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Rupert · 09-05-2017, 11:26 AM

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

It would appear that the bubble is made of lighter, but rather more expensive materials, which seems fair for something of its nature. For a passage tube that's intended to be light, sealed, and reusable (which a bubble isn't really), I'd be inclined to use the higher of both price and weight, giving this table for the tube:

Code:

 
TL   Cost  Wt.
 9   $17K  140
10   $13K   95
11   $8.5K  70
12   $6.5K  45

I'd chuck a bit more on for the fittings at each end:

Code:

Passage Tube
TL   Cost  Wt.
 9   $20K  200
10   $15K  150
11   $10K  100
12   $7.5K  75

Compared to most spaceships, the cost is almost nothing, and the weight likewise. I've always included them as standard equipment that comes with an airlock. Thus a new, or well maintained ship will have one per lock. An old ship, not always kept up to spec, might well not have any, or have one much-patched and sometimes leaky one. If the PCs don't think to check before blasting off into the wild blue yonder, their trip could be more exciting than they anticipated.

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.

09-05-2017, 11:26 AM	#6
Rupert Join Date: Aug 2004 Location: Wellington, NZ	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 It would appear that the bubble is made of lighter, but rather more expensive materials, which seems fair for something of its nature. For a passage tube that's intended to be light, sealed, and reusable (which a bubble isn't really), I'd be inclined to use the higher of both price and weight, giving this table for the tube: Code: TL Cost Wt. 9 $17K 140 10 $13K 95 11 $8.5K 70 12 $6.5K 45 I'd chuck a bit more on for the fittings at each end: Code: Passage Tube TL Cost Wt. 9 $20K 200 10 $15K 150 11 $10K 100 12 $7.5K 75 Compared to most spaceships, the cost is almost nothing, and the weight likewise. I've always included them as standard equipment that comes with an airlock. Thus a new, or well maintained ship will have one per lock. An old ship, not always kept up to spec, might well not have any, or have one much-patched and sometimes leaky one. If the PCs don't think to check before blasting off into the wild blue yonder, their trip could be more exciting than they anticipated. 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. __________________ Rupert Boleyn "A pessimist is an optimist with a sense of history." Last edited by Rupert; 09-05-2017 at 11:42 AM.