DescentBB

Looks like the U.S. has got a large scale working railgun now.

You mean you just found out about it now. :P

Hadn't seen it in the news before now.

Well that's not so surprising, is it? ^_~

Har, har.

no it's new, video was recorded 2nd Dec 2010.

YOUTUBE VIDEO DESCRIPTION wrote:The Office of Naval Research Electromagnetic Railgun located at the Naval Surface Warfare Center Dahlgren Division, fired a world-record setting 33 megajoule shot, breaking the previous record established January, 31, 2008.

Wait... These things actually exist?

Fox is not into weapons.

Yes the physics of them are acctually preaty amazing, no gunpowder or proppelant is used, insted a massive bank of capasitors is charged up and then a deliberate short circut is made which drains the capasitors very rapidly, the amount of current traveling thru this circut which also contains the projectile creates a little know electric effect called elctro-motive-force. Basically the object is accelerated and a 90º angle from the direction of current travel. there is no known limit on how fast a railgun projectile can go, the technology is limited by the melting point of the materials its made out of.

roid wrote:no it's new, video was recorded 2nd Dec 2010.

Pro tip: Just because the video was recorded in 2010, doesn't mean it's new. It's "new" to you. =P

Pbfffffffffffft! It's \"NEW\" video Neo!

When they fire this thing, doesn't that destroy the rails? Wouldn't that make for one hell of a long reload?

You're with the military, aren't you? :P

Don't bother Grendel, he can't read.


I think these things are partially made of plasma while firing no? From what i understand, the metal electrical bridge conducts so much energy that it has no choice but to vapourise into a plasma when fired, but it still works since plasma is conductive. Then this PLASMA bridge is then accelerated down the rails by the force Kida mentioned, pushing the slug infront of it. (the plasma itself dissipates prettyfast as it leaves the muzzle, leaving only the slug). The rails can also get kinda damaged, hell even the wires and capacitors tend to melt during shots.
It's been a while since i read about the first shot from a few years back, so i probably butchered the physics in that explanation.

Kida wrote:...there is no known limit on how fast a railgun projectile can go, the technology is limited by the melting point of the materials its made out of.

This is why in my mind developments in plasma physics ("magnetohydrodynamics"... say that twice fast lol) are so exciting. When the material in question is physically something that can't be melted/vapourised anymore than it already is - and thus it's strength limits are purely constrained by the power available to your electromagnetic containment - there is no limit.
Basically the Tech used in magnetic confinement fusion reactors (ie: Tokamaks) and VASIMR rocket engines, taken to the inevitable next level.

I'd like to eventually see structural elements (ie: joints/beams/etc) of objects and vehicles made outof magnetically contained plasma. Like an amped up version of an electromagnetic bearing. Need more strength? Just up the juice.
*salivates at the engineering thought experiment*

(ie: what if that entire railgun was made outof plasma?)
In b4 kneejerk non-imaginative "no".

This engineering thought experiment is sadly discussed so rarely, too outlandish? Come on guys, i'm throwing down the geek gauntlet. How would we make it so in real life?

What about the speed of light as a limit... heck, what if we used railgun projectiles to test relativity?

Also, I haven't seen Roid here in like... forever.

Neo wrote:You're with the military, aren't you?

Nope. Just like to blast robots in Descent with the best possible weaponry, especially projectile weapons like the Gauss gun. A nice, throaty sound that means business.

Speaking of gauss gun, here we have a smaller version of the rail gun called a 'Coilgun' or yes, a 'Gauss' gun. Works on a similar principle of magnetic linear acceleration.

http://en.wikipedia.org/wiki/Coilgun

Alter-Fox, I don't think any railgun or linear magnetic motor would be able to accelerate a mass or object anywhere near the speed of light. The energy requirements would be astronomical and well out of our ability to generate. We just don't have materials that wouldn't vaporize instantly when the required charge was dumped into the rails. That's why you see all that plasma shooting out of the end of the gun, it's generated by the heating and ionization of the rails, hence the very short life in repeated use. The other problem is that the rails repel one another when charged and have to be held very securely, but there is only so much structure one can make that would contain the higher and higher charges needed for light speed velocities if one wants high, instantaneous acceleration. Now slow and steady may be more in line with present human technological ability, like ion engines for space flight propulsion.

roid, to make things out of plasma, we need the ability to contain it, which we haven't really mastered yet. The magnetic fields required to hold plasma need to be very strong and stable, eg., superconducting and supercooled exotic magnets. If science could figure out a way to contain plasma consistantly, we could generate endless power from fusion reactors. Yes, we might then be able to generate force fields or structural integrity fields, because we would have mastered those all important magnetic fields. So first we need to work on magnetic fields and containment before we deal with plasma.

But here's something cool along the lines of a magnetohyrodynamic drive, a water driven motor with no moving parts for propelling a boat. Not very efficient at the moment since we need very large supercooled, superconducting magnets and a lot of power just to move a reasonable amount of water at any speed, but we may get there someday.

http://en.wikipedia.org/wiki/Magnetohydrodynamic_drive

http://www.physicscentral.com/explore/p ... pd-exp.cfm

http://en.wikipedia.org/wiki/Polywell

Someone needs to come up w/ the magnetic equivalent of phased arrays..

Phased arrays are sweet.

Alter-Fox wrote:What about the speed of light as a limit... heck, what if we used railgun projectiles to test relativity?

Also, I haven't seen Roid here in like... forever.

to get anywhere near those kinds of speeds, you would need on orders of magnitude more advanced materials to create said system.

you humanz and your gunz :P

I say we conduct Alter-Fox's experiment :P

tunnelcat wrote:roid, to make things out of plasma, we need the ability to contain it, which we haven't really mastered yet. The magnetic fields required to hold plasma need to be very strong and stable, eg., superconducting and supercooled exotic magnets. If science could figure out a way to contain plasma consistantly, we could generate endless power from fusion reactors. Yes, we might then be able to generate force fields or structural integrity fields, because we would have mastered those all important magnetic fields. So first we need to work on magnetic fields and containment before we deal with plasma.

Well we've kinda got VASIMR working well already, which magnetically contains & directs a relatively diffuse plasma (ie: nowhere near atmospheric pressure). And we've mentioned how we can contain/pinch a sudden PULSE of dense plasma to incredibly large densities enough to fuse hydrogen nuclei.
I'm not suggesting it's easy - as you say the technology of plasma manipulation is in it's infancy. But it seems plausible, inevitably anyway. This seems like an interesting goal / engineering-thought-experiment.

Before we tinker with plasma for this purpose though, there are other minor steps that could be played with.

A step would be to just ramp-up ordinary magnetic bearings to see what they're capable of. You could hold up an entire building with an electromagnetic bearing, if you give it enough juice.
The main problem seems to me to be that such a system inevitably just redirects the forces around itself - to whatever girder the bearing is attached to (ie: the bolts holding the bearing will bend/break). So i'm just trying to think of ways to continually redirect the forces from one magnetic bearing to another all the way along the structure WITHOUT ever dumping it into the internal structure itself (but redirecting the force until it can be finally dumped into the floor or something else that can handle it). So the structure basically becomes one large continuous magnetic bearing. The whole point is to explore the concept of using deceptively small structures to handle incredibly large loads - by exploiting forces rarely considered for structural engineering (such as electromagnetism, electrostatics, or even fluids).

Anyway hopefully the process of people telling me why this can't possibly work, will teach me some much needed lessons about magnetics.
Shoot!