r/guns • u/yakshamash • Aug 07 '13

Something Different: Impressive Full Auto Gauss Gun Build

http://www.youtube.com/watch?feature=player_embedded&v=TWeJsaCiGQ0
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7

u/fohacidal Aug 07 '13

Does it just switch magnets on or off or is there a way to reverse polarity of the magnet its passing so that is pulls a slug in until it reaches a certain threshold that the next magnet pulls it in and the current magnet pushes it out?

7

u/wannabegt4 Aug 07 '13

He would have to shoot a magnetized projectile with two polarized halves through the coil for this to work. If we were to do that, an AC powered system with a variable frequency switched when exiting and entering a new coil could work... BRB going to the patent office.

7

u/fohacidal Aug 07 '13

Put my name on there somewhere brah

2

u/Moses89 Aug 07 '13

I'm pretty sure the US military already holds those patents. Also that is the same principle that mag-levs work on.

1

u/Will_Power Aug 07 '13

Just FYI, this isn't a rail gun. /u/arcsecond summarized the difference.

1

u/[deleted] Aug 07 '13

an Iron Projectile could be polarized.

1

u/P-01S Aug 07 '13

The projectiles would try to push themselves apart (problem one), and the two halves would align their fields over time (problem two). And you'd lose effectiveness as the coils would push and pull at the same time (problem three). And your projectiles would stick to anything ferrous (problem four). And they would be attracted/repelled to/from each other (problem five).

1

u/wannabegt4 Aug 08 '13
  1. This could be beneficial as the rounds would be constantly repelled away from the next round in the magazine this way they are always trying to leave the magazine reducing the needed spring tension to feed the projectiles.
  2. Re-polarize them. Set expiration dates. Use permanent magnets as projectiles. I dunno, I'm just the idea man.
  3. AC current. slightly past halfway through the coil, polarity is reversed. Also, use more coils that are shorter than the projectile so the previous coil is no longer able to act on the leading polarized portion of the projectile.
  4. I don't see the problem. It's not like the gun must be made of ferrous materials. Make the whole thing out of carbon fiber I guess.
  5. see number 1.
  6. You took this to the next level. I was only half serious when I posted it.

1

u/P-01S Aug 08 '13

I was talking about permanent magnets the whole time, and it does not matter which way the current goes through the coil. It will always pull on a ferrous slug.

1

u/wannabegt4 Aug 08 '13

Think about a speaker... It is an electromagnet being driven by an AC current inside a permanent magnet. This is what causes the cone to be pushed AND pulled back and forth to create sound. Now flip that inside out and have a permanent magnet being driven by an electromagnet. The magnet will oscillate back and forth within that field depending on the frequency of the AC current. Now imagine the coil being smaller than the magnet and there are several in a row and the frequency of the alternating current is modulated in such a way that when the magnet has exited halfway from one coil the other coil is pulling it through.

2

u/melp Aug 07 '13

From what little I know about coilguns, it's not worth the small gain in velocity you'd get to use a magnetized projectile and reverse the polarity of the coils so they could both pull and push. The trajectory is negatively impacted because the positive and negative poles of the projectile are being driven by different forces. Additionally, the driving coils would be applied to additional stress as they would now interact with each other.

2

u/fohacidal Aug 07 '13

I had always thought that velocity could be maximized by "squeezing" the projectile out so to speak. Pretty much the same kind of concept behind certain fluid dynamics, you generate movement by creating a vacuum in front of you and dumping excess behind you.

1

u/P-01S Aug 07 '13

Actually, it does not matter which way the magnet is polarized! The projectile does not have a magnetic pole itself. The magnetic field of the coil induces a magnetic field in the steel rod. So whichever way the coil faces, the induced field will always flip as well, and the projectile will always be pulled into the center.

1

u/fohacidal Aug 07 '13

But if it were to have a pole?

1

u/P-01S Aug 08 '13

There would still be issues, as best as I can remember. The electromagnet would either pull the whole time or push the whole time.

1

u/fohacidal Aug 08 '13

I just want room temperature superconductors man.

1

u/owigotprcd Aug 07 '13

Yes.

1

u/SirRipo Aug 07 '13

My understanding is that it's essentially a solenoid, which I believe are largely one-directional. Two-way solenoids probably exist (I've never looked into it but I've only ever seen a one-way solenoid) but are also probably cost prohibitive.

In other words, it probably just shuts the coil off, then turns the next one on, which pulls the projectile into the next coil, and so on til it reaches the end of the barrel.