Starship Hull design

Discuss the Traveller RPG and its many settings
h1ro
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Re: Starship Hull design

Postby h1ro » Sun Apr 30, 2017 11:31 pm

With a firm but extravagant hand wave...
phavoc
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Re: Starship Hull design

Postby phavoc » Mon May 01, 2017 12:57 am

Not only a vigorous hand wave, but two snaps and a twist...

https://www.youtube.com/watch?v=0VSO-88E8qo
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Re: Starship Hull design

Postby Reynard » Mon May 01, 2017 1:38 am

Well....
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Re: Starship Hull design

Postby h1ro » Mon May 01, 2017 4:15 am

:)

Do we have a consensus on cost and power? (OK, a consensus in this case might mean me and phavoc).

Same cost as drop tanks buys you a container that can withstand vacuum, 4 degrees K, 1G acceleration and costs no power?

Same cost as a hull buys you the same as a hull but needs power?

Same power requirement as a hul?
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Re: Starship Hull design

Postby Condottiere » Mon May 01, 2017 11:09 am

Drop tanks cost the same as an ungravitated hull.

At this point, just grab a rock, and hollow it out.

You'll get life support, insulation and gravity/inertial compensation.
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Re: Starship Hull design

Postby Nobby-W » Fri May 19, 2017 12:17 pm

phavoc wrote:
Thu Apr 27, 2017 10:12 pm
Does anyone else design ships that don't land in a different manner than those that are meant to land on the surface of a planet? I've always adopted the idea that ships who dock with stations would be long and narrow, with their primary cargo/passenger boarding in the nose of the ship. Why? Because on a spacestation there is a finite amount of space available for docking externally, especially when you consider you won't be docking on every nook and cranny.
[ . . . ]
Some things I learned from Kerbal Space Program:
  • Space stations grow organically by docking bits onto them. You can realistically expect to build loads of docking ports on a space station, and they could stick out at all angles.
  • I've designed some awkward ships such as heavy cargo landers for vacuum worlds. Getting them into orbit can be a challenge, but once there they can dock onto space stations as long as there isn't anything docked to adjacent docking ports that would obstruct the docking.
  • Having your docking port in the nose of a spaceship makes it a whole lot easier to manoeuvre into a docking position, but it's not strictly necessary if you have an autopilot that can control the docking.
  • There is no such thing as too many docking ports. You will wind up with landers, shuttles, supply ships (tankers in KSP) lighters, ships for missions and all sorts of odds and sods parked at the docking ports of your space station. If you had a complete economy you will end up with all sorts of other kit docked there as well.
There are differences between KSP and Traveller, obviously, but if one brought in a space station from elsewhere (i.e. to a world without the capability to manufacture one locally, or where it is more economical to import) the space station would have to be built from parts that could fit into a freighter and be assembled in situ. As the requirements evolve, additional modules can be added to the station, which will grow organically in the way stations that are actually being used tend to in KSP.
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Re: Starship Hull design

Postby Infojunky » Sun May 21, 2017 10:53 am

Nobby-W wrote:
Fri May 19, 2017 12:17 pm

Some things I learned from Kerbal Space Program:
  • Space stations grow organically by docking bits onto them. You can realistically expect to build loads of docking ports on a space station, and they could stick out at all angles.
  • I've designed some awkward ships such as heavy cargo landers for vacuum worlds. Getting them into orbit can be a challenge, but once there they can dock onto space stations as long as there isn't anything docked to adjacent docking ports that would obstruct the docking.
  • Having your docking port in the nose of a spaceship makes it a whole lot easier to manoeuvre into a docking position, but it's not strictly necessary if you have an autopilot that can control the docking.
  • There is no such thing as too many docking ports. You will wind up with landers, shuttles, supply ships (tankers in KSP) lighters, ships for missions and all sorts of odds and sods parked at the docking ports of your space station. If you had a complete economy you will end up with all sorts of other kit docked there as well.
There are differences between KSP and Traveller, obviously, but if one brought in a space station from elsewhere (i.e. to a world without the capability to manufacture one locally, or where it is more economical to import) the space station would have to be built from parts that could fit into a freighter and be assembled in situ. As the requirements evolve, additional modules can be added to the station, which will grow organically in the way stations that are actually being used tend to in KSP.
I so wish there was a LIKE button here.

In Traveller terms 30 dTon modules, at least in terms of quick and easy expandable station cores....
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Re: Starship Hull design

Postby Condottiere » Sun May 21, 2017 11:18 am

After a certain size, just adding on small modules would make the structure fragile.

And things do go bump in the night.
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Re: Starship Hull design

Postby phavoc » Tue May 23, 2017 6:19 pm

Nobby-W wrote:
Fri May 19, 2017 12:17 pm
Some things I learned from Kerbal Space Program:
  • Space stations grow organically by docking bits onto them. You can realistically expect to build loads of docking ports on a space station, and they could stick out at all angles.
  • I've designed some awkward ships such as heavy cargo landers for vacuum worlds. Getting them into orbit can be a challenge, but once there they can dock onto space stations as long as there isn't anything docked to adjacent docking ports that would obstruct the docking.
  • Having your docking port in the nose of a spaceship makes it a whole lot easier to manoeuvre into a docking position, but it's not strictly necessary if you have an autopilot that can control the docking.
  • There is no such thing as too many docking ports. You will wind up with landers, shuttles, supply ships (tankers in KSP) lighters, ships for missions and all sorts of odds and sods parked at the docking ports of your space station. If you had a complete economy you will end up with all sorts of other kit docked there as well.
Space stations will run the gamut, from total chaos to completely planned. Any station will follow some sort of plan, even if that is no plan and you just stick things on to it in a totally haphazard fashion. At some point even the chaos station is going to have to bring some order to chaos if it hopes to function or to grow beyond a certain size.

There are also some common sense factors - you aren't going to put major cargo areas next to your station habitable areas since cargo containers and foot traffic don't mix. Plus it just makes sense to have dedicated areas for specific functions - passengers won't be going through customs while you unload cargo, at least not any volume of passengers. Cargo is going to be stored or transloaded to other cargo ships, etc, etc.

There is such a thing as too many docking ports. :) Each time you cut into your hull and put a docking port you put structural weakness and vulnerability into your hull. So you'll want to minimize those as much as possible. Conceptually you also have to account for different sizes and shapes of vessels. Those ships will need proper clearance to dock. And as you dock your ships and you want to board the station you still have to account for different gravity fields, as they could be perpendicular to one another and transitioning between them needs to be thought out as well. Popping out of the ceiling or climbing out of the stations floor isn't exactly conducive to boarding either ship or station.
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Re: Starship Hull design

Postby Nobby-W » Tue May 23, 2017 7:26 pm

phavoc wrote:
Tue May 23, 2017 6:19 pm
[ . . . ]
There is such a thing as too many docking ports. :) Each time you cut into your hull and put a docking port you put structural weakness and vulnerability into your hull. So you'll want to minimize those as much as possible.
[ . . . ]
Image
Try not to think of a monolithic hull for a space station. A space station is composed of modules, which include hubs that other modules - including docking arms - hang off. You expand the station by adding hubs and modules hanging off the hubs.

The picture above is a space station that I built in KSP. it largely exists to support fuel mining operations on the Mun, although the miner isn't docked to it in the picture (it's sitting on the surface, mining). In the case of KSP, it's easier to mine fuel here and use a space station orbiting the mun as a fuelling base.

Attached to the station you can see various craft hanging off it. From right to left, they are:
  • A heavy lift lander to land large items such as mun base parts.
  • A lab ship and science lander (in KSP you collect science to unlock the tech tree)
  • A fuel tanker to take fuel to a similar space station in orbit around Kerbin.
  • A couple of landers and a utility tug, which is largely used for handling parts to dock to the space station.
The station was comprised of parts small enough to get in orbit and docked together in situ. While this is KSP, this scenario has some similarities to the life cycle a space station might take in Traveller. Imagine the following scenario:

New Scunthorpe (Outer Hicksville 0208, D645754-8, Poor) is a world in an outlying imperial sector. The government have successfully applied for a grant from an Imperial economic development fund and they now have Cr50 billion to upgrade their starport to a Class C facility with a high port, 4 downports on 3 major continents, a fuel processing station to go into orbit around the system's small gas giant. In addition, the bid includes a fleet of orbit shuttles and fuel scooping and transport shuttles.

The winning bid comes from the Leyland-Futanari corporation, who won the hotly contested tender against Ling-Standard and Sternmetal Horizons LIC. It consists of a modular highport, a modular fuelling station and associated shuttles and tenders. They will manufacture the station at their shipyards on LV426, some 15 parsecs distant. The parts must be shipped on a freighter that can operate in frontier conditions (i.e. it can refuel without a high port present), so they can't be too large. This is a standard product for Leyland-Futanari, and is a modular, expandable station composed of standard parts that can be assembled in orbit. The parts allow a variety of different configurations depending on the requirements, and the station can be expanded later by docking additional hubs and service or accommodation modules of various types. As it uses standard docking attachment ports, a variety of custom and third-party modules can also be docked to the station.

This type of station is widely used in frontier regions precisely because it can be shipped long distances and assembled in situ. A similar modular station is also assembled in orbit around the gas giant, but this one is fitted with fuel refineries and tankage.

As the economy expands (the economic development programme is successful), the stations can be expanded up to a certain size. 50 years later, a larger facility may be built, as there is now enough infrastructure to bring a large freighter in-system and assemble a much larger model of space station. Our original station, however, remains viable for smaller ships as it is completely amortized and can charge lower fees for smaller ships to dock. It, and its attendant downports, have also had time to develop a seedy startown, a healthy smuggling channel and all sorts of nefarious activities going on the side.

phavoc wrote:
Tue May 23, 2017 6:19 pm
[ . . . ]
Those ships will need proper clearance to dock. And as you dock your ships and you want to board the station you still have to account for different gravity fields, as they could be perpendicular to one another and transitioning between them needs to be thought out as well.
[ . . . ]
Making the transition between gravity fields will be a perennial problem, probably largely solved by keeping low (0.1-0.2g) fields in the docking areas and hubs, especially around the areas where the direction of gravity changes.
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Re: Starship Hull design

Postby phavoc » Wed May 24, 2017 4:36 pm

Large stations housing hundreds of thousands of people will be built with a purpose and overall design. There are many examples in a number of the different books.

I do agree that smaller stations will often grow organically. But with contragravity you don't need to limit yourself to small modules lifted by rockets. You will instead be able to easily lift entire sections pre-built on the ground (or, conversely, you'll be able to easily bring large quantities of materials to orbit for assemble there).

While you can control gravity in docking tubes and such, and even work on keeping variable fields going, for large numbers of passengers - especially those who spend little time in space - you need to make it as close to normal planetary conditions.
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Re: Starship Hull design

Postby paltrysum » Wed May 24, 2017 6:14 pm

Nobby-W wrote:
Tue May 23, 2017 7:26 pm
The parts must be shipped on a freighter that can operate in frontier conditions (i.e. it can refuel without a high port present), so they can't be too large.
Shipping all those parts would be really expensive. Perhaps many of them would use whatever 3D printing technology is present at the Imperial technical average (i.e., TL 12). An enterprising starport builder, like the Trojan Reach's GeDeCo, could move their 3D printing device around from system to system, making key components while present.

Shoot, sounds like a good mercenary ticket, defending such a device when building starports on the frontier.
"Spacers lead a sedentary life. They live at home, and their home is always with them—their starship, and so is their country—the depths of space."
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Re: Starship Hull design

Postby Nobby-W » Thu May 25, 2017 5:23 am

paltrysum wrote:
Wed May 24, 2017 6:14 pm
Shipping all those parts would be really expensive.
Compared to what? Building a local shipyard so you can fabricate it in situ?

Some parts might be 3D printed, although this still requires you to lug a large 3D printing device in-system and keep it maintained. Given the size of the system it might also have to be assembled in orbit.

Unless you're building a lot of space stations in system I don't see any compelling reason why shipping the parts wouldn't be cost-effective. Modules could still be hundreds of tons each - or even bigger, depending on what sort of freighters you can support in-system.
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Re: Starship Hull design

Postby Nobby-W » Thu May 25, 2017 5:37 am

phavoc wrote:
Wed May 24, 2017 4:36 pm
Large stations housing hundreds of thousands of people will be built with a purpose and overall design. There are many examples in a number of the different books.
This sort of station is going to be confined to wealthy, high-population systems with the money and facilities to build a large space station locally. The example above is for a space station product designed to be used in a variety of locations that might not necessarily have a handy local shipyard.
phavoc wrote:
Wed May 24, 2017 4:36 pm
But with contragravity you don't need to limit yourself to small modules lifted by rockets. You will instead be able to easily lift entire sections pre-built on the ground (or, conversely, you'll be able to easily bring large quantities of materials to orbit for assemble there).
This is a straw man argument. The modules themselves could be rather larger than what you might see in KSP, although I've managed to get some real Heath-Robinson contraptions into orbit in that game.

Your parts for the space station still have to be accelerated to orbital velocity, so you're still up for a heavy lift shuttle big enough to carry the parts. Just lifting it straight up isn't going to be enough. Unless there's a compelling reason for a single component weighing 50,000 tons that can't be shipped in parts, I don't see why people wouldn't ship parts in standard heavy lifter shuttles and assemble the station in orbit - if nothing else, it allows it to be done without needing exotic, specialised hardware. Nobody's going to design and build a custom 100,000 ton anti-grav platform - and get it certified to operate over populated areas - if there's an easier way to do the same job with off-the-shelf hardware.

Of course, if 50,000 or 100,000 ton heavy lift shuttles are a thing in your 'verse, feel free to proceed. I'm a bit of a small ships man, myself.
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Re: Starship Hull design

Postby Condottiere » Thu May 25, 2017 6:42 am

Take six slabs of metal.

Weld together.

Fill with air.

Deploy a team of engineers and an interior decorator.
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Re: Starship Hull design

Postby Reynard » Thu May 25, 2017 1:16 pm

I know it may be considered the long way around. Rather than shuttling the entirety of a station out of a gravity well, make use of belter mining and orbital factories to construct the majority of components in microgravity. Factory ships can be brought in to systems with little to no inherent technology or resources but needs highport facilities. The same factory facilities become part of the shipyards and/or normal microgravity production for the system.
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Re: Starship Hull design

Postby AnotherDilbert » Thu May 25, 2017 1:28 pm

A, say, 100 kT space station will cost billions to build and millions to transport. Build it at the cheapest shipyard and transport it to where it is needed, the transport costs will be a small fraction of the total cost.

At least the Navy has tenders that can jump hundreds of thousands of dTons (damaged battleships).
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Re: Starship Hull design

Postby phavoc » Thu May 25, 2017 3:39 pm

Nobby-W wrote:
Thu May 25, 2017 5:37 am
This sort of station is going to be confined to wealthy, high-population systems with the money and facilities to build a large space station locally. The example above is for a space station product designed to be used in a variety of locations that might not necessarily have a handy local shipyard.
Not necessarily. Some systems may purchase an entire station in pieces for local assembly. Pre-fab construction in one place and assembly elsewhere is quite common today. Why would that concept change?
Nobby-W wrote:
Thu May 25, 2017 5:37 am
This is a straw man argument. The modules themselves could be rather larger than what you might see in KSP, although I've managed to get some real Heath-Robinson contraptions into orbit in that game.

Your parts for the space station still have to be accelerated to orbital velocity, so you're still up for a heavy lift shuttle big enough to carry the parts. Just lifting it straight up isn't going to be enough. Unless there's a compelling reason for a single component weighing 50,000 tons that can't be shipped in parts, I don't see why people wouldn't ship parts in standard heavy lifter shuttles and assemble the station in orbit - if nothing else, it allows it to be done without needing exotic, specialised hardware. Nobody's going to design and build a custom 100,000 ton anti-grav platform - and get it certified to operate over populated areas - if there's an easier way to do the same job with off-the-shelf hardware.

Of course, if 50,000 or 100,000 ton heavy lift shuttles are a thing in your 'verse, feel free to proceed. I'm a bit of a small ships man, myself.
Why would any world be using rockets for anything? That would be equivalent to expecting Somalia to use horse-drawn wagons instead of 777s to move people to/from their country. It is ludicrous to expect any world to not be using contragravity vehicles to get to/from orbit. They are easily available throughout known space. Sure, you have to import them, but that's no different than how TL5 countries today purchase and operate TL7 airliners, ships or anything else.

You are also not taking into consideration contragravity capabilities. It's very simple to build and operate a cargo lighter that is essentially a large flat surface, load your objects on board and levitate straight up to orbit. You don't need to lift 50-100k at a time when 100-500 pieces will work as well. As far as certification goes, if you have any contragrav vehicles operating they need certification too. Getting specialized construction and assembly equipment to a planet isn't that hard. It's done today all the time for large construction projects. It just takes time and money.
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Re: Starship Hull design

Postby Condottiere » Thu May 25, 2017 6:13 pm

Importing early fusion reactors and anti gravity by any pre interstellar economy that could afford to is almost automatic.

Whatever you\re paying out now, you'll make it back a thousandfold.
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Re: Starship Hull design

Postby Nobby-W » Thu May 25, 2017 6:24 pm

phavoc wrote:
Thu May 25, 2017 3:39 pm
[ . . . ]
Why would any world be using rockets for anything?
You're back to the straw man argument. I'm not talking about using rockets for anything. I was originally discussing shipping the parts from a third-party shipyard and assembling them at the destination.
phavoc wrote:
Thu May 25, 2017 3:39 pm
[ . . . ]
They are easily available throughout known space. Sure, you have to import them, but that's no different than how TL5 countries today purchase and operate TL7 airliners, ships or anything else.
It feels like you are arguing semantics. You talk about a lighter. I talk about a heavy lift shuttle or a freighter to ship to the destination.
phavoc wrote:
Thu May 25, 2017 3:39 pm
[ . . . ]
You don't need to lift 50-100k at a time when 100-500 pieces will work as well.
Apart from my view that the best place to build the parts for a space station would be an established shipyard that employed engineers familiar with the process, I don't see how this is materially different from what I discussed above.
phavoc wrote:
Thu May 25, 2017 3:39 pm
You are also not taking into consideration contragravity capabilities. It's very simple to build and operate a cargo lighter that is essentially a large flat surface, load your objects on board and levitate straight up to orbit.
That's not how this works. That's not how any of this works. Orbital velocity on Earth is around 7000m/sec. You don't just float up to 200km and park there - you need a substantial horizontal velocity for the station to remain in orbit. Go play a bit of KSP and learn something about orbital mechanics. It's quite cheap - about £30 - but if you have the patience to wear the learning curve it's a very rewarding game. I'd be happy to bet Cr50 that you will have an aha! moment if you do that.

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