Although I know we should not try to enforce too strict standards of reality on the WH40K , I do try think it is vital for any Roleplaying Universe to be as realistic as possible, considering the given parameters of the world. Especially, if one has a party of well educated players who do like things to fit (and I am one of the worst examples. I once ruined a campaign because I could not make myself trust the NPC's sending our party on a mission of such importance, that I could not think of a good IC reason why they should not do it themselves. Or just round up the whole of Battlefleet Calixis and do it themselves, rather than try and make a starting Rogue Trader do so).

So I am wondering about trade. I am trying to calculate how many and how big the ships should be that carry the produce of an agri world and a mining station to Scintilla. In keeping with the WH40K lore, I do not wish too much ship traffic to happen. I envisage a rather regular trade of 2 to 4 shipments a year (corresponding to 1 or 2 ships shuttling to and fro). Up to now, good and simple and without too much mathematics.

Starting with those, I will use a real example: Argentina. Without going to far into the details of her economy, this nation produces some 100 million tonnes of cereal, some 50 million tonnes of soy and some 5 million tonnes of meat. An astonishing amount, which demands a continual flow of ships to export these riches. You can check it live on internet. However, to keep things simple and for the tone of the story, the agri world in question has not got Argentina's diversified economy. The Adeptus Administratum has ordered it to provide protein through Grox farming. So doing a bit of rough math, taking about 6 times the area of Argentina as useable territory and allowing for some corn farming to feed the Grox when the grazing is lean (hunger amongst the lower classes is important for the story), I can easily produce 60 million tonnes of prime Grox meat if not more. Quite probably a lot more if corn and soy would be directly converted into meat (about a 7 to 1 efficiency), which would make me hit 150 million tonnes, or about 6 kilo's of Grox meat for every Scintillan. Not an unreasonable amount. Now again going to the real world to estimate the volume, at about 20 tonnes of weight for a classical 1 TEU container, that gives me the equivalent of 7.500.000 TEU, or about 750 10.000 TEU container ships.

Now back to Warhammer40K. If I give an average vagabond class trader about half its length and half its width (with an equivalent height) in cargo space capacity, I arrive at something like 1000 by 200 by 200 cubic meters of cargo space, or a neat 40.000.000 cubic meters. I could theoretically fit about 1.000.000 container inside, so now we are getting there. This gives us a handy comparison with the real world as well: one small Imperial trader can carry about the same amount as 100 real world large container vessels. Or about 25 million tonnes of cargo.

So I guess I can skip further math and go from there. For all this meat, I would need about 6 to 8 ship movements. And added to that, we have the mining station, producing vast amounts of raw metal for the forges of Scintilla.

But luckily, we have larger ships. If I use the same rough math on a Goliath size ship, I get a ship with about 2400 by 400 by 400 internal cargo space, a massive 384.000.000 cubic metres or about 9 to 10 vagabond traders (and 900 to 1000 real world ships). The equivalent of about 250 million tonnes. Which seems to obliviate the need to think even larger, and go for the Universe class mass transporter. According to the same rough math, this ship would be able to have an internal volume of 6000 by 600 by 600 cubic metres or 2.160.000.000 cubic metres or between 5 to 6 Goliath class ships and about 50 to 55 Vagabond class traders. Or 5000 real world ships and 1.500 million tonnes of cargo.

Wow, I hope the math fits. Now to just get such a volume into orbit *groans* I think we will need a lot more than 40 ton capability lighters.

To summarise (and hoping the above math fits), the cargo capability of Imperial trade ships is in real terms, with a lots of ifs and whens added:

- Typical Vagabond class trader: ca. 40.000.000 cubic metres, allowing for the equivalent of 1.000.000 containers or 25.000.000 metric tonnes of cargo. Corresponds to about 100 large container ships.

- Goliath sized trader: about 9 to 10 Vagabonds, allowing for the equivalent of 10.000.000 containers or 250.000.000 metric tonnes of cargo. Corresponds to about 1.000 large container ships.

- Universe class transporter: about 5 to 6 Goliaths and 50 to 55 Vagabonds. Allowing for the equivalent of 50.000.000 to 60.000.000 containers and 1.500.000.000 metric tonnes of cargo. Corresponds to about 5.000 to 6.000 large container ships. In a real world perspective, this is about twice the amount of containers that Singapore deals with in a year.

I'm not checking your math, but it all sounds about right. The actual size of the cargo hold varies with the size of the hull, since the cargo components' size is fixed and its size varies as a pecrecentage of the hull. You've stumbled upon 2 incontrovertible realities of 40k. 1) The cargo capability of these ships is enormous, and 2) Halo barges are completely inadequate as lighters.

Lynata has kit upon a key concept here, that of a trading hub. An agri-world has the potential to be a waystop for many systems since many systems need foodstuffs. The agri-world may well have orbital docks and warehousing to service a wide expanse of world and traffic having nothing to do with the agri-world itself. These worlds may use the agri-world as a meeting place for trading the various products of all these worlds.

At the same time, Lynata, I'd point out that human population does grow exponentially without the need for immigration. Argentina is not a very good example, being the most urbanized of Latin America, already something of an anomaly in more normal patterns. Argentina also has modernized faster than most developing countries and its natural growth rate has dropped to near zero as a result. The Average Fertility Rate of Argentina is about 2.2, barely above replacement rate. Argentina now only grows as a result of immigration. Nigeria, on the other hand, is a good example of human population growth. In 1950 it had a population of 38 million. Nigeria now has a population of 178 million, and that's in spite of net out-migration. Then again, Nigeria has an Average Fertility Rate of nearly 5.8, which while outrageous by today's standards is more the norm in a world that wants population growth (i.e. an imperial agri-world).

All that said, a colony, if the average woman had 4 babies that survived to have 4 babies of their own, would double it population about once every 35 years, meaning in 2000 years it would have a population of 1000 x 2 ⁵⁷ (my calculator says 1.44115193e+17) or enough people to populate the galaxy again. Humans are a fecund race.

I use orbital stations alot in my campaigns. The goods of primitive worlds can't fill the cargo hold of one of these ships. Halo barges are sufficient to the task of shuttling off a primitive world. For any world with even a single hive an orbital platform and orbital warehousing becomes a necessity. This allows those halo barges to shuttle things to orbit constantly, even when there is no ship up there to take on cargo. Then when a ship does show up there's a warehouse already brimming with goods to be directly onloaded to that ship...and the shuttles never stop.

But that's my take on the economics and population of 40k.

Yes, the old problem of planet to ship movements (and vice versa). A subject the books hardly give any attention, but which is quite important, whether we talk about trade or about invasions. There are several possibilities.

- Halo Barges: Practically impossible to load a ship just using these. If a Vagabond can carry about 25.000.000 metric tonnes (see above) it would take the 40 ton capable Halobarge no less than 625.000 flights to load or unload a ship. So unlikely we can forget about it.

- Landing on planets: According to BFG smaller ships (up to frigate size) might do this. Although the physics are daunting, we might go with it. But it will cause terrible wear and tear on the ship and should be risky, both for the ship and the planet. A settled system with regular trade would not use this. If you allow it, keep it for risky endaveours in deep space or contested landing operations.

- Large lifters: The most likely possibility. Larger lifters (like the Lamprey https://community.fantasyflightgames.com/topic/41177-hanger-bays/page-2?hl=lamprey#entry411653) will cut down the number of flights immeasurably. If you can lift a (still massive) 200.000 tonnes you can load a Vagabond in about 125 missions. This becomes quite doable. Especially if combined with...

- Space stations: The logical trade hub of a civilised planet, a docking station in space. Here the produce of a planet can be gathered at a leisure and loaded directly unto the largest warp capable void ships. These space stations will be supplied by aforementioned large lifters and/or other technical means, such as space elevators.

So we can suppose that every system that expects a bit of regular trade will probably have invested in a decent space station, capable of handling traders. More primitive worlds will be serviced by cargo ships with their own large lifters or by landing directly on their surface (if you permit that).

If Halo barges carried 4 standard ISO container (something Quicksilver posted a thread on), then 428 barges, ferrying 1 load per day, 365 days per year, could make that 625,000 load figure you cited. This is actually doable. It's even conceivable that shuttles could make more than 1.0 trips per day, and something more than 4 ISO containers is also possible. Of course, you still need that orbital dock and warehousing available...

I personally love the space elevator idea...been waiting and wanting to put one in my 40k 'verse.

All that said, a colony, if the average woman had 4 babies that survived to have 4 babies of their own, would double it population about once every 35 years, meaning in 2000 years it would have a population of 1000 x 2 ⁵⁷ (my calculator says 1.44115193e+17) or enough people to populate the galaxy again. Humans are a fecund race.

That's true, but only when resources are available, and barring various setbacks such as epidemics and wars, or stuff like death at childbirth. This being the Imperium, we shouldn't forget about the crass differences in quality of life between the social classes...

But I guess it'd also depend on just how much the Administratum squeezes the planet for its tithes (meaning foodstuff availability directly affecting population growth), and whether the planet was colonised and the settlement intended for this one purpose already, or whether the Imperium came upon a native population and just took over / converted the colony, thus being able to rely on a larger population from the beginning.

Crazy about Nigeria, though! And it's certainly true that larger families sound rather fitting for pseudo-medieval-style farming societies.

Space stations: The logical trade hub of a civilised planet, a docking station in space. Here the produce of a planet can be gathered at a leisure and loaded directly unto the largest warp capable void ships. These space stations will be supplied by aforementioned large lifters and/or other technical means, such as space elevators.

This might actually make a really cool place to explore! Imagine a lush breadbasket world largely untouched by artificial constructs save for a single big city, but with acres upon acres of crops, green flatlands full of grox herds, and tiny villages and farms ... and a huge, dirty spaceport hanging in the upper atmosphere, with an AdMech-operated orbital elevator connected to the ground.

I remember that at least one space elevator being mentionned in the fluff : one on Mars destroyed during the Horus Heresy, in the Mechanium novel.

And isn't the Orbital Spire in Warhammer 40000 Space Marine a space elevator?

http://www.spacemarine.com/gallery/h380/artwork/TheOrbitalSpire.jpg

Interesting. Most plans for a Terrestrial space elevator are based on the concept of a mobile unit floating on the ocean. Theoretically it wouldn't even be all that expensive if built of steel. But it would be massive. They are waiting for the next generation of building material, carbon nanotubes, which already exist but only in the lab. For this project they'd need to mass produce the stuff, of course.

I have been thinking (and calculating) a bit more, and I have made a vital mistake: the equivalent of containers a ship could carry, is obviously not the same as the net tonnage a ship could carry. A container is a highly efficient way to transport computers, clothes and all the like, but not for bulk loads. Those are - as implied in the name - transported in bulk. Additionally, there is little nasty gravity in space, so the weight of goods transported should be far less of an issue than in transport overseas. Taking this into account, the equivalent transport capacity should be:

- Typical Vagabond class trader: ca. 40.000.000 cubic metres (allowing for the equivalent of 1.000.000 containers, 100.000.000 metric tonnes of iron ore or 316.000.000 metric tonnes of steel). Corresponds to about 100 large container ships.

- Goliath sized trader: about 9 to 10 Vagabonds ca. 384.000.000 cubic metres (allowing for the equivalent of about 10.000.000 containers, 960.000.000 metric tonnes of iron ore or 3.036.000.000. metric tonnes of steel). Corresponds to about 1.000 large container ships.

- Universe class transporter: about 5 to 6 Goliaths and 50 to 55 Vagabonds ca. 2.160.000.000 cubic metres (allowing for the equivalent of 50.000.000 to 60.000.000 containers, 5.400.000.000 . metric tonnes of iron ore or 10.706.400.000 tonnes of steel). Corresponds to about 5.000 to 6.000 large container ships. In a real world perspective, this is about twice the amount of containers that Singapore deals with in a year.

Holy ****. Using Arvus lighters to load a Vagabond with steel will take 316.000.000 divided by 40 is....7.900.000 flights. Or 1580 Lamprey missions.

Weight might disappear in space, but mass stays the same under any gravity. I wouldn't go far down that road. When you're already figuring tens of millions of cubic meters, the difference between a load of feathers and a load of lead becomes astronomical. Suspension of disbelief is your friend here. Your original point is the key question to running a game. There needs to be a ship-to-planet interface, either a better lighter, actual landings, or orbital platforms...something to solve that problem.

It's a game, so keep it simply silly.

Yea, but that suspension of disbelief. I need to get some serious heavy lifters to do all the work loading the ships.

It's a game, so keep it as far simply or complicated as far your players enjoy.

Didn't someone create stats for heavy lifters based of GW fluff?

Of course it is a game. But my campaign will revolve on a mining space station and an agri planet, so I numbers need to fit reasonably well. A few Arvus lighters won't be able to lift , say, 80.000.000 tonnes of Grox meat.

I'm really bad at searching these forums for past threads, but Quicksilver started a thread some time ago about lighters and interchangeable standardized containers. It's a good read and quite a few people hashed through this topic. It gave really good numbers and solutions for the orbit-to-surface interface. It would be well worth your while. Or maybe he didn't start it and that's why I can't find it. Someone else?

I think it's mentioned somewhere in one of the below forum posts.

https://community.fantasyflightgames.com/topic/185677-vehicles-and-the-likes/?hl=barge#entry1747347

https://community.fantasyflightgames.com/topic/130737-frigates-cargo-bays-4th/?hl=barge

https://community.fantasyflightgames.com/topic/121545-landing-barges/?hl=barge

And I found an old gem. I love fan based material, it adds flavor to the game.

https://community.fantasyflightgames.com/topic/107167-heavy-transports-concepts/?hl=barge

is there any reason that only the ship's lifters are the only method of transport? I would imagine that the there would be landers based on the planet to help handle large transport loads, and if not, and no orbital docks to just unload at and you needed to unload the entire ship in one place ( and seems like it is being replaced with another commodity) the ship would probably just land to speed up the process.

You got it there, Nameless. Those are all good threads. They are all about this same topic. The first is the one I was talking about...Quick's Baum lander. I never much cared for the transports in the last thread, though. I think they are all workable ships and well-thought out, with fair SP values, but...

I've always thought that the STC-centered Imperium would only have a few actual classes of transports, albeit with a ton of local variations due to manufacturing differences, but with a wide variety of STC-produced cargo components. You have refrigerator components to carry perishable food items, hydroponics components to carry live plants, etc. When you get to the orbital dock just unlatch that cryo-ammonia component and hook up the livestock component and you're off again. That makes a lot of assumptions about commerce, though.

You got it there, Nameless. Those are all good threads. They are all about this same topic. The first is the one I was talking about...Quick's Baum lander. I never much cared for the transports in the last thread, though. I think they are all workable ships and well-thought out, with fair SP values, but...

I've always thought that the STC-centered Imperium would only have a few actual classes of transports, albeit with a ton of local variations due to manufacturing differences, but with a wide variety of STC-produced cargo components. You have refrigerator components to carry perishable food items, hydroponics components to carry live plants, etc. When you get to the orbital dock just unlatch that cryo-ammonia component and hook up the livestock component and you're off again. That makes a lot of assumptions about commerce, though.

I think this is largely correct. Also remember that while Warp capable Voidships are comparatively rare, System ships are far less so. Further, there are numerous references in the fluff of of various short and long range system ships. These range in size and purpose from small long range shuttles capable of intra-system travel to bulk heavy lifters that rival some smaller voidships in size! On developed worlds like hiveworlds the latter would be absolutely necessary to transfer the volume of material even coming and going to the planet's surface!

And don't forget the STL-drive Free Captains that still fly interstellar voyages.

Seems to me that a volume with:

1) More Warp capable trader hulls

2) Extensive rules for travelling within a system

3) Details of the planet to orbit possibilities

4) Loads and loads of non warp capable system ships, from orbital lifters to mining craft and the like.

5) As we are talking about in-system, let's include some pew-pew and include planetary defences, orbital defences and system monitors.

6) Some nice rules for trading.

Would rather fit the bill.