First off, thanks for taking the time to write the reply.
Captain Jonah said:
More numbers for the bottled air question.
Re the bottled air idea. A human uses roughly 550 litres of oxygen a day in a normal state and double or triple that if exercising or engaged in heavy physical activity. This is just to replace the oxygen consumed by breathing, something would still need to strip the CO2 out of the air. If you are simply dumping the used air and replacing it then you need a base of 11,000 litres of air to maintain one atmosphere.
At 210 Bar (scuba tank pressure) 1Dton will hold roughly 345,000 litres of air. By using the same cryonic system that keeps the H liquid for fuel you can with liquid oxygen you can pack in almost 5 times that much but this is pure oxygen and you would need CO2 scrubbers to dump the CO2 and replace it with oxygen.
So if you are using stored air and simply venting the old air one Dton will keep one person breathing for 31 days. With a system to scrub and dump the CO2 and with stored liquid oxygen one Dton will keep the same person breathing for 3000 days.
I think on my future ship designs where I show any of this detail I'm going to go with possibly 1 dT per stateroom of stored LOX (maybe half that if we could reasonably assume some sort of basic chemical scrubber that requires no power to operate, plus the available air already in the ship's internal spaces would help). Here's why. According to the published rules, unpowered life support can keep people breathing for up to 2 weeks. I'm assuming unpowered means whatever high tech CO2 scrubbers the ship has can't operate and so am assuming there is 2 weeks of stored/bottled oxygen per stateroom. We also know you can put up to 2 people per stateroom but no more without "straining the life support beyond its limits", so air for 2 people for 2 weeks is roughly one month, hence the 1 displacement ton. This also makes sense to me from a safety standpoint in ship design. Jump travel means anywhere from a few hours to 1-2 days to reach the 100 D jump limit, then approx 1 week in jump space, and possibly 2-3 days travel back once you come out of hyperspace (depending on how good your astrogator is). That's nearly 2 weeks time during which you'll be either completely on your own or 1 or more days away from rescue. Thus having 2 weeks of bottled air as a minimum guarantees that no matter what happens, even if the ship completely loses all power, everyone will at least still be breathing. Further, if the ship get's depressurized in combat, it explains where the air to replace it comes from and how much there is available.
I would put the pipes and cables in a run under the floor and above the ceiling, areas that are easily accessible because they are the corridors and use that half meter of height that exists outside of the human inhabited bit.
Pondering this has actually given me several ideas which has also partly prompted some of my questions. For example, say I'm building a 100 dT aerodyamic ship that is a fairly "flat" design... much longer and wider than it is high. In that design my life support, "piping", etc. might be between rooms rather than over or under them.
Another example, on a larger ship, and again assuming decks are 3.5m total height but standard interior height is 2.5m, by arranging the decks I can have 2m of height between alternating decks which would give a significant "maintenance" deck in between every other deck like so...
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command deck
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2m maintenance deck
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crew deck
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passenger deck
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2m maintenance deck
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cargo deck
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Just an idea this discussion prompted for maybe a lil more variety in ship design.
I would think that due to the need for piping and multiple systems (water would be cold with a rapid heater in the staterooms), air fresh and used, human and galley waste water, solids would probably be stored in situ and cleaned out regularly as I cannot really see a starship having 3-4” waste pipes from the freshers.
I think it would depend on the ship. Smaller ships say 100 dT to around 800 dT as a rough benchmark would probably just vent solid waste directly to space... easiest way to deal with it (and through a freak chance of nature one day a Belter discovers a giant turd asteroid...). Larger ships, probably getting over the 1,200 dT mark and definitely capital ships would probably have to have some sort of waste piping simply to hand the volume of waste involved. Too many cabins might be well in the interior of the ship and I don't see someone going round to manually collect it from a trap each day (oh god Captain... not waste retrieval duty... ANYTHING but that!), no easy way to directly vent it to space, so some sort of piping would have to exist. Hmm... guess that means somewhere on your 50k dT cruiser there's the ship muck tank... "quick, through this hatch before the guards catch up to us.... wait... what the.... ewwwwwww.... I think I'd rather faced the guards....". :lol:
Call it 10 people per Dton for a life support system that handles air and water and waste.
If you are economy class bunking with two or three people in narrow bunks per Dton then you can pack in 9 people in 3Dtons and one Dton of life support.
I tend to add luxuries and extra Dtons for crew and passengers anyway but looking at this I can also set a limit on how many people can be supported by the life support. A liner with35 Staterooms but just 4Dtons of life support and fully booked is going to be in trouble when it goes to rescue the 30 odd people who just abandoned the transport that just exploded. On the other hand that rugged free trader with 12 staterooms but 2Dtons of life support can carry 40 people if they are sleeping in chairs and on the deck.
This is a really important point and another reason I've been pondering this. The passenger liner in your example could effect rescue if it just left the starport, but it would have to turn around and head right back. If it just came out of jump, it probably doesn't have enough air left. Then again, if we use 2 weeks bottled air as a standard, and assuming the CO2 scrubbers are fully functional, it could handle them without trouble... though the air might get slightly stale after a few days.
In terms of food and consumables storage. With minimal packing you can get about 5000 MREs into a Dton. Fresh food comes with a lot of storage problems, odd shapes, packing etc with significantly reduces the amount you can store. Plus as you add the higher quality stuff like passengers who want wine in bottles not those plastic boxes and you use yet more space.
With higher tech space meals packed for lower volume you could probably get 1000 person days out of a Dton including some fresh and drinks. Good quality stuff or mostly fresh is going to take up more volume, probably twice the space or 500Days. This is just food and Drink.
And this is exactly the kind of problem with stored food that's been bugging me. Hi-tech prepackaged food is great if you're restocking somewhere that has the industrial base to support producing it. But if you're on a Tech 4 world... you've got a whole new set of problems. Given the wide variety of Tech levels in the Imperium, naval architects would have had to consider this. So I would imagine food storage would allow for more "bulk" food in its figures. Either that or we could say that part of that high cost for life support goes to the SPA who ensure that nifty pre-packaged food is available at all starports... even that Class D downport on a Tech 2 world. Personally, I'd rather a more "rugged" and versatile allowance for bulk food storage for when those Free Traders invariably go somewhere "interesting". We could even use a mixture of the two... you can get that nifty but expensive hi-tech pre-packaged stuff at the starport... or you could head outside the starport and see what the locals have to offer at probably much cheaper prices.... course... just remember, all that air is recycled and nobody wants a repeat of how those Dfurrnan buritos made Nyx the Aslan gassy... REALLY gassy...
Terra/Sol broke it down to pallets of stores that are used as and when. For example you buy a Dton of standard life support (each cabin holds 0.25Dtons of stores within its 4Dtons so you can drop them in without needing extra tonnage) which lasts you 50 person weeks(Cr250 per week). Economy stuff lasts 60 Weeks (Cr200/week) but cannot be used for passengers, luxury stuff lasts 35 weeks but is more expensive (Cr450/week). Each pallet contains a little extra air, water, consumables, fresher supplies etc as well as food and drink.
Very nice... gonna have to break down an go buy those books soon as I get the spare cash.
A Dton as a galley is going to be half kitchen fittings and half standing room for the cook (measure out 3m by 1.5m of your kitchen ), if this area is food prep you should be able to feed 10-12 people at a time from this but with maybe half of it being storage as it is all food processors and cookers and the like. Unless you are a passenger liner feeding more than 12 at once isn’t needed so 1Dton for the galley will do most small ships. Food storage needs to cover the expected time between resupplies on a bad run plus a bit more. Call it at least 6 weeks or for easy math 50 days. So one Dton of stores will do for 10 people for good to luxury meals or 20 people for crew rations. Use the storage in the galley for extras not regular supplies (the cooks spices and little specialities).
Nicely thought out.
So your Liner with up to 50 passengers and 20 crew would be using better quality supplies and therefore would have approx 7Dtons of stores maximum. Subsidised ships or ships built to make set runs out and back could easily manage with half of that.
So for your free trader with 12 staterooms (48Dtons) 2 Dtons of life support, a 1Dton gallery and another 1Dton of stores (the extra four peoples stores would fit into the galley) leaving 12 2Dton staterooms and another 20Dtons for corridors, the lounge etc.
The liner would run to three galleys, 7Dtons of stores, 4Dtons of life support or 14Dtons. With 25 Staterooms taking up 3Dtons each and 10 staterooms taking up 2Dtons each that leaves 31Dtons for the lounge, corridors etc. The liner has more spacious staterooms but needs a lot of extra luxuries and space to match the room available to the much smaller free trader.
Nice set of example, only thing I would change is the amount of space going to bottled air as discussed above. Otherwise very much the kind of ideas and descriptions I was looking for. Hope Mongoose takes some notes as well.
