Fluffy Bunny Feet
Cosmic Mongoose
High Guard 2016 :
So it should be possible to mate the cargo hatch with a cargo airlock (or optimistically another cargo hold though I wouldn't allow it) for transfers.
Mating Airlocks to Cargo Hatches
- Thread starter Terry Mixon
- Start date
High Guard 2016 :
So it should be possible to mate the cargo hatch with a cargo airlock (or optimistically another cargo hold though I wouldn't allow it) for transfers.
Terry Mixon
Emperor Mongoose
Another factor that drives which containers are used is cost. One rated for vacuum will be pricier (perhaps significantly so) than one that isn’t. The cost notes are vague, but here they are.
“Containers vary in price by size, type and TL, from barely Cr50 for a simple 4F00/5 portable steel box up to roughly MCr0.5 for a 4A92/F that might act as a noble’s stateroom. Between the metallurgy and precision required, even the simplest of these containers are rarely made to lower than TL5 standards.”
Cost is always a factor for shipping and having the ship maintain pressure and temperature is cheaper in the long run than making the containers more expensive.
“Containers vary in price by size, type and TL, from barely Cr50 for a simple 4F00/5 portable steel box up to roughly MCr0.5 for a 4A92/F that might act as a noble’s stateroom. Between the metallurgy and precision required, even the simplest of these containers are rarely made to lower than TL5 standards.”
Cost is always a factor for shipping and having the ship maintain pressure and temperature is cheaper in the long run than making the containers more expensive.
Terry Mixon
Emperor Mongoose
The robotic Type C Cargo Loader in the Robot Handbook is only good for up to 5 dtons of cargo, so I bumped its size up and gave it two sets of forklifts to allow up to 10 dtons and thus most common cargo containers. Welcome the robotic Type G Cargo Loader.
Only @Geir can say if that’s legit, but I think the load sharing would work. One set lifts one end, the arms help guide it, and the second forklift wedges under the far side from underneath to lift and load the container. As the heavy ones are the most unwieldy, this makes sense to me. YMMV.
I can see herds of both types making short work of unloading cargo pods at highports and downports across the Imperium and beyond.
Only @Geir can say if that’s legit, but I think the load sharing would work. One set lifts one end, the arms help guide it, and the second forklift wedges under the far side from underneath to lift and load the container. As the heavy ones are the most unwieldy, this makes sense to me. YMMV.
I can see herds of both types making short work of unloading cargo pods at highports and downports across the Imperium and beyond.
The container cost is met by the shipper, but again your presumption is they need to be proof against vacuum. Which trade goods actually suffer from vacuum? Aircraft holds are usually not pressurised. Not having a pressurised hold also removes a number of hazards, from fire to contamination of the life support from dodgy cargo. Unplanned explosive decompression of a compartment is a hazard easily eliminated by evacuating the compartment at a time of choice.
The fact that cargo airlocks are an option but are rarely fitted to any spaceship in the books speaks volumes. It is a waste of tonnage for a start. The small craft book provides a number of little utility craft that tow containers. Since these containers are open to vacuum when being towed, placing them in vacuum when loading isn't a big deal. If you want to pressurise after loading and the cargo doors are closed then you are free to do so at no additional cost.
If you can cite a reference in one of the books that explicitly states that cargo holds need to be pressurised then it might be easier to believe that this is more than a solution in search of a problem.
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Condottiere
Emperor Mongoose
It tends to get speculative.
A variant would be opening up the hangar doors.
A variant would be opening up the hangar doors.
AndrewW
Emperor Mongoose
I can't do that Condottiere.
Terry Mixon
Emperor Mongoose
There isn’t one, just as there isn’t one that says the run depressurized. The fact, as stated in the in the SOM that the standard cargo container is not protected is all we get.
Also, low pressure isn’t no pressure. The two are not the same and I would wager that would make a difference.
Now, with that given, there will be cargos that don’t care for vacuum. Many, if not a majority, of things shipping from one place to another could react badly to that type of environment. The ship spends little on maintaining a shirt-sleeves environment, so there really is no call to depressurize. No life support cost, no extra maintainance costs.
With that being the case, it’s hard to imagine why they would want to depressurize the cargo hold. Of course, your universe, your choice. I’m doing this for those that don’t share that basic assumption about cargo transport.
Condottiere
Emperor Mongoose
That would only apply if you were in an Element class cruiser, and had a bay in a pod.
As you size the containers up you have to think about how they will be moved. At 5Dtons you are looking (roughly) at a standard 20' container. You could use a loader that used tines to pick it up from the middle and move it, but not length-wise. At 10Dton is going to be equivalent to about a 45' container. That's way too long to pick up from the ends, and even picking it up in the middle can run into issues related to weight distribution.
Most containers are picked up from the top with a loading apparatus that applies lift at the ends (or in the middle). As I see it, with grav tech your loaders will lift from the top of the container. A grav-lift device would just need to elongate enough to distribute the weight and it would probably me 24" thick for the grav lifter itself, then you'd need power cells and a mechanism to retract claws/lifting grabbers at both ends. With a little though you could make it a universal device that can lift 5 or 10dton containers with equal ease, and can be stowed very easy on a ship or elsewhere.
Forklifts or other type of gear only work well for smaller, say 3dton and down, style loads. While you can indeed get lifters that can lift larger containers, they have to be of a certain size to counterbalance the mass. It just seems to make more sense with less logical gyrations to take advantage of grav tech and mate it with simple lifting tech to get you what you need.
Honestly, it's probably more convenient to leave all sections of the ship pressurised, just from an engineering point of view. If you depressurise a section that means the pressurised sections on the other side of the bulkheads are straining to equalise with it.
Huh.
I just rabbitholed the effects of gravity on pressure, and I could be wrong, but turning off the gravity might have an effect on it. Certainly, it's the weight of atmosphere that causes that on a planet. In free fall you'd fall back on pressure from a gas in an enclosed volume.
Should be a known thing, from the space stations.
Huh.
I just rabbitholed the effects of gravity on pressure, and I could be wrong, but turning off the gravity might have an effect on it. Certainly, it's the weight of atmosphere that causes that on a planet. In free fall you'd fall back on pressure from a gas in an enclosed volume.
Should be a known thing, from the space stations.
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Fluffy Bunny Feet
Cosmic Mongoose
Heavy Grappling arms seem made for the role. Either at the station or on the ship.
Container costs will vary greatly. It's one of those "it depends" issues. There are a LOT of containers out there in the world owned by 3rd parties and leased, and you have some that are owned by the party whose cargo is inside, and then there are those owned by the merchant doing the transporting. I think the majority are 3rd party owned and wet-leased to various parties. LTL (less than truck load, i.e. you aren't buying the entire trailer/container) is quite prevalent as lots of people ship in lots smaller than a full container.
I believe most containers will be non-pressurized and simple is because of the reason cited already - cost. Simple aluminum or similar cheap materials to give you a sealed box that keeps the weather out, but is not pressurized nor insulated - those would be specialized containers.
First off you want to keep gravity there because otherwise your cargo will be in zero-g inside of the container, and unless it was magically packed, that's a problem. And your cargo inside of the boxes will also float freely and can shift and when brought back under G could be damaged. It's cheaper for shippers to take basic precautions and assume their cargo will remain under G. While entirely possible to NOT do that, you make that package under G and it's received under G, ergo the expectation is it will remain that way for the duration of its journey. Secondly, I don't see any reason why a freighter would depressurize a hold. The power requirements for life support are tiny, and keeping the temp relatively stable makes too much sense. Otherwise shippers will have to worry about very low temps - and many cargo's could do quite poorly at very low space temps. If you have to worry about unplanned decompression, you'd worry about that for your entire ship as well (and it's not one I'd want to travel on as a crew member).
I agree that most ships aren't going to have full cargo airlocks. The cargo hold will function as such, but care would need to be taken if both ends of your journey do not offer full seals for shirt-sleeve cargo transfer. And a ship is going to have a very good idea of the facilities available on both ends before doing any sort of cargo run.
All the logic of cargo transport points toward keeping things under G and under pressure as a standard routine. It just makes too much sense and it costs a ship operator essentially nothing. Bulk transport of ores, grains, and other materials (at least between systems) is often uneconomical due to the high costs of transport vs the low cost of the items. That's a bit of a dichotomy in the game. It points more towards shipping finished goods than raw materials. Intra-system transport is a different beast though.
Perhaps. But the arms would (or should) have issues reaching into a hold to grab the cargo. And your arms are going to be limited to where they are fixed in place. The top-of-container lift gives you total freedom to be in/out of a ship and to move your cargo wherever you need to put it (warehouse, just outside, on a trailer, etc).
Terry Mixon
Emperor Mongoose
The five ton model is in the Robot Handbook, so blame @Geir.
How about a flatbed vehicle with a winch to pull them onto a tiltable flatbed? Toss in 9 arms to attach tiedowns and you're golden, right? This can handle up to 8 dtons of container (the largest standard size).
One thought is that costs are relative, and total.
That is, the cheapest shipping containers for a given cargo's TOTAL journey will differ, depending on that journey.
If it's apples, you may be fine with a simple unpressurised box if shipping it from the dirtside farm to the flying city nearby. If that cargo needs to be sent to another system, it would be kept in a low temperature environment - maybe a container, maybe a cargo hold that handles that aspect. If it has to be handled at any point where high temperatures are expected, it would need to be a temperature controlled container.
That is, the cheapest shipping containers for a given cargo's TOTAL journey will differ, depending on that journey.
If it's apples, you may be fine with a simple unpressurised box if shipping it from the dirtside farm to the flying city nearby. If that cargo needs to be sent to another system, it would be kept in a low temperature environment - maybe a container, maybe a cargo hold that handles that aspect. If it has to be handled at any point where high temperatures are expected, it would need to be a temperature controlled container.
Condottiere
Emperor Mongoose
Actually, my calculations came up with a forty foot container being five tonnes.
Depressurisation of the cargo hold is only NEEDED if you don't have a cargo airlock and if you transfer cargo in open space. Depressurising is an option that can bring benefits (but also imposes disadvantages).
You don't need to depressurise if you load:
on a low port where the planet has an appropriate atmosphere
on a low port where the planet has a difficult atmosphere but a sealed docking bay
on a high port with a sealed docking bay
Those three conditions are pretty likely in the majority of cases in my opinion as those offer the quickest route for unprotected cargo and crew to transfer between ship and port.
The purpose of an airlock is so that you can move something into the non-ship atmosphere (be that vacuum or toxic atmosphere etc.) without exposing the entire ship to that non-ship atmosphere. If that is the situation then the thing being moved needs to be independently protected from the non-ship atmosphere once it gets out there. If you are moving standard containers that cannot withstand the non-ship atmosphere then you will not be connecting to a non-ship atmosphere and so you don't need an airlock.
If you are making a semi-permanent connection between two ship type atmospheres you don't need it to be an airlock, including if you dock with onto another ship while in space. The connection itself is the airlock (which is what I think the OP was suggesting).
Small Craft makes it clear that containers iiiiiin spaaaaace is a thing. They will be protected containers but to load them you just need to depressurise the cargo hold while you load them. If you want to repressurise afterward that is your option.
Since we don't seem to have any definitive information about the different types of container other than listing the types (which seem to be read across from real world ISO containers and extrapolated for space needs):
It could be that standard containers are not the most common in space transport and are limited to planetary use.
All space going freight might use airtight containers, the non-airtight ones are in use in benign atmospheric environments.
Containers may only spend a relatively short time in transit, not long enough to loose much air.
As you are paying by the DTon you probably want that container packed so full that there may not be much air in there anyway.
Temperature control is also an issue but this is true for many goods in benign atmospheres too, this could be cheaply achieved.
The cost of an airtight standard container might not be significantly higher than that of a non-airtight one. Standard containers could be one use (many real world ISO containers are). The cost is still low compared to the cost of the contained goods plus the cost of movement but that may be because we are wasteful of resources. Most real world ones are also exposed to a hostile environment (sea crossings) and salt corrosion and contamination from the contents might render them uneconomical to re-use . They are the padded envelopes of the shipping industry. Special purpose containers may cost more, but they also seem to be re-used. Overall the cost per use might actually be lower.
The difference in pressure between a standard atmosphere and absolute vacuum is 1 atmosphere. A beer bottle can withstand several atmospheres pressure and usually has a factor 3 safety margin. A bottle of beer left in a sealed but evacuated hold will be fine. In open space it might be irradiated if in sight of a radiating body and the contents boil to the point of bursting the container or alternatively if it isn't it will freeze and burst the container. It will also be subject to other forces (cosmic rays, micrometeors, non-gravity - best have a high gravity beer). If it was in a metal box with a decent thermal mass and proof against cosmic rays it could probably be transported though open space from the shuttle to the cargo bay of the receiving ship without too much trouble. I don't think a washing machine would care one jot.
Consider where these are going to and from. After unloading or while awaiting loading they might well sit in a container park for an extended period. If you are unloading/unloading somewhere with a non-benign environment standard containers must be stored inside. If they are protected containers you can stack them up outside (as many real world containers are). Internal storage space tends to cost a lot in an environment that needs it. The cost of building and maintaining a shelter, which needs to be as big as the peak DTonnage it will store plus extra for access, airlocks, equipment to maintain the environment etc. will likely far outweigh the additional cost of protecting some containers and you only need to protect the containers you use. If you store outside you only need enough airlock to handle one container at a time. It is likely the containers will be destined elsewhere than the port and will need to be protected for that part of the journey as well. The customer may be perfectly happy to pay extra shipping costs to have a protected container at the end point to reduce his own storage overhead. That protected container may end up forming a permanent part of a remote facility offsetting the additional cost the shipper will pass onto the customer.
Most of the cargos IMTU are also being moved in cutter modules and either being manoeuvred into holds as a unit or are clamped externally. As such the cargo bay pressure is largely irrelevant as the module itself ensures the correct atmosphere. Where individual cargos are loaded in space it will be via small utility pods and in sealed cargo containers. Loading at high ports and on inhospitable planets is conducted entirely in sealed docking bays. Only when smuggling does this become more interesting - as it should.
You don't need to depressurise if you load:
on a low port where the planet has an appropriate atmosphere
on a low port where the planet has a difficult atmosphere but a sealed docking bay
on a high port with a sealed docking bay
Those three conditions are pretty likely in the majority of cases in my opinion as those offer the quickest route for unprotected cargo and crew to transfer between ship and port.
The purpose of an airlock is so that you can move something into the non-ship atmosphere (be that vacuum or toxic atmosphere etc.) without exposing the entire ship to that non-ship atmosphere. If that is the situation then the thing being moved needs to be independently protected from the non-ship atmosphere once it gets out there. If you are moving standard containers that cannot withstand the non-ship atmosphere then you will not be connecting to a non-ship atmosphere and so you don't need an airlock.
If you are making a semi-permanent connection between two ship type atmospheres you don't need it to be an airlock, including if you dock with onto another ship while in space. The connection itself is the airlock (which is what I think the OP was suggesting).
Small Craft makes it clear that containers iiiiiin spaaaaace is a thing. They will be protected containers but to load them you just need to depressurise the cargo hold while you load them. If you want to repressurise afterward that is your option.
Since we don't seem to have any definitive information about the different types of container other than listing the types (which seem to be read across from real world ISO containers and extrapolated for space needs):
It could be that standard containers are not the most common in space transport and are limited to planetary use.
All space going freight might use airtight containers, the non-airtight ones are in use in benign atmospheric environments.
Containers may only spend a relatively short time in transit, not long enough to loose much air.
As you are paying by the DTon you probably want that container packed so full that there may not be much air in there anyway.
Temperature control is also an issue but this is true for many goods in benign atmospheres too, this could be cheaply achieved.
The cost of an airtight standard container might not be significantly higher than that of a non-airtight one. Standard containers could be one use (many real world ISO containers are). The cost is still low compared to the cost of the contained goods plus the cost of movement but that may be because we are wasteful of resources. Most real world ones are also exposed to a hostile environment (sea crossings) and salt corrosion and contamination from the contents might render them uneconomical to re-use . They are the padded envelopes of the shipping industry. Special purpose containers may cost more, but they also seem to be re-used. Overall the cost per use might actually be lower.
The difference in pressure between a standard atmosphere and absolute vacuum is 1 atmosphere. A beer bottle can withstand several atmospheres pressure and usually has a factor 3 safety margin. A bottle of beer left in a sealed but evacuated hold will be fine. In open space it might be irradiated if in sight of a radiating body and the contents boil to the point of bursting the container or alternatively if it isn't it will freeze and burst the container. It will also be subject to other forces (cosmic rays, micrometeors, non-gravity - best have a high gravity beer). If it was in a metal box with a decent thermal mass and proof against cosmic rays it could probably be transported though open space from the shuttle to the cargo bay of the receiving ship without too much trouble. I don't think a washing machine would care one jot.
Consider where these are going to and from. After unloading or while awaiting loading they might well sit in a container park for an extended period. If you are unloading/unloading somewhere with a non-benign environment standard containers must be stored inside. If they are protected containers you can stack them up outside (as many real world containers are). Internal storage space tends to cost a lot in an environment that needs it. The cost of building and maintaining a shelter, which needs to be as big as the peak DTonnage it will store plus extra for access, airlocks, equipment to maintain the environment etc. will likely far outweigh the additional cost of protecting some containers and you only need to protect the containers you use. If you store outside you only need enough airlock to handle one container at a time. It is likely the containers will be destined elsewhere than the port and will need to be protected for that part of the journey as well. The customer may be perfectly happy to pay extra shipping costs to have a protected container at the end point to reduce his own storage overhead. That protected container may end up forming a permanent part of a remote facility offsetting the additional cost the shipper will pass onto the customer.
Most of the cargos IMTU are also being moved in cutter modules and either being manoeuvred into holds as a unit or are clamped externally. As such the cargo bay pressure is largely irrelevant as the module itself ensures the correct atmosphere. Where individual cargos are loaded in space it will be via small utility pods and in sealed cargo containers. Loading at high ports and on inhospitable planets is conducted entirely in sealed docking bays. Only when smuggling does this become more interesting - as it should.
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Condottiere
Emperor Mongoose
I would say that packing and packaging for experienced interstellar logistics companies is a non issue.
They know what's required to get the cargo at the destination without spoilage and breakage.
Possibly, also without shrinkage.
I see various quotes for a new twenty foot shipping container, so the ballpark may be between seven hundred to five thousand greenbux.
If you want to have a more or less guaranteed vacuum proof one, you'd have to buy a five tonne hull.
They know what's required to get the cargo at the destination without spoilage and breakage.
Possibly, also without shrinkage.
I see various quotes for a new twenty foot shipping container, so the ballpark may be between seven hundred to five thousand greenbux.
If you want to have a more or less guaranteed vacuum proof one, you'd have to buy a five tonne hull.
NOLATrav
Emperor Mongoose
Traits for cargo containers - standard atmo, vacuum, refrigeration, etc.
Requires knowledge of the freight being shipped and possibly some requirements for the shipper. Like, refrigeration containers require ship power, vacuum-rated can be carried in external hull clamps, etc.
Requires knowledge of the freight being shipped and possibly some requirements for the shipper. Like, refrigeration containers require ship power, vacuum-rated can be carried in external hull clamps, etc.
Condottiere
Emperor Mongoose
Nets and tow cables.
Probably have to follow terms and conditions of service, especially in regard to vacuum exposure.
Lack of atmospheric pressure probably would cause frozen pork bellies to explode.
Probably have to follow terms and conditions of service, especially in regard to vacuum exposure.
Lack of atmospheric pressure probably would cause frozen pork bellies to explode.
