Efficient space only freighter design

[phavoc]

Mark Lucas made some great designs for container ships, which can be seen on his Flickr:

https://flic.kr/p/6MLGUD

https://flic.kr/p/6kjZ5A

This is an interesting design oriented around the ubiquitous 30Dton cutter module. For certain markets it could do well. Cutters are pretty common. Would have to see about the cost of the cutter module and add in the cost of it to your shipping rates. I could see a modified box-style module that while less aerodyanmic, would hold more cargo in a square configuration. Still expensive since you are paying hull costs for the container, but you are also getting a space-rated version.

Nice find!

 

[phavoc]

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.

Fill a container with water and add some piping and you can refuel yourself out in the gaps between planets.

And you are correct - using containers for bulk cargo (like ore, coal, grains, etc) are not common since it's a bit messy to load/unload them. THough if you look at some of the ideas upthread, a 50Dton module is sufficiently sized to get into the old LASH barge sizes, and you have the equivalent of about 5 containers in one. Still not as totally effecient as bulk ship built to carry that kind of cargo specifically, but there is more flexibility there. So much depends on your market and types of cargoes needing to be carried as to whether the process can be done economically or not.

 

[steveh]

I was thinking about megafreighters such as these on my blog a few weeks ago. (I can't link to it here, but search for fourlettersatrandom.blogspot and then search for "Cargo and freight".)

Following a train of thought that assumed I would have to import food to feed the 26 billion people on Rethe (a desert world with a very thin atmosphere - so not a great place for growing crops), I worked out I would need 75,000 Far Traders every week delivering "red kibble".

75,000 seemed rather a lot, so I designed a small fleet of vast, 1.8 million-ton freighters that would travel back and forth between Inthe (an agricultural world) and Rethe purely to keep Rethe fed.

I tried to make it as efficient as possible by minimising in-system time. So the design included huge modular cargo pods attached to the ships in orbit (I know Rethe doesn't canonically have a highport - it has a Class E starport, but I questioned the canon in an earlier post.) I also wondered about removing the M-drives from the main ship and using tugs to transfer it to and from the jump points. Modular fuel tanks would speed refuelling.

Anyway, it was a fascinating thought experiment that shows where you can end up if you think about things in Traveller. (I made a lot of assumptions in my thinking, all of which can be questioned.)

But I think my point is that many of these big freighters will be built to serve a specific route. They are unlikely to be tramp freighters roaming the systems, they will shuttle back and forth between two or three systems.

 

[Condottiere]

After a hundred kilotonnes, its probably a case of diminishing returns.

Exactly how much money are you saving by using megafreighters?

 

[steveh]

After a hundred kilotonnes, its probably a case of diminishing returns.

Exactly how much money are you saving by using megafreighters?

Oh, I didn't calculate the cost of the ships.

Calculating costs would have been meaningless as the whole enterprise would require dedicated infrastructure, of which the ships would be only one part (and possibly not even the biggest part). I'm sure that if it was a real situation, teams of very clever people would ensure it was delivered as cheaply as possible - and they'd no doubt optimise it differently.

 

[phavoc]

I was thinking about megafreighters such as these on my blog a few weeks ago. (I can't link to it here, but search for fourlettersatrandom.blogspot and then search for "Cargo and freight".)

Following a train of thought that assumed I would have to import food to feed the 26 billion people on Rethe (a desert world with a very thin atmosphere - so not a great place for growing crops), I worked out I would need 75,000 Far Traders every week delivering "red kibble".

75,000 seemed rather a lot, so I designed a small fleet of vast, 1.8 million-ton freighters that would travel back and forth between Inthe (an agricultural world) and Rethe purely to keep Rethe fed.

I tried to make it as efficient as possible by minimising in-system time. So the design included huge modular cargo pods attached to the ships in orbit (I know Rethe doesn't canonically have a highport - it has a Class E starport, but I questioned the canon in an earlier post.) I also wondered about removing the M-drives from the main ship and using tugs to transfer it to and from the jump points. Modular fuel tanks would speed refuelling.

Anyway, it was a fascinating thought experiment that shows where you can end up if you think about things in Traveller. (I made a lot of assumptions in my thinking, all of which can be questioned.)

But I think my point is that many of these big freighters will be built to serve a specific route. They are unlikely to be tramp freighters roaming the systems, they will shuttle back and forth between two or three systems.

I think it's reasonable to think of classes of ships built to spec by operators - we see something similar today. Large tankers or container ships generally are built to specs by a single line even though they may each carry approximately the same amount of cargo. And, some of them at least, are built to serve specific routes (Shanghai to Los Angeles, or say persian gulf to the LOOP terminal off LA).

Big ships require big cargoes and high loading percentages to maintain profitability. That's actually one of the arguments used against making ships even bigger - that your flexibility goes down as you are now limited to servicing specific routes because you cannot operate anywhere else. Your Rethe example would work as an outlier since Rethe HAS to have that level of supply to exist. Call it a captive market I suppose.

 

[Alqualonde]

I toyed a bit with container ships in HighGuard.
At TL-12 you can design a 60k dT ship capable of moving up to 140k dT of containers at 1G & Jump-2. This ship will have no way to refuel on its own (it has less than 1 200 dT available for hangars, & internal cargo space), and Jump-2 is short in a frontier area.
Making it a Jump-3, will reduce the containers to 73 333 dT. And for Jump-4, it will be limited to 40k dT.

	dT	MCr	EP
Hull 60k dT - Close Structure		2 400	40 000 (for ship + containers)
Jump Drive - J2 (for 200k dT)	10 005	15 007.5	40 000
Maneuver Drive - 1G (for 200k dT)	2 000	4 000	20 000
Powerplant	5 360	5 360	+80 400
Fuel - J2 + 4 weeks	40 536	-	-
Bridge	60	300	-
Core/40	-	45 + 13 for software	-
Civilian Sensors (-2DM)	1	3	1
10x Double Pulse Laser Turrets	10	25	90
170 Staterooms	680	85	-
Commom Area	170	17	-
External Cargo Mount (140k dT)	-	140	-
Remaining space	1 178	-	-
Total	60 000	27 375.5	309 remaining EP

Softwares includes Anti-Hijack/2 & Virtual Gunners/1 (to replace all gunners).
Crew: Captain, 1 Pilot, 1 Navigator, 248 Engineers, 30 Maintenance, 15 Admin, 2 medics & 14 Officers.
It can be optimized a bit more by reducing the powerplant by 20 000EP (so that the ship needs to dim light before jumping).

I also tried with a TL-11 150dT ship transporting a 20dT shuttle for unloading & refueling and a 6dT pod for manipulating the containers (loading the shuttle). I managed to cram 124dT worth of containers. Such a ship would transport containers to world lacking the infrastructure (and population) required by large ships.

	DT	MCr	EP
Hull - 150dT Close Structure		6	54 (for ship + containers)
Jump Drive - J2 for 300dT	35	52.5	60
Maneuver Drive - 1g for 300dT	3	6	30
Power Plant	13	6.5	+130
Fuel - J2 + 4 weeks	62	-	-
Bridge	10	.75	-
Computer /10/Bis	-	.24 + 2.2 for software	-
Civilian Sensors (-2 DM)	1	3	1
1 Double Pulse Laser Turret	1	2.5	9
3 Staterooms	12	1.5	-
Common Area	3	.3	-
Fuel Processors - 20dT per day	1	.05	1
External Cargo Mount for 31x 4dT Containers - 124dT total	-	.124	-
2 Type I Docking Clamps	2	1	-
Cargo	7	-	-
Totals	150dT	84.614 MCr	5 remaining EP

Software includes Jump Control /2 & Fire Control /1 (to replace the gunner). Crew : Pilot, Navigator & Engineer.
Since the containers are usually unpowered, I consider the ship needs to provide the energy for life support should the containers needs it (at least for the artifical gravity). Thus the 54 EP on the Hull line.

Possible optimization : It should be possible to make the staterooms double occupancy & reduce the powerplant so that you need to dim lights for jumping. That would free 9 dT (4dT room + 1dT common area + 3dT powerplant & 1 dT fuel). Move the 6dT pod to a docking space (remove 1 clamp, takes 6 dT and free 6dT for containers). Replace the 20dT shuttle by a 12dT one (but only 8dT worth of containers/fuels can be transported) & add 8dT worth of containers... Total 138dT of external cargo & 9dT of internal cargo. But I like the unoptimized version.

The 20dT shuttle is capable of transporting 12 dT worth of containers or 13dT of fuel (Fuel/Cargo containers, HG p49), and thus can serve to refuel the ship. (Unless I missunderstood the Fuel/Cargo containers rules), has 4G, a dual cockpit and 1 additionnal seat.
The 12dT shuttle is capable of transporting 8 dT worth of containers or fuel, has 2G, a single cockpit and 2 additionnal seats.

 

[phavoc]

I toyed a bit with container ships in HighGuard.
At TL-12 you can design a 60k dT ship capable of moving up to 140k dT of containers at 1G & Jump-2. This ship will have no way to refuel on its own (it has less than 1 200 dT available for hangars, & internal cargo space), and Jump-2 is short in a frontier area.
Making it a Jump-3, will reduce the containers to 73 333 dT. And for Jump-4, it will be limited to 40k dT.

	dT	MCr	EP
Hull 60k dT - Close Structure		2 400	40 000 (for ship + containers)
Jump Drive - J2 (for 200k dT)	10 005	15 007.5	40 000
Maneuver Drive - 1G (for 200k dT)	2 000	4 000	20 000
Powerplant	5 360	5 360	+80 400
Fuel - J2 + 4 weeks	40 536	-	-
Bridge	60	300	-
Core/40	-	45 + 13 for software	-
Civilian Sensors (-2DM)	1	3	1
10x Double Pulse Laser Turrets	10	25	90
170 Staterooms	680	85	-
Commom Area	170	17	-
External Cargo Mount (140k dT)	-	140	-
Remaining space	1 178	-	-
Total	60 000	27 375.5	309 remaining EP

Softwares includes Anti-Hijack/2 & Virtual Gunners/1 (to replace all gunners).
Crew: Captain, 1 Pilot, 1 Navigator, 248 Engineers, 30 Maintenance, 15 Admin, 2 medics & 14 Officers.
It can be optimized a bit more by reducing the powerplant by 20 000EP (so that the ship needs to dim light before jumping).

I also tried with a TL-11 150dT ship transporting a 20dT shuttle for unloading & refueling and a 6dT pod for manipulating the containers (loading the shuttle). I managed to cram 124dT worth of containers. Such a ship would transport containers to world lacking the infrastructure (and population) required by large ships.

	DT	MCr	EP
Hull - 150dT Close Structure		6	54 (for ship + containers)
Jump Drive - J2 for 300dT	35	52.5	60
Maneuver Drive - 1g for 300dT	3	6	30
Power Plant	13	6.5	+130
Fuel - J2 + 4 weeks	62	-	-
Bridge	10	.75	-
Computer /10/Bis	-	.24 + 2.2 for software	-
Civilian Sensors (-2 DM)	1	3	1
1 Double Pulse Laser Turret	1	2.5	9
3 Staterooms	12	1.5	-
Common Area	3	.3	-
Fuel Processors - 20dT per day	1	.05	1
External Cargo Mount for 31x 4dT Containers - 124dT total	-	.124	-
2 Type I Docking Clamps	2	1	-
Cargo	7	-	-
Totals	150dT	84.614 MCr	5 remaining EP

Software includes Jump Control /2 & Fire Control /1 (to replace the gunner). Crew : Pilot, Navigator & Engineer.
Since the containers are usually unpowered, I consider the ship needs to provide the energy for life support should the containers needs it (at least for the artifical gravity). Thus the 54 EP on the Hull line.

Possible optimization : It should be possible to make the staterooms double occupancy & reduce the powerplant so that you need to dim lights for jumping. That would free 9 dT (4dT room + 1dT common area + 3dT powerplant & 1 dT fuel). Move the 6dT pod to a docking space (remove 1 clamp, takes 6 dT and free 6dT for containers). Replace the 20dT shuttle by a 12dT one (but only 8dT worth of containers/fuels can be transported) & add 8dT worth of containers... Total 138dT of external cargo & 9dT of internal cargo. But I like the unoptimized version.

The 20dT shuttle is capable of transporting 12 dT worth of containers or 13dT of fuel (Fuel/Cargo containers, HG p49), and thus can serve to refuel the ship. (Unless I missunderstood the Fuel/Cargo containers rules), has 4G, a dual cockpit and 1 additionnal seat.
The 12dT shuttle is capable of transporting 8 dT worth of containers or fuel, has 2G, a single cockpit and 2 additionnal seats.

For such a large ship I'd expect it to rely completely on each destination system for refueling and to load/unload the containers.

For frontier travel I would suspect that it would use external docking clamps and carry cargo lighters or transports to unload the containers. A lighter would be more of a simple barge and the containers would get stacked and strapped and it would make it's way to the planetary surface to drop them off (I think it's fair to assume that any planet getting that much cargo would have at least some ground support so that the ship would not need to carry additional cargo loaders for surface work).

There are a few challenges with carrying your cargo externally - the containers themselves have to be space rated and able to be be sealed against vacuum and temperature spikes for most cargo's. That drives up the cost of the container considerably since you'd have to have space-craft level materials to stop micrometeroids and such. And then you have to think about the cargo inside. Unless everything is perfect packed inside the container the cargo/packages will drift in zero-G, and then come back together - possibly not in the best way - when they come back under gravity. Carried inside a cargo hold one can assume they'd be protected by the internal system with gravity, intertial dampeners and temperature controls. Carried outside the hull leaves it without such protection. It works for some cargo's, but others may not be able to be safely transported like that. That's always been one of the challenges to carrying cargo externally that's often overlooked.

 

[Alqualonde]

For such a large ship I'd expect it to rely completely on each destination system for refueling and to load/unload the containers.

For frontier travel I would suspect that it would use external docking clamps and carry cargo lighters or transports to unload the containers. A lighter would be more of a simple barge and the containers would get stacked and strapped and it would make it's way to the planetary surface to drop them off (I think it's fair to assume that any planet getting that much cargo would have at least some ground support so that the ship would not need to carry additional cargo loaders for surface work).

There are a few challenges with carrying your cargo externally - the containers themselves have to be space rated and able to be be sealed against vacuum and temperature spikes for most cargo's. That drives up the cost of the container considerably since you'd have to have space-craft level materials to stop micrometeroids and such. And then you have to think about the cargo inside. Unless everything is perfect packed inside the container the cargo/packages will drift in zero-G, and then come back together - possibly not in the best way - when they come back under gravity. Carried inside a cargo hold one can assume they'd be protected by the internal system with gravity, intertial dampeners and temperature controls. Carried outside the hull leaves it without such protection. It works for some cargo's, but others may not be able to be safely transported like that. That's always been one of the challenges to carrying cargo externally that's often overlooked.

For space rated containers, they need their own artificial gravity, otherwise you'll need to tightly pack your goods to avoid damage. Doable but would reduce the amount of goods per dT.
For lighters, carrying containers strapped on their hull would probably make them unstreamlined (IIRC the rules), and would still require the containers to be space rated. I used a streamlined cargo shuttle with internal cargo space in my previous post just to ensure the container were safe. Plus the shuttle can transport fuel back to the mothership.

For frontier travel, it seems better to have internal cargo. At least you won't have to transport a lighter to get the containers down & fuel up the gravity well. So more space for cargo. And no need for space-rated containers.
A small drawback (that depend on ship size) will be the bridge. The 150dT ship I posted had a 10dt bridge. Making it a 300dT ship with all the cargo inside the hull means you need a 20dT bridge. A small price, but one that would reduce a bit the amount of cargo.
I ran the numbers, making the 150dT container ship a 300dT standard streamlined ship will cost 15MCr more, but it would transport 144 dT of cargo instead of 124 dT of external containers + 7 dt of internal cargo (mainly for spare parts & food).

 

[phavoc]

For space rated containers, they need their own artificial gravity, otherwise you'll need to tightly pack your goods to avoid damage. Doable but would reduce the amount of goods per dT.
For lighters, carrying containers strapped on their hull would probably make them unstreamlined (IIRC the rules), and would still require the containers to be space rated. I used a streamlined cargo shuttle with internal cargo space in my previous post just to ensure the container were safe. Plus the shuttle can transport fuel back to the mothership.

For frontier travel, it seems better to have internal cargo. At least you won't have to transport a lighter to get the containers down & fuel up the gravity well. So more space for cargo. And no need for space-rated containers.
A small drawback (that depend on ship size) will be the bridge. The 150dT ship I posted had a 10dt bridge. Making it a 300dT ship with all the cargo inside the hull means you need a 20dT bridge. A small price, but one that would reduce a bit the amount of cargo.
I ran the numbers, making the 150dT container ship a 300dT standard streamlined ship will cost 15MCr more, but it would transport 144 dT of cargo instead of 124 dT of external containers + 7 dt of internal cargo (mainly for spare parts & food).

One of the drivers of containerization is that they are relatively cheap to build. Having to give them both spacecraft-rated hull and gravity plating would make them more expensive than their terrestial counterparts (or their equivalents of todays' containers). I'd think a lot of frontier transports would be landing and dropping them off in-atmo, so there'd be no need for that.

One question I've not quite figured out is what would it cost to build a space-rated container and include essentially starship deck-plating inside to provide gravity and inertial dampening (a necessary thing).

 

[Vormaerin]

Right. We think it would be expensive or complicated, but we don't know. Because there's no info about it. Just breezy "as easy to travel between stars as continents today" type stuff. Maybe grav plates and vaccuum sealing is easy peasy in the 57th century. Maybe it's tricksy. 2300 treats them as pretty straightforward. But that's a different paradigm.

 

[Alqualonde]

Right. We think it would be expensive or complicated, but we don't know. Because there's no info about it. Just breezy "as easy to travel between stars as continents today" type stuff. Maybe grav plates and vaccuum sealing is easy peasy in the 57th century. Maybe it's tricksy. 2300 treats them as pretty straightforward. But that's a different paradigm.

I agree.
With a few tens of thousand years of use, space tech should be quite advanced compared to what we know. We already have ships without armor, so why not space containers.
That makes more ship's types to plunder for a Drinax campaign. .

 

[AnotherDilbert]

I agree.
With a few tens of thousand years of use, space tech should be quite advanced compared to what we know. We already have ships without armor, so why not space containers.

It's not vacuum and normal space we primarily need to worry about:

MgT JTAS#2, "Jumpspace", p124:
Strong Hull
The hull of a starship must not only be constructed to withstand normal space; it also must withstand the rigors of jump space. Starship hulls contain as an integral part of their structure a network of wiring, which maintains the jump field around the ship. Without this field, the natural physics of jump space would intrude into the ship’s interior and the alien physical principles would make life impossible, operation of equipment unpredictable and even the passage of time would be altered. Breaks in the protective network within a starship’s hull are a primary cause of the loss of ships when jumping.

The need for this network in a ship’s hull also indicates what happens to matter (personnel, small craft, missiles and so forth) ejected from a ship while jumping, becoming subject to the physics of jump space. People die; equipment malfunctions; small craft disappear.

Armour 0 is still quite a bit of metal...

 

[Vormaerin]

It's not vacuum and normal space we primarily need to worry about:


Armour 0 is still quite a bit of metal...

Which is even less helpful, because we at least know a bit about normal space. We know nothing about jumpspace. I have no problem thinking that 2300 style 50 dton containers are feasible in an environment with anti gravity, maneuver drives, and jump technology. I find that they increase rather than decrease the number of interesting situations possible in the game, so therefore they are a good thing. Someone else might reasonably find that it hurts their brain to imagine such a thing and not want to use it.

 

[AnotherDilbert]

Which is even less helpful, because we at least know a bit about normal space. We know nothing about jumpspace. I have no problem thinking that 2300 style 50 dton containers are feasible in an environment with anti gravity, maneuver drives, and jump technology.

Just make the external containers as normal hulls? It's not that expensive.

By MT and Striker, "unarmoured" hulls are something like 8.5 cm of crystaliron.

 

[phavoc]

Generally speaking it's going to cost a lot more. Why? Because of how they are made.

Today a basic trailer container is cheap because it's basic. The walls are basic and built to do their job. Floors are wood or wood covering the metal because it's cheap and functional.

A 52nd century container to operate in space and provide gravity and inertial compensator capability would need a much thicker wall to protect against micrometorites, and the flooring would need to project a gravity source. Both issues are going to be far more expensive than aluminum walls or even light steel (for ocean containers which are sturdier and more expensive than general containers).

We don't really have costs for deck plates, but we know anti-grav belts aren't cheap, nor are basic grav vehicles like an air raft. I think it's pretty safe to say cost would remain a factor.

 

[MasterGwydion]

Generally speaking it's going to cost a lot more. Why? Because of how they are made.

Today a basic trailer container is cheap because it's basic. The walls are basic and built to do their job. Floors are wood or wood covering the metal because it's cheap and functional.

A 52nd century container to operate in space and provide gravity and inertial compensator capability would need a much thicker wall to protect against micrometorites, and the flooring would need to project a gravity source. Both issues are going to be far more expensive than aluminum walls or even light steel (for ocean containers which are sturdier and more expensive than general containers).

We don't really have costs for deck plates, but we know anti-grav belts aren't cheap, nor are basic grav vehicles like an air raft. I think it's pretty safe to say cost would remain a factor.

Gravity Plates and such are included in the cost of the container's "hull". You would also need to account for power for however long it took from the time of offload, until they could be reconnected with a new external power source to cover the 20% Basic Systems power requirement. Likely some form of battery. If they were to be used for non-jumpcapable craft, they could use solar panels to keep them powered, since they are external anyhow.

 

[phavoc]

Gravity Plates and such are included in the cost of the container's "hull". You would also need to account for power for however long it took from the time of offload, until they could be reconnected with a new external power source to cover the 20% Basic Systems power requirement. Likely some form of battery. If they were to be used for non-jumpcapable craft, they could use solar panels to keep them powered, since they are external anyhow.

Agreed. But what's the price for a space-rated 10dt container with deck plating?

 

[Vormaerin]

Generally speaking it's going to cost a lot more. Why? Because of how they are made.

Today a basic trailer container is cheap because it's basic. The walls are basic and built to do their job. Floors are wood or wood covering the metal because it's cheap and functional.

A 52nd century container to operate in space and provide gravity and inertial compensator capability would need a much thicker wall to protect against micrometorites, and the flooring would need to project a gravity source. Both issues are going to be far more expensive than aluminum walls or even light steel (for ocean containers which are sturdier and more expensive than general containers).

We don't really have costs for deck plates, but we know anti-grav belts aren't cheap, nor are basic grav vehicles like an air raft. I think it's pretty safe to say cost would remain a factor.

I'm just saying that 2300 has containers and ships that are essentially giant tugs with a long tail for the containers to be clamped to. I'm not an astrophysicist. Maybe that's as woo-woo physics as anti-grav, maneuver drives, and jumpspace. But, frankly, I'm inclined to think "building a good deep space container" is not remotely close to the top of any list of "hard science breaches" in the game. YMMV.

 

[Vormaerin]

Agreed. But what's the price for a space-rated 10dt container with deck plating?

Lv5000 per ton for a basic sealed container. Double if its designed for liquid or gas storage. Which, for reference, is 1/4 of what a basic ton of starship hull costs in 2300)