BetterThanLife
SOC-14 1K
Lets just hope the leaky valve isn't on the O2 bottles. Leaky valve, 14,700 atmospheres pressure.... What is the pressure wave on a Nuke?
Starship Economics, Book 2
- Thread starter Random Goblin
- Start date
What's the difference between KCr1 per week and KCr2 per 2 weeks?
If Mid Passage is cheaper, then the T20 numbers are different from the CT numbers that I (and others) have been complaining about. Cr750 per week is certainly better than Cr1000 per week, but not, IMO, enough.
I'm afraid I can't follow your argument here. The pressure is presumably 1 atm. and whatever the amount of air it takes to fill a ship, the per occupant cost must be however much oxygen a human being consumes in the time he spends aboard.
I don't understand that at all. Are you saying that a human being uses 27 cubic meters of pure oxygen per day? Are you sure of that figure? It sounds like a lot.
I think that is an excellent argument for rejecting your assumption that there is no rebreathing equipment on a starship. As soon as you assume that some or all of the oxygen is extracted from the CO2 (and a starship engine certainly provide enough energy to do so), you not only get much more reasonable figures for the amout of storage space the oxygen requires, you also eliminate the problem of how to dispose of the CO2.
You keep ignoring my argument that at the canonical prices there is is enough to be saved from the difference between how much a passenger burdens the life support and how much a crewman burdens it to make a difference to an average free trader's operation. At the operating budgets we've seen in various CT (and T20) adventures, several thousand credits per jump is something my players would jump at.
My point exactly. Even if Cr2,000/fortnight was reasonable (which you haven't convinced me is the case), the costs are still broken because it charges the same for 9 days worth of consumption as for 14 days.Of course while on the surface of a planet with a breathable atmosphere you could avoid using your O2 by the simple expedient of leaving the doors open and mounting a few fans to circulate the air.
Hans
Lets just hope the leaky valve isn't on the O2 bottles. Leaky valve, 14,700 atmospheres pressure.... What is the pressure wave on a Nuke?
BetterThanLife
SOC-14 1K
What's the difference between KCr1 per week and KCr2 per 2 weeks? </font>[/QUOTE]The difference is only important if you don't have the ship occupied for the full two weeks.
They are different. I never said they were the same. I was just quoting a canon source to attempt to break down the KCr2. Since the cost of lifesupport is fixed in canon.
I'm afraid I can't follow your argument here. The pressure is presumably 1 atm. and whatever the amount of air it takes to fill a ship, the per occupant cost must be however much oxygen a human being consumes in the time he spends aboard.
I don't understand that at all. Are you saying that a human being uses 27 cubic meters of pure oxygen per day? Are you sure of that figure? It sounds like a lot.
I think that is an excellent argument for rejecting your assumption that there is no rebreathing equipment on a starship. As soon as you assume that some or all of the oxygen is extracted from the CO2 (and a starship engine certainly provide enough energy to do so), you not only get much more reasonable figures for the amout of storage space the oxygen requires, you also eliminate the problem of how to dispose of the CO2.
You keep ignoring my argument that at the canonical prices there is is enough to be saved from the difference between how much a passenger burdens the life support and how much a crewman burdens it to make a difference to an average free trader's operation. At the operating budgets we've seen in various CT (and T20) adventures, several thousand credits per jump is something my players would jump at.
My point exactly. Even if Cr2,000/fortnight was reasonable (which you haven't convinced me is the case), the costs are still broken because it charges the same for 9 days worth of consumption as for 14 days.Of course while on the surface of a planet with a breathable atmosphere you could avoid using your O2 by the simple expedient of leaving the doors open and mounting a few fans to circulate the air.
Hans </font>[/QUOTE]I personally don't dive but I know that the standard tank carries enough air for a half hour dive. The standard tank is about 80 cubic feet and pressurized between 2700psi and 3200psi. So if that is what it takes, then the rest of the numbers is just extrapolating it to longer time frames. If an 80 cubic foot tank, pressurized to 2700psi is good for 30 minutes then at that pressure you would need 160 cubic feet per hour. 24 hours, 3840 cubic feet. 3840 Cubic feet is 108.736 Kiloliters which is 8 displacement tons. And all we are doing is supplying one person with enough air to breath through a SCUBA regulator. That is at 2700psi. What about those numbers make no sense? That is strictly air, the percentage of O2 you might actually need and can reclaim, etc is another matter.
I agree there ought to be better ways. I am not saying there aren't. However, given that, I can see no reason to say that the KCr1 per week is not all that expensive.
Just remember it is ill defined in canon. This is but one possible explaination.
BetterThanLife
SOC-14 1K
Perhaps we can get the numbers for the International Space Station or the Shuttle, or even the Apollo craft? That would give us a better read on how much air it actually takes for space flight.
mike wightman
SOC-14 10K
Finding out how much the oxygen generation machinery (the one that keeps breaking down 
) and the CO2 scrubbers cost may bbe informative as well.
Ok, economies of scale and all that, so how about the cost of the life support system in a nuclear sub on a weekly basis?
) and the CO2 scrubbers cost may bbe informative as well.Ok, economies of scale and all that, so how about the cost of the life support system in a nuclear sub on a weekly basis?
BetterThanLife
SOC-14 1K
The costs of operating a Nuclear Sub would be classified and probably more fiction than reality, as the government is paying itself. Even internally within the Navy. I mean this is a government that can justify $5000 toilet seats, $4334 nuts, $700 hammers, etc. Money gets shuffled all the time to cover things like cost overruns.Originally posted by Sigg Oddra:
Finding out how much the oxygen generation machinery (the one that keeps breaking down
Ok, economies of scale and all that, so how about the cost of the life support system in a nuclear sub on a weekly basis?
Are the British any better at accounting for this kind of stuff? I know you couldn't get accurate figures out of the former Soviet Union.
mike wightman
SOC-14 10K
Nope - classified.
But at least we know that our £3000 a roll wallpaper isn't funding secret research into Alien spaceships...
But at least we know that our £3000 a roll wallpaper isn't funding secret research into Alien spaceships...
No information on costs, but a fair amount on volume, weights and pressures here:
http://www.projectrho.com/rocket/rocket3g.html
And possibly enough information to put together a reasonable kit for long-duration cruises away from starports.
It might be interesting to purchase life support as a commodity with prices based on starport type, tech level and planetary atmosphere. On the other hand, players will soon be asking how high they can pressurize the cargo hold and go into business as air merchants. Or air pirates.
http://www.projectrho.com/rocket/rocket3g.html
And possibly enough information to put together a reasonable kit for long-duration cruises away from starports.
It might be interesting to purchase life support as a commodity with prices based on starport type, tech level and planetary atmosphere. On the other hand, players will soon be asking how high they can pressurize the cargo hold and go into business as air merchants. Or air pirates.
Fritz_Brown
Super Moderator
Air pirates... Oh no, it's Spaceballs!
Bhoins,
Disregarding the occasional scandal, most of those expensive items are for outer space, or some such. You would actually want that $5000 toilet seat (actually the whole sit-on assembly) in the space shuttle. Otherwise... well, let's just say it would hit the fan... and everything else in the craft.
I would say that one of the elements that went into the kCr/week idea is that everything is just that much harder in space. Admittedly, Traveller has artificial gravity, and all. But, you still have to deal with:
how many openings do you really want in the skin of the ship (what hoses have to be drug through the stinking airlock when you dock?),
cleaning out the mold that grows in the VERY inaccessible ducts (where do you think that S-type funk comes from?),
hair that clogs the fresher drains (how many characters have long hair, hmmm?) (and you can't just pop some toxic chemical in there while in space),
having to seperate chunky food items, rather than running them down the disposal (eventually, your reprocessed water will start to taste like pizza, or whatever),
dust everywhere (it's truly amazing how much dirt/dust can accumulate on a ship in the middle of the atlantic ocean),
etc.
Bhoins,
Disregarding the occasional scandal, most of those expensive items are for outer space, or some such. You would actually want that $5000 toilet seat (actually the whole sit-on assembly) in the space shuttle. Otherwise... well, let's just say it would hit the fan... and everything else in the craft.
I would say that one of the elements that went into the kCr/week idea is that everything is just that much harder in space. Admittedly, Traveller has artificial gravity, and all. But, you still have to deal with:
how many openings do you really want in the skin of the ship (what hoses have to be drug through the stinking airlock when you dock?),
cleaning out the mold that grows in the VERY inaccessible ducts (where do you think that S-type funk comes from?),
hair that clogs the fresher drains (how many characters have long hair, hmmm?) (and you can't just pop some toxic chemical in there while in space),
having to seperate chunky food items, rather than running them down the disposal (eventually, your reprocessed water will start to taste like pizza, or whatever),
dust everywhere (it's truly amazing how much dirt/dust can accumulate on a ship in the middle of the atlantic ocean),
etc.
BetterThanLife
SOC-14 1K
Actually the $5000 toilet seat was not from the Shuttle but from the C-5 Galaxy. (Basically a big airliner.) The only advantage that the C-5 Seat, at least from the pictures I have seen, has over a traditional toilet seat is that it has an area attached to the traditional seat that fills the space between the seat and the wall and the seat and the sink. (BTW it is plastic, not some high tech alloy or composite structure.)
I think I read someplace that 80+% of dust is actually skin shed by the occupants and visitors. So there wouldn't be much of a dust reduction, even in space.
Like I stated earlier, we can do wand waving and silly incantations to arrive at the per week/per jump cost for life support. I was just taking the known components and calculating costs.
BetterThanLife
SOC-14 1K
I looked at it and their air calculations have to be off by quite a bit. If they aren't then a standard SCUBA tank would last more than a day. (And since you can't stay underwater more than about 30 minutes if you go below 9M depth (About 30 feet.) there is very little reason that the standard tank would be as big as it actually is. (80 cubic Feet at 2700PSI or 2.27 cubic meters of tank, pressurized to 18,615kPa.) If we carry Air and use their number of 48L of air per day, then a SCUBA tank, at one atmosphere carries enough air to last just over 47 days. At 48L per hour that same tank at standard pressure lasts almost 2 days. At typical SCUBA tank pressure that same tank will provide enough air to last over 400 days!!! You really think people would lug 400 days of air for a 30 minute dive?Originally posted by Piper:
No information on costs, but a fair amount on volume, weights and pressures here:
http://www.projectrho.com/rocket/rocket3g.html
And possibly enough information to put together a reasonable kit for long-duration cruises away from starports.
It might be interesting to purchase life support as a commodity with prices based on starport type, tech level and planetary atmosphere. On the other hand, players will soon be asking how high they can pressurize the cargo hold and go into business as air merchants. Or air pirates.
mike wightman
SOC-14 10K
He means eighty cubic feet of air at normal atmospheric pressure, squashed into a backpack container so that it is under a pressure of between 2700 and 3200psi
Oh dear. Embarrassing. I'm tempted to delete my post, but I guess that wouldn't be right.Originally posted by Sigg Oddra:
He means eighty cubic feet of air at normal atmospheric pressure, squashed into a backpack container so that it is under a pressure of between 2700 and 3200psi
Hans
mike wightman
SOC-14 10K
If it's any consolation I didn't know what psi meant
I had to google the answer
I had to google the answer
I looked at it and their air calculations have to be off by quite a bit. If they aren't then a standard SCUBA tank would last more than a day. (And since you can't stay underwater more than about 30 minutes if you go below 9M depth (About 30 feet.) there is very little reason that the standard tank would be as big as it actually is. (80 cubic Feet at 2700PSI or 2.27 cubic meters of tank, pressurized to 18,615kPa.) If we carry Air and use their number of 48L of air per day, then a SCUBA tank, at one atmosphere carries enough air to last just over 47 days. At 48L per hour that same tank at standard pressure lasts almost 2 days. At typical SCUBA tank pressure that same tank will provide enough air to last over 400 days!!! You really think people would lug 400 days of air for a 30 minute dive? </font>[/QUOTE]No, I don't think that. But we're not actually talking SCUBA here. The air requirements are part of a closed-cycle system using recyclers, scrubbers and various other hi-tech gadgets. The air requirements are to refresh and maintain the air already in the ship; not to provide the total breathing mixture.
Yes, the 48l per day number seems low. I should have checked the numbers better.
My bad.
Further on he does mention the 48l per hour requirement more in keeping with SCUBA standard. But unless you know the volume of air in the vessel, the amount of fresh oxygen needed to replenish it, and the exact needs of each person, the calculations are going to get meaningless pretty fast.
Fritz_Brown
Super Moderator
Ummm, I don't think you could fit 48l of air into a SCUBA tank, unpressurized, Bhoins. I haul 3 1l bottles of water to work, every day (and refill them during the day. I am pretty certain that 48l would be larger than a SCUBA tank's volume.
Am I missing something in what you're saying?
Am I missing something in what you're saying?
They are, but in the opposite direction from what you think. The actual oxygen requirement for a human is approximately one kilogram per 4-5 thousand calories spent, which will in fact allow a human to last for days on the amount of oxygen you can store in a scuba tank. The reason scuba tanks have such short duration is because they don't capture exhaled air, filter out the CO2, and dump the result back into the system (a system which did this would be unreasonably heavy and expensive for a scuba system, which is why it isn't used). This does, however, reduce tank endurance by 1-2 orders of magnitude.
Fritz_Brown
Super Moderator
But, of course, you don't store O2 in a SCUBA tank. You store air. If you only stored O2, there would be all kinds of physiological problems with diving. And, that is a big reason they don't last that long (you're not using a large portion of the contents).
Besides, how much volume does a kilo of O2 take?
It appears that 1kg of O2 at standard atm. pressure takes up approx. 700l
It appears that 1kg of air (which is about 20% O2) is about 778l
That's about 1m x 1m x 3/4m.
(The above is based on this website: http://kids.earth.nasa.gov/archive/air_pressure/weather.html
(And, I think I stand corrected about 48l in a SCUBA tank, as long as you are talking a double tank, uncompressed.)
Besides, how much volume does a kilo of O2 take?
It appears that 1kg of O2 at standard atm. pressure takes up approx. 700l
It appears that 1kg of air (which is about 20% O2) is about 778l
That's about 1m x 1m x 3/4m.
(The above is based on this website: http://kids.earth.nasa.gov/archive/air_pressure/weather.html
(And, I think I stand corrected about 48l in a SCUBA tank, as long as you are talking a double tank, uncompressed.)
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