09-02-2017, 12:29 PM | #1 |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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[Spaceships] Passage Tubes? Stats? Cost?
Greetings, all!
SS1:42 mentions using a Passage Tube to connect two spaceships, and gives dimensions. How much would one such tube be in terms of cost, mass and DR for various TLs (primarily interested in TL9)? Thanks in advance! |
09-02-2017, 01:01 PM | #2 |
Hero of Democracy
Join Date: Mar 2012
Location: far from the ocean
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Re: [Spaceships] Passage Tubes? Stats? Cost?
We're looking at around 100 cubic yards of space. Or perhaps 100 square yards of material. Pages 75 and 76 of ultra-tech may help us with costs to fill that space.
Our options are: Envirobag Modular Environmental Cage Pressure Tent -- in three sizes. Each of the five options would provide its own point of data. The simplest extrapolation is the cage, of which we require 10. We pay $100k and haul around 2 tons. I bet the tents give better numbers. And ones that change with TL. EDIT: if we go with the envirobag being fairly roomy (7 feet long and 3 feet in radius), we get much cheaper. $12k, and 225 lbs if extrapolating volume. 4400$ and 85 lbs if we extrapolate surface area.
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Be helpful, not pedantic Worlds Beyond Earth -- my blog Check out the PbP forum! If you don't see a game you'd like, ask me about making one! Last edited by ericthered; 09-02-2017 at 01:24 PM. |
09-02-2017, 01:21 PM | #3 |
Join Date: Jun 2017
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Re: [Spaceships] Passage Tubes? Stats? Cost?
In third edition, passage tubes cost $1000 took 40 cf of space, and weighed 1000 lb and had a DR of 12. Armored passage tubes cost $1000 more, weighed 2000 lb more and had DR 20.
Hope that helps. |
09-02-2017, 01:27 PM | #4 |
Hero of Democracy
Join Date: Mar 2012
Location: far from the ocean
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Re: [Spaceships] Passage Tubes? Stats? Cost?
That's 67 units to make the full tube. so 67,000 $ and 33.5 tons.
These numbers are all over the place.
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Be helpful, not pedantic Worlds Beyond Earth -- my blog Check out the PbP forum! If you don't see a game you'd like, ask me about making one! |
09-02-2017, 02:19 PM | #5 |
Join Date: Jun 2017
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Re: [Spaceships] Passage Tubes? Stats? Cost?
No, those number were for the full tube. They took 40 cf of space when folded up not in use.
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09-05-2017, 11:26 AM | #6 |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: [Spaceships] Passage Tubes? Stats? Cost?
The tube in Spaceships is ~30 yards long, and ~2 yards in diameter. The relevant characteristic for cost, weight, etc. would be surface area, plus a bit extra for the fittings at each end. An open cylinder of this size has an area of about 2 x 3.1416 x 30 = 190 yards^2, or ~1700 ft^2.
Relevant comparisons would be Envirobags (but they have insulation that a tube won't need), Pressure Tents (but they have air tanks and locks, so I'll ignore them), and Rescue Bubbles. A sleeping bag or Envirobag probably has a surface area of about 35 ft^2 (4 yards^2). A rescue bubble can be walked in, so is presumably 5' or more in diameter, and thus has a surface area of about 80 ft^2 (9 yards^2). This gives us costs and weights per square yard of: Code:
Bag Bubble TL Cost Wt. Cost Wt. 9 $40 0.75 $88.9 0.444 10 $20 0.5 $66.7 0.333 11 $10 0.375 $44.4 0.222 12 $5 0.25 $33.3 0.167 Code:
TL Cost Wt. 9 $17K 140 10 $13K 95 11 $8.5K 70 12 $6.5K 45 Code:
Passage Tube TL Cost Wt. 9 $20K 200 10 $15K 150 11 $10K 100 12 $7.5K 75 EDIT: I forgot - DR1, like a rescue bubble. Actual armour would add quite a bit to weight, especially at lower TLs. Hmm. Using UT's armour rules, and assuming a person has a surface area of about 20 ft^2, a layer of standard thickness ballistic cloth (8 lbs, $1200 for a suit) would add 8 x 1700 / 20 = 680 pounds in weight, and $102K in price. We can probably halve the cost, because this doesn't have to be cut to fit a human body shape, but the weight wouldn't change. Making it thinner would lighten and cheapen the armour as usual. Any armour will add considerably to the storage volume, as it changes from a thin tube to a rather thicker and less flexible one. I'm happy to assume a DR1 system as the standard, because no sensible DR will keep out debris hitting at the speeds you get from radically different orbits, etc., and a baggy outer skin of mylar+foil will do for micrometeors and the like, while DR1 is enough to survive normal bumps and scrapes.
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Rupert Boleyn "A pessimist is an optimist with a sense of history." Last edited by Rupert; 09-05-2017 at 11:42 AM. |
09-05-2017, 11:58 AM | #7 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: [Spaceships] Passage Tubes? Stats? Cost?
Weight actually scales in part with volume, that is probably not very interesting on the scale of a passage tube.
In general, the force trying to split apart a circular tube is (tube radius) * (pressure within tube) * (distance over which you are measuring) -- i.e. if the tube is at 0.2 bar (about right for pure oxygen) and a 1m radius, the force trying to split the tube walls is 20,000N/m. If the tube walls have a strength of 200MPa, they need to be 0.1mm thick, and the total wall volume is 6.3e-4m^3/m; assigning a convenient density of 1600kg/m^3, that's about 1 kg/m, or 27 kg (about 60 lb) for the entire tube. This can be adjusted somewhat based on materials and desired safety margin. Note that it can't be collapsed unless the air is drained from it. Based on my experience with collapsing tubes, it's probably around 5% volume when collapsed. |
09-07-2017, 10:59 AM | #8 |
Join Date: Jun 2013
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Re: [Spaceships] Passage Tubes? Stats? Cost?
Armor cost and weight wouldn't be too difficult to work out, using the armor design articles from Pyramid. You're looking at 1700 sf of fabric. There could be a discount for not needing any basic tailoring, but I think it would probably be too small to worry about. At TL 9 you're probably using magnetic liquid armor (high-end reflex armor), for 1088 lb and $217,600 per point of all-around dDR (dDR is doubled against piercing and cutting attacks). At TL 10, you'd use bioplas, for 765 lb and $459,000 per point of all-around dDR (dDR is tripled against piercing and burning attacks). At TL 11, you'd actually still be using bioplas, but at half the price. At TL 12, you'd switch to energy cloth, for 238 lb and $119,000 per point of dDR.
There may be a limit to how thick such an armored tube can get before it's unable to be properly retracted, which will result in some sort of maximum DR for each of the above materials, but I'm not certain.
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09-08-2017, 03:33 PM | #9 | |
Join Date: May 2007
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Re: [Spaceships] Passage Tubes? Stats? Cost?
Quote:
But it would make the likelihood of puncture (requiring two simultaneous punctures of armored and presumably-self-sealing tubes) very unlikely. Oh, yeah -- and wear a form-fitting spacesuit with pull-on flexible helmet when you're in the twin tubes. |
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Tags |
docking, passage tube, spaceships |
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