Efficient space only freighter design

[phavoc]

I was thinking about how to make a space-only freighter ad efficient as possible to load and unload. But also taking into account that to fully use all available cargo space you have to store your freight basically container to container. And if you do that, how do you that with limited dock space at a station?

I think first some caveats:

1) containers are going to be the top choice of moving cargo. Its efficient and allows for it to move from warehouse to warehouse before you have to crack the seals. So that's just like containers today (also allows them to be on truck and rail, or their 52nd century equivalent).

2) containers will be standard size. Large freight lines will most likely standardize on 5 and 10dton sized ones. They are well sized to move most items and are a good match as we've seen from terrestrial modern equivalents.

3) smaller freighters would handle the 5 ton ones, and maybe for smaller locations you'd get as small as 3 dton. That's reasonable sized to allow smaller ships to easily handle them.

4) space docks are going to have limited space to allow a ship to remove cargo if they need to get containers at the back. A good load master will load it in the order it would come off, but new cargo to be loaded can potentially fill up any spaces you just removed. So how to be able to access older cargo as you make your route (assuming you aren't point to point)?

5) stations will have limited surface space to allow for physical docks. So ship forms that are longer than they are wider, and load from the nose seem the best suited for space-only loads.

Right now the most efficient design I'm coming up with is a ship that stores containers in a rotary like mechanism, with the cargo in the outer rim and the center where crew, engineering and fuel are stored. Think of it like a ferris wheel, except cargo containers instead of people pods. Since traveller only counts internal hull displacement, the fact that you have a large circular portion with empty space in the middle, you don't lose any displacement volume to such a design - just what you have enclosed in the hull area.

This is kind of equivalent of a container ship, taking into account you are in space and your cargo can't be exposed to vacuum (cheaper to buy regular containers than always using vacuum rated ones-plus zero g can make a mess of stored cargo).

Gaming wise few, if any, go to this level of detail. 40 tons cargo always magically fills the space and nobody cares about how it's stored or loaded/unloaded - it's just a number.

What got me thinking was the practicality of a design, and that drives how ships are built and how they look. And that drives deck plans and, if you get to it, how boarding and other actions may play out. Especially if you are using miniatures and like to game at that level.

So if anyone else was trying to design a ship that would have to follow real world limitations and operational limitations, how would you make it?

 

[AndrewW]

Could add multiple cargo doors so stuff near the front or back could both be gotten to.

With the anti-grav at least the gravity field can be adjusted to make loading/unloading easier.

 

[Condottiere]

Would depend on the cargo transported.

I'm inclined to think it's a series of diminishing containers.

 

[phavoc]

Could add multiple cargo doors so stuff near the front or back could both be gotten to.

With the anti-grav at least the gravity field can be adjusted to make loading/unloading easier.

True. Which would work well for ground-based starports or if your containers/cargo modules are vacuum rated and your internal cargo is packed for zero-g (in theory you could put grav plating in a container - but that makes it prohibitively expensive for average cargo).

The question of how you'd unload it at a space dock remains. If you had long docking arms that could attach to port/starboard cargo hatches then you'd, in theory at least, be able to unload from three access points. That could be quite effective for larger ships, or those that want to quickly load/unload and depart the station.

 

[phavoc]

Would depend on the cargo transported.

I'm inclined to think it's a series of diminishing containers.

How/why would you have nested containers?

 

[MasterGwydion]

I was thinking about how to make a space-only freighter ad efficient as possible to load and unload. But also taking into account that to fully use all available cargo space you have to store your freight basically container to container. And if you do that, how do you that with limited dock space at a station?

I think first some caveats:

1) containers are going to be the top choice of moving cargo. Its efficient and allows for it to move from warehouse to warehouse before you have to crack the seals. So that's just like containers today (also allows them to be on truck and rail, or their 52nd century equivalent).

2) containers will be standard size. Large freight lines will most likely standardize on 5 and 10dton sized ones. They are well sized to move most items and are a good match as we've seen from terrestrial modern equivalents.

3) smaller freighters would handle the 5 ton ones, and maybe for smaller locations you'd get as small as 3 dton. That's reasonable sized to allow smaller ships to easily handle them.

4) space docks are going to have limited space to allow a ship to remove cargo if they need to get containers at the back. A good load master will load it in the order it would come off, but new cargo to be loaded can potentially fill up any spaces you just removed. So how to be able to access older cargo as you make your route (assuming you aren't point to point)?

5) stations will have limited surface space to allow for physical docks. So ship forms that are longer than they are wider, and load from the nose seem the best suited for space-only loads.

Right now the most efficient design I'm coming up with is a ship that stores containers in a rotary like mechanism, with the cargo in the outer rim and the center where crew, engineering and fuel are stored. Think of it like a ferris wheel, except cargo containers instead of people pods. Since traveller only counts internal hull displacement, the fact that you have a large circular portion with empty space in the middle, you don't lose any displacement volume to such a design - just what you have enclosed in the hull area.

This is kind of equivalent of a container ship, taking into account you are in space and your cargo can't be exposed to vacuum (cheaper to buy regular containers than always using vacuum rated ones-plus zero g can make a mess of stored cargo).

Gaming wise few, if any, go to this level of detail. 40 tons cargo always magically fills the space and nobody cares about how it's stored or loaded/unloaded - it's just a number.

What got me thinking was the practicality of a design, and that drives how ships are built and how they look. And that drives deck plans and, if you get to it, how boarding and other actions may play out. Especially if you are using miniatures and like to game at that level.

So if anyone else was trying to design a ship that would have to follow real world limitations and operational limitations, how would you make it?

Easy. Use an UNREP System. Nothing in Traveller is faster nor more efficient. It works for cargo as well as fuel.

 

[AnotherDilbert]

I think first some caveats:

I agree with your premises. A freighter should be constructed around the cargo and handling thereof.

Right now the most efficient design I'm coming up with is a ship that stores containers in a rotary like mechanism, with the cargo in the outer rim and the center where crew, engineering and fuel are stored. Think of it like a ferris wheel, except cargo containers instead of people pods.

The geometry is iffy, you can't fill a rounded torus with square boxes (containers).

My first thought is something like this:

Still wastes a lot of space in the middle.

Or:

Fairly space-efficient, but lots of machinery. Allows random access to any container.
Less space-efficient than simply stacking containers.



This wastes space both in the middle and in the wedges between the containers.

Since traveller only counts internal hull displacement, the fact that you have a large circular portion with empty space in the middle, you don't lose any displacement volume to such a design - just what you have enclosed in the hull area.

Agreed, whether you count volume or mass, empty space does not count. However, a torus (donut) would be a hull-inefficient design with lots of surface area, hence expensive hull with heavy shell. A sphere or box is simply cheaper, which is a limiting concept.

 

[phavoc]

Easy. Use an UNREP System. Nothing in Traveller is faster nor more efficient. It works for cargo as well as fuel.

UNREP is a system, not a ship design. There are multiple USN ships that perform UNREP. Depending on the timeframe you had carriers and battleships refueling destroyers, you had small cargo ships and tankers refueling carriers. Today you have larger ships using fuel booms, cabling and even helicopters doing underway replenishment.

I'm looking for how a ship might actually be designed/look to be closer to what they might look like. For decades cargo ships were similar to the design of Liberty ships - forward holds serviced by 1 or 2 cranes, the bridge and crew quarters amidships, more holds/cranes aft and then the aft section (which sometimes was built up, other times not). Later you see specialized ships emerging - supertankers, RO/RO, small, and then super-container ships. Ships continue to evolve, but aside from size the designs are pretty efficient for the ships functions and where they operate.

We don't really see that in the game for the most part. I'm looking for what the workhorses of the sectors might look like.

 

[NOLATrav]

In the MgT 1e game I’m currently playing in, we recently scored a 400 ton freighter. The main cargo bay is two decks tall, with no flooring between them; just a giant cavernous hold. Our cargo master worked out a system of magnetic buckles where cargo containers are fastened to the walls and ceiling, more buckles are attached to these locked-in-place containers and like an onion, another layer of containers are buckled to the ever-shrinking walls and ceiling. Eventually the “working tunnel” backs up to the bay doors and the last 10 or 15 tons are buckled to the floor.

Personally I’m not sure it’s feasible but it’s been a fun thought experiment.

 

[phavoc]

I agree with your premises. A freighter should be constructed around the cargo and handling thereof.



The geometry is iffy, you can't fill a rounded torus with square boxes (containers).

My first thought is something like this:

Still wastes a lot of space in the middle.

Or:

Fairly space-efficient, but lots of machinery. Allows random access to any container.
Less space-efficient than simply stacking containers.


View attachment 1658
This wastes space both in the middle and in the wedges between the containers.


Agreed, whether you count volume or mass, empty space does not count. However, a torus (donut) would be a hull-inefficient design with lots of surface area, hence expensive hull with heavy shell. A sphere or box is simply cheaper, which is a limiting concept.

My assumption would be something like the first illustration for smaller ships - a corridor in the middle that at least allowed you to load containers to the sides. A clever loadmaster would figure out a way to fill the sides first and then fill the middle with only the cargo that would for sure be unloaded at the next stop.

That may work for smaller ships, but larger ones may have multiple levels and then your system would start to become strained as you stacked containers on top of one another, making movement unwieldy unless you had dock space to unload units to get to the ones you needed. That's why I was thinking of a rotary style system that, while possibly with a large radius, could stretch length-wise perpendicular to the station and have multiple wheels. With grav tech being able to quickly shunt a container from its position would be a breeze. The rotary mechanism would function like a revolver (I don't recall the B-grade Japanese sci-fi movie that had wedge-like space ships that used a rotary mechanism to launch fighters, but it's a similar principle).

I know there's drawbacks to it, but still, how would a 10k dton freighter be able to be loaded and unloaded quickly without exposing your cargo to vacuum. If you can, then it's quite easy to do so. A LASH concept would allow you to unload pods and then lighter them around, but there's drawbacks to that concept as well. I'm drawing a bit of a blank to figure out how something like a 10,000 TEU ship a) would look like, and b) be able to unload/load like a container ship does today, albeit without the 'cheat' of just adding more cranes on the dock. Which is something you couldn't quite do in the same way in space.

 

[phavoc]

In the MgT 1e game I’m currently playing in, we recently scored a 400 ton freighter. The main cargo bay is two decks tall, with no flooring between them; just a giant cavernous hold. Our cargo master worked out a system of magnetic buckles where cargo containers are fastened to the walls and ceiling, more buckles are attached to these locked-in-place containers and like an onion, another layer of containers are buckled to the ever-shrinking walls and ceiling. Eventually the “working tunnel” backs up to the bay doors and the last 10 or 15 tons are buckled to the floor.

Personally I’m not sure it’s feasible but it’s been a fun thought experiment.

The standard fat merchant allows you to stack 2 high, and to load from front and back. The challenge at a station though is the front is a clamshell door and not a lock. And if you are docked forward and need cargo from the middle or back you have to unload the front first. Which isn't a big problem - but dock space may be limited and you may not be able to drop your cargo, get what you need, then load it back (or possibly load additional containers).

Standard container ships are similar - you start at the bottom and load vertically. Generally you start in the middle and load outwards, though you have to balance your loads to prevent the ship from listing. Sort of like Tetris. A ship that can only unload from the nose doesn't have that ability, and one that has a route to make and isn't point-to-point will have additional challenges as you load and unload units. I'm thinking that many ships will probably operate only system to system, so maybe they fully unload at each destination. But in-system craft, especially tramp freighters, will have routes where they will constantly be shifting current and new loads. So how would that work, and how would it look?

This is mostly an academic exercise as it's not needed for gaming. Though I do like to try and match logic to fantasy whenever its possible and practical. I find it helps to design scenarios and explain situations that make sense and people don't have to do lots of mental backflips to explain away. I prefer to keep the hand wavium to a minimum and apply where it's actually needed.

 

[NOLATrav]

The idea with the ship I mentioned is that you actually start at the top of the hold and build down. But yeah, you gotta be careful if you have cargo for multiple destinations.

 

[AnotherDilbert]

My assumption would be something like the first illustration for smaller ships - a corridor in the middle that at least allowed you to load containers to the sides. A clever loadmaster would figure out a way to fill the sides first and then fill the middle with only the cargo that would for sure be unloaded at the next stop.

I don't think there is all that much of a problem in practice. Large freighters would go directly between large worlds, with little through traffic, something like a large container ship shuttling between Shanghai and Rotterdam. Unload it all, fill a new load, go back, and so on. The port will distribute the cargo to new transportation.


Smaller ships would handle the small worlds with random access to the cargo, but this is not what you are discussing, I think. This is what we know something about from the Traveller trade rules. My go-to design would be something like the aforementioned Subbie: A large square cargo bay with drives and people tacked to the side. Access to the bay by plenty of cargo hatches, front, rear, and sides, just like the Subbie. You can carry other things than containers as needed.

First choice: Land. You have plenty of space for unloading and restacking, if needed.
Second choice: Enter a bay in the Highport. You have some space.
Third choice: Dock and unload, hatch by hatch. Slowly...

Cargo handling equipment should be in the port, not in the ship where it would be unused 99% of the time. It's cheaper to have a Highport bay with automated cargo handling that can process a Subbie in a few hours, than to have the same cargo handling equipment in dozens of Subbies.

 

[phavoc]

I don't think there is all that much of a problem in practice. Large freighters would go directly between large worlds, with little through traffic, something like a large container ship shuttling between Shanghai and Rotterdam. Unload it all, fill a new load, go back, and so on. The port will distribute the cargo to new transportation.


Smaller ships would handle the small worlds with random access to the cargo, but this is not what you are discussing, I think. This is what we know something about from the Traveller trade rules. My go-to design would be something like the aforementioned Subbie: A large square cargo bay with drives and people tacked to the side. Access to the bay by plenty of cargo hatches, front, rear, and sides, just like the Subbie. You can carry other things than containers as needed.

First choice: Land. You have plenty of space for unloading and restacking, if needed.
Second choice: Enter a bay in the Highport. You have some space.
Third choice: Dock and unload, hatch by hatch. Slowly...

Cargo handling equipment should be in the port, not in the ship where it would be unused 99% of the time. It's cheaper to have a Highport bay with automated cargo handling that can process a Subbie in a few hours, than to have the same cargo handling equipment in dozens of Subbies.

The subbie is a good candidate, though it's forward lock is clamshell. It may be possible to make a good seal, but it's not ideal from an ease of use perspective. For regular cargo you could put rails in to stack containers at two levels, which would alleviate the need to physically use the one below to hold. So some ease there for slotting. The challenge to having hatches on multiple sides is having the necessary station ability to access them. Multiple arms are a possibility.

For this question landing is out of the scenario. This would be space-based only, which also puts docking a landing bay out of the question as the ship is to be external to the station.

I'd think you find a mix of equipment for unloading/loading. Some places may offer it (for a fee), while others may not or it may even be broken. We're talking smaller stations/ships and not the big boys. Ship-based would be oriented around loading from dock to inside, and unloading from inside to the dock area in front of you. from there it's the stations responsibility. Cherryh's Merchanter ships used an internal can system of similar sorts, so it's not unheard of.

 

[MasterGwydion]

UNREP is a system, not a ship design. There are multiple USN ships that perform UNREP. Depending on the timeframe you had carriers and battleships refueling destroyers, you had small cargo ships and tankers refueling carriers. Today you have larger ships using fuel booms, cabling and even helicopters doing underway replenishment.

I'm looking for how a ship might actually be designed/look to be closer to what they might look like. For decades cargo ships were similar to the design of Liberty ships - forward holds serviced by 1 or 2 cranes, the bridge and crew quarters amidships, more holds/cranes aft and then the aft section (which sometimes was built up, other times not). Later you see specialized ships emerging - supertankers, RO/RO, small, and then super-container ships. Ships continue to evolve, but aside from size the designs are pretty efficient for the ships functions and where they operate.

We don't really see that in the game for the most part. I'm looking for what the workhorses of the sectors might look like.

Ahhhh... You are looking more for a deck plan. My apologies. I misunderstood.

 

[AnotherDilbert]

The subbie is a good candidate, though it's forward lock is clamshell. It may be possible to make a good seal, but it's not ideal from an ease of use perspective.

If you want to be streamlined, there will be non-square surfaces.

If you don't, just make a square box for a hull.

For this question landing is out of the scenario.

For small ships, it shouldn't, not all worlds would have a highport.

For big ships, I can agree.

This would be space-based only, which also puts docking a landing bay out of the question as the ship is to be external to the station.

Why? A docking bay would be so much easier and safer. Space stations aren't nearly as constrained by space as they have no drives, it's just a floating hull. Another 1000 Dt for a bay is cheap.

Enter the dock to unload or load for a few hours, exit and dock externally for parking. Not many bays would be needed for a small highport.

 

[MasterGwydion]

I don't think there is all that much of a problem in practice. Large freighters would go directly between large worlds, with little through traffic, something like a large container ship shuttling between Shanghai and Rotterdam. Unload it all, fill a new load, go back, and so on. The port will distribute the cargo to new transportation.


Smaller ships would handle the small worlds with random access to the cargo, but this is not what you are discussing, I think. This is what we know something about from the Traveller trade rules. My go-to design would be something like the aforementioned Subbie: A large square cargo bay with drives and people tacked to the side. Access to the bay by plenty of cargo hatches, front, rear, and sides, just like the Subbie. You can carry other things than containers as needed.

First choice: Land. You have plenty of space for unloading and restacking, if needed.
Second choice: Enter a bay in the Highport. You have some space.
Third choice: Dock and unload, hatch by hatch. Slowly...

Cargo handling equipment should be in the port, not in the ship where it would be unused 99% of the time. It's cheaper to have a Highport bay with automated cargo handling that can process a Subbie in a few hours, than to have the same cargo handling equipment in dozens of Subbies.

Cargo handling only on the station would work as the rules state that only one ship needs the UNREP System and it moves both fuel and cargo at a very high rate. Most ships I design can be fully unloaded and reloaded in 2 hours, 1 for unloading and 1 for loading. If you have this on the Station, then the ships need no cargo handling equipment. That frees up a bit of space.

 

[AnotherDilbert]

Cargo handling only on the station would work as the rules state that only one ship needs the UNREP System and it moves both fuel and cargo at a very high rate. Most ships I design can be fully unloaded and reloaded in 2 hours, 1 for unloading and 1 for loading. If you have this on the Station, then the ships need no cargo handling equipment. That frees up a bit of space.

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.

 

[Condottiere]

How/why would you have nested containers?

For the same reason we have cardboard boxes and wooden pallets.

I don't think there's a golden mean for the ratio, but goods aren't going to be stuffed into a one size fits all, and you will need some form of structure to hold multiples of containers especially if you take into account megafreighters.

I think Classic had kilotonne containers, so in theory it's downwards from there.

The smallest is probably four tonnes - for simplicity, let's say three by three by six metres.

You could have a container that holds sixty four of them, which would be two hundred fifty six tonnes, as an example.

 

[steveh]

I was thinking about how to make a space-only freighter ad efficient as possible to load and unload. But also taking into account that to fully use all available cargo space you have to store your freight basically container to container. And if you do that, how do you that with limited dock space at a station?

Having recently read The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger, I would expect the design of the ships, the ports and the containers to go hand in hand.

So, where there is a high volume of shipping between two worlds, ships/ports/containers will evolve to make everything as efficient as possible, with compatible systems and standards.

These ships aren't adventuring from subsector to subsector - they're purely delivering cargo between two or three systems. They're probably ugly and modular - and if they're going from highport to highport, the containers may even be stacked on the outside of the ship and shuttled up and down separately. They might be highly automated.

From a gaming perspective, all this happens in the background. They deliver the bulk goods on the main routes while the more flexible but less efficient Free and Far Traders serve a different market.