ISB Cargo Containers

[far-trader]

Figured I'd start a new thread rather than clog the peripheral thread in case this topic generates more discussion.

Originally posted by Michael Brinkhues:
Far Trader:

I suggest to look up ISO container on the Web...
I do not mean "copy ISO containers 1:1". More use them as a ready-made starting point.

Thanks Michael, that's exactly what I did the first time I looked at doing some Traveller containers, ages ago

Briefly I took the ISO 20' (TEU) as the standard and soft converted that to the 6.0m deckplan standard. I then subtracted for a reasonable (imo) 0.3m ship bulkhead thickness (and a worst case hold dimension of just 3m x 6m), subtracted again for the dimensional elements of the container at about 0.15m for the box steel corners and container floor/flatbed, and a little rounding and wiggle room, coming up with 5.5m final outside length. Next I looked at the ISO height of 8.5' and converted that to about 2.5m using the same method above, and made it square so it's also 2.5m wide, outside dimensions.

I didn't bother with High Cubes since they won't fit into the standard deck height. I do see half-height being used though.

Originally posted by Michael Brinkhues:
IMHO your "tara" dtons are to high compared to real world boxes.

Sorry, I don't quite understand this bit.

Originally posted by Michael Brinkhues:
Most containers won't be pressurised hulls but simple steel boxes with sides similar to a JU52 plane (Wellblech, that wavy-presses steel) for added stability

Actually I think they will have to be pressurized and able to withstand wide pressure exposure. Interstellar cargo is shipped to and from many vacuum destinations and some high pressure ones, and exposure to same while loading and unloading will be expected in many cases. There's also the potential for exposure during shipping for a variety of reasons. That said it doesn't need to be space-worthy in a hull sense. For those reasons I did model mine on the corrugated steel but made it full dimensional at 0.05m thick and figure that would suffice for strength, permeability and isulation for brief exposures. That's my standard panel inserts. The "security" panels (i.e. armored) are thicker and offer a Striker armor level of 1. The big difference between the ISO and ISB containers would be in the seals being vacuum and overpressure rated.

Originally posted by Michael Brinkhues:
Actually I can see ISB (Imperial Standards Bureau) Containers to start with a basic cube, say 2x2x2m or "Starship useabel deck hight - Space for forklift-equivalent" per side. And bigger ones using multiple length, maybe even multiple modules weldet together and the inner wall ommitted/left out.

It's bad enough with my few dimensional options losing about 50% of the volume

I think basing the standards on a dimension that isn't easily broken into the standard deck dimensions is going to mean even more waste volume. I don't even like mine for that reason but see no way around it in a real world. In one where the dimensions are line thin and overlap like that of the old Traveller deckplans sure, but it's not realistic to fit a 4ton container into a 4ton hull space with both of them having real materials rather than a simple drawn line if you follow.

 

[mbrinkhues]

Originally posted by far-trader:
Figured I'd start a new thread rather than clog the peripheral thread in case this topic generates more discussion.

</font><blockquote>quote:</font><hr />Originally posted by Michael Brinkhues:
Far Trader:

I suggest to look up ISO container on the Web...
I do not mean "copy ISO containers 1:1". More use them as a ready-made starting point.

Thanks Michael, that's exactly what I did the first time I looked at doing some Traveller containers, ages ago

Briefly I took the ISO 20' (TEU) as the standard and soft converted that to the 6.0m deckplan standard. I then subtracted for a reasonable (imo) 0.3m ship bulkhead thickness (and a worst case hold dimension of just 3m x 6m), subtracted again for the dimensional elements of the container at about 0.15m for the box steel corners and container floor/flatbed, and a little rounding and wiggle room, coming up with 5.5m final outside length. Next I looked at the ISO height of 8.5' and converted that to about 2.5m using the same method above, and made it square so it's also 2.5m wide, outside dimensions.

I didn't bother with High Cubes since they won't fit into the standard deck height. I do see half-height being used though.

</font>[/QUOTE]High cubes won't fit. Agreed.

But I thing you leave too much "dead" space compared to real world containers. You loose fifty+ percent of hull space and that are rates that won't be acceptabel in Traveller (Where shipment is volume based after all).

</font><blockquote>quote:</font><hr />Originally posted by Michael Brinkhues:
IMHO your "tara" dtons are to high compared to real world boxes.

Sorry, I don't quite understand this bit.

</font>[/QUOTE]Difference between occupied and useable space.

</font><blockquote>quote:</font><hr />Originally posted by Michael Brinkhues:
Most containers won't be pressurised hulls but simple steel boxes with sides similar to a JU52 plane (Wellblech, that wavy-presses steel) for added stability

Actually I think they will have to be pressurized and able to withstand wide pressure exposure. Interstellar cargo is shipped to and from many vacuum destinations and some high pressure ones, and exposure to same while loading and unloading will be expected in many cases. There's also the potential for exposure during shipping for a variety of reasons. That said it doesn't need to be space-worthy in a hull sense. For those reasons I did model mine on the corrugated steel but made it full dimensional at 0.05m thick and figure that would suffice for strength, permeability and isulation for brief exposures. That's my standard panel inserts. The "security" panels (i.e. armored) are thicker and offer a Striker armor level of 1. The big difference between the ISO and ISB containers would be in the seals being vacuum and overpressure rated.

</font>[/QUOTE]I disagree here. The majority of settled planets will be "human normal" or close enough that you don't need heavy seals. The number of planets that require such environments is limited enough that special containers exist and are only used for those cases(1).

</font><blockquote>quote:</font><hr />Originally posted by Michael Brinkhues:
Actually I can see ISB (Imperial Standards Bureau) Containers to start with a basic cube, say 2x2x2m or "Starship useabel deck hight - Space for forklift-equivalent" per side. And bigger ones using multiple length, maybe even multiple modules weldet together and the inner wall ommitted/left out.

It's bad enough with my few dimensional options losing about 50% of the volume

I think basing the standards on a dimension that isn't easily broken into the standard deck dimensions is going to mean even more waste volume. I don't even like mine for that reason but see no way around it in a real world. In one where the dimensions are line thin and overlap like that of the old Traveller deckplans sure, but it's not realistic to fit a 4ton container into a 4ton hull space with both of them having real materials rather than a simple drawn line if you follow. </font>[/QUOTE]Question: What do you mean with "standard deck dimensions"? The 2x2x2 was an example (that's what the "or whatever can fit" phrase after that meant).

And from the looks at some container ships you can stack those beasts really close. Maybe takes a bit on/offloading if you don't plan right. And Traveller container will likely be "bottom loaded" forklift style since few ships have the overhead space for anything else. And with that, you can basically stack them side to side.


(1) Similar to the "heavy" boom we used to transport 5to+ elements in the mine instead of the "light" boom normaly used. The heavy had more rollers, a thicker build and was longer meaning an engine could only pull two instead of four.

 

[far-trader]

Originally posted by Michael Brinkhues:

But I thing you leave too much "dead" space compared to real world containers. You loose fifty+ percent of hull space and that are rates that won't be acceptabel in Traveller (Where shipment is volume based after all).

I agree, and was a bit shocked when it worked out to over 50% lost volume. I had figured some, maybe as much as 25%, but it blew my mind when I came up with about 1.8tons internal. Even at about 2.5tons externally as a shipping volume in a 4ton area is a lot of lost volume. However it seems realistic, at least more so than presuming one can actually pack 4tons in a 4ton area.

I'm not sure what kinds of clearances are allowed when putting ISO aboard ship but what I came up with for my ISB (after bulkhead and container dimensions*) is a side clearance of 0.1m for air circulation and loading tolerances. That's not a lot of wiggle room for the size of the container. Top clearance is a little more at 0.2m when the container is sitting on the deck.

* Bulkheads of 0.3m thick meaning a clear deck height and square of 2.7m less the outside dimension of the container standard of 2.5m cubes.

True, in a large hold this gets you 0.5m between adjacent containers, but that is just enough for a person to squeeze through sideways, and that seems like a reasonable minimal access allowance.

And larger containers have a little less waste, since they add 0.5m for each extra deck square.

Got any ideas on making it less wasteful?

Originally posted by Michael Brinkhues:
Most containers won't be pressurised hulls...

Actually I think they will have to be pressurized...

Originally posted by Michael Brinkhues:
I disagree here. The majority of settled planets will be "human normal" or close enough that you don't need heavy seals. The number of planets that require such environments is limited enough that special containers exist and are only used for those cases.

Perhaps so, but depending on the way the worlds are created the minority is a not insignificant. It approaches 50%, or more if one includes tainted atmospheres.

And there is the chance, depending on practices presumed, of vacuum exposure during shipping. Some ships may pump down the hold to eliminate potential pest problems picked up on shirtsleeve worlds and others may do so to prevent explosive decompression and loss of atmo in the case of hull damage from combat. Heck, old tramp traders may even have slow leaks and rather than lose the atmo or drain the life support they might pump it down or let it leak and only pressurize when they need to. I think pressurized containers make sense. But this is one issue we'll probably have to agree to disagree on. It really didn't make a difference in my materials or cost assessment for the container anyway.

Originally posted by Michael Brinkhues:
Question: What do you mean with "standard deck dimensions"? The 2x2x2 was an example (that's what the "or whatever can fit" phrase after that meant).

Ah, maybe we are talking different standard deck dimensions. I'm using the 1.5m squares and 3.0m height of CT. TNE used 2.0m squares and 3.5m height which would change things. Not sure what GT uses, 5 foot squares iirc but I'm not sure what the height was. But all those dimensions don't include deckplates or bulkheads and such.

 

[far-trader]

Just because

here's a look at my current rough model of a nominal 4dton container made up of basic modular pieces.

The one end is open, and you can see the slots that the panels sit in at that end, as well as the slots in the middle interior where the bridge modules gap between two sections. Normally the slots would have filler pieces to avoid damaging the slots if left exposed.

The base has slots for lifting at regular intervals that also allow it to lock into standard deckplates and transport beds to prevent shifting in transit. One could also use the same slots and some matching rails attached to the top to allow stacking.

The black line around the outside at the base is the 3m by 6m margin.

 

[mbrinkhues]

Great picture. And I love the concept with connector and all.


I guess the width of the space between container and outline is the main difference between our concepts of useabel space respectively the major part to reduce "waste" size.

The question is wether one needs access space between the containers. Some maneuvering space for sure since that will be needed to move the container but maybe one can skip accesability during flight.

As for GURPS, the deckplans assume 1yard hexagonal grid with 8-9foot headroom and some room under the deckplates (GT, 1st Ed, Pg 153).

After looking at some plans, GT makes a minor allowance for bulkheads but basically none for walls, CT is worse and seems to lack fuel tanks on occasions. Granted, I never "counted out" the deckplans.

 

[flykiller]

The question is wether one needs access space between the containers. Some maneuvering space for sure since that will be needed to move the container

even if gravity in the bay is dialed down to zero?

 

[mbrinkhues]

Originally posted by flykiller:
</font><blockquote>quote:</font><hr />The question is wether one needs access space between the containers. Some maneuvering space for sure since that will be needed to move the container

even if gravity in the bay is dialed down to zero? </font>[/QUOTE]IMHO yes. Otherwise you will quickly get scratches and dents, leading to maintenance. And if you drop the pressure you might get what IIRC is called vacuum welding.

While we had an internal grappler for out "gondolas" (1) we always parked them with empty space when empty.

(1) 3x0.8x0.7m open topped metal containers for material transport using an overhead monorail system

 

[atpollard]

Look at how the containers stack on a containerized ship. They do not need much room, perhaps as little as 1 centimeter for a guide rail to align them. The corrugated sides will prevent an airtight seal from forming between the containers.

The old CT Subsidized Merchant, for all of its flaws, listed standard containers as 3m x 3m x 6m. This is the size that I used for the Liberty Ships (in the design contest thread). Given the CT 14 cubic meters per dTon, a 2 dTon cube would be 3.0366 meters per side. If we use multiples of 3.0366 meters for the height, width and length of a containerized cargo bay, that would leave 3.6 cm between containers at the side and 7.3 cm at the end of the containers. Enough to prevent an airtight seal, to provide a small guide rail between the containers and room to grab a container from above (mechanical "fingers" will fit between the containers to lift them).

A 3m x 3m x 6m container would be 54 cubic meters on the outside and would fill 3.86 dTons of cargo hold per container (96% of the 4 dTon nominal size). A concrete container would need only 0.1 meter thick sides (thickness determined by required cover over steel reinforcing mesh). So a concrete container would have interior dimensions of 2.8m x 2.8m x 5.8m (45.5 cubic meters) or 3.25 dTons of interior storage volume (81% of the 4 dTon nominal size). This container could be manufactured at TL 4 and any later TL would be able to use materials that would be thinner than the 0.1m concrete sides, so 0.1 m represents a maximum wall thickness for a non-wood container. Modern containers are stacked up to 9 high (a 9G load), so the current intermodal containers are strong enough for space applications. They might need welded seams and better door seals, but not thicker walls.

For costs, I would suggest that since a drop tank costs 10,000 cr plus 1000 cr per dTon, that the 10,000 credits is for the jump grid and automatic ejector and the 1000 cr per dTon is for the box that is space rated and capable of surviving multiple jumps. A nominal 4 dTon container could cost 4000 credits since it has no jump grid in the walls and cannot be dropped before a jump. The container is made from the same material as a drop tank.

 

[far-trader]

Originally posted by Michael Brinkhues:
Great picture. And I love the concept with connector and all.

Thanks Michael. I just wanted to get an idea of what might be used in the setting. Not an exact copy of the Intermodal model but there are so many good bits of that to use it'd be wrong to not start there at least.

Originally posted by Michael Brinkhues:
I guess the width of the space between container and outline is the main difference between our concepts...

The question is wether one needs access space between the containers. Some maneuvering space for sure since that will be needed to move the container but maybe one can skip accesability during flight.

There could be a tighter spacing as you say, but then how does one play "Hunt the alien monster in the cargo hold" or "Fight off the space pirate scum among the cargo containers"

But that's only part of my reasons for some space (dark, claustrophobic inducing space

) between containers. It more stems from a need in some (at least) deckplans to get through the cargo hold to access other spaces, like engineering, without having to go EVA or cheat and draw a 200ton cargo hold as 250tons so there corridors through it.

There's also the issue of the bulkhead thickness, at least around the perimiter, and as mentioned some space for handling the containers.

And too, more so for small traders, the size will be limited to a reasonable dimension for a cargo loading hatch.

Thanks for the note on GT deckplans, not sure where I got the 5' from.

And yep, most deckplans seem to take the approach of being just maps rather than concerned with anything as "trivial" as dimensions for walls and such More on that in the reply to atpollard below...

 

[far-trader]

Originally posted by flykiller:
</font><blockquote>quote:</font><hr />The question is wether one needs access space between the containers. Some maneuvering space for sure since that will be needed to move the container

even if gravity in the bay is dialed down to zero? </font>[/QUOTE]Actually putting the hold in zero-g would probably just make cargo operations trickier. Once a container is moving it'd have no reason to stop if you quit pushing/pulling and a bump from another container could set it drifting.

And the contents might not like being exposed to zero-g in some cases.

Hmm, there's another good reason to make the containers vacuum capable Michael. Even if the containers themselves aren't subject to the vacuum welding you mention* some contents might very well be. Some items may even expand explosively if subjected to a pressure drop.

* And I'd think they'd be designed to resist such if they were designed for vacuum but maybe not otherwise.

 

[far-trader]

Originally posted by atpollard:
Look at how the containers stack on a containerized ship. They do not need much room, perhaps as little as 1 centimeter for a guide rail to align them.

I have, as best I could, and it looks like much more than 1cm. I think my 0.1m spacing is pretty close. The guide rails used don't seem to change the spacing, they seem to just allow a quicker more precise loading operation when stacking. And while the same could be set up horizontally as most Traveller ships are that would require that the whole hold dimension be open, which is not seen in most Traveller ships, for good reason.

Originally posted by atpollard:
The old CT Subsidized Merchant, for all of its flaws, listed standard containers as 3m x 3m x 6m.

And that would be one of the more glaring flaws

As noted above, the old CT deckplans are more maps than plans. Like a road map that shows streets and roads as a simple line when we know it's really at least several meters wide, the deckplans show bulkheads and cargo containers as simple full dimension lines when we know they must have some thickness for structure, insulation, and other elements within which means they are not as drawn.

There's no way you can put a 6m x 3m x 3m box (the cargo container) within another 6m x 3m x 3m box (the cargo hold) and have 6m x 3m x 3m of stuff (the actual 4dtons of cargo) inside the first box. Well not in the normal universe

My solution was that cargo is shipped as nominal dtons based on a close approximation. I had hoped that it was going to be much closer but it isn't. I could fudge a little more room but it wouldn't be significant and would result in odd sizes. So instead I've settled on some dimensions and rounded it to, for example, 2dtons of contents packed in a nominal 4dton container. This actually helps since the mass will come a little closer to the displacement. And by calling it a (nominal) 4dton container the economics aren't changed.

Originally posted by atpollard:
This is the size that I used for the Liberty Ships (in the design contest thread). Given the CT 14 cubic meters per dTon, a 2 dTon cube would be 3.0366 meters per side. If we use multiples of 3.0366 meters for the height, width and length of a containerized cargo bay, that would leave 3.6 cm between containers at the side and 7.3 cm at the end of the containers. Enough to prevent an airtight seal, to provide a small guide rail between the containers and room to grab a container from above (mechanical "fingers" will fit between the containers to lift them).

Interesting. Not quite standard to my mind but the idea of cubes is a fresh take. TNE came close to this by redefining a dton as 2m square by 3.5m high (just shy of two 2m cubes stacked).

Originally posted by atpollard:
A 3m x 3m x 6m container would be 54 cubic meters on the outside and would fill 3.86 dTons of cargo hold per container...

Shouldn't that be 4dtons?

Originally posted by atpollard:
A concrete container would need only 0.1 meter thick sides (thickness determined by required cover over steel reinforcing mesh).

Well I won't debate the required thickness, that would depend on the expected content mass and a few other things. I'm just wondering why in the worlds you'd use concrete? It's danged heavy stuff. The density is a nice feature, and also the resistance to a lot of things but did I mention it's heavy

Originally posted by atpollard:
...Modern containers are stacked up to 9 high (a 9G load), so the current intermodal containers are strong enough for space applications.

Not quite. Stacking 9 high does not equate to a 9G load on the bottom container so we can't call that a proof of space suitability. It really says nothing about that.

The stacking limit is the load limit of the bottom container's structure and is dependant on the weight of all the containers above it including contents. And this is the most common container failure cause. Stacking overloaded containers too high. The bottom container reaches it's failure point, which is often less if not new due to dents, age and metal fatigue, and it crushes usually causing the container stack to fall. Either into another stack, and so in falling domino fashion, or into the side of the ship causing damage to it, or over the side into the water, or onto the ground if already offloaded. Some ships have even capsized due to the load shift.

But I will grant that the ISO Intermodal model is strong enough and only lacking suitable insulation and sealing, and perhaps materials more suited.

Originally posted by atpollard:
For costs, I would suggest that since a drop tank costs 10,000 cr plus 1000 cr per dTon, that the 10,000 credits is for the jump grid and automatic ejector and the 1000 cr per dTon is for the box that is space rated and capable of surviving multiple jumps. A nominal 4 dTon container could cost 4000 credits since it has no jump grid in the walls and cannot be dropped before a jump. The container is made from the same material as a drop tank.

That's probably not a bad way to go. I wouldn't for a lot of reasons though, the chief one being that even as a fair model for drop tanks it makes no sense.

I got a rough price for the 6m/20foot container of between Cr6500 and Cr9000 (depending on dimensions used) using Striker, for hard steel construction. That fits pretty close to the current Real World price of about $2500 with the traditional conversion of Cr3 to $1 (iirc the conversion). So I'm happy with that. I'd peg your drop tank cost model as a little low. One could write that off as a less durable version I suppose as drop tanks are described as single use and replace.

 

[atpollard]

3m x 3m x 6m = 54 cubic meters

In Classic Traveller, 1 dTon = 14 cubic meters, so 54 cubic meters = 3.857 dTons. 4 dTons = 56 cubic meters = 3.036m x 3.036m x 6.073m

IIRC, in Mega-Traveller, 1 dTon = 13.5 cubic meters, so 54 cubic meters = 4 dTons = 3m x 3m x 6m.

All of the other versions of Traveller use either 13.5 or 14 cubic meters per dTon.

 

[far-trader]

Ah, that's right

I was just forgetting that the actual volume is not the full 14m3 but 13.5m3 Thanks for the reminder atpollard.

 

[atpollard]

I think that 1 Cr = $2 to $3, so a $2500 ISO container would cost about 1000 Cr.

A ground car costs 4000 Cr x $3/Cr = $12,000.
A ground car costs 4000 Cr x $1/3 Cr = $1,333.

 

[atpollard]

I chose concrete because it was the worst practical material, so any "reasonable" container would have thinner walls. I agree that concrete is a terrible choice (the drives better be mass independent if you are going to haul concrete boxes around).

PS. I do like the look of your container.

 

[far-trader]

Hmm, that Cr conversion makes more sense, I think I have gotten it backwards in my mind.

Ah, concrete as a worst case point, got it

Thanks for the praise, it needs work but it's mostly just to give my thoughts on it something to look at. A visual aid.

 

[far-trader]

Hey, I keep forgetting, thanks for having a look and kicking in some feedback, it is much appreciated.

 

[chshrkt]

Originally posted by far-trader:
Just because

here's a look at my current rough model of a nominal 4dton container made up of basic modular pieces. <snip> cool container image</snip>

The only thing I see missing from that fantastic image are the corner fittings that lock the containers together in a vertical stack and horizontal matrix. That also provides the air gap to prevent them from sticking together (and of course adds a bit more "wasted space".

Check out this Wikipedia Entry, 5th paragraph in that section, first sentence and the middle photograph of the corner fitting, or "Twistlocks".

 

[vargr1]

http://www.solentwaters.co.uk/Loading%20Cargo/Loading%20Cargo%201/page4.html shows many different connectors for containers, including a small slideshow showing how to use one of them.