Rail gun damage?

[Markdoc]

I was thinking of having some supercooling system to avoid the railguns overheating. That was how I was going to explain it. This is a futuristic campaign, so I can include a little superscience there, right? .

Sure - if anyone asks, tell 'em they run on high-temperature labile superconductors That's the current holy grail for railgun technology - a material that superconducts (so you don't get such violent inductive heating (followed by explosion inside your gun) but made of a material as labile as steel, so it doesn't simply shatter (as modern superconductors do under even moderate current flux) - and capable of working at room temp or near room temp.

cheers, Mark

[Old Man]

How hard would it be to employ disposable one-shot rails? Not very sexy, but might be more feasible than using magic superconducting unobtainium that doesn't exist.

[Bygoneyrs]

We need Plasma Rifles...

Penn

[braincraft]

We need Plasma Rifles...

Penn

Phased plasma rifle, forty-watt range.

[Thia Halmades]

I built that.

[tkdguy]

How hard would it be to employ disposable one-shot rails? Not very sexy, but might be more feasible than using magic superconducting unobtainium that doesn't exist.

In the heat of battle it may not be too practical. If the first volley doesn't disable the enemy, you'll be vulnerable to their counterattack.

If they can fire several times before failing and are relatively easy to replace in spacedock, that may be a feasible solution.

[Zeropoint]

What if the rails are effectively part of the ammunition, and the gun itself has a mechanism for ejecting the old rails and loading new ones.

OOH! What if the gun fires the old rails???

[tkdguy]

That would drive up the cost!

[Markdoc]

How hard would it be to employ disposable one-shot rails? Not very sexy, but might be more feasible than using magic superconducting unobtainium that doesn't exist.

It'd certainly be easier, but as you say, it's not very sexy - and the navy is selling their development with sexy - hundreds of shells a minute raining down on targets 200 miles inland...

In theory, you could do that, although the cost and bulk (the "rails" currently are big flat sheets of metal stacked one atop the other to form a steel block weighing several tons) makes it a pretty unattractive option. They're made that way to provide maximum lateral strength so that they don't warp too much when you fire the thing.

At this point, I get the sense that they are trying to just see if anything useful can be made out of the technology at all.

Just a thought, though - while the weight and bulk make disposable rails not so attractive, for fixed defenses (like for example, antimissile protection for buildings, or on larger vessels such as capital ships) it might be an option. As I understand it, the materials are not that expensive and the fact that you don't get repeated shots is not such a big deal if you have a battery designed to fire (say) a dozen bursts of 20 slugs, rather than an offensive weapon that can expect to see repeated use. For short range antimissile use, it might be a better option than things like the Patriot system since you get maximum acceleration almost instantly.

The same could apply to space ships, if they are large and expensive.

cheers, Mark

cheers, Mark

[tkdguy]

Would it be possible to repair the rails somehow? And if not, would they still be useful in some way, perhaps be recycled for other uses?

[Narratio]

... That's the current holy grail for railgun technology - a material that superconducts but made of a material as labile as steel, so it doesn't simply shatter (as modern superconductors do under even moderate current flux) - and capable of working at room temp or near room temp.

I seem to remember a joke from an 80's edition ofANALOG which said "Gallium Arsenide, the superconductor of the future. Always has been... always will be. Room temp superconductors? We're still at Unobtanium.

[Markdoc]

I seem to remember a joke from an 80's edition ofANALOG which said "Gallium Arsenide, the superconductor of the future. Always has been... always will be. Room temp superconductors? We're still at Unobtanium.

Yeps. It's why I'm such a grouch, when the perennial discussion of new railgun weapons and new laser weapons do their annual tour through the discussion boards. Both them will make awesome new weapons as soon as we solve the materials science problems that have prevented them becoming awesome new weapons since the 1960's.

I'm an old science grognard, so I remember all the artist's impressions of flying laser weapons that were "under development right now!" from the 1970's. The only difference today is that they come with nifty computer-generated movies. And what's happened in between, is that the technologies that were seen as wanting 30 years ago have been pushed to their (admittedly technically impressive) limits - and are still wanting.

cheers, Mark

[Thia Halmades]

Hey Mark, this is a question you can likely answer:

What are the odds of us being able to build a stable orbital tethered platform? I've read up on all the 'nanowire' that they want to use, with some massive multiplier the tensile strength of steel for some massive divisor of actual thickness, creating a new, massive wire that's nigh invulnerable and can shuttle things to and from orbit fairly easily. It would enable an actual "shipyard in space" at its peak, I suppose, but I don't know all the ins and outs.

I want to use it for a campaign, and I have an "orbital elevator" already, but it's very rubbery, and if I can make it a little bit harder, I'd like to do so. What are your thoughts on the topic? What's feasible, what's not, what's the cost, where would it likely be built to remain in stationary orbit (i.e., which LaGrange point would most easily correspond? An ocean?) and just how effective would it be?

[Markdoc]

Hey Mark, this is a question you can likely answer:

I'm sure there are people better placed to answer that question than me on these boards (in fact, I know there are) but basically my answer is similar - no material we have to hand (and by that I mean "able to produce, even in minute quantities" fully meets the engineering specs.

But that's why it's sci-fi, right? Internally buttressed carbon nanotubes? Unobtanium cables? If you assume the material can be made, then you are basically food to go - as long as you build the concept that we now have relatively cheap, really, really strong fibres: it'd have implications for building body armour for a start

As to cost, I have no freakin' idea, but we can assume that if one gets built at all, the cost would have to be more than competitive with building rockets (or similarly climbing up out of the gravity well on some kind of fuel-powered ride) - so not outrageous. Once in place, most analyses have shown it'd be a very cost effective way of getting loads off planet.

As far as feasibility goes plenty of smart people have said "yes - if you can make a material strong enough" so I'm happy with that.

As for the other questions, you don't need to aim for the Lagrange point - all that's needed is a geostationary orbit - which is easiest at the equator. You either need a really long cable sticking out past the stable orbit as a counterweight or a large object (orbital platform?) to keep the cable upright and taut. Build both and you get an ideal launch point for interplanetary travel as anything launched off the cable gets effectively "free momentum" just from its distance from earth.

As to what it's anchored to groundside, you have two options. Like I said you need a geostationary orbit, so on the equator is easiest. Where? Well, one attractive option (cost wise) is not to send your elevator cars down the cable, but simply drop them. You don't want then landing in people's backyards, so why not drop them in the sea? Build your cable either seabed-anchored or on a massive floating platform and you not only avoid entanglement with the politics of equatorial nations - none of whom seem rich enough to build this themselves - but you get a simple landing place for your dropped elevators. You also get a major seaport/airport - which is easily protected by a strong navy - and by mass-drivers on the platform itself, providing increased security and also a small amount of protection from collateral damage, should (god forbid) something happen to the elevator itself. The offshore, equatorial location means that hurricanes and major storms are not a major concern (not impossible, just unlikely)

Sounds outrageous, but tiny little Dubai is building masses of artificial islands right now, which have an area of a couple of hundred square km - so it's not impossible.

Last of all, you could go the skyhook route where the end station is actually hanging in the air off the orbital - this sounds bizarre, but is apparently possible and has the advantage that it lessens the amount of cable you need (which is a big deal) - but it raises issues of power supplies and getting things onto your platform - most "plans" favour an earth anchor for that reason.

Since some enthusiasts say "we could start building by 2015!" (Yes, they say it and no, ain't gonna happen) the idea of a beanstalk in a near-future game is perfectly plausible - assuming improved materials.

cheers, Mark

[Nyrath]

How hard would it be to employ disposable one-shot rails? Not very sexy, but might be more feasible than using magic superconducting unobtainium that doesn't exist.

Not a bad idea, actually. I gather that the rails are just solid bars of alloy, no electronics or anything expensive like that.

Anybody remember the Galactic Patrol Primaries in E.E."Doc" Smith's LENSMAN series? They were a super-weapon where the gun projectors were used like ammunition.

You see, somebody discovered that if you took a standard energy beam projector on a warship, and fed it 1000 times the energy it was rated for, it would emit an energy beam 1000 times as strong as usual. The drawback was that the projector would operate for about half a second, then explode.

So they made a new weapon that was fed projectors like they were giant shells, firing the projectors inside a special armored chamber then ejecting the spent projectors.