Author Topic: Standardized container cargo system for Cargo MCT  (Read 23441 times)

Online envy887

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Re: Standardized container cargo system for Cargo MCT
« Reply #40 on: 06/08/2016 08:00 PM »
The cosine losses from always having the engines gimballed way outboard do get annoying, but they are only ~3.5% if the gimbal is about 15 degrees. And once lift isn't a factor (which is a LOT of the flight profile for MCT), you can shut down all but 1 engine and thrust close to or right through COM... and the cosine loss goes close to zero.

If that allows you to always accelerate in the same direction (nose first launch, tail first reentry), then the savings on structure mass might more than make that up. And not having to return a huge, empty, cargo container to earth is a huge benefit, probably worth more than 3.5%, since the return fuel is a lot more expensive than Earth launch fuel!

Offline Impaler

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Re: Standardized container cargo system for Cargo MCT
« Reply #41 on: 06/09/2016 03:25 AM »

So you want different container shapes for pressurised vs unpressurised? Because at some point you ARE going to need pressurised containers, and box shaped ones are not going to work (too heavy).

I would be interesting to know how much cargo can be transported unpressurised.

My current WAG is 50% split initially. Without a great deal of self sufficient systems (farm, 3D printers, feedstock melters/formers, atmosphere recycle and production from Mars atmosphere) the base will need a lot of pressurized supplies. As the base matures more supplies/cargo will be un-pressurized (mining equipment, material processing, solar arrays, etc).

Having these supplies used inside the base shipped as un-pressurized will mean it all has to transition through an airlock. This is extremely time consuming and waste a lot of base atmosphere in purge Mars atmosphere and pressure cycling. Also dust control will be very difficult to manage as well with so many cycles.

If you design your pressurized container/habitat so that most of it can be manufactured from ISRU, this will also shift the % of type of cargo as well from bulk materials to complex machines/electronics. This would allow the base to increase its volume and provide even greater m^3 space per person than what was available initially.

The containers need to be simple constructable on Mars even though they may weigh more. Its not weight but costs that is important in the $/effective task/utility:
-cost of the equipment,
-shipping costs [trip on MCT to Mars $/kg, NOTE: SpaceX goal is to get this below $500/kg, initially it will be ~$8,000/kg],
-handling time loading and unloading [this is probably the most precious resource both on Mars and Earth], and
-other considerations such as multi use so that there is little dead weight shipped everything has a use on Mars especially pressurized containers)


People are literally the only things that will travel pressurized, the pressurized containers will be different but they are not part of this topic because this is a topic about CARGO CONTAINERS.

So far no one has articulated a single type of cargo that actually NEEDS pressure, just a nebulous 'need' unsupported by any reasoning, or at best reflexive copying of ISS methodology.  The gap between the logistical paradigm need to do colonization and most commenters suggestions is huge.  We are not talking about an initial landing here were talking about logistics to support hundreds of thousands of tons of cargo a year.

Atlas Guy points to logistics of moving into and out of airlocks, but this ignores the fact that connecting a large pressurized container to a habitat is a very slow process, it takes hours in zero-g.

The kind of air-lock I'm suggesting would naturally be the size of a shipping container (cause it probably is a specialty container similar to the tank posted earlier) and hold nearly it's entire contents.  Dust is controlled by having a large tented garage like space covering the whole 'yard' where the containers being unloaded sit, containers enter the yard by truck through a dust trap, robots unload pallets and place them in the air-locks.  Or if we can send a large enough airlock (perhaps inflatable) then the whole container can go into it directly off the transport truck.

Empty containers are going to be accumulating on Mars clearly, but their are a million uses for them other then trying to LIVE in them, which is incredibly shortsighted because habitation on Mars is not just having a pressure vessel, it's having several tons of life-support equipment too.  Uses for disassembled containers would include using them as foundation slabs, roofing to support regolith over real habitats, melting down the aluminum and making simple rods and spare parts for virtually every other piece of machinery.  Their is literally no end of things you would do BEFORE trying to live inside a cargo container.

Now naturally their WILL be pre-fabricated living units sent to Mars and these could be in the shape of a container, but it's more likely to be an expandable Bigelow type habitat folded up inside the container.  Again that's a topic for another thread.

Offline JamesH65

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Re: Standardized container cargo system for Cargo MCT
« Reply #42 on: 06/09/2016 09:46 AM »

So you want different container shapes for pressurised vs unpressurised? Because at some point you ARE going to need pressurised containers, and box shaped ones are not going to work (too heavy).

I would be interesting to know how much cargo can be transported unpressurised.

My current WAG is 50% split initially. Without a great deal of self sufficient systems (farm, 3D printers, feedstock melters/formers, atmosphere recycle and production from Mars atmosphere) the base will need a lot of pressurized supplies. As the base matures more supplies/cargo will be un-pressurized (mining equipment, material processing, solar arrays, etc).

Having these supplies used inside the base shipped as un-pressurized will mean it all has to transition through an airlock. This is extremely time consuming and waste a lot of base atmosphere in purge Mars atmosphere and pressure cycling. Also dust control will be very difficult to manage as well with so many cycles.

If you design your pressurized container/habitat so that most of it can be manufactured from ISRU, this will also shift the % of type of cargo as well from bulk materials to complex machines/electronics. This would allow the base to increase its volume and provide even greater m^3 space per person than what was available initially.

The containers need to be simple constructable on Mars even though they may weigh more. Its not weight but costs that is important in the $/effective task/utility:
-cost of the equipment,
-shipping costs [trip on MCT to Mars $/kg, NOTE: SpaceX goal is to get this below $500/kg, initially it will be ~$8,000/kg],
-handling time loading and unloading [this is probably the most precious resource both on Mars and Earth], and
-other considerations such as multi use so that there is little dead weight shipped everything has a use on Mars especially pressurized containers)


People are literally the only things that will travel pressurized, the pressurized containers will be different but they are not part of this topic because this is a topic about CARGO CONTAINERS.

So far no one has articulated a single type of cargo that actually NEEDS pressure, just a nebulous 'need' unsupported by any reasoning, or at best reflexive copying of ISS methodology.  The gap between the logistical paradigm need to do colonization and most commenters suggestions is huge.  We are not talking about an initial landing here were talking about logistics to support hundreds of thousands of tons of cargo a year.

Atlas Guy points to logistics of moving into and out of airlocks, but this ignores the fact that connecting a large pressurized container to a habitat is a very slow process, it takes hours in zero-g.

The kind of air-lock I'm suggesting would naturally be the size of a shipping container (cause it probably is a specialty container similar to the tank posted earlier) and hold nearly it's entire contents.  Dust is controlled by having a large tented garage like space covering the whole 'yard' where the containers being unloaded sit, containers enter the yard by truck through a dust trap, robots unload pallets and place them in the air-locks.  Or if we can send a large enough airlock (perhaps inflatable) then the whole container can go into it directly off the transport truck.

Empty containers are going to be accumulating on Mars clearly, but their are a million uses for them other then trying to LIVE in them, which is incredibly shortsighted because habitation on Mars is not just having a pressure vessel, it's having several tons of life-support equipment too.  Uses for disassembled containers would include using them as foundation slabs, roofing to support regolith over real habitats, melting down the aluminum and making simple rods and spare parts for virtually every other piece of machinery.  Their is literally no end of things you would do BEFORE trying to live inside a cargo container.

Now naturally their WILL be pre-fabricated living units sent to Mars and these could be in the shape of a container, but it's more likely to be an expandable Bigelow type habitat folded up inside the container.  Again that's a topic for another thread.

Cargo that need to be pressurised and possibly heated (unpressurised means no heating)? Few things off the top of my head.

People
Basic Electronics (unless hardened)
Food stuffs (unless you really really ensure there are no air pockets in the packets)
Anything with mechanical bearings for surface use (can get round this)
Some plastics. In fact anything that cannot withstand very very low temperatures.

Sure there are lots more.


Online Lumina

Re: Standardized container cargo system for Cargo MCT
« Reply #43 on: 06/09/2016 10:41 AM »
It makes most sense if there is a single standardized pressurized module master design for everything, people, factories, workshops, garages and cargo.

- Because you would want to interconnect every module to create a large walkable interior space

- Because you want to maximize the pressurized volume and total extent of the base:
   
    - for psychological and comfort reasons

    - for safety reasons (multiple redundant options)
   
    - for productivity reasons (minimize EVA's required for equipment maintenance)

    - to maximize the growth rate of the size of the base

- Because you would prefer to minimize spare parts and design complexity to keep maintenance reqs down

- Because you would prefer almost all the base equipment to be operating "inside" in Earth-like conditions

- Because this is aligned with current SpaceX practice: the current cargo Dragon is pressurized.

So it makes sense that the cargo/hab/factory modules that BFS will be leaving behind on Mars might be standardized, modular, pressurized and ready to connect to the rest of the base using a standard system. In turn, to the extent that the standardization, modularity etc. become compelling design features for the future colony, this would inform the design of the entire MCT architecture so that the BFS can reliably deliver such modules to Mars surface, refuel and then return to Earth for more.

Of course a robotic system to pick up the modules from the point they were dropped off and walk them a few hundred metres to the base will also be needed. A square grid layout for the base would work well enough - hexagonal is probably more trouble than it's worth.

The master design of the module should probably have a water tank as its roof (which doubles as radiation shield) and a ground level consisting of all the "public" spaces, walkways and connection ports to adjacent modules. The middle level(s) and to some extent the ground level would be customized depending on the intended function of the module (e.g. hab, factory, medical center, etc). Alternatively, it might be better to put all the public spaces and walkway interconnections at high level just below the roof and locate the constantly inhabited areas closer to the ground. More radiation protection, and clearance between modules for rovers and robots to have access to any module from the outside.

(Note for Impaler: this is one articulation of reasons why everything should be pressurized. There are plenty more.)
« Last Edit: 06/09/2016 11:04 AM by Lumina »

Offline GWH

Re: Standardized container cargo system for Cargo MCT
« Reply #44 on: 06/09/2016 03:21 PM »
One thought I just had regarding benefits of pressurized cargo vessels is on the ground (Earth) processing.  Given the expectation or requirement that this is a multi-national effort one would reason that pre-processing of cargo and outfitting of habitats would be handled at a multitude of facilities and shipped to the launch site.  If the cargo vessel is a fully sealed and pressurized unit it can be shipped in a sterile state internally where only the exterior would need to be sterilized prior to loading.  In small scales I would think this would be overkill, but if one were looking at dozen's of MCT flights per synod the cost reduction through simplified logistics at the launch site could really add up.

Online oldAtlas_Eguy

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Re: Standardized container cargo system for Cargo MCT
« Reply #45 on: 06/09/2016 04:29 PM »
I just had an additional thought and that was increasing the MCT cargo content agnostic factor.
- Cargo container
   - Un-pressurized
   - Pressurized
     - Un-manned
     - Manned

The pressurized container/habitat module has all the equipment for support of humans during the flight it only need internal outfitting for human transport. Thus the basic MCT for manned and unmanned is identical only whether the container is outfitted to transport humans or just cargo.

The other thought is that if the pressurized containers are in 25mt load size (1/4 of the cargo volume) with each representing what amounts to a single floor when at Mars, 4 are shipped and only 1 is returned (100 people out only 25 back). This is the ultimate agnostic standpoint. The MCT is not specialized at all for any of its payload that it carries only the container are outfitted internally different. This also makes it possible to use for the trip back a different MCT (one that shipped plain cargo) than what was used on the trip out (that transported humans) without requiring any modifications. Just load the container with humans in it and launch from Mars surface.

Offline Lar

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Re: Standardized container cargo system for Cargo MCT
« Reply #46 on: 06/09/2016 04:49 PM »
A lot of things can't handle zero pressure.  embryos and live animals, for example. A lot of foodstuffs. A lot of materials that would outgas.... I think pressure is going to make things a lot simpler, actually.
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Online oldAtlas_Eguy

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Re: Standardized container cargo system for Cargo MCT
« Reply #47 on: 06/09/2016 07:36 PM »
A lot of things can't handle zero pressure.  embryos and live animals, for example. A lot of foodstuffs. A lot of materials that would outgas.... I think pressure is going to make things a lot simpler, actually.
Yes the farm. Seeds, shoots, algae, and fish embryos. Possibly other stuff such as dry fertilizers which if not pressurized will out-gas. These would be sealed up anyway but a flexible airtight bag vs a rigid container is a big difference. In fact the entire farm with all its stuff to get it going would be shipped probably as a special outfitted pressurized container. The farm has a great deal of complex equipment that it would be better to ship as a complete ready to use. Only a small amount of setup should be required by the residents.

Many of the confusion factors for foods comes from the term vacuum packed foods. This does not mean packed at 0 pressure but at a reduced pressure from sea level usually the 10Kft level or a bit higher. Packing at 0 pressure would destroy the food or basically supper freeze drying it. It would then take a lot of work to re-hydrate prior to being edible an even then it still may not be edible.

Offline Lobo

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Re: Standardized container cargo system for Cargo MCT
« Reply #48 on: 06/09/2016 10:09 PM »
in this scheme does the entire long side of a container need to be airtight when mated to an adjacent one and the interior walls removed? That's a fairly tall order I think. Requires some very stable foundations I would expect.

Not undoable. But I could see them using something flexible and a several centimeter gap, so that the joins don't have to be perfectly aligned. Put bridge plates on the floor at the joint and put plates on the walls and ceiling to protect the flexible material.

Think how an articulated tram/streetcar/bus has accordion pleating joints between sections.

Perhaps something like NASA envisioned some time ago.  But it wouldn't need to land itself.  Just have the wheels and legs that can be jacked up and leveled on feet.  Multiple units connected together with semi-flexible connectors.  Each unit could have up to four ports for connecting on 1, 2, 3, or 4 sides.


Offline Lar

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Re: Standardized container cargo system for Cargo MCT
« Reply #49 on: 06/10/2016 01:34 AM »
I definitely think flexible couplings and doors to separate if there are issues but wonder about whether trenching is needed long term...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
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Online oldAtlas_Eguy

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Re: Standardized container cargo system for Cargo MCT
« Reply #50 on: 06/11/2016 02:04 PM »
I don't think trenching is the way to go for an expanding Base. Even if the clusters are all in a row. But the earlier suggestion of the water tanks on a layer at the top may be better in short term with then a solid sheet of something thin that is then cover with regolith on top over the older base clusters so that no regolith is between the modules only on top. The requirement would be a significantly sized flat plain separated by small hills from other significantly sized flat plains that can be used as the landing a launch areas. if the hills are more like sand dunes with access routes around them even better else the digging equipment would have to cut a S shaped access route to maintain protection of the base from launch and landing craft.

Alas I think we are getting to far away from just container discussion and into Mars Base design. I did not find any specific Mars SpaceX colony base design thread but several specific architecture designs threads most without regards to the SpaceX effort.

 It may be time for another SpaceX thread on discussion of "Spacex Mars base/colony design/architecture". The container thread and MCT design threads would affect and it would affect the other two.

Offline MickQ

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Re: Standardized container cargo system for Cargo MCT
« Reply #51 on: 06/12/2016 12:38 AM »
in this scheme does the entire long side of a container need to be airtight when mated to an adjacent one and the interior walls removed? That's a fairly tall order I think. Requires some very stable foundations I would expect.

Not undoable. But I could see them using something flexible and a several centimeter gap, so that the joins don't have to be perfectly aligned. Put bridge plates on the floor at the joint and put plates on the walls and ceiling to protect the flexible material.

Think how an articulated tram/streetcar/bus has accordion pleating joints between sections.

Perhaps something like NASA envisioned some time ago.  But it wouldn't need to land itself.  Just have the wheels and legs that can be jacked up and leveled on feet.  Multiple units connected together with semi-flexible connectors.  Each unit could have up to four ports for connecting on 1, 2, 3, or 4 sides.

Once these modules are jacked up and connected together they will likely not be moved again so the wheels could be re-used on later arriving modules and/or vehicles such as trailers made on site to move people from the LZ to the base.

Offline biosehnsucht

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Re: Standardized container cargo system for Cargo MCT
« Reply #52 on: 06/12/2016 02:59 AM »

Once these modules are jacked up and connected together they will likely not be moved again so the wheels could be re-used on later arriving modules and/or vehicles such as trailers made on site to move people from the LZ to the base.

This is why I proposed something like the PODS Podzilla, something that attaches to the container, moves it in place, then goes elsewhere. You could get by with just one in a pinch, but more would be helpful to speed things up.

Offline lamontagne

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Re: Standardized container cargo system for Cargo MCT
« Reply #53 on: 06/12/2016 03:50 AM »
Here is my suggestion for a standard container:
Fits snugly in a Skylon cargo Bay.
Fits in a Falcon 9 fairing.
A group of them could fit in an MCT cargo bay.
Pressurized, self heated, self powered, self cooled.  Insulated with multilayer insulation.
Connectable, stackable, buryable.
Has standard cargo ports at the ends, one male, one female.
Orange band is solar cells, black bands are radiators.
I've also included a view of an eventual nuclear OTV with a stack of them.

What do you think?



« Last Edit: 06/12/2016 03:54 AM by lamontagne »

Offline biosehnsucht

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Re: Standardized container cargo system for Cargo MCT
« Reply #54 on: 06/13/2016 07:01 AM »
How do you place those cylindrical contaniers on Mars surface, or move them about? How do you unload them? It seems they'd be unstable (being round and long) in any orientation.

I think a more or less standard intermodal-style container is likely (in terms of being rectangular and having standardized attachments of some kind, though the standard may be unique to MCT/SpaceX), or at least something with at least one flat side. That doesn't mean the contents can't be round (such as pressure vessels built into a intermodal style frame, etc).

Here's a rough idea of how you could move around intermodal style containers. Basically the teal part attaches to the container using ISO standard twistlock at the top and bottom. The orange section is where all the brains and power would be mounted, and it can move linearly against the teal part (effectively to raise/lower the container) as well rotate against the green part (to rotate the wheel assembly). Electrically power the wheels and you could drive this thing as a self balancer over to the container, hook up, then once you have 4 (or as many as 8, if they're completely separate as depicated rather than pairs operating together at each end) connected to a container, team them and drive them as one big martian RC car. Software-wise, that's all super easy. The same ISO style twist locks and such can be used to tie the containers to the cargo deck, etc.

You'd still have to get them off the MCT to begin with, so unless your cargo hold is on the bottom and you have a way of getting a sufficiently low angle ramp to drive down, the best bet is an overhead crane with spreader bar attachment system (again, using those ISO attachment points).

When placing the containers in-place, you could help in leveling by having "foot" modules that attach via the ISO connectors on the bottom, and either serve to minimize the area that must be leveled (allowing for some gap underneath elsewhere that isn't necessarily flat) or having a leveling mechanism built in (so that the ground doesn't need to be prepared). You could built the leveling into the containers, but not all containers may need them all the time, and by making them modular you can add them on once at Mars as needed and not have them either take up cargo container volume or cargo hold volume.

Some great reference imagery of all this ISO nonsense:

http://www.william-cook.co.uk/assets/files/William%20Cook_Intermodal_Container_ProductsCHANGED.pdf

http://www.william-cook.co.uk/assets/files/William%20Cook_Intermodal_TwistlocksCHANGED.pdf

Offline lamontagne

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Re: Standardized container cargo system for Cargo MCT
« Reply #55 on: 06/13/2016 10:08 AM »
Thanks for the comments biosehnsucht,

I've changed the structure so the container are more ISO.
I believe that answers the worries about turning, without compromising how they can fit in existing and future fairings.

Containers are not strong in torsion, the single wheel arrangement proposed would twist them out of shape.
They are always handled and supported using spreader beams, than hold them at their ISO corners, so the forces are always normal.  Even on trailers, they are actually supported by a small structural frame beneath the container.

In an MCT architecture, they would be handled by cranes with spreader beams, as they are on Earth.
I expect there would be shorter half length versions as well.

Offline lamontagne

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Re: Standardized container cargo system for Cargo MCT
« Reply #56 on: 06/13/2016 10:28 AM »
A few more stiffeners added

Offline Lar

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Re: Standardized container cargo system for Cargo MCT
« Reply #57 on: 06/13/2016 11:28 AM »
A few more stiffeners added
If you make the spaceframe 6 sided, it wastes a bit more space around the cylinder than an 8 sided one, but the containers can be packed much more easily as a regular hexagon tiles a surface, but a regular octagon does not, it leaves square shaped hollows.

I like rectangular containers better, and will again advocate for standard 20 foot sizes that are compatible with the current terran system. we want there to be so much freight that avoiding transship repack or difficulties interfacing with terran container handlers becomes important.
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"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline JamesH65

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Re: Standardized container cargo system for Cargo MCT
« Reply #58 on: 06/13/2016 12:55 PM »
A few more stiffeners added
If you make the spaceframe 6 sided, it wastes a bit more space around the cylinder than an 8 sided one, but the containers can be packed much more easily as a regular hexagon tiles a surface, but a regular octagon does not, it leaves square shaped hollows.

I like rectangular containers better, and will again advocate for standard 20 foot sizes that are compatible with the current terran system. we want there to be so much freight that avoiding transship repack or difficulties interfacing with terran container handlers becomes important.

Why on earth (!) would you need to be compatible with Terran containers? So they fit on trucks, or trains, or ships?  No reason to do that, and very likely to damage the containers anyway. Make the containers fit the task, not the task fit the containers.

And as for measuring in Feet - I though the world had got over using imperial for things like this?

Offline lamontagne

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Re: Standardized container cargo system for Cargo MCT
« Reply #59 on: 06/13/2016 03:32 PM »
A few more stiffeners added
If you make the spaceframe 6 sided, it wastes a bit more space around the cylinder than an 8 sided one, but the containers can be packed much more easily as a regular hexagon tiles a surface, but a regular octagon does not, it leaves square shaped hollows.

I like rectangular containers better, and will again advocate for standard 20 foot sizes that are compatible with the current terran system. we want there to be so much freight that avoiding transship repack or difficulties interfacing with terran container handlers becomes important.
Iso containers are sized in mm, that just happen to correspond to exact measurements in feet ;-)
I chose 8 sides because this gives us two contact points with a side container when packing laterally, but 6 sides only gives us 1 point, for a less robust stack.  I also plan do illustrate an interface 'dock' that allows a group of these to be connected into various shapes as habitats or stations.

Rectangular containers would need to have at least semi-curved walls to reduce the need for stiffeners, as a straight wall cannot withstand 15 psi without considerable reinforcement.  They would necessarily be heavier.  However, we could have rectangular ends, like stackable ISO liquid containers already do.  That might create problems with some narrow fairings though, and not fit as well in circular rockets.

I think that creating a new infrastructure in space and on Mars is a opportunity to standardize on larger containers.  These are easier to repurpose than the relatively narrow containers of today, that have constraints due to the history of road construction and not necessarily for logical reasons.
Might be better to go with 4m diameter x 6,8 or 12m though.  I originally sized these containers for a Skylon Cargo hold, and I freely admit that since they don't exist yet they are hardly a solid design criteria!!





« Last Edit: 06/13/2016 04:11 PM by lamontagne »

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