GURPS Spaceships, upscaling sizes

[SRoach]

I agree that it should be possible to produce total life support in a package that is no bigger than whatever is consuming the life support.
UltraTech has a Suitcase Universal Replicator, on page 93, that can produce a quarter pound of material in 10 seconds. Assuming it can do that once per minute without overheating, and extrapolate that up to 24 hours, and you have a production capacity of 360 pounds of production capacity per day. Most of that time could be spent turning atmospheric CO2, and sealed waste containers from the head, into breathable air and "sanitized" feedstock modules for later use, in something that could fit under the galley counter. Or as part of it. That would certainly make for a diet that was more interesting, and desirable, than rotating the same 3 E-Ration flavors for the duration of the journey.

A little digging gave me some ROUGH numbers for CO2 production and O2 consumption for an adult human. It's Something like 1.73lbs of O2 consumed per day, and something higher than that for CO2, (2.2kg, for an active adult, per the EPA's guidelines, with a lot of wiggle room, as one would expect from a government agency). Data is taken from two different websites.
(Personally, I'd take that 2.2kg, divide it by 44 and multiply it by 32, or the molar mass of the O2, with the C cracked off, as that's where the majority of the CO2 is coming from. That gives us an upper bounds of 1.6kgs of O2 consumed.)
Still, (1.6kg+2.2kg)*2.2=8.4lbs, is well within the materials handling capabilities of a suitcase nanofac from Ultratech, (UT92), making the throwaway line on page 17 of Spaceships ("Alternatively, vessels with replicators....can be assumed to be able to manufacture all necessary food.")

It does, however, conflict with the numbers for replicators, found on page 16 of Spaceships under "Factory (TL8) [ANY!]", which not only precludes putting ANY factory on an SM+5 craft, (which is too bad, as that seems like a fine size for a Von Newman probe), but would also limit a roughly 1.5 ton module to about 0.15lbs of output per hour. (Values extrapolated.)

[cvannrederode]

Originally Posted by SRoach

A little digging gave me some ROUGH numbers for CO2 production and O2 consumption for an adult human. It's Something like 1.73lbs of O2 consumed per day, and something higher than that for CO2, (2.2kg, for an active adult, per the EPA's guidelines, with a lot of wiggle room, as one would expect from a government agency). Data is taken from two different websites.
(Personally, I'd take that 2.2kg, divide it by 44 and multiply it by 32, or the molar mass of the O2, with the C cracked off, as that's where the majority of the CO2 is coming from. That gives us an upper bounds of 1.6kgs of O2 consumed.)

If you haven't already, do a search for "Design Rules for Life Support Systems", a 2003 paper by NASA. Among other things, it has an input and output table per crew member. (Did you know that humans produce about 1/3 kg per day of water by metabolizing food, in addition to the 1 kg of CO2.)

Thoughts I have on this: it's easy to convert a couple of seats into a stretcher or bed for someone to sleep, but "cabin" spaces imply a galley for food preparation and head for toilet and hygiene needs, in addition to life support with enough regeneration to support the crew for as long as they have food (I presume this since the rules include $ and weight for food only). This means gas and liquid recovery and recycling, maybe even complete reduction of CO2 to O2 and carbon they can sell back to the food producers.

There's also rules in Pyramid #3/34 Alternate Spaceships that effectively halve the weight requirements for cabins if they omit all the "life support" features save an AC. This allows four cabins in one SM+7 cabin system, by mass, or 7,000 lbs, which will give you a modest bunkroom. This is still a bit off for an RV...our camper is 7,000 lbs, and can officially sleep 10, but I think that's very generous. With out converting the table and couch, you get a queen bed, and four single bunks...but they're cozy, almost too cozy for a 6'5" person like me.

I also, in my own handling of the rules, recognize two different Size Modifiers. Most everywhere else, you use a "Size" SM base of linear measurement, but for spaceship design there's a separate "Mass" SM that is used. I use the armor value rules in Pyramid #3/34 Alternate Spaceships as a springboard to use the Mass SM for design, but then once that's done and I work out a actual size (I have big spreadsheet with tools that include volume->mass->linear size->SM calculations), I'll develop a "Size" SM at the end and list that in its stat block.

RAW let you make a design with an "effective" SM three less than the design SM, if you have 18 or more armor systems, and a high-efficiency design from Pyramid #3/40 Vehicles.

This spreadsheet also can do system stats for non-integer SMs. So I can put in that the RMS Titanic was 52,310 tons (displacement, which is mass), get (mass)SM 11.48, which gives about 350 cabin spaces per system, or 700 with only climate control.

[dcarson]

The Titanic between passengers and crew had 2200.

[Tyneras]

Going by wikipedia Titanic was 52k tons, making it SM+11, and had a capacity of about 3,400 or 3,600 total. 200 cabins per habitat system by default, at 2 people per cabin that would be 9 systems, though there would obviously be a difference between first class and steerage. That doesn't sound to terrible for a passenger ship.

With no automation (GURPS Spaceships 7 p.20) and assuming 15 crewed systems, the ship would need 450 crew, the Titanic's 847 would just about cover 2 shifts.

Increasing the passengers per habitat system and reducing the number of crewed systems likely helps make it closer to the actual Titanic. I've hardly accounted for cargo or fuel or other systems.

[Phantasm]

Originally Posted by Tyneras

Going by wikipedia Titanic was 52k tons, making it SM+11, and had a capacity of about 3,400 or 3,600 total. 200 cabins per habitat system by default, at 2 people per cabin that would be 9 systems, though there would obviously be a difference between first class and steerage. That doesn't sound to terrible for a passenger ship.

With no automation (GURPS Spaceships 7 p.20) and assuming 15 crewed systems, the ship would need 450 crew, the Titanic's 847 would just about cover 2 shifts.

Increasing the passengers per habitat system and reducing the number of crewed systems likely helps make it closer to the actual Titanic. I've hardly accounted for cargo or fuel or other systems.

Using the "No Life Support" option in Alternate Spaceships (Pyr #3/34: Alternate GURPS) goes a long way to providing these, IIRC, doubling the number of cabin equivalents and passenger seats, though that reduces the steerage cargo to 2.5 tons per cabin space.

[Ulzgoroth]

Originally Posted by Phantasm

Using the "No Life Support" option in Alternate Spaceships (Pyr #3/34: Alternate GURPS) goes a long way to providing these, IIRC, doubling the number of cabin equivalents and passenger seats, though that reduces the steerage cargo to 2.5 tons per cabin space.

Which is straightforwardly just making the steerage cargo trade-in match the half-weight cabin unit...

(Though steerage trade-in is a bit odd, in that except at SM +6 you get back ~2/3 of the total system tonnage, but nothing seems consistent with the rest having any particular use.)

[weby]

Originally Posted by Ulzgoroth

(Though steerage trade-in is a bit odd, in that except at SM +6 you get back ~2/3 of the total system tonnage, but nothing seems consistent with the rest having any particular use.)

It is a bit odd, but I guess it is meant to represent the fact that steerage cargo is pressurized and climate controlled, though the spaceships entry for carrying things like livestock does not sound like it would work due to running out of lifesupport fast that way..

In my games I assume that steerage cargo does indeed contain long term lifesupport for four or short term for 15/5 ton chuck as the designer wants and that accounts for the extra mass...

[Varyon]

Originally Posted by Ulzgoroth

(Though steerage trade-in is a bit odd, in that except at SM +6 you get back ~2/3 of the total system tonnage, but nothing seems consistent with the rest having any particular use.)

Steerage cargo would basically just be a completely unfurnished room with no partitions and maybe a water spigot you can attach a hose to for cleaning, filling up a waterbowl, etc. Habitats normally have beds, storage areas for clothing and personal effects, and a sink, and also at least a portion of a bathroom, kitchen, shower, etc. The ~1/3 of a system it lacks compared to a Cargo Hold is to account for it being pressurized, having some degree of life support (typically Limited, for air and water only, but Full if you have replicators or Open Space, for food), etc. At least, that's the assumption I would work under.

[weby]

Originally Posted by Varyon

Steerage cargo would basically just be a completely unfurnished room with no partitions and maybe a water spigot you can attach a hose to for cleaning, filling up a waterbowl, etc. Habitats normally have beds, storage areas for clothing and personal effects, and a sink, and also at least a portion of a bathroom, kitchen, shower, etc. The ~1/3 of a system it lacks compared to a Cargo Hold is to account for it being pressurized, having some degree of life support (typically Limited, for air and water only, but Full if you have replicators or Open Space, for food), etc. At least, that's the assumption I would work under.

According to spacehips there is not extra lifesupport for steerage cargo.

[Varyon]

Originally Posted by weby

According to spacehips there is not extra lifesupport for steerage cargo.

Does it state this explicitly? Steerage cargo really can't be used to transport animals or people without the risk of overwhelming life support if it doesn't contribute to it. Reviewing the rules, it looks like steerage cargo is indeed not counted when determining the Occupancy, and that is what's used to determine if life support is at risk. I'd argue that each cabin of steerage cargo should provide +4 to possible Occupancy, the same as Bunks and Cells. Maybe instead of A for Accommodations (Full/Total Life Support + Furnished living area) this should be noted as B for Basic Accommodations (Full/Total Life Support only)?