Efficient space only freighter design
- Thread starter phavoc
- Start date
I love this conversation.
I also think the big guys are more important - everyone WANTS the bumig guys to cone to them, even though obviously this mostly doesnt happen.
So id design the big guys, because the biggest worlds will absolutely be the ones with the most efficient designs. (10k to 100k freighters, and the Class A+s that support them)
Then you get the smaller worlds, that connect to those big ones (5k freighters) who therefore fit into the big model, but the medium worlds need to accomodate them (class A starports)
That design then determines what the medium guy looks like (1-2k freighters), which turn governs the class B starports.
Anything under 500 tons is then just tetrised in to those designs - its very possible dozens that if theres a spare mega freighter berth, and the megafreighter isnt due for a few days, that even though the megafreighter may be (for example) front loading, the berth is so large that dozens of free traders unload and load in it without being exposed to space.
I also think the big guys are more important - everyone WANTS the bumig guys to cone to them, even though obviously this mostly doesnt happen.
So id design the big guys, because the biggest worlds will absolutely be the ones with the most efficient designs. (10k to 100k freighters, and the Class A+s that support them)
Then you get the smaller worlds, that connect to those big ones (5k freighters) who therefore fit into the big model, but the medium worlds need to accomodate them (class A starports)
That design then determines what the medium guy looks like (1-2k freighters), which turn governs the class B starports.
Anything under 500 tons is then just tetrised in to those designs - its very possible dozens that if theres a spare mega freighter berth, and the megafreighter isnt due for a few days, that even though the megafreighter may be (for example) front loading, the berth is so large that dozens of free traders unload and load in it without being exposed to space.
If you are looking for further reading material, check out Conways History of the Ship series. There are two books that cover the massive changes in merchant marine from 1900 to 2000. There's a companion set of books for warships that covers the era of the big gun and then the transition to missiles and aircraft. It's a great source of information that you can use for gaming ideas and ways to fill in conceptual gaps.
You are correct that containers would (or should) remain supreme for cargo movement in the future. Aside from gravitics I doubt anyone would notice much difference from today to a TL15 world.
The odd thing about the gap is that we see a lot of material oriented around ships players would also never use in gaming - the massive warships, or even the lowly 5,000 dton destroyer that would just squash any adventure class ship. Warships are a staple of most gaming, and for Traveller High Guard came out before Merchant Prince. While we were given ships up to 500k dtons, the largest merchant (off top of my head) is the 1,800 ton Leviathan. I'd have to check the latest MGT ship book to see if they added some more.
When I worked at UPS in college I sometimes worked the air sort. They had a very simple, but very efficient method of moving air containers around - there were wheels set in the floor about 12" apart. It was all level so containers of various sizes (we never did the belly load, just the ones that went on the main deck of DC-10s and such) never "drifted". If you wanted to stop it from moving all together you could retract the wheels into the floor and it wouldn't go anywhere. While it took a little muscle power to overcome inertia, I was able to move 4.000lb containers from loading areas on to the dock scales by myself - but always had to remember inertia is a bitch and I got run over a few times by my own container!Quite, UNREP is quite magically good, but i think the OP is trying to visualise what it would mean.
He is also, I believe, working in a CT context where UNREP is unknown.
I generally make do with Cargo Cranes, which I see as a compact overhead crane, capable of moving containers in and out of the cargo hold:
It's in the same ball-park as large as UNREP, but undefined loading speed.
The depth required for that was about 6" in total - including the space protruding from the floor to the space below. It's so simple yet so effective. I'd think it would be much better myself for freighters since it gives you 360 degree capabilities in a hold without the limitation of an overhead rail system. Though it would stop at the edge of the deck - an integrated system overcomes that. Our transport flatbeds had the same rollers built into the beds as did the lift equipment at the airport.
For movement outside of a hold or integrated system an overhead grav device that hooked on to the four corners of a container - same as container cranes do today, would give you all the flexibility of a crane without having to have the infrastructure. It'd be a container equivalent of a grav belt.
Yup. Graph paper and circular hulls do not match well. Which is why right-angles and non-streamlined holds rule the day for cargo vessels.
The original question was related specifically to space-only vessels. Being able to land completely changes the scenario and opens up more possibilities.
Yes, stations should have space to burn as it's cheap to expand in a zero-g environment not really constrained by dimensions. Docking bays work for small ships, but any ship berthed in one ties it up. Ships just docking to load/unload and then moving out of the space for the next one also means you have a super-effecient process that's happening on the station. While some places might be hyper-effecient, most are going to be average (or worse). So your model would nee to account for the range of possibilities. Not every port is as good and fast as the next one, and that's never been the case.
Since you need to double your tonnage for the size of ship you want, even stations will get to the point it's not economical to keep adding them. For small ships its ok, but I can't imagine having a 20,000 dton docking bay.
MasterGwydion
Emperor Mongoose
My guess is that for those larger ships, they would use exterior docking cradles with some kind of an airlock system to connect the ship to the station. A 20kDton docking bay would likely be more for 200 heavy fighters or a mix of heavy fighters and other SDBs so that maintenance can be done.
AndrewW
Emperor Mongoose
Cargo Carrier (3,000 tons), High Guard Update 2022 page: 223.
Freighter (200,000 tons), High Guard Update 2022 page: 274.
But yes there is a bit more on the military side for larger ships.
Traveller was also intended to be used for space fleet and mercenary roleplaying. GDW was a wargaming company and they made a lot of Traveller related wargames. Which bled over into the mindset for the RPG.
Striker for ground combat. Azhanti High Lightning for shipboard actions on a warship. Mayday for ship to ship fighting. Invasion: Earth and Fifth Frontier War for large scale conflicts.
Striker for ground combat. Azhanti High Lightning for shipboard actions on a warship. Mayday for ship to ship fighting. Invasion: Earth and Fifth Frontier War for large scale conflicts.
I was thinking of something like that - docking arms that extended out and accessed vertical hatches in the dorsal deck (or even ventral - one can do all sides after all). Still sealed though as I think most containers that are just in transit will be kept out of vacuum so that they can be cheaper. Obviously one CAN make them airtight - but you'd have to recertify them all the time and that gets expensive.
I will have to go look at those. Seems like a rather large gap - 3,000 to 200,000. The 200,000 sized freighter seems at odds with how shipping works. It's TOO big to be practical. The newer container ships (those that hold 20,000+ TEU) are still finding themselves in a questionable economic situation. I had read an economic paper that was modeling container shipping - the new super-sized ships is showing a very small impact on profits. Though that's an economics paper and so far we need more actual empirical data from years of operations to know whether or not they'll have a fully positive impact.
It's similar to how SeaLand built it's fast 30kt container ships for transatlantic trade and found that the added cost to shave days off your transit times were not embraced by shippers. They were happier with lower rates and slower times. SeaLand ended up selling their fast ships to the USN who appreciated a 30kt replenishment vessel and is relatively price-insensitive to fuel costs.
MasterGwydion
Emperor Mongoose
Yeah, huge gap. I would venture to say that most extremely large space-only cargo vessels would also be mostly automated with only 1-10 actual living crew on board. Also, all large vessels such as this would be owned by businesses that also rent Starport space. Within that rented Startport space would be fuel and fuel purifiers, so they'd only be paying 100Cr/Dton of fuel instead of 500. So, if that huge 200kDton J-1 ship needs refueled, they will only be paying 2MCr instead of 10MCr every 2 weeks. The big boys have a lot of advantages over Us Tramp Traders.
Condottiere
Emperor Mongoose
Probably Nestle, who gets unrefined fuel for a token cost.
In practice, most efficient designs I've come up with all use an external cargo mount. As long as you apply enough engineering to move your desired load, your actual ship volume becomes somewhat irrelevant. Basically the ship is just a central support covered in a skin of containers.
Condottiere
Emperor Mongoose
Panamax.
There probably are minimum, optimal, and maximum volumes, and (hull) configurations.
There probably also are differences between external and internal intended containers.
Construction costs and existing infrastructure would be the two leading determinants.
There probably are minimum, optimal, and maximum volumes, and (hull) configurations.
There probably also are differences between external and internal intended containers.
Construction costs and existing infrastructure would be the two leading determinants.
Container ships are probably the best way to go for manufactured goods, as containers are readily intermodal, and could be readily moved to shuttles, and land transport without needing unpacking. As has been pointed out it fits perfectly with Traveller spaceship concept. You could even have a flexibility in the ships' J and M ratings this way - just carry fewer containers and you can jump farther and thrust faster, or more containers if it is a shorter trip.
However, containers IRL aren't generally used for bulk goods - these often have specialized bulk carriers for them with specialize port facilities to load them. I imagine these kinds of ships would exist too, with vast holds. They'd probably only be seen on certain routes where large quantities of specific low value substance need to be shipped along well defined routes - grain seems like an obvious one, since there are so many planets with high pop and hostile environments that would need huge food imports. Iron ore maybe, though maybe it is too ubiquitous to be worth shipping interstellar - if you can't get it on your planet, you probably can find an asteroid. Wood. Petrochemicals. Packing these into containers would be an extra cost.
However, containers IRL aren't generally used for bulk goods - these often have specialized bulk carriers for them with specialize port facilities to load them. I imagine these kinds of ships would exist too, with vast holds. They'd probably only be seen on certain routes where large quantities of specific low value substance need to be shipped along well defined routes - grain seems like an obvious one, since there are so many planets with high pop and hostile environments that would need huge food imports. Iron ore maybe, though maybe it is too ubiquitous to be worth shipping interstellar - if you can't get it on your planet, you probably can find an asteroid. Wood. Petrochemicals. Packing these into containers would be an extra cost.
It would be an interesting thing to research and model. Makes sense for any large vessel to have fuel refining gear onboard to buy cheaper Lhyd, but if they invested in their own fuel tankage system they could buy (or even get their own raw gas to refine). Game numbers are good to really economically model it in a fair cost/loss/profit/savings. If they were a volume buyer expect discounts from the normal fees charged.
It's interesting. The one burning question I'd love to really figure out is are space-rated containers economical to build and transport? Its like the difference between a 48ft standard truck container and a 48ft ocean going one. Ocean going ones are much more expensive, but they have to be for their environment. Regular containers don't do well on ocean voyages, but they are cheap.
Which gets to the other part of the cycle - do you go from origin planet warehouse fully loaded in a space-rated container to destination warehouse for unloading, or do you transload it somewhere? There are pro's and con's to both models. So if it's cheaper to use standard containers they you have to build your ships and infrastructure to support that rather than have pods unloaded in space, let them float and add them to a cargo lighter to take down to a planet (or tug into a station) where they can be moved to their final destination.
One thing to keep in mind that is going to help drive the process is the overall infrastructure to move these containers. A 10dton container is a close match to standard containers today - not too big or not too small. You have roads, rails, etc all designed to support these with maximum system efficiency. I think that's going to drive it. A standard container that can be transported by grav vehicles, wheeled, railed or ship and placed at any cargo loading bay has got to have a very powerful lure to the merchant looking to spend the fewest credits to move his cargo.
