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The Military Science

World's Most Powerful Rail Gun Delivered to US Navy 615

An anonymous reader writes "The world's most powerful functional rail gun capable of accelerating projectiles up to Mach 8 has been delivered to the Navy. The new rail gun is a 32-megajoule Electro-Magnetic Laboratory Rail Gun. The Navy eventually hopes to have 64-megajoule ship mounted rail guns. 'The lab version doesn't look particularly menacing -- more like a long, belt-fed airport screening device than like a futuristic cannon -- but the system will fire rounds at up to Mach 8, drawing on tremendous amounts of electricity to generate the current for each test shot. That, of course, is the problem with rail guns: Like lasers, they're out of step with modern-day generators and capacitors. Eight and 9-megajoule rail guns have been fired before, but providing 3 million amps of power per shot has been a limitation.'"
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World's Most Powerful Rail Gun Delivered to US Navy

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  • How silly (Score:5, Funny)

    by JesseL ( 107722 ) * on Monday January 28, 2008 @04:19PM (#22212106) Homepage Journal
    An effective military rail gun would need a huge vessel to carry the capacitor bank and a nuclear power station to make a rail gun practical. Where is the Navy going to get something like that?

    Oh wait...
    • by Anonymous Coward on Monday January 28, 2008 @04:25PM (#22212234)
      I noticed that almost every story today has this tag on it. What could possibly go wrong if you stop using this tag for every article?
       
      • by halivar ( 535827 )
        They would go back to "welcome our overlord" jokes, which is worse.
      • Re: (Score:2, Redundant)

        Railgun? I always think of this [mc.net]
        • by Chris Mattern ( 191822 ) on Monday January 28, 2008 @05:53PM (#22213656)
          Meh. He's got some cute pictures, but his grasp of military history is teh fail. The French did *not* discount the possibility of the Germans coming through the neutral Low Countries; in fact, they expected it--it was what they'd done last time, after all. That's what did them in. All their decent units were all lined up on the Belgian border and rushed into the Flanders plain to meet the expected oncoming Germans as soon as Belgium was invaded. But the Germans broke through at the pivot point, in the Ardennes, getting behind the Allied forces now in Belgium and then driving west to the sea to bottle them all up quite nicely, including the British (who managed to evacuate out of the pocket from Dunkirk).
      • by stephencrane ( 771345 ) on Monday January 28, 2008 @04:48PM (#22212644)
        Seriously. This tag is being used way too much. A rail gun is, for all its complexity, a relatively straightforward concept. A story about, oh, releasing genetically-manipulated mosquitoes into the wild really should set the benchmark. Standards, people, standards. We're -geeks-, fer crissakes.
        • Re: (Score:3, Funny)

          well, a simple mis-application of Fleming's left-hand rule could result in anyone standing directly behind the gun from getting a fairly substantial hole put in them. That could go wrong.
      • by Goaway ( 82658 ) on Monday January 28, 2008 @06:40PM (#22214330) Homepage
        It's simply an expression of the closet technophobia that affects so many Slashdotters.
    • Re:How silly (Score:5, Interesting)

      by paganizer ( 566360 ) <thegrove1 AT hotmail DOT com> on Monday January 28, 2008 @04:26PM (#22212252) Homepage Journal
      I'm vaguely remembering a conversation I had when I was in the Navy, but from what I remember, the USS Enterprise was over engineered to have 8 reactors when they knew only 4-6 were really necessary because they had some thoughts of mounting energy weapons. since the Enterprise was drawn up in the late 50's I'm not sure whether to doubt it or not.
      • Re:How silly (Score:5, Interesting)

        by AKAImBatman ( 238306 ) <akaimbatman AT gmail DOT com> on Monday January 28, 2008 @04:37PM (#22212464) Homepage Journal
        The Enterprise was the prototype. Plus, Nimtz carriers only have 2 reactors. So it wouldn't surprise me if they overengineered her power supply for the intent purpose of mounting experimental weapons.

        That being said, the Nimtz reactors are a bit more advanced than the Enterprise (lessons learned and all that), so that has a lot to do with the reduction in the number of reactors.

        Everything beyond that is classified. I could tell you, but then I'd have to shoot you. (Assuming that I already knew and therefore had been shot. :P)
        • by Baddas ( 243852 ) on Monday January 28, 2008 @05:38PM (#22213428) Homepage
          Wait wait, are we talking a simple flesh wound here? Or like, a through and through to the calf? Because it might be worth it. Did it hurt when they shot you?
        • by Duhavid ( 677874 ) on Monday January 28, 2008 @07:59PM (#22215572)
          "Everything beyond that is classified. I could tell you, but then I'd have to shoot you."

          You have it backwards! Shoot them first, then tell them.

          And to optimize this, you can remove the 'nop', and just shoot them.

          I mean, telling them and shooting them is not good, unless they
          support transactions. ACID and all that.
      • Re:How silly (Score:5, Interesting)

        by jollyreaper ( 513215 ) on Monday January 28, 2008 @04:53PM (#22212744)
        As I recall, the ship had eight reactors because that's how many it took to keep the thing moving. They were expensive and Congress wanted the Navy to go back to fuel oil. As I recall, the JFK was conventional. When the Nimitz class came about, the reactor technology had progressed to the point where they could get away with two and the operational costs came down enough that Congress relented. What the Navy really likes about nuclear is that it gives the carriers so much operational flexibility. A modern carrier has fourteen days of combat stores onboard. The reactors also produce the steam to fire the catapults, a very energy-intensive process. I also heard something about some nuke carriers carrying bunker fuel to help keep the destroyers topped off but that seems a bit silly since there are already fleet oilers to perform that task.
        • Re: (Score:3, Interesting)

          by Shakrai ( 717556 ) *

          I also heard something about some nuke carriers carrying bunker fuel to help keep the destroyers topped off but that seems a bit silly since there are already fleet oilers to perform that task.

          Actually, they do, and it's not that foolish when you think about it. Fleet oilers are generally too slow to keep up the battle group and require escorts of their own. The carrier can't entirely replace the fleet oiler but it does add flexibility to the options of the task force commander.

        • Re: (Score:3, Interesting)

          by Alsee ( 515537 )
          I also heard something about some nuke carriers carrying bunker fuel to help keep the destroyers topped off but that seems a bit silly

          I agree it's silly.
          With all that excess reactor power they should just run a really long extension cord to the destroyer.

          Hmmmm.... I intended that just as a silly joke, but the more I think about it the more I realize some sort of variation on that concept might actually be viable. Plenty of engineering headaches (probably the main difficulty being ships generally not equippe
      • Re: (Score:3, Interesting)

        by Anonymous Coward
        The funny thing is that there are other technologies (ram accelerators, combustion light gas guns) [wikipedia.org] that can reach the same velocity but without the burly power requirements. And for a fraction of the cost... And the projectile doesn't turn into plasma on the way out... And the rails don't wear out after five shots... Seriously, what I hear from people in the field is that the railgun people are scamming the government, especially when there is other cheaper tech out there that will solve this problem.
        • Disclaimer: I lack the knowledge to have a legitimate informed opinion on this topic.

          Ram Accellerators may be cheaper in terms of raw dollars, but I wonder how well they scale relative to Rail guns? Specifically, economies of scale for mass production, and for the mass per projectile.

          Once the technology is figured out for Railguns, I suspect the primary cost will be the power generation. The projectiles themselves will probably be very cheap, and be easier to manufacture than those used by a Ram Acceller
          • Re: (Score:3, Interesting)

            by pragma_x ( 644215 )
            I think you're on to something there. If you work the kinks out of the technology, such that the gun itself doesn't wear out very fast, then all you need is a lot of electricity.

            Add on a few nuke reactors, and/or a nice capacitor bank, and you're suddenly only restricted by how many projectiles you can carry. As you mention, these are going to be simple - basically just metal slugs. There's no more powder or fuel required for the task, which is in sharp contrast to conventional weaponry.
      • Re:How silly (Score:5, Interesting)

        by DerekLyons ( 302214 ) <[moc.liamg] [ta] [retawriaf]> on Monday January 28, 2008 @05:52PM (#22213634) Homepage
        I suspect that's an urban legend. (Lots of 'em floating around the Navy.) I've never seen anything, anywhere, indicating that the Navy was looking at energy weapons in that time frame.
         
        At any rate, the reactor plant of the Enterprise was originally sized on the need to launch full (Vigilante) sized aircraft while steaming at maximum speed. Plus some additional capacity for operational reserve, in case one or more reactors were down, plus a fudge factor for future growth and to cover against concerns about reactor performance. There was also a general concern in the Navy at the time over the profliferation of electronic systems and their increasing demands for power.
         
        Since the reactors ended up performing reliably and more-or-less to spec, and big aircraft didn't become common in the fleet - Enterprise ended up considerably overpowered, much more so than follow on CVN's. The follow on CVN's carry fewer reactors partly because of this, and partly because the individual reactors are so much more powerful and specifically designed for carriers. (The A2W reactor used by Enterprise is actually a slightly uprated C1W reactor - originally intended to be used in pairs for cruisers.)
         
        In fact, Enterprise ended up with so much excess steam capacity - that (IIRC) half the steam recievers (a sort of capacitor to hold steam for the catapults) she was built with have subsequently been removed. Off-and-on there has been discussion of mothballing a pair of her reactors in place.
      • by LeafOnTheWind ( 1066228 ) on Monday January 28, 2008 @07:17PM (#22214918)
        I'm afraid you're misinformed: the USS Enterprise is equipped with a single power generator - a deuterium matter-antimatter power plant. In addition, while the Enterprise does employ a variety of energy weapons, including a full bank of 12 phaser arrays, the primary purpose of the warp core is to provide the energy for warp-speed interstellar travel.
    • As TFA points out, the Navy is planning to put one on the DDX destroyer, the smallest serious ship the Navy floats.
      • The DDX Destroyer is just the first step in the Navy's futurization of the fleet. The CVNX project [wikipedia.org] intends to modernize carriers in the same way that the DDX Destroyers will be modernized.

        Some of the features:
        • Better, more powerful reactors (3x increase in available power!)
        • Stealth
        • Electromagnetic catapults
        • Greater automation leading to reduced crew complement
        • Better survivability in a fight (like that's been a big concern :P)
        • Advanced arresting gear (no idea what that means)
        • Dual Band Radar support
        • "Flexible ship infrastructure" (i.e. We can mount some kewl energy weapons once Congress gives us the green.)


        Navy Fact File [navy.mil]

        As I recall, the original list of superweapons was much more impressive. It just got pared back a smidge when Congress balked at the price tag.
      • Re: (Score:3, Interesting)

        Thats what I suspected.

        On large ships, other kinds of weapons are preferable.

        This will be more like a traditional gunboat, carrying only one primary gun. Also, as it says in the article, the recoil makes it unlikely that this gun will fire many shots in one battle.

        I think this will be a bit like a naval sniper, aiming to destroy major vessels command center before its even detected, and then leave the area quickly and let the big ships take over.

        So we won't see many ships with this configuration, but in cer
        • by Shakrai ( 717556 ) * on Monday January 28, 2008 @05:12PM (#22213014) Journal

          I think this will be a bit like a naval sniper, aiming to destroy major vessels command center before its even detected, and then leave the area quickly and let the big ships take over.

          Uhh, wouldn't that require a line of sight to the intended target? Naval combat within visual range went out of style after Coral Sea [wikipedia.org]. If you don't need a LOS then it would seem to be that this is a guided projectile and you don't exactly need a railgun for that (see harpoon, exocet, etc, etc).

          I would suspect that the Naval interest in rail-gun technology is probably aimed at point-defense (i.e: shooting down incoming anti-ship missiles) more then anything else.

    • I hope that the Navy's new Rail Gun doesn't require a brief but critical period to charge before firing, and I hope that is does not require all non-essential power systems to be deactivated, leaving the ship powerless and adrift for a short time after firing... (wiki [wikipedia.org])
    • Re:How silly (Score:5, Informative)

      by ThePeices ( 635180 ) on Monday January 28, 2008 @04:52PM (#22212740)
      The majority of people here seem to think the rail gun is powered by a huge capacitor bank which takes a long time to charge, or required a nuclear power station to run it in a ship....bollocks.

      A Megajoule class railgun is powered by a Compulsator, a type of modified alternator ( compensated for low inductance to provide enormous current pulses )...the rotor is spun up by a large engine, and the rotational energy in the rotor is turned into multiple high current pulses...in earlier test systems ( still megajoule class ), they can fire a burst of 10 shots on one spinup. These things can be scaled to fit in a modern tank, or up to naval gun size.
  • by clonan ( 64380 ) on Monday January 28, 2008 @04:21PM (#22212154)
    The REAL reason Fusion power will be perfected...so the Generals can fire their fancy guns more than a few times an hour.
    • by kabocox ( 199019 ) on Monday January 28, 2008 @04:29PM (#22212326)
      The REAL reason Fusion power will be perfected...so the Generals can fire their fancy guns more than a few times an hour.

      Non-solar fusion won't produce that much energy any time soon. What we need is serious solar energy collection; I'm talking about solar powered orbital microwave death rays. That's how to properly power your death dealing toys. With a proper number of death rays, you should be able to fry any acre of land on the globe fairly easily. It's assumed that frying the land will kill off all enemy soldiers, peasants, and nature lovers that may be hiding there.
    • Nah, first we'll have the fusion bomb, then we'll have the fusion reactor.

      Whenever we get a new energy source, we set something on fire with it, or blow something up.
    • by Sycraft-fu ( 314770 ) on Monday January 28, 2008 @04:39PM (#22212504)
      We get a lot of cool technologies because the military wants new toys. You can argue about if it should be that way or not, but it is how things go. GPS is a great example. No civilian organization would invest in something that big. Are you crazy? Who would want that? However the cost wasn't a problem for the military and hence we got one of the most amazing navigational aids ever. Even now that the technology has been proven feasible and useful, or rather essential, the military run systems remains the only one. The European civilian governmental version remains snarled up in political battles.

      So while you jest, there could be truth in the statement. Fusion is all well and fine, but there's only so much money going to be thrown at it. We have other cheap power sources in terms of commercial use, so not a lot of commercial dollars, and it just isn't sexy or pressing enough to get much government research dollars... However if there's a major military application, well that could get billions easily.

      That's one reason I'm not always opposed to defense spending. Though it is very often wasteful and it seems there are better things to do with the money, it does seem to be one way for getting projects that just don't get built otherwise. A great many things come directly from defense research.
  • by Anonymous Coward on Monday January 28, 2008 @04:21PM (#22212164)
    Amps of power?
  • Beowulf? (Score:2, Funny)

    by iceyone ( 123598 )
    Imagine a beowulf cluster of these!
  • by INeededALogin ( 771371 ) on Monday January 28, 2008 @04:25PM (#22212232) Journal
    Seriously, how much energy does it take to kill someone.
    • by KublaiKhan ( 522918 ) on Monday January 28, 2008 @04:27PM (#22212282) Homepage Journal
      There is no such thing as overkill. There is only "still firing" and "out of ammo."
    • Re: (Score:3, Insightful)

      by JesseL ( 107722 ) *
      The energy required to kill someone is nil.
      The energy required to poke a hole in someone is somewhat higher.
      The energy required to poke a hole in enemy armor is higher still.

      This isn't for killing 'someone', it for poking big holes in things that are very hard.
    • by e2d2 ( 115622 )
      Someone? not much at all. Just enough to sever limbs and cause major bleeding or trauma.

      But a missile traveling at high speed a few feet above the water? Well thats gonna take a lot of power to stop. Also, this type of energy weapon limits the danger to the crew. No longer do they have to expose themselves to explosives. The dangerous levels of energy come from the power behind it. Since this is electricity and has been around for year, we know how to use it safely. Probably more safely that we could ever h
    • Quite a bit, apparently.

      Really though, I would think that this would be something that you would use to, say, sink the enemy's ship, maybe shoot their nuclear reactors, or otherwise destroy infrastructure. It would have a really strong psychological factor too. I remember reading somewhere that they deliberately made the sound of the Apache attack helicopter distinctive to try and intimidate any enemy ground troops they were going up against. I don't know if it worked, but I doubt it (if it's true).

      • Re: (Score:2, Interesting)

        by icebrain ( 944107 )
        Probably not with the Apache, but Germany's Stuka dive bombers (Spanish civil war/WWII) had sirens fitted specifically for that reason.
      • Re: (Score:3, Informative)

        The Apache's distinct sound comes from the offset blades of it's tail rotor. If you look at them they are not a 90 degree "X", but instead are offset 55/125 degrees to one another. The goal was to try and reduce the "whop-whop" rotor noise that comes from the main/tail rotor interaction to make the aircraft quieter from a distance. The fact that it sounds scary as hell was just an added bonus.
    • In all seriousness, the article speaks of ship mounted guns, so I don't really think they are made to kill individuals. I would think that no amount of energy can ever be enough when it comes to sinking warships.

      It makes me wonder, though -- they say 32 MJ per shot, but how much energy is in a normal-sized conventional weapon? They also say Mach 8, but how fast are normal rounds fired?

    • OK it can fire a round, but they say the rail and conductors etc can get distorted by firing. A gun that requires extensive repair after each shot is hardly functional.

      There might be some cool theoretical replacements to explosive propellants, but it is difficult to see them being deployed meaningfully any time soon.

    • by Monokeros ( 200892 ) on Monday January 28, 2008 @04:40PM (#22212516)
      That clearly depends on how awesomely you want to kill them.
    • by rahvin112 ( 446269 ) on Monday January 28, 2008 @06:51PM (#22214528)
      The Railguns serve a purpose which right now is being filled by EXTREMELY expensive weapons. The cruise missile has a range of about 600 miles, it also moves at a speed that makes them very easy to shoot down. To compensate for this they fly them at extremely low elevation, but they can still be shot down and you can hear them approaching for quite a while before they get there, making it much easier to avoid being hit by one.

      The railgun on the other hand currently has a range roughly 1/3rd the distance of a cruise missile and IIRC the 64MJ version has a range around 2/3 the range of a cruise missile. Not only that but the projectile cannot be shot down as no weapon could catch it, nor even if they could (fired head on) would the interceptor be able to stop it as the kinetic energy of the blob of metal would simply disintegrate anything that tried to stop it with almost no deflection of the weapon. Not only that but the railgun offers extremely high energy on impact, far in excess of the 500-2000lb bomb on cruise missiles. I've heard estimates that place the energy release on impact with that of around 15000lbs of TNT, the explosive energy release is huge but the big blob of metal becomes millions of small pieces of metal that fly in every direction along with rocks and dirt moving at ultra high velocities from the impact site. And above all this the railgun projectile is under $500 in comparison to the $1 million dollar tag for the cruise missile.

      The railgun essentially allows the USN to toss moderately sized meteorites at enemies. Whenever a naval article comes up everyone likes to talk about how vulnerable the USN is because of Sunburn and other antiship missiles. What they fail to realize is that once the DDX destroyers come online the fleet wouldn't even need to get in sunburn range to absolutely destroy even fortified coastal positions. Take a couple DDX destroyers and the new CDX carriers and you have a fleet that can sit 400 miles off the coast and bombard all the coastal defenses into oblivion before moving further in to bombard the cities and fortifications further in from the coast. The railgun projectiles also have extreme penetration, they can cut through 10's of feet of reinforced concrete with ease, and even underground facilities become susceptible as 10 projectiles could likely cut a massive hole and penetrate buried facilities that could then be followed up with bombs dropped from planes. There is also another advantage, cruise missiles aren't effective against mobile targets because it takes so long for them to get there, at mach 8 the railgun projectiles flight time is extremely small, along with the no advanced warning (no sound preceding impact) gives the projectile a much better chance at hitting mobile targets without having to use manned aircraft.

      The USN is also trying to find guidance systems that can survive the G forces in the hope of having some minimal guidance.
  • Obligatory (Score:4, Funny)

    by DeadDecoy ( 877617 ) on Monday January 28, 2008 @04:26PM (#22212246)
    They need to attach some focal confirmation for when you hit the target:
    Headshot!
  • by Anonymous Coward on Monday January 28, 2008 @04:26PM (#22212254)
    Let me know when the flux capacitors get fully charged...
  • So who'll be the first genius to fling a toilet bowl through it?
  • Oblig (Score:5, Funny)

    by MobileTatsu-NJG ( 946591 ) on Monday January 28, 2008 @04:28PM (#22212292)
    A spokesman for the Iranian Navy was reported as saying ..."Camping faggots!"
  • Newton (Score:5, Funny)

    by dorix ( 414150 ) on Monday January 28, 2008 @04:28PM (#22212294)
    It's also capable of propelling ships in reverse at speeds of up to Mach 3.
  • by koa ( 95614 ) on Monday January 28, 2008 @04:29PM (#22212312)
    As far as I can tell- the article mentions nothing about the types of ammunition they fire with this- however upon closer inspection,
      I may have found a clue:

    "Installation of the laboratory launcher is currently under way"

    Seems like a waste of some perfectly good laboratories!
    • Re: (Score:2, Funny)

      by Anonymous Coward
      That's just a cover-up. The production model is going to launch lavatories, but since that's biological warfare, they can't just call it what it is.
  • and what colour trail did the Navy pick?
  • by cthulu_mt ( 1124113 ) on Monday January 28, 2008 @04:30PM (#22212336)
    God, this is why I love being an American.
  • by Anonymous Coward on Monday January 28, 2008 @04:30PM (#22212348)
    No one needs more than a 64-megajoule rail gun.
  • Space Gun (Score:5, Interesting)

    by Doc Ruby ( 173196 ) on Monday January 28, 2008 @04:31PM (#22212370) Homepage Journal
    Mach 8 [google.com] is about 9800KPH. Escape velocity [wikipedia.org] from the Earth's surface is 40,320KPH. This gun is already firing at over 24% of escape velocity. A 64Mj gun would be almost 50%; a 132Mj gun would shoot projectiles right into orbit.

    I wonder whether coming generations of this gun could shoot unmanned exploration vehicles or satellites out into space. The Pentagon will probably try to use it just to shoot down spacecraft, but instead we could use their budgets to increase space industry and exploration.
    • Re:Space Gun (Score:4, Interesting)

      by afidel ( 530433 ) on Monday January 28, 2008 @04:40PM (#22212520)
      The problem with using a railgun to launch anything but raw materials into space is acceleration. If you have to impart enough energy into the object over a track that at a maximum is a couple kilometers long you're going to be impacting too many g's for much of anything to stand up to.
      • by Quila ( 201335 ) on Monday January 28, 2008 @04:56PM (#22212786)
        An article a while ago had a plan for a circular track a few miles wide. The launch vehicle would be magnetically accelerated along the track and on the last trip around be diverted to a straight launch rail for that last bit of acceleration to target. It was still quite a few gees sideways going around, but a lot less than achieving orbital velocity in a short straight acceleration.
        • Re: (Score:3, Interesting)

          by Doc Ruby ( 173196 )
          A circular track could accelerate the payload gradually around a lot of cycles, rather than stress it with high-G acceleration.

          What if the payload were also spiraled around its axis that's parallel to the circle, as it's accelerated along that axis. Wouldn't that neutralize the centripetal effect on the payload, so the total acceleration wouldn't damage the contents of the payload?

          Of course a little turbulence in the barrel could really wreck things, and humans would get scrambled. But an evacuated barrel a
    • Re: (Score:3, Informative)

      by CodeBuster ( 516420 )

      I wonder whether coming generations of this gun could shoot unmanned exploration vehicles or satellites out into space.

      This has been considered many times over the years and some startups are even working on some pie in the sky concepts, but basically there are two (2) major problems with the gun-type or single energy input launch mechanisms. First, the package being launched has to be hardy enough to survive the massive acceleration G forces and shock of hitting the atmosphere at orbital velocity right from the start (i.e. sea level) which brings up the second point. The package must also be able to survive a trip through

    • Re:Space Gun (Score:5, Informative)

      by Cochonou ( 576531 ) on Monday January 28, 2008 @04:43PM (#22212572) Homepage
      Kinetic energy equals mass times speed squared.
      Deploying twice the energy should only send the projectile 1.4 (the square root of two) times faster.
  • Looks nice (Score:5, Interesting)

    by OeLeWaPpErKe ( 412765 ) on Monday January 28, 2008 @04:33PM (#22212400) Homepage
    I wonder how many times this thing can be fired. They need to get 32 megajoules of energy out of the gun, and without the metal that this power passes through melting. That's not an easy thing to do.

    Railguns today tend to melt after each shot, leaving one to replace the rails (the biggest, conducting the part of the gun, the bit in contact with the "bullet").

    I wonder what the efficiency is. 32 megajoules come in, how many leave in the bullet. (Generally they only get about 2%-5% efficiency).

    An alternative, easier and safer, is a coil gun. Here's a nice index of coilguns : World's coilgun arsenal [coilgun.ru]. But like their railgun brothers, they're not very efficient. The very best of them have the bullet speed of a mini handgun, but they're trivial to make, and rely only on batteries and metal.
    • Re: (Score:3, Interesting)

      Could they not use ceramic rails rather than metal ones? The input efficiency of the gun appears to be 40%. (The 64 MJ weapon needs 16 MW of power firing every ten seconds = 6.4 MW / 16 MW.) Too bad they don't specify the kinetic energy of the projectiles.
  • by sakdoctor ( 1087155 ) on Monday January 28, 2008 @04:37PM (#22212476) Homepage
    I don't know if World War III will be fought with railguns or belt-fed airport screening devices, but World War IV will be fought with sticks and stones.
    • Re: (Score:3, Funny)

      by xleeko ( 551231 )

      I don't know if World War III will be fought with railguns or belt-fed airport screening devices, but World War IV will be fought with sticks and stones.

      No, no ... you got the quote all wrong.

      "World War III will be fought with radioactive Monkey-Snake Hybrids, World War IV will be fought with watermelons and trebuchets, World War V will be fought with intelligent berzerker cheeses, and World War VI will be fought with sticks and stones ... the size of planets!"

  • It's all fun and games until someone decides to make a nuclear-capable artillery shell for this thing. Missile defense? I don't think so.
    • by AKAImBatman ( 238306 ) <akaimbatman AT gmail DOT com> on Monday January 28, 2008 @05:16PM (#22213084) Homepage Journal

      It's all fun and games until someone decides to make a nuclear-capable artillery shell for this thing.

      There are some serious problems to mounting a nuclear munition on this sucker. First off, the weight of the round currently being fired is actually quite small. The weapon would need to be scaled up by many, many fold just to fire the nuclear munition.

      Second, no existing type of warhead would survive the shock of launch. A gun-type device would detonate on launch. (NOT good.) An implosion device requires that the plates surrounding the charges that surround the plutonium core be carefully calibrated. A single charge or plate out of place and the bomb will fizzle out. Advanced hydrogen weapons are out as well, as they require an atomic explosion as a trigger. Plus, the cores of hydrogen bombs need to be kept even more precisely in place in relation to the uranium shell of the weapon.

      All in all, the only thing you'd accomplish by combining a rail gun with a nuclear warhead is to either blow yourself up or damage your highly-expensive-bomb-that-could-have-been-more-easily-deployed-with-a-super-sonic-missile.
  • by Phat_Tony ( 661117 ) on Monday January 28, 2008 @04:41PM (#22212544)
    I had a physics teacher who used to work at Los Alamos who did some consulting for the military on the side. In the late 80's/early 90's, they had him evaluate the results of some rail-gun tests. They were shooting a small ball projectile at tanks. The projectile left a perfectly round smooth bored hole all the way through the tank, wherever it was fired. The military wanted to know if they could use this to disable things (fire through the engine block) without destroying other things (people, electronics, paperwork, whatever) inside.

    In evaluating it, they found that the internal air temperature flashed to something really high (like an oven) in the microsecond the ball travelled through, and that the vaporized steel from the first surface of the tank would kill everyone in the compartment.

    It brings home what kind of speeds we're talking about here.

    I'm waiting until they start listing the speeds of rail guns in terms of [decimal]c. Full of relativistic goodness. Of course, if they're only at Mach 8, they've got a way to go. The X-15 was near mach 7 and the scramjet tests have hit mach 10, and I'm sure those were more massive than the rail gun's projectiles.
    • Re: (Score:3, Informative)

      by San-LC ( 1104027 )
      I remember watching a movie called the Pentagon Wars where they were dramatizing the tests of the M2/M3 Bradley Fighting Vehicle. In it (based on a true story), they tested the aluminum armor plating by launching an anti-tank warhead against it and seeing what would happen inside. They used sheep in the place of humans, and all of the sheep were killed via overheating due to the internal air temperature flaring up.
  • by jollyreaper ( 513215 ) on Monday January 28, 2008 @04:48PM (#22212646)
    Are these things going to be turret-mounted like with battleships or will the rail have to be as long as the ship, requiring the whole vessel to turn to align the weapon?
  • Vs Light Gas Gun? (Score:4, Informative)

    by IdeaMan ( 216340 ) on Monday January 28, 2008 @04:50PM (#22212688) Homepage Journal
    I think the jury is still out on whether rail guns or light gas guns [astronautix.com] will be the next step.

    Let me list the current advantages/disadvantages:
    Rail Gun:
    + Simple firing mechanism (Two rails, one plug, massive juice)
    +Very little muzzle flash
    +Very rapid fire (Gatling configuration to spread out heat on rails)
    *Acceleration limited by current carrying capability of rails.
    - Complex/heavy electrical system (Banks of caps + power supply to charge them)
    - Rail wear
    -Heavy projectiles increases support structure significantly

    Light Gas Gun:
    + Heavy projectiles scales up rather well.
    * Medium complexity (More complicated than Gatling mechanism)
    * Acceleration limited by maximum chamber pressure.
    - Bore wear
    - HUMONGOUS muzzle flash (hydrogen combusting)
    - Medium rate of fire.

    Bottom line: Flechettes: Rail gun; Sub Orbital or ship killer: Light Gas Gun

    Currently light gas guns emit a huge fireball out the end of them, which may tend to limit their use for a shoulder fired weapon (anti-tank, anti-air). On the other hand it is a lot easier to store and release obscene amounts of energy in a gas or powder than in electrical form. I would imagine porting the barrel would allow recovery of some of the hydrogen.

    One advantage the railgun might have is it might allow different projectile shapes like fins that would be difficult to achieve with a light gas gun.

    We should be using light gas guns to ship fuel up to the bottom of a chain of a LEO space elevators.

  • Amps != Power (Score:5, Informative)

    by BlueParrot ( 965239 ) on Monday January 28, 2008 @04:54PM (#22212760)
    Ampere is a measure of current, not power.

    To put it this way, the European Spallation Source is a planned particle accelerator which is planned to have a proton-beam current in the range of a few milli-ampere. That is, comparable to the current drawn by your LCD monitor in standby. The catch is that ESS will be using proton energies up to a billion electron volts, thus making the power output of the accelerator comparable to a small nuclear reactor.

    You can NOT quote power in terms of ampere without specifying the voltage. Conversely I've generated several thousands of volts using my bare hands and a piece of nylon, but because the current was rather small nobody noticed.

    What is even more interesting is the time over which you can sustain a given power output. Over at our physics department we have lasers with power outputs beyond all the worlds nuclear reactors taken together. The pulse doesn't last very long however...
  • Watts! (Score:5, Insightful)

    by Roger W Moore ( 538166 ) on Monday January 28, 2008 @04:59PM (#22212830) Journal
    Eight and 9-megajoule rail guns have been fired before, but providing 3 million amps of power per shot has been a limitation.

    I agree. This would be extremely hard to achieve since amp is a unit of current. The problem is not that but rather that in combination with the voltage required to drive it.
  • Respawn... (Score:4, Funny)

    by Misch ( 158807 ) on Monday January 28, 2008 @05:09PM (#22212956) Homepage
    The editor who posted this was fragged with the BFG, but respawned this article [slashdot.org] a few days later.
  • Interesting Facts (Score:5, Interesting)

    by timias1 ( 1063832 ) on Monday January 28, 2008 @05:11PM (#22212988)
    I sat next to one of the directors of the Navy's rail gun program, during a flight to Boston, and I had one of the most interesting talks with him. The projectiles fired experience about 30,000 g's of acceleration, compared with 12,000 g's for a conventional gun. The major problem is that about 20% of the g's are experienced laterally because the projectile bounce when it is traveling down the rails. The projectiles do not contain explosives, because the kinetic energy is enough to do some pretty good damage. The materials problem with the rails was solved a while ago, and they need to survive for about 1000 shots to be comparable to today's guns. They also don't store the energy for very long before firing, because of losses and safety.

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