• Welcome to the new COTI server. We've moved the Citizens to a new server. Please let us know in the COTI Website issue forum if you find any problems.
  • We, the systems administration staff, apologize for this unexpected outage of the boards. We have resolved the root cause of the problem and there should be no further disruptions.

Long cruises and patrols...

So according to the numbers, that works out to be .045Dtons of space to supply everything required for 1 person for 1 week. That seems rather... small.

Your number seems to be off, lets work through it.

1 dTon = 150 Man-Weeks

so

14 cubic meters / 150 weeks = 0.093 Cubic Meters/week of supplies

or

0.093 cm/week * 1000 liters = 93.3 Liters/week

or

93.3 Liters * 1000 cubic centimeter = 93333 cc/week

Which if you take the cube root of gives the dimensions of one side of a cubic box.

(93333)^(1/3) ≈ 45 cm square box.
 
0.093 cm/week * 1000 liters = 93.3 Liters/week

That's not huge, but probably adds up to around 40 or 50kg of supplies. Lets say half of that is taken up by 'shared' consumables and parts such as filters, cleaning fluids, medical supplies, etc. That leaves maybe 25 kg for food, drinks concentrates (water is recycled and not consumed), personal hygien products, etc for personal use.

If the military reckons 6lb (3kg) of supplies will feed one person for one day, that leaves 4kg over for the week. Given that this is a very rough analysis, with plenty of wiggle room depending on your assumptions, the numbers seem to work out pretty reasonably.

Simon Hibbs
 
93.3 Liters * 1000 cubic centimeter = 93333 cc/week

Which if you take the cube root of gives the dimensions of one side of a cubic box.

(93333)^(1/3) ≈ 45 cm square box.

I found a visual representation of the 45cm cube. It's not terribly huge. A couple of other things. There isn't any space set aside for packaging. Even efficient packaging takes up additional space. Usually people don't think about things like that, they just take the size of the object and go from there.

Granted some larger things, like tanks of compressed gasses and such don't have to be made to be part of the separate 45cm box per week, per person.

It just seems a bit small to me to accommodate 3yrs worth of supplies for a person.
 
There isn't any space set aside for packaging.

A allowed for 50% to be used for shared resources, and an average density of 1kg per 2 litres for the space reserved for personal consumables. I think those assumptions allow for packaging.

It just seems a bit small to me to accommodate 3yrs worth of supplies for a person.

I think there's a difference between what a person could reasonably live off for one week in jump between starports, and expecting someone to live off the same x156 for 3 years with no breaks. A reasonable set of supplies for the first case wouldn't necessarily cut it for the second case.

So how long could a person last on a 45cm cube of supplies per week? I don't think there's an arbitrary cutoff point. "For x many weeks it's ok, but for x+1 weeks it's not enough." Rather, it's going to become progressively less comfortable and more unsatisfying the longer you have to do it.

Simon Hibbs
 
A allowed for 50% to be used for shared resources, and an average density of 1kg per 2 litres for the space reserved for personal consumables. I think those assumptions allow for packaging.

Very much vital. If each week's food is 21 MREs, then there is going to be a lot of packaging. If it consists of ten pound tubes of ground beef in the freezer, institutional sized cans of dehydrated vegetable base, frozen cut spuds (for some reason, tater-tot hot dish sounds like something that would be served in a traveller galley), then the packaging demands go down, although the prep and storage costs go up (but that's probably assumed in the living space and cost requirements).

I think there's a difference between what a person could reasonably live off for one week in jump between starports, and expecting someone to live off the same x156 for 3 years with no breaks. A reasonable set of supplies for the first case wouldn't necessarily cut it for the second case.

So how long could a person last on a 45cm cube of supplies per week? I don't think there's an arbitrary cutoff point. "For x many weeks it's ok, but for x+1 weeks it's not enough." Rather, it's going to become progressively less comfortable and more unsatisfying the longer you have to do it.

Simon Hibbs

Exactly. Over 3 years, you will need changes of clothing. Over 1 week, probably just detergent (although these might be futuristic stay-clean clothes), and extra clothes would be the person's responsibility. Same with all sorts of other bits and bobs.
 
I was thinking the other night we have some real-world examples to look at to get an idea. First off we have our very own space station orbiting the planet. And then we've got many decades of data using SSBN's and even older diesel subs from WW2 days that stayed out to sea for months on end.

The space station receives a cargo run about once every 90 days, and the cargo is around 5,000 tons (mass). I'd say it's about 1Dton in size if you look at what the Soyuz or Dragon capsules are capable of carrying. The station has somewhere around 6 months of supplies on hand at any one time to buffer against delayed deliveries. These supplies consist of everything the station needs (food, additional water/gases to replace lost, supplies, spare parts, gifts, etc).

SSBN's are a better example than regular SSN's since once they go down they don't come back to port for their entire mission. While not as cluttered as older diesel subs, storage space is at a premuim when they first leave and supplies are stored everywhere until they are drawn down. Fresh food goes first, then they eat into their canned and frozen food (again, just like old WW2 diesel subs - cept the food is much tastier, and ice cream!).

A ship on patrol will need to get fuel, so they potentially could stop at a gas giant and get all the O2 they want, and then combine that with hydrogen to replace water lost, and roughly the same thing to replace atmosphere too. All the various sundries though would have to come from another ship, station or planet. But keep in mind that the USN does underway replenishment all the time. The ships get food and fuel and mail during these times.

I would suspect a ship on long-range patrol or a multi-month would occasionally be scheduled to meet up with a supply ship. The exceptions would be those ships that need to keep a lid on their movements, and thus would need to haven sufficient supplies on board to remain totally independent.

Also, in regards to the packaging comment, keep in mind that food doesn't always come in efficient forms. Take broccoli for example, or some types of melons, or even a bag of potatoes. Packaging does, or at least should, factor into the concept. Though I do understand it's just a game and this is just a number to be used in the game. Players want to know how much more loot or cargo they can carry all the time.
 
For reference, Dragon Cargo/Resuply Vessel's internal cargo volume is 11.2 cubic meters, 0.8Td, with a . The "trunk" (unpressurized up-only cargo) is 14 cubic meters.
The cargo mass limit is 3310 kg upward between both internal and external cargo volume. The pressurized return mass limit is 2500kg. 810 kg of disposal mass can be carried back to reentry.

So... 2 way cargo: 2500kg, 0.8Td. 223kg/cu m density limit.

And the station's resupply is almost always internal only.
 
Very much vital. If each week's food is 21 MREs, then there is going to be a lot of packaging.
MRE's involve a huge amount of excess packaging, relative to shipboard use. This is because they are field rations. IMTU, the "TV Dinner" model is the norm for military or middle passage, and are optimized for low volume, variety, and ease of preparation. (Stick it into the warmer/cooler and each component is warmed/cooled/left alone, as appropriate).
Over 3 years, you will need changes of clothing. Over 1 week, probably just detergent (although these might be futuristic stay-clean clothes), and extra clothes would be the person's responsibility. Same with all sorts of other bits and bobs.
Yes. The cleaners appropriate for clothes, persons, and cabin are part of the "life support," which in CT was Cr 1,000 /person/week. That included, IMTU, all of these, plus the filters, supplies, etc. necessary for the life support of the stateroom. I figured this little bit of stuff for a week would all fit into a package of a nominal 32 liters, such that a 30 person/weeks of life support would fit into a nominal 1000 l (1 m cube) small shipping container/crate, along with some truly minimal sundry packs. If so packed, I would put 26 of such crates in a 2 dton shipping container, containing continuous life support supplies for 15 persons for a year. An additional crate would be for long-term issue items, such as replacement clothing, minimal recreational media, etc. Such a 15 person "long cruise" pack would cost MCr .78

I presume long-wear synthetics, washing done in a very small unit integral to the fresher; a space leaving on a long cruise would take all the clothing they anticipated needing, but the fabrics and washing cycle would minimize this. If I was packing clothes for a year I would be bringing much more, because of washing, weather, activity, fashion (slave to it!), etc. I personally would have to worry about various uniforms, civvies, casual, dirty work, professional work, etc. Naval and marine uniforms would be specifically designed to minimize these issues, and cultural norms adjusted accordingly.

On a long cruise, shore leave would be essential, of course, to minimize the effects on morale. Some field rations, cheaper but more bulky, would thus extend the length of the cruise, as would opportunities to eat locally, and stock up on a small amounts of local produce ("Oh, GRANPA.....").
 
The space station receives a cargo run about once every 90 days, and the cargo is around 5,000 tons (mass). I'd say it's about 1Dton in size if you look at what the Soyuz or Dragon capsules are capable of carrying.

Are you sure it is 5000tons and not 5000kg?

We could almost put a nuclear sub in orbit if we had rockets capable of lifting 5000t.
 
Are you sure it is 5000tons and not 5000kg?

We could almost put a nuclear sub in orbit if we had rockets capable of lifting 5000t.

Whoops. Yeah, that should read pounds, not tons. Pretty efficient rockets we got eh? :)

If we use Aramis' Dragon capsule numbers, the .8DTons provides food and supplies for about 12 weeks for the six man crew. This would mean the crew consumes roughly .13 Dtons of supplies per week, or .022 Dtons per person, per week.

If we use the 150 man week number being debated, and using the ISS supply numbers, 150 weeks x .022 Dtons per week = 3.3Dtons. Even adjusting for rounding that's a 300% variance. But it feels like it would be a more realistic number.
 
If we use the 150 man week number being debated, and using the ISS supply numbers, 150 weeks x .022 Dtons per week = 3.3Dtons. Even adjusting for rounding that's a 300% variance. But it feels like it would be a more realistic number.
Yes, triple the tonnage and divide the cost by three and I think you'd hit closer to realistic life support figures.


Hans
 
Whoops. Yeah, that should read pounds, not tons. Pretty efficient rockets we got eh? :)

If we use Aramis' Dragon capsule numbers, the .8DTons provides food and supplies for about 12 weeks for the six man crew. This would mean the crew consumes roughly .13 Dtons of supplies per week, or .022 Dtons per person, per week.

If we use the 150 man week number being debated, and using the ISS supply numbers, 150 weeks x .022 Dtons per week = 3.3Dtons. Even adjusting for rounding that's a 300% variance. But it feels like it would be a more realistic number.

Note that not all the CRS mission loads are LS supplies. Every trip has been at least 500kg of new equipment. Usually under half.

Google's cache of https://www.nasa.gov/sites/default/files/files/Orbital_CRS3_mission_overview.pdf
notes the following:

Flight Crew Equipment273.4 pounds124 kg
Food Supply1360.3 pounds617 kg
Flight Procedures Books15.4 pounds7 kg
Spacewalk Equipment145.5 pounds66 kg
814 that looks like 814 kg for that 3 month block. so... 814/(12*6)=11kg per person per week in crew and EVA supplies.

But CRS3 wasn't dragon, it was a cygnus mission. Note that most food is only slightly denser than water, (I'd estimate 1.2 kg/L, but Timerover is going to have a better handle on that.)
 
True, but we should assume the same for any long-duration mission, right? Things will break in the future as well. Military ships also will do live-fire exercises and other activities that means they will be drawing down on any stored shipboard stores and armaments.
 
Not, sure I would bundle all maintenance and engineering stores with Life support. I would say something like 1% engineering volume per week for engineering stores, costed as per repair parts... (Cr10,000 per dTon per MgT)
 
Somehow those parts and stores would need to be combined (displacement wise at least) somewhere. Not that they have to be stored in the same place, but the idea here is to establish how much tonnage (including food and other stores) is necessary. This makes a good reason for having cargo holds to keep stuffed full of things you use or may need to use.
 
Back
Top