Coil Gun?


June 20, 2006, 04:31 AM

The term DIY is used pretty loosely here, so don't go looking for instructions or the like... but basically is this a working version of a Coil Gun, a close relative of the Gaussian Rail Gun. Better yet, they seem to be getting effective vellocities out of a platform the size of a Desert Eagle or Mk. 23 or somesuch. :)

To be honest, this looks really cool to me. Would one of these even fall under the definition of "firearm?" Would it be a feasible project for one to do at home, if one were to find out how?

And it looks like it's got a few advantages over standard firearms as well... no lead dust, much quieter, ammunition isn't a fire hazard by any stretch of the imagination...

What do y'all think?

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June 20, 2006, 04:44 AM
Very cool. I'd like to see something bigger.... like on a tank. Or mounted on an orbital weapons rig. I could be fired in a vacuum, therefore it could be the future of space combat. That idea has been thought of before in quite a few sci-fi books and movies. The first one that comes to mind is the X-files episode "Kill Switch."

June 20, 2006, 04:44 AM
They're a great idea, but much like laser guns, are hamstrung by the lack of a stable, portable high-energy reservoir to power them.

I do look forward to lasers and eventually electromagnetic guns being deployed more widely though, probably down to the level of running off of the generator of a modified transport vehicle.

June 20, 2006, 04:45 AM
The trick to making Guass/coil/railguns effective small arms is the power supply. Like lasers and even particle beams, they're very possible, but providing the juice is the trick.

They'd have many advantages, though. Very quiet, compared to guns. Adjustable muzzle velocity. And very few moving parts. The most complicated part of the weapon would be the feed device and power source.

June 20, 2006, 04:49 AM
What about capacitor technology? Are there any out these that could recharge to full capacity fast enough to ensure a decent rate of fire? I'm thinking of including everything from SMGs to HMGs here. :D

And, going further, what about cooling issues? Something tells me that this easily has the potential to heat up faster and hotter than a standard firearm.

Jim Watson
June 20, 2006, 09:06 AM
There is some work being done in capacitor design to the point they are being considered as battery replacements in low drain - long life use like a computer. But you still have to charge the capacitor from somewhere. OK for a vehicle mount, I guess, but for a sidearm you would need a loooong extension cord. Waste heat would probably be a problem in rapid fire.

I doubt the coils would drive a projectile through a rifled barrel and don't see how you could wind the coils to induce stabilizing spin. So shoot fin stabilized fletchettes or round balls.

June 20, 2006, 09:24 AM
My understanding is that they are the same thing as a linear DC motor. Just bigger. In a liner DC motor the coil(s) can be atached to a series of rails (maby 6 of them) and if the rails happen to he spun around, that should mimic a rifiled barrel.

June 20, 2006, 10:25 AM
What about rifling the projectile itself, like a rifled shotgun slug?

Or somehow making a multiple-material projectile, and placing ferrous material in certain places within the projectile itself. The interior of the barrel has only certain points exposed to the magnets in a rifle-like spiral, thus spinning the projectile...

(something I just whipped up in MSPaint, and added lighting effects in Photoshop)

How 'bout it? :)

June 20, 2006, 10:56 AM
There are a lot of sites dealing with this. A lot of experimenters of which some share and some do not.

Rail guns are not coil guns and do not work on the same principal but both require huge amounts of stored energy and high efficiency capacitors and switching systems. For both systems what they need is power, with a high density electric storage system equal to or better than gasoline with a high discharge rate. Baring that then a low discharge rate feeding high efficiency, high discharge current capacitors. I think you'll see a big rail gun system first, the Navy seems to be pushing for it so they may know it's very close to becoming deployable or they just really really want it. ;)
The rails of a rail gun are the limiting factor, they are eaten up in most of the systems experimenters are working with. There are various means to combat this but it's a problem. There are some interesting departures from the 'puck must move down rails' to the billiard approach of 'plasma moves down rails and slams puck throwing it to target' which seems promising based on a study done I think for the military or Darpa.

The DD(X) all electric warship should have the capacity to run a rail gun. If it were nuclear as some want it would easily run one with loads of capacity to spare. The Navy figures about 240 miles and at least a kiloton energy equivalent delivered for projectiles from a rail gun. Couple that with slug throwing coil guns capable of rediculous rates of fire for anti-missle and anto-aircraft use and it would be one tough b*tch of a ship and all the nuclear one would need to carry is the right bits of metal for them, no propellant needed, no explosive needed in the warhead.
Coil guns are tougher and may get up to standard rifle velocities. Once that's worked out accuracy can be addressed. Benefits of a coil gun are no barrel/rail wear and the potential for impressive range, rate of fire and accuracy and with proper design it has the potential to be dead quiet other than the supersonic or hypersonic crack.

June 20, 2006, 11:02 AM
And, in time, even that might be overcome with an electonic muffler. :) Muffler picks up the sound, and nearly instantaneously emits the opposite waveform at the same intensity, which nearly silences the sonic crack. Kinda like electronic shooting muffs.

June 20, 2006, 11:18 AM
I'm not sure when the crack happens but if you can calc that well enough it would cancel it. Timing errors, temperature, humidity all make that unlikely. :(

June 20, 2006, 11:22 AM
What happened to the Russian gent with the Gauss pistol and rifle?

Jim Watson
June 20, 2006, 12:02 PM
1. Electronic shooting muffs do not work on phase cancellation. A gunshot is an impuse and by the time the circuit could generate an out of phase signal, the shot has come and gone. Muffs simply shut down or reduce amplification when the impulse is detected.

2. The supersonic crack of a projectile launched from an EM gun could not be "muffled" by phase cancellation, either, because it it generated as a shock wave down the entire track of the bullet, departing rapidly from the "muffler."

the naked prophet
June 20, 2006, 01:41 PM
Some electronic shooting muffs do work on phase cancellation. Sound is very slow, especially compared to electronics. They simply place the microphones on the outside of the muffs, and the speaker on the inside. The outside microphones detect the noise, and by the time the noise gets to the inside, the speaker is ready to cancel it.

As to the energy supply problem, small arms could be made to work by using fuel cells. That's what I work on. Even a low energy density fuel like butane or alcohol has 5000 times more energy per volume than a battery. A small fuel cell in the weapon could generate energy, and all you would need to do is insert a small fuel tank.

June 20, 2006, 04:00 PM
What about capacitor technology? Are there any out these that could recharge to full capacity fast enough to ensure a decent rate of fire? I'm thinking of including everything from SMGs to HMGs here.

Charge time isn't changed by construction. RC= tau... 5*tau= full charge. Where in R=resistance, and C=capacitance.

June 20, 2006, 04:29 PM
Wow. That is just too cool for words. I have a little extra money and just might have to build one of these. Near as I can tell it's not a firearm. But I won't go walking around NYC with it :p

June 20, 2006, 05:53 PM
Now y'all went and done it! I'm of course going to try this at home. :D

June 20, 2006, 05:54 PM
I heard somewhere that the US Navy had a destroyer or something around that size with a turret-mounted railgun.

Allegedly, the ship has the gun, a generator for powering it, and that's about it for defense.

One thing, would a railgun be an ideal weapon for launching nukes? It shouldn't be a great leap to program airburst capabilities into the warheads, and it wouldn't be as easily detected as an ICBM.

(I just got in from doing a show, so I may be talking complete crap here. Apologies.)

June 20, 2006, 05:56 PM
Could one write a program that calculates the inverse wave-form, given variables such as ambient temp, humidity, projectile velocity, etc.? Maybe even give it a rudimentary AI so that it could predict the correct waveform based on previous events... of course, it would require a "break-in" period, but that isn't a problem if it's fun to fire. :)
From a conventional firearm, though, how much of the report is the sonic crack, how much of it is the propellant burning, and how much of it is action noise?
How much do the ratios vary from caliber to caliber?
Is a sonic boom the same across the board, or is it louder with, say, an object moving 3 Mach as opposed to one moving only 2?

Also, how would recoil be different? The phrase "equal reaction for every action" comes to mind, but I can't really see how it would have much, given that there's apparently nothing for the projectile to push against... :scrutiny:

Also, could one incorporate a laser guidance system that uses a standard high-grade visible (or IR for low-light use) laser (or two) to determine distance and an anemometer to determine windage? With these factors, plus input regarding projectile weight and velocity, a set of servos could automatically adjust POI... no more sighting-in required. Back-up sights would still be a good idea, of course.

How would one go about a feeding system? A few come to mind...
1) Cloth belt-fed. An electric motor works the feeding system, and an electromagnet pulls/ pushes the projectile out of the loop into the chamber. The EM disengages and retracts to pick up another projectile during launch. If timed correctly, a rate above a multi-barreled cannon is quite possible if one can keep it adequately cool.

2) Gravity-feed/ hopper. Since there's no "primer end" to really speak of, this is a bit more feasible, especially if both ends of the projectile are identical (like an elongated football). You could easily reload in the middle of the hopper while firing, but reliability could be an issue.

3) Magazine fed. If done right, the feed lips of the magazine could be re-worked so that the magazine actually slides into the chamber itself. Reloads like a conventional box-magazine-fed cartridge gun, but capacity is greatly limited. See below:

One thing that comes to mind with feeding mechanisms, though, are springs. Is it possible to make a spring without the use of ferrous material?

I can see someone spending thousands of dollars and weeks of time building something really cool, but on the first shot it rips itself to pieces. Or, even worse, they accidentally reverse the polarity on the coils, and the projectile is launched into the shooter... :eek: :uhoh:

it wouldn't be as easily detected as an ICBM.
Not sure about that... what temperatures might the projectile reach due to atmospheric friction? Would the radar cross-section be any different? :confused:

June 20, 2006, 06:13 PM
You can make decent springs with beryllium copper. Big $$$ tho.

Sheldon J
June 20, 2006, 06:23 PM
let me know when they make one for CCW.:evil:

June 20, 2006, 06:23 PM
What material can shield a magnetic force of 15000 Gauss (or higher), yet still be small and lighweight enough for use in a rifle-sized shoulder-fired weapon? Has anything like that even been discovered/ invented yet? :confused:

June 20, 2006, 07:03 PM
I don't know much about all this science stuff, but I do know that my birthday is only 8 months away, so you guys had better get crackin' on this. Also, how would recoil be different? The phrase "equal reaction for every action" comes to mind, but I can't really see how it would have much, given that there's apparently nothing for the projectile to push against... Sure there is. Take apart anything with an electric motor, hold the motor in your hand, and give it power. You'll feel it recoil. Electromagnetism is just like any other force. It pushes (or pulls) both ways simultaneously.

June 20, 2006, 09:02 PM
My power supply crapped out, so I used the next best thing...;) I think I may just need to play with this some more:D (Sorry about the photobucket tile-o-vision)

June 20, 2006, 10:59 PM
What is it we're seeing? Is that a car battery... ?:scrutiny: :uhoh:

June 20, 2006, 11:42 PM
It's a lead acid battery either auto, marine or special purpose. I think it's mentioned in the text.
He's not on a government budget where he can order a million dollar battery. :neener:

evan price
June 21, 2006, 02:58 AM
Any of you ever checked out MetalStorm technology? They use multiple barrels containing stacks of caseless projectiles ignited by electric impulses.
There are videos on the site of the 36-barrel prototype firing 180 rounds at 600 RPM (Sounds like Ma Deuce), 30,000 RPM (Big fart) , 60,000 RPM (Sounds like a bigger faster fart) then 180 rounds @ 1,000,000 rounds per minute. Sounds like a shotgun firing ONCE.
Neat, worth a look! Esp. the 40mm grenade video including reloading.

June 21, 2006, 04:54 AM
Any of you ever checked out MetalStorm technology?
... which isn't even remotely related to coilguns. MetalStorm is either an overmarketed gimmick, or a niche application, depending on how you look at it. Those cited figures are not sustainable - they are, in essence, single-shot devices in that once they are fired, reloading time is very significant.

A large battery of many MetalStorm platforms *might* be of limited use for things like CWIS and anti-artillery. Completely impractical for replacement of almost any other small arm.

On a side note, coilguns are not "firearms" in the legal sense. :D Better buy your high-cap, full-auto coilgun while you can!

June 21, 2006, 06:41 AM
Metalstorm is an unperfected version of the roman candle. :evil:

I've not yet heard of any products deployed by any military. I've not even heard they've got a contract for anything but R&D.

Sheldon J
June 21, 2006, 08:04 PM
Metalstorm is an unperfected version of the roman candle.

I've not yet heard of any products deployed by any military. I've not even heard they've got a contract for anything but R&D.
a genuine one shot pony, electrically timed and fired tubes just like a blasting cap, puts one massive volly out then it's all done. Sort of like a minature bank of class B fireworks in rapid fire mode.:D

evan price
June 26, 2006, 01:40 AM
Interestingly enough, all you see are prototypes... if they can get the reloading time down, then how "trick" is it? Why would a single barrel/ammo assembly be any harder to load than a BMG round? If properly designed that is. Miniguns or gatling guns would be a pretty comparable way to utilize this technology.

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