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Shield system

Prevent shootings in public buildings
  [vote for,

Star Wars may be science fiction, but it yields some promising ideas if you read into it, and it allowed me to come up with this half-baked scheme: Deflector shields can be used, practically, in some applications. You need 2 or more electromagnets of the same charge, in tandem. As a shooter's bullet, which are usually made of conductive metals such as copper, steel, or tungsten passes through the first field, it picks up the magnetic charge. As it continues through successive fields, it encounters increasing resistance, dramatically reducing the damage it could do (for instance, a hollow-point bullet wouldn't hit hard enough to expand properly) and very likely altering the trajectory of the bullet. With the emerging nanotechnology of today, I don't think it's inconcievable that one could be built small enough to use in, say, banks and courthouses and the like. Just put it in front of the people it's intended to protect, like judges, cashiers, etc. It would also slow down any shrapnel that may occur from bombings.
21 Quest, Jan 13 2006


       Ok, I admit I don't much about metallurgy, but the point is the same. Copper is ferrous, and is used as the jacket. Slowing this would slow the bullet regardless of what the bullet is made of, and if it came off, it would f*** up the bullet's trajectory. If you have some constructive critcism, please share it with me. I'm always open to new ideas.
21 Quest, Jan 13 2006

       [Marked-for-deletion] Bad science. The writer--as he freely admits--"don't much about".
ldischler, Jan 13 2006

       //Copper is ferrous// It is? I thought it was cuprous

//It would also slow down any shrapnel// And probably a few cardiac pacemakers.
AbsintheWithoutLeave, Jan 13 2006

       It wouldn't mess with pacemakers unless the person with the pacemaker crossed into the field. Reaching your arm across the counter, where it would be, wouldn't put you in harm's way. Anyway, there would be signs posted. Sorry I offended so many people. I'm kinda new here, and I thought from the name of the place ("halfbaked") it would be a little more accepting. It's not like I'm seeking a patent or anything. Just an idea is all.
21 Quest, Jan 13 2006

       Just be glad you can spell.
moomintroll, Jan 13 2006

       //It wouldn't mess with pacemakers unless the person with the pacemaker crossed into the field// How do you contain a magnetic field?
AbsintheWithoutLeave, Jan 13 2006

       Look, I know my research into this is shoddy on a good day, but that's because I haven't taken time to research it yet. It just sort of came to me earlier today. That's why it's called "halfbaked" right?
21 Quest, Jan 13 2006

       I haven't researched it much, but from my limited understanding of magnetics, it wouldn't need to be contained, if it was focused properly. magnetic fields only reach so far, which is why the magnets on your refrigerator have to be put close enough by hand to grab on to it. I'm talking about a focused, straightline magnetic field, and I know that is possible.
21 Quest, Jan 13 2006

       Quit digging...
AbsintheWithoutLeave, Jan 13 2006

       /As a shooter's bullet, which are usually made of ferrous metals such as copper, steel, or tungsten passes through the first field, it picks up the magnetic charge./

       [21] is right. Any conductor passing through a magnetic field will develop an electrical current which produces another magnetic field, opposing the external one. It does not need to be ferrous (copper is not). So, I would expect that a copper bullet moving through a magnetic field would slow down faster than a ceramic bullet in the field, or the same copper bullet without an external field.

       This would be a fun science project for a student with access to an MRI. Maybe you could use an array of permanent magnets instead of the MRI. One could experiment with various nonferrous (!) beads and a straw. You would shoot them like a peashooter (perhaps with a standardized puff of air) and see how far down the MRI tunnel they would go. One would predict that turning the MRI on would slow copper or aluminum beads, but not clay or plastic beads. If so, a cool corollary would be to have two similar beads, one of crumpled aluminum foil and the other the same, but with the foil sandwiched in waxed paper. The waxed paper should prevent current loops and thus prevent the development of an induced magnetic field.

       I am sure the physics of this could be worked out. I suspect that the magnetic repulsion from the field produced by the bullet would be very small compared with the kinetic energy of the bullet. Thus the external field meant to slow the bullet would have to be very large or very strong. I bet with a strong set of lungs, you could still get the copper bead a fair distance down the active MRI.

       It is hard for me to imagine how this could be applied to, say, soldiers in Iraq. I can imagine it used to defend against space debris. Imagine a set of hoops around a station. A projectile entering hoop1 crosses a laser, discharging a capacitor into the hoop2. This produces a very strong and short lived field just as the projectile enters hoop2 - possibly slowing it enough to decrease damage.

       Do not be discouraged, [21]. Do not quit digging, ever. This idea is squarely within the strike zone of the bakery. Keep up the good work.
bungston, Jan 13 2006

       // That's why it's called "halfbaked" right // I've always thought of that as referring to the dubious nature of the need being fulfilled, or the dubious practicality, but never the dubious nature of the science. In general, as long as you're not breaking any scientific laws, you're okay.
Welcome to the HB, by the way!
moomintroll, Jan 13 2006

       " squarely within the strike zone of the bakery "

       I like that concept. In baseball, the strike zone is anywhere between the knees and shoulders of the batter, as long as the ball is also over the plate.

       How would one define the strike zone of the halfbakery? Anywhere between the ears ?
normzone, Jan 13 2006

       I was thinking more about the science fair aspect of this. It would be slick. Imagine a Nerf rocket launcher or some similar standardized way of launching a low velocity projectile. The Nerf rocket would be good because they are light, cheap, not dangerous and would avoid the problem of wild throws. The projectile travels thru a large ring of wound copper wire. An off the shelf motion detector is in front of the ring, with a piece of cardboard so it detects motion only in front of the ring. When tripped, the motion detector sends electricity thru the ring (probably from a car battery).

       People visiting the exhibit would try to send a series of objects through the ring to hit a target. With the motion detector on (if this works), it would not be possible to hit the target with conductive projectiles: they would fall short as though they hit an invisible wall of goo. You would need to wrap some Nerf rockets with copper foil, aluminum foil etc.

       The slickness of this and the participation factor would outweigh pedantic concerns (e.g.: see previous annos) about applicability.
bungston, Jan 13 2006

       Isn't this the same principle as a rail gun, but in reverse?
egbert, Jan 13 2006

       It is the same principle as a coil gun, in reverse. Except coilguns need a ferrous / magnetic projectile. Railguns are different. I think. Or maybe not.
bungston, Jan 13 2006

       A rail gun uses a non-ferromagnetic projectile (induced eddy currents), whilst a coil gun uses a ferromagnetic one ( magnetic attraction).
I once attended a schools lecture by Prof Eric Laithwaite, and saw an aluminium bolt driven hard into a block of wood by one of his motors, but I don't see this working without the use of huge superconducting magnets with the sorts of energies and separations you'd need in a deployable system .
So yes, halfbaked, but a hint [21 Quest], never admit ignorance to an HBer -it is like acting fearful near a dog - they can smell it, and they'll go straight for your throat, without any of the sniffing or leg humping.
coprocephalous, Jan 13 2006

       He understates the problem. There's plenty of leg-humping goes on around here, it's only that some of us don't mind, some are offended, and some of us - Hey, get down, get down!
normzone, Jan 13 2006

       I like it - dogs smell better
po, Jan 13 2006

       /A rail gun uses a non-ferromagnetic projectile (induced eddy currents), whilst a coil gun uses a ferromagnetic one ( magnetic attraction)./

       Really, then, this is like neither. It uses induced currents, but repels because of the induced magnetic field.
bungston, Jan 13 2006

       //it picks up the *magnetic charge*// Not just shoddy research; had you ever taken a physics class your grade would have been a fatal flogging with a snake-hair whip.

       You can pick up an *electric charge* by emerging from the process with a surplus or deficit of electrons. Magnetism is not a *charge*, it is a measure of field strength contributed by orderliness of crystalline molecular domains, and you don't generally obtain it in a fly-by.

       Anyway, throw out "ferrous" - just make it "conductive". A conductor in motion in a magnetic field will generate an electric current. Usually this is passed into a wire to use the electricity outside the conductor in which it is generated, but you could just leave it there. The current will flow around the inside of the conductive projectile in the largest uninterrupted loop possible perpendicular to the magnetic field lines cut by the projectile. Whatever heat this generates is subtracted from the kinetic energy of the projectile. The eddy loop size is of great importance here. For example, the motion of a metal plate pendulum swinging in a magnetic field will be damped much less if you cut slots in the plate. Thus, if the projectile were an aluminum frisbee, thrown perpendicular to the magnetic field, the effect would probably be noticeable. Turn it edgewise, it would be negligible. A copper bullet? Barely warmed.

       //emerging nanotechnology// ain't much use in building a big-assed magnet.
lurch, Jan 15 2006

       Not a bad idea, I've seen stuff like this done before, but on a much smaller scale.
MikeOxbig, Jan 17 2006

       I think this is a perfectly appropriate halfbakery idea and disagree with the MFD.

       Yeah, it'd probably require ridiculous power and still not work well but it might work a little.
bristolz, Feb 01 2006

       This is the first honest-to-god workable shield I've ever seen. BUN! BUNBUNBUNbunbunbunbunbunbun, bun bun BUNBUNBUN damnit!
Voice, May 24 2007


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