Rail Gun How To (Pictures included)

Discussion in 'Off-Topic' started by maxpower097, Feb 29, 2012.

  1. maxpower097

    Thread Starter Well-Known Member

    Feb 20, 2009
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  2. hwy101

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    May 23, 2009
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    Yup, saw that on Discovery channel 2 weeks ago, I want one :)
     
  3. Sparky49

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    Jul 16, 2011
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    I've always thought of BAE as a cutting edge manufacturer.

    Amazing stuff.
     
  4. Wendy

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    Mar 24, 2008
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    Have some neighbors that are giving us problems, are we?
     
  5. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    Rail gun? Looked explosive based to me. Why all the fire out of the barrel?
     
  6. maxpower097

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    Speed of the projectile might catch the oxygen on fire if its that pressurized. Think about the friction of an object going 6000mph just in the air. Look at the space shuttle, that gets glowing hot in space. Not that thats the answer but I'm sure its something like that. Read the comments and I'm sure some nerd knows.
     
  7. Wendy

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    Actually it is the plasma caused by both the intense magnetic fields and some electrical discharge. It would burn you just like power, if not worse. I is much hotter I believe.

    Anytime you pack enough energy in a small space, there will be plasma. Fire is a type of plasma, this is electrical discharge plasma.
     
  8. hwy101

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    May 23, 2009
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    ha ha ha, right on target Bill
     
  9. Wendy

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    Really, I thought that was them?
     
  10. magnet18

    Senior Member

    Dec 22, 2010
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    Hobbyists can build these, though theyre generally only good for one use before the rails need repaired, and they're a LOT smaller (32gJ of energy in any form in a civillian setting would have the feds all over it, considering that it's more than enough energy to level an entire block)
    I'm also very glad that the navy is considering using these, definatley a step in the right direction for a science "fiction" filled future :)

    as for the fire, you're moving a large object extremley fast using gigajoules of energy; somewhere in the process theres going to be massive amounts of heat, creating plasma/fire/smoke/explosion
     
  11. Wendy

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    Please note that as far as AAC is concerned they are taboo. They are specifically mentioned in the ToS. There are many sites out there that cater to them though. There is no lack of information.

    If super caps ever become real in a large sense then there will be firearms based on the technology. There are super caps, but they tend to be limited at this time.

    It helps that the navy tends to have on board nuclear reactors on their larger capital ships. When rail guns are ready for prime time they will have a long reach, they are actually a form of artillery. They would also make excellent anti satellite and anti air craft weapons.
     
  12. steveb

    Senior Member

    Jul 3, 2008
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    Yes, the main limitation of supercaps is that they are low voltage devices. There may also be some dynamic issues with very short pulse times, but I'm not sure about that. However, they can provide hundreds of amps of current in short bursts.

    One of the latest supercaps can store over 13 kJ of energy. That is impressive since it weights 7 oz and has 10 times more potential energy than the kinetic energy of a 44 bullet. Still, dynamite has 100 times the energy density of this supercap. Since energy in a capacitor is proportional to voltage squared, the supercap is about 1 order of magnitude too low in voltage to be a practical replacement for chemical energy in small scale weapons. - and, there are other practical issues too.

    Speaking of capacitors, I hope everyone takes notice of the capacitor stacks you can see in the background at about 20 seconds into the video. Even on a nuclear powered ship, those special capacitors are the only way (well maybe a flywheel and generator could do it) to get that much electrical energy transfered in such a short burst. Consider that a ship needs a nuclear power plant, a huge capacitor stack and a highly advanced rail gun design to exceed the capability of a simple explosive shell in a cannon. The additional capability makes it worth it, no doubt.
     
    Last edited: Mar 1, 2012
  13. joeyd999

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    Jun 6, 2011
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    Ok. But something doesn't make sense.

    If the projectile is truly hypersonic, there should be a nearly perfect vacuum on the trailing edge of the projectile. No air, no plasma, no fire. Additionally, there should be plasma evident on the leading edge due to ultra-high gas compression.

    Perhaps the 'plasma' temperature on the trailing edge is hot enough that its local speed of sound exceeds that of the projectile (speed of sound in air ~330m/s + 0.5 m/s/°C), thereby negating a vacuum, but that still doesn't explain the lack of plasma on the leading edge, especially since this is purposefully a 'non-aerodynamic' projectile.

    FYI, I've never seen before a hypersonic projectile, so I am basically pulling this out of my butt. But it didn't meet expectations...

    One thing that is *really* neat about the video is you can clearly see the change in the index of refraction of air due to compression (and/or heating) as the projectile passes through it.
     
  14. maxpower097

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    They been dreaming of rail guns my whole life. I remember all the sci fi dungeons and dragons crap had em. So you know all those guys making it have dreamed of this since 85.
     
  15. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I've been dreaming of rail guns ever since Mike suggested we throw rocks at 'em.



    (The Moon is a Harsh Mistress: well worth the read)
     
  16. magnet18

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    Dec 22, 2010
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    plasma actually forms best in a low pressure environment, look at farnsworth fusors
     
  17. Wendy

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    Beat me to it. Whenever you want to make a plasma easily, as in florescent lights, neon tubes, whatnot, you need low pressure. However, enough voltage will beat anything, as in thunderstorm lightning.
     
  18. maxpower097

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    Well every explosion forms a vacuum and implosion. Just look at the old Vietnam bomb videos of the wind blowing all the trees out, then sucks them back in real quick.
     
  19. magnet18

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    Dec 22, 2010
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    yep
    the explosion and massive release of energy pushes all the air away, then suddenly the explosion is over and it all rushes back in
     
  20. maxpower097

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    I read somewhere that this shockwave is actually what causes the most casualties in an explosion like that. I guess the force hits you so hard it damages your internal organs. Like when people die from getting shot with a shotgun even though the slug or pellets didn't hit anything vital. The brute force of the shotgun shell hitting the body destroys the internal organs.
     
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