Oolite Bulletins

Before being able to build ships in space, we'll need to have produced space elevators.
When these will be available, it will be possible to build ships parts on the planet, and later assemble them in orbit.

So the idea that everything needs to be done in space, and nothing on-planet is perfectible (false).

Mazur wrote:

Torpedoes will be rarely useful, since the enemy will be able to see them coming from a long way off and sleep on how to destroy/misdirect them before they hit

Unpowered projectile weapons, on the other hand - clouds of black, nonreflective ball-bearings, say, launched by electromagnetism (no muzzle flash to give them away) and arriving at their target with a relative speed of several thousand miles per hour - could do a lot of damage, and probably be a lot easier to hit with.

Day wrote:

...we'll need to have produced space elevators.
When these will be available, it will be possible to build ships parts on the planet, and later assemble them in orbit.

So the idea that everything needs to be done in space, and nothing on-planet is perfectible (false).

While I love the concept of a Space Elevator, it just strikes me as one of those things that won't work. The engineering challenges are too enormous.
However, we are at the point now where serious consideration is being given to mining asteroids and we have been investigating chemistry and manufacturing processes in space for years already, albeit on a small scale.
Add into the mix our pretty good track record with industrial robotics and 3D printing technology, and you can see a clear path to extraction and processing of raw materials, and subsequent manufacture in orbit.
Making the things you need for space in space, from stuff got from space has to be the logical approach.

Smivs wrote:

While I love the concept of a Space Elevator, it just strikes me as one of those things that won't work. The engineering challenges are too enormous.
However, we are at the point now where serious consideration is being given to mining asteroids and we have been investigating chemistry and manufacturing processes in space for years already, albeit on a small scale.

I would have said the engineering challenges to mine in space were greater than to build a space elevator, aren't they ?

Smivs wrote:

Making the things you need for space in space, from stuff got from space has to be the logical approach.

Well yes, once you've got your plants in space, but before?

Day wrote:

I would have said the engineering challenges to mine in space were greater than to build a space elevator, aren't they ?

No. For one thing it doesn't rely on as-yet-to-be-invented unbelievably strong hundreds of kilometres long microfilaments!

A shipyard on the Moon might be a possibility, I reckon.

Like some of you I think the low poly designs seem realistic.

In my mind, there's no planet landing in Oolite - except for cargo ship that carry goods from/to the station - because it's incredibly expansive energy-wise. Why is cost important? Because in the future, it's the poor people, not the rich people who has to live in this hostile and insecure environment.

Spaceships are to be built in space stations for the same reason. Although stations are huge there are still constrains. One of them is that doing metal smelting jobs on a station is an idea as good as doing blacksmith work on a corvette... So premade sheets of metal are imported from planets or moons. They are then cut as needed with powerful lasers (again no flame, because oxygen is always relatively precious). In order to cut costs, no complicated round shapes are made.

Shape is generally triangular because it presents some advantages in combat (low profile), as well as with deflecting floating natural or artificial objects. Cockpit is reduced to the absolute minimum because it is a structural weakness. And if you ask me I think there should be no cockpit at all but rather a swarm of cameras sprinkled all around the hull. Much more useful.

Furthermore, drifting away from Oolite:

Torpedoes/missiles are inefficient, because the hull already has to resist kinetic damage (see above), nukes are not so good without an atmosphere (plus it always be dangerous for the owner itself) and lasers are also not really good because their power is limited by the strength of the focusing optics; plus, being the only viable weapon it's easy to make a thermal-resistant alloy (at the cost of making the work of ship builders harder though). However, acid torpedoes could be used in order to weaken the hull make the job of lasers easier.

Also if we restrict ourselves to the solar system "only", speeds on the order of magnitude of 0.1 C is good enough to reach Pluto in maybe a few days. All it takes is a generous source of energy that would allow to eject a low amount of mass at very high speed for propulsion. So we don't really need artificial gravity for ships that hop from station to station.

Diziet Sma wrote:

ffutures wrote:

The problem is that any transfer of mass around the triangular hull (e.g. someone walking from one of the corners to the middle of the triangle's side) is going to change the balance a bit. You'd need to have ballast tanks to compensate, and pump fluids around the hull to keep the ship from drifting off course, keep exactly the same amount of cargo in each side and at each corner, etc.. To an extent this is still needed with a long thin hull, but the forces involved have smaller magnitude - basically, it's harder to put the thing seriously off-balance if you can only move a relatively small distance in and out from the central axis.

There are ways around this with e.g. multiple engines under computer control, or some sort of gravity drive that affects the ship as a whole rather than pushing from a particular locus on the ship, but the former enormously complicates control issues (e.g. you might get feedback problems such as wobbling), and the latter doesn't really work well with the natural laws we can currently manipulate.

All the above makes the (IMO unwarranted) assumption that the engine(s) are constantly supplying thrust. In other words, always accelerating or decelerating. Which, while it's the fastest way to get from A to B, is hugely wasteful of fuel. It's far more likely that thrust would be applied up to whatever speed was wanted, and the engines then shut down until needed for slowing down at the destination.

With thrust off, any changes in balance are irrelevant. So long as mass distribution is properly balanced, and locked in place (crew included) whenever thrust is being applied, there would be no problems.

How many years do you want to spend travelling? I went with constant thrust because without it you're talking say a year to Mars, several years to the outer planets.

Constant thrust is desirable certainly. As well as vastly reducing journey time, a constant thrust of say 0.5G would overcome most of the gravity issues. Fuel wouldn't be a problem either - water mined from moon/asteroids would do the job.

I have a very crude Excel template for times from one planet to another, just the crudest - "accelerate halfway then decelerate" calculation based on distance only and ignoring things like planetary orbital speeds etc.

http://www.forgottenfutures.com/game/te ... avtime.xls

Try not to think about how much energy you need to do this...

Disembodied wrote:

Mazur wrote:

Torpedoes will be rarely useful, since the enemy will be able to see them coming from a long way off and sleep on how to destroy/misdirect them before they hit

Unpowered projectile weapons, on the other hand - clouds of black, nonreflective ball-bearings, say, launched by electromagnetism (no muzzle flash to give them away) and arriving at their target with a relative speed of several thousand miles per hour - could do a lot of damage, and probably be a lot easier to hit with.

Exactly! An electric railgun is one of the weapons I thought of as a possibility. Or a spear fired at high speed. But again, with ballistics distance is going to be a factor in limiting effectiveness. Not because of friction, but because of time.

Mazur wrote:

An electric railgun is one of the weapons I thought of as a possibility.

There's a Railgun OXP, which requires a certain skill to hit moving targets at distance.

Cody wrote:

Mazur wrote:

An electric railgun is one of the weapons I thought of as a possibility.

There's a Railgun OXP, which requires a certain skill to hit moving targets at distance.

In the real world I'm certain it would require computer aiming. As with most weapons, to be honest.

Mazur wrote:

I should have the ICBM coordinates for a certain building in Redmond, WA, around here, somewhere.

I knew there was a reason I liked you..

One thing to consider (and has been touched on above) is the framework that holds the thing together. Although materials science will improve and create new alloys/compounds/welds/glues etc. that will be space worthy (strong, light, flexible, radiation resistant and non-porus), any construction joint will always be a point of structural weakness. All points of weakness need to be reinforced, which takes up valuable space and increases mass.

Framework and reinforcement is inversely proportional to size. There will be a size that a ship becomes inefficient to construct and still be useful for a given role. At the other end of the scale, the number of joints in a frame or hull is somewhat inversely proportional to its integrity. The bigger and more complex a ship, the stronger the framework has to be to support it against inertial stresses (torsional/centrifugal/impact) – I guess this is one of the reasons why large ships are less manoeuvrable. So although less important, there would probably be an upper size where a ship is inefficient to construct for a given role. I tend to think that for larger constructions, framework would also tend to be more exo-skeletal, pushing to contain the atmosphere (like a net holding a balloon) rather than pulling it in.

This tends towards Smivs idea that space constructions for holding people/life forms would be geometrically simple. But consider, as is seen in Oolite, simple geometric shapes can be joined to generate many shapes and simulate practical 3D-shapes for space (increased volume and decreased surface area).

In general, therefore (and from a 21st century perspective), what we see in in earthly vehicle design (for all translational media) will probably be reflected in spaceship design. Small and fast tends to be sleek and expensive, small and slow tends to be bulbous, large and slow tends to be bulbous (and to my mind exo-skeletal) and large and fast tends to be inefficient.