lift off and jump home, but I think it doable. I think a crew of four could definitely pull it off, and a crew of 6 to 8 players certainly could get a enough fuel (again, perhaps not a full tank), but enough to get off and get home.

*edit* if the fuel source is liquid, then I'm thinking a starship probably has an old fashioned hand pump to help fill the tanks. I can see snow being vacuumed up into the tanks, and then the power plant doing its work to keep the ship toasty, working, and to keep the tanks full.

Ergo, if you can't refuel on a gas giant, you can always shovel snow. It won't be easy or pleasant, but it can be done.

Did/does this account for "void" spaces in the shovelful? Snow isn't a solid.

Also, just how do you/ will you mine ice? With what tools?

I'm thinking that if you still have the ability to generate heat (engines aren't "cold") then it would be more practical to melt the snow or ice and pump up the remaining water. (This assumes a lot of snow or ice in one space or the ability to move the ship/ smallcraft around to the location(s) required to acquire the snow or ice.

 

[Blue Ghost]

Did/does this account for "void" spaces in the shovelful? Snow isn't a solid.

Also, just how do you/ will you mine ice? With what tools?

I'm thinking that if you still have the ability to generate heat (engines aren't "cold") then it would be more practical to melt the snow or ice and pump up the remaining water. (This assumes a lot of snow or ice in one space or the ability to move the ship/ smallcraft around to the location(s) required to acquire the snow or ice.

Good points all around. As for ice, well, you're screwed I guess unless you have a chainsaw or ax or something. If you have a robot that can operate at those low temps, then you're in good shape. Ah heck, I don't know. Splurge on a Magnus ship.

 

[HG_B]

I don't have the math for this kind of changing function, but is my gut correct that you will reach vacuum with enough velocity to coast out to a point where your maneuver drive is stronger than the local gravity?

If you have reached the modified escape velocity. (Planet G's - Drive G rating = gravity number to figure escape velocity from)

 

[Carlobrand]

Erm, when did jets come into this?

My thought a few posts back was that you could deal with the problem of insufficient thrust from the maneuver drive during that gas-giant skimming operation by building jets into the maneuver drive system: draw in some atmosphere, tap the waste heat and apply it to the local atmosphere, and you're cooling your power plant while gaining a bit more thrust. The maneuver drive isn't very efficient at providing thrust - I think I figured something like 4 or 5 percent of the power you put in comes out as gravitic thrust - so there's a lot of energy that isn't doing anything but radiating away as waste heat. Then I blew the calculation.

 

[HG_B]

The maneuver drive isn't very efficient at providing thrust - I think I figured something like 4 or 5 percent of the power you put in comes out as gravitic thrust - so there's a lot of energy that isn't doing anything but radiating away as waste heat. Then I blew the calculation.

Except, your figures have no real world basis to determine Grav drive efficiency. They could be 99% efficient for all we know.

 

[BytePro]

Re: ice/water refueling - This has never been an issue IMTU.

IMTU, the leading edge of scoops and hoses instantly vaporizes ice and water to create high temp steam that is pulled into an 'arbsorber' that releases separated H2 for liquifying. The idea comes from a 1975 NASA Tech Brief titled 'Using Permeable Membranes to Produce Hydrogen and Oxygen From Water'. (I'll try to post a scan later).

The absorber system (piping made of a permeable material) is also used for normal gas giant skimming to separate out H2. The system requires back flushing and purging for reliable use - and the permeable material is not perfect, as some contaminants always get through. Hence fuel purifiers.

[Duh - no need for a scan - a quick google yielded the Tech Brief! http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750000314_1975000314.pdf]

 

[HG_B]

Re: ice/water refueling - This has never been an issue IMTU.

IMTU, the leading edge of scoops and hoses instantly vaporizes ice and water to create high temp steam that is pulled into an 'arbsorber' that releases separated H2 for liquifying.

How does a hose suck in vaporized ice while in vacuum?

 

[aramis]

How does a hose suck in vaporized ice while in vacuum?

Press the mouth firmly down to the surface.
Vaporize only inside the mouth sufficient to generate some pressure.
cycle the compression chamber between lower than this pressure and higher, with the higher feeding to a storage bladder.

Restage compression from the bladder to the tank.

Doable, but not very practical. Requires not melting the ice around the mouth of the hose. And hanging onto the ice elsewhere to maintain seal.

 

[BytePro]

How does a hose suck in vaporized ice while in vacuum?

With enough heat, ice sublimes directly into water vapor at low enough pressure including a 'vacuum'. As is the case with comet tails.

If there is ice, there is some sublimation, so the vacuum is not as it would be in deep space - generally some trace atmosphere will exist in environs with surface ice.

 

[Blue Ghost]

If you're too scared to ride the storms in Jupiter, or a Jupiter like world, then land on Europa and do one of the following;

shovelling snow for fuel; http://www.youtube.com/watch?v=lp_Rwbp8S1k

Or, for ice; http://www.youtube.com/watch?v=TBEtcYFNb-o

 

[BytePro]

Press the mouth firmly down to the surface.
Vaporize only inside the mouth sufficient to generate some pressure.
cycle the compression chamber between lower than this pressure and higher, with the higher feeding to a storage bladder.

Restage compression from the bladder to the tank.

Doable, but not very practical. Requires not melting the ice around the mouth of the hose. And hanging onto the ice elsewhere to maintain seal.

Hose simply goes through a large diameter 'cover' to maintain gases. Fairly rigid 'hoses' (more of a flexible plastic tube) can use a hose pusher.

Still, hoses are a highly inefficient way of getting a quantity of fuel - useful in emergencies only, IMTU. Better to shovel it in with great big shovels. I.e. 'scoops'.

The outer atmo of 'gas giants' are composed of various ices - Ammonia, Methane, Hydrogen Sulfide, Ammonium Hydrosulfide and Water - depending on layer/depth. So scooping ice and liquids is not uncommon IMTU - gobbling up a bunch, vaporizing to extract H2 (dumping the rest) and repeat.

Skimming water and ice is no free ride IMTU - I describe it as tantamount to multiple 'controlled crashes'. Skimming gas is only marginally better. Ships are designed to do it, but buying fuel is a lot better proposition in the long run - the maintenance for scoops, absorbers, pumps, fuel processors and the risk and stresses on ships gets costly (i.e. - adventure hooks ).

 

[HG_B]

Press the mouth firmly down to the surface.
Vaporize only inside the mouth sufficient to generate some pressure.
cycle the compression chamber between lower than this pressure and higher, with the higher feeding to a storage bladder.

Restage compression from the bladder to the tank.

Doable, but not very practical. Requires not melting the ice around the mouth of the hose. And hanging onto the ice elsewhere to maintain seal.

Of course. I know you can muck around like that but it'd take forever to 'get 'er done'.

 

[HG_B]

With enough heat, ice sublimes directly into water vapor at low enough pressure including a 'vacuum'. As is the case with comet tails.

If there is ice, there is some sublimation, so the vacuum is not as it would be in deep space - generally some trace atmosphere will exist in environs with surface ice.

Close enough to absolute vacuum to make my point valid and correct. Also, comets don't have 'tails' until they well into the inner system area...

 

[Vladika]

Another thing, you can't suck through a hose. A pipe yes, a hose no.

The large nearly ridge black "hose" lengths you see on firetrucks are in fact short, nearly rigid and are actually "pipes".

However, if you think you can suck through a hose, give it a try. Lay down (or stand up) with your mouth on a length of garden hose about 2 feet below the surface of a pool. Suck till you asphyxiate, pass out, or have a heart attack, but you aren't going to suck air. (You can't do this with a rigid pipe either. Don't believe it? Try it.)

Or, try sucking water through a long flexible hose. It will collapse in both of the given cases. (In either case pumping works just fine.)

 

[BytePro]

Close enough to absolute vacuum to make my point valid and correct.

Dad had to setup a special dirty vacuum chamber for testing the LRO instrument used to confirm water on the moon. Technically no where near an 'absolute vacuum'.

Since I never said ice melts in a vacuum - it vaporizes - and simply responded to your question, not sure what point you are trying to be 'valid and correct' on. <shrug>

Also, comets don't have 'tails' until they well into the inner system area...

Yes - because of the sun.

 

[BytePro]

Another thing, you can't suck through a hose. A pipe yes, a hose no.

Semantics - one can suck through a non-collapsing tube. Last I checked, bendable straws work just fine and so does the hand pump siphon I use all the time.

 

[Vladika]

Semantics - one can suck through a non-collapsing tube. Last I checked, bendable straws work just fine and so does the hand pump siphon I use all the time.

It was only posted so people wouldn't think they could run 100 plus feet of hose and refill. You could pump it through a very long hose though. (A "non-collapsing tube" is a pipe. Interestingly enough fire departments occasionally collapse the pipe water mains under the streets.)

So, in the ships locker, we'll need all kinds of things often forgotten. Might be interesting to make a list of things needed for refueling unconventionally.

 

[Carlobrand]

Except, your figures have no real world basis to determine Grav drive efficiency. They could be 99% efficient for all we know.

Well, lessee. Free Trader in CT displaces 200 dT and puts out 500 Mw power to achieve 1G, but there's no figure on mass. My CT calculation was based on applying the MegaTrav weight CT - might have been off by a couple hundred tons, but it was likely a good ballpark figure. In MegaTrav, it masses about 2300 metric tons loaded, draws either 260 Mw or 280 Mw for the maneuver drive, depending on the tech level, and delivers 1G performance for that power.

1G performance means 2300 tons at 10 m/s^2 means 23 million Newtons.

MegaTrav's 260 Mw means 260 million watts means 260 million Newton*meters. And, CT's 500 Mw means 500 million Newton*meters.

Now, again, I'm not good at physics past a certain fairly basic point, but I don't see 99% efficiency in those numbers. Maybe someone can show me where I'm not understanding this right.

Another thing, you can't suck through a hose. A pipe yes, a hose no.

The large nearly ridge black "hose" lengths you see on firetrucks are in fact short, nearly rigid and are actually "pipes".

However, if you think you can suck through a hose, give it a try. Lay down (or stand up) with your mouth on a length of garden hose about 2 feet below the surface of a pool. Suck till you asphyxiate, pass out, or have a heart attack, but you aren't going to suck air. (You can't do this with a rigid pipe either. Don't believe it? Try it.)

Or, try sucking water through a long flexible hose. It will collapse in both of the given cases. (In either case pumping works just fine.)

Actually, that's not true - the garden hose bit. Every summer I buy a free-standing pool for my kids: about 2 1/2 feet deep, enough for them to splash about and cool off in. And, every summer, I end up having to repeatedly clean the thing out. Algae forms on the bottom, dirt gathers from the kids stepping in and out, and so forth. My solution every year is to stick one end of a water hose into the pool, take another end to a convenient end of the yard that's a foot or so lower than the pool bottom, suck hard on that end of the hose and then immediately drop the hose. Water comes up into the hose from my inhalation, and when I drop the hose it coasts down toward the low end of the yard, creating a draw behind it that draws more water into the end of the hose in the pool. Then I go to the pool end of the hose and use that draw to suck up the algae and junk, which ends up pouring out the other end at that low point. It's kind of a trickle, but it seems to be just enough to keep the flow going.

The garden hose is just inflexible enough to put up with that bit of suction without collapsing. I doubt I'm drawing more than a foot or two of water into the hose, but it's enough to get the water past the lip of the pool and on its way downward, and then that downward pull does the rest of the job for me. I suspect you're right that if I had some real suction, the hose would collapse, but I can't put out that kind of power with my lungs. The little bit of power I can apply is just enough to get the job started without exceeding the hose's strength. As long as you don't exceed a certain level of suction, the hose acts as a pipe.