[Stryke 9]

Hmm... Think you'd need a track about 4 miles long to get that speed...


And you wouldn't wanna see the result, most likely. See the bullet hit the planet and come out the other side.

[Knight Templar]

Not with a rail gun.

IIRC it was like a 10 - 20 foot barrel tops (3-6 meters)

[Stryke 9]

Hmm...

(2.25x60*60=...8100)

8100km/h ain't shabby. maybe not FOUR miles, I was guessing 2.25/s to be a much higher speed than it is, but at least one. Those things can only accelerate so much per magnet.


... though I suppose, without air resistance, that wouldn't necessarily be true. Depending on the mass (inertia) of the slug, could be relatively short...

Thing'd still be ****ing huge, though. By far the biggest installation in space.

[Shrike]

Originally posted by Maeglamor
[color=66ff00]Uhhh, have I missed  something? 200nm is like 200 *10E-9 meters. If it travels that distance in six minutes it would be blimmin slow!

I hope they just misquoted the guy or the US military might not have the weapon they think they have.
[/color]

Considering that the range data is undoutedly in Nautical Miles......

[Knight Templar]

Originally posted by StrykeIX
Hmm...

(2.25x60*60=...8100)

8100km/h ain't shabby. maybe not FOUR miles, I was guessing 2.25/s to be a much higher speed than it is, but at least one. Those things can only accelerate so much per magnet.


... though I suppose, without air resistance, that wouldn't necessarily be true. Depending on the mass (inertia) of the slug, could be relatively short...

Thing'd still be ****ing huge, though. By far the biggest installation in space.

It wouldn't need to be biger than the house sized one on TV, would it?

[Shrike]

Originally posted by Maeglamor
[color=66ff00]2.25km a second sounds a bit more reasonable. (Who the hell am I kidding? Reasonable? More like insane! )
[/color]

Modern tank guns go 1.6 km/s, and the new 140s and 152s probably even higher.  It's not that insane.

The 36 km/s ones the russians tested, those were insane.

[Stryke 9]

Ah, but you're talking about launching a smallish projectile in an explosion so massive that you need something as heavy as a tank to keep the recoil down. With a railgun in space, you're launching a metal cylinder about ten feet in diameter twice the speed gradually using electromagnets. That IS pretty impressive. And since it'd speed up due to gravity on the way down, it'd do a ****load of damage, too. Take out a whole city block, that, if not more.

[Shrike]

Originally posted by StrykeIX
Ah, but you're talking about launching a smallish projectile in an explosion so massive that you need something as heavy as a tank to keep the recoil down. With a railgun in space, you're launching a metal cylinder about ten feet in diameter twice the speed gradually using electromagnets. That IS pretty impressive. And since it'd speed up due to gravity on the way down, it'd do a ****load of damage, too. Take out a whole city block, that, if not more.

Point noted and dismissed.  Maeglamor's comment had nothing to do with projectile weight, merely velocity.

A railgun in space is a rather inefficient weapon system for planetary bombardment, because of the energy costs of getting your kinetic kill projectiles into space to begin with.  A high-energy FEL (probably nuclear powered) would probably make a much more efficient weapon system.

[Stryke 9]

Which is what I said. They're better air-ground weapons, or long-range line-of-sight artillery.

I don't dig on the lasers, though. I say, go all Heinlein and drop big canisters of rocks from orbit, or at least some of the crappy old sattelites we aren't using.

[Shrike]

Originally posted by StrykeIX
I say, go all Heinlein and drop big canisters of rocks from orbit

Maybe once we can get rocks from the moon, where the energy required to lift said rocks into orbit is relatively low.

As an interesting note, do you know how big of a rock you need to make a 1 kT equivalent blast?  A iron sphere 2.6 meters in diameter, travelling at 11.2 km/s.  Far more efficient to use an ICBM.

[ZylonBane]

Originally posted by Shrike
A railgun in space is a rather inefficient weapon system for planetary bombardment, because of the energy costs of getting your kinetic kill projectiles into space to begin with.

This is exactly why the "Mass Drivers!" episode of B5 bugged me so much (the one where the Centauri bombard Narnia using mass drivers). Collecting rocks to chuck isn't enough... you have to collect rocks big enough that they won't burn up in the atmosphere, AND dense enough that they won't explode before impact, AND heavy enough that they'll hit the ground before achieving terminal velocity.

Since you're sitting at the edge of a gravity well, it makes more sense to simply drop the rocks. Gravity will take care of the acceleration. And it makes the most sense of all to use something higher-yield than a frelling rock.

JMS can write a lot of things, but credible science fiction isn't one of them.

[Setekh]

Originally posted by ZylonBane


"Mass drivers?!"

Oh Londo, I haven't seen you for a while.

What I'm watching for is how long it takes everyone else to get this kind of arsenal.

[Stryke 9]

Seeing as, as has been said here, railguns are cheap and easy to make, and next to useless in space (at least, against planets), I'd say that, for example, Ethiopia has a fair chance of beating the US to it.

[deep_eyes]

just wait till they wanna make a Metal Gear...

[LtNarol]

Personally, I don't think any of these weapons are practical navy weapons, they all require too much power unless you have a generator the size of a fairly large mall right next door feeding your guns.  Far more practical for land-based home defense and long range artillery I should think, but then again, thats just me.

[Anaz]

If you want to read about a cool gun, read the book Snow Crash by Neal Stephenson (IIRC). The coolest gun in fiction is in there. Its name is Reason.

[Nobilis Draco]

Jane's:mad:!  have you ever looked at thier book prices? I wanted to buy All The Worlds Aircraft but it's a wallet theiving $900 and some odd dollars. provided it is a book about every plane in the world and quite detailed. but $900 dollars? Damn it!

[Cannikin]

Bah, people dream too much.

A VERY basic scientific principle:  You can only get energy out of something what was put into it in the first place! A hunk of metal sitting there has absolutely NO kinetic energy (other than molecular vibrations) no matter how big it is. If you want a 10 megaton explosion from a, say, 10 ton shell fired from orbit, gravity sure isn't gonna provide that kind of energy . You want that bigass "meteor impact", you're gonna have to provide the 10 megatons worth of energy in the first place. So you basically have to take a 10 megaton nuke, detonate it, somehow channel all that energy into propelling the shell (without utterly vaporizing it and the launcher and anything in the area, as well as preventing the imminent EMP that would spread across the world on the planet's magnetic field and the light that would instantly burn any exposed skin below and blind anyone looking that way...). Makes me wonder why anyone would possibly think these are more efficient than current weapons.

These futuristic weapons people keep imagining are vastly inefficient and fairly useless. Not only do they use up an amount of energy impossible to realistically achieve, they fail an enormous amount of the time. Just take a look at the old Star Wars project. The dumb laser failed about 40 times before it hit it's target even once. And the plane mounted laser took a freakin Boeing 707 commercial jet to fly. One of the people on the project joked that it would do more damage by dropping the sucker on the enemy than shooting with it (which was probably true).

Modern missiles are faster, more accurate and can deliver a far greater punch than you could ever hope with these hunks of metal coming down from the sky.

[Fury]

Neutral Particle Beam (NPB)

Mid-Infrared Advanced Chemical Laser (MIRACL)

Space Operations: Through The Looking Glass
(Global Area Strike System)

ANALYSIS: Lockheed-Martin F-35 Joint Strike Fighter

Raptor could hatch a delta bomber

FB-22 Fighter Bomber

General Dynamics F-111 Aardvark

Thanks to E.T over at 'Exedrae in posterum' forums for all those neat links.

[Kazashi]

Originally posted by ZylonBane
This is exactly why the "Mass Drivers!" episode of B5 bugged me so much (the one where the Centauri bombard Narnia using mass drivers). Collecting rocks to chuck isn't enough... you have to collect rocks big enough that they won't burn up in the atmosphere, AND dense enough that they won't explode before impact, AND heavy enough that they'll hit the ground before achieving terminal velocity.

Since you're sitting at the edge of a gravity well, it makes more sense to simply drop the rocks. Gravity will take care of the acceleration. And it makes the most sense of all to use something higher-yield than a frelling rock.

JMS can write a lot of things, but credible science fiction isn't one of them.

Remember 1908? Well, chances are you weren't alive back then, but you'd certainly know what I'm talking about when I mention Tunguska. The object that exploded in the air was not a heavy metal asteroid, it was either a carbonaceous asteroid or a comet. In either case, it only measured 100m across, and is composed of loosely compressed matter. Nevertheless, the resulting explosion would've wiped out a major city. Those Primus vessels aren't tiny, so the rocks they were hurling would've measured at least in the dozens of metres across, perfectly capable of exploding in the atmosphere (note, more damage can be done by detonating a nuke above a city rather than on the ground, so there's no need for an asteroid to survive in one big piece to leave a crater) and wiping out large tracts of land. So bombarding a planet with asteroids (forgetting how they're launched at this point) isn't such a bad idea.

Letting the rocks fall at a relatively leisurely rate that you've mentioned wouldn't do much at all. The current crop of deadly rocks are dangerous because they have been moving around in space, influenced by millions of years worth of gravity and high relative speeds. An artificial bombardment requires artificially produced speeds, and that's where issues of physics come into play. But bear in mind that there's more to it than "energy in launching = energy out from destruction".