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DIY gauss rifle

catsmate

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catsmate
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A 1.25kJ model in fact. :gear_cool2:
http://gizmodo.com/5643971/watch-this-125-kilojoule-diy-coilgun-smash-household-items and http://www.popsci.com/diy/article/2010-09/video-diy-coilgun-turns-voltage-projectile-power

The battery-powered projectile-blaster took 2 years to complete, according to its creator, YouTube user Larsplatoon, and it packs four capacitor housings, a 2-volt high drain battery, and an old cell phone regulator board to keep it from overcharging.
Larsplatoon dubs it a "1.25kJ Coilgun"—that's some 78 times the amount of energy lethal to human beings—though Make points out that that's likely the capacitor's theoretical maximum output. By their calculations, 1.25kJ of muzzle energy would give the coilgun more oomph than a .45, and while it certainly has no problem tearing through those glasses, it's not exactly shattering them into a million pieces.
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By comparison a 9mm Parabellum round typically has 5-600J of KE and a 5.56mm round 1,6000 to 2,000 Joules.
 
Just because the thing's rated at 1.25Kj, doesn't mean that anything like that is being transferred to the target via the projectile.

In any case kinetic energy is a really unhelpful way to look at wound ballistics (at least for projectile weapons). All that matters is the size of the hole being poked through the body, and what vital structures it hits. The size of said hole may be increased by tumbling, and the secondary wound cavity that at handgun velocities has no effect outside of inelastic structures (e.g. brain, liver) may come into play at velocities over perhaps 2500fps.

Which is not to say that this thing isn't extremely cool. It clearly is. If we knew the mass of the projectile and the muzzle *velocity* it produces, we might be better placed to compare it to chemical firearms. Or the guy could knock up some 10% ordnance gel blocks.
 
The projectile itself has about 37J (see description in the youtube) which is not a lot. So it would not be traveling very fast. Nor would its rate of fire be very fast. So it would not make rifles obsolete any time soon. However there can be several improvements made to the gun.
 
Reminds me of a discussion that I had with a couple of friends a few years back where they were asking me (since I know a few thing about making weapons) if I could build a ‘rail gun’ (or ‘gauss gun’ as called here). In short, I worked up some calculations and then I explained to them that such a thing could be made using current technology that is available to the general public.

However, if you really want a gun that will compare to even a low caliber percussion weapon, then it the gun will be quite expensive and it will still only be able to shoot one round about every minute or so. Sort of like a matchlock rifle.

Whereas even a low cost, low caliber percussion weapon will have just as much energy and be much smaller and be able to shoot several rounds per minute.

Therefore, one is better off using a percussion weapon.
 
Exactly - you'd be better off (cool-factor notwithstanding) spending the time perfecting a home-made electrical ignition system like some of the modern-day black-powder rifles that exist.

A gun blogger has estimated a velocity of 100fps with that big projectile (c800grains?), which is less than half what a pistol crossbow can produce (albeit with a lighter projectile). It's rather like getting a burly gentleman to hurl the 'bullet' at the microwave. Assuming he could stabilise it enough, you'd probably get a similar effect on target to what we see in the video (smashing of glass, holes in thin sheet steel but virtually no penetration etc).

But hey, this is all missing the point rather. Props to the guy.
 
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I saw this the other day on the Make magazine site. Interesting. The fellow who had put it up on his blog questioned the actual energy imparted to the projectile along the lines rjh01 points out.
Am I correct in assuming this is a magnetic-accelleration device rather than a true "rail gun" (a different beast altogether, with huge power requirements)?
 
Well, even a rail gun is a magnetic acceleration device.

As I understand it, there are rail guns and coil guns. Guass guns....I'm not sure where they fit in...I think they're similar to coil guns.

Anyway, a rail gun has two parallel rails, which are electrically connected by the projectile. When the current flows, the magnetic fields produced by the electric current combine in such a way that they push the projectile along the rails. Actually, the power requirements for a small railgun aren't really that large. They are currently associated with large power requirements because the research being done currently is in large applications (naval destroyer mounts and such). But people build small rail guns at home, as well. I'd imagine the power requirements are similar tot his coil gun...1.25kJ of capacitor output for about 37J of projectile energy.

A coil gun, on the other hand, uses a coil of wire to produce a magnetic field that then acts on the ferrous component of the projectile to pull it through the coil and accelerate it.

I think (but I'm not sure, others can check me if I'm incorrect) a guass gun is similar to a coil gun but instead uses a series of electromagnetic rings that fire in a carefully timed sequence, so each pulls the projectile along from teh one before.

They're all using magnetic acceleration, but it's how they accomplish it that is different.
 
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Hellbound said:
Well, even a rail gun is a magnetic acceleration device.

As I understand it, there are rail guns and coil guns. Guass guns....I'm not sure where they fit in...I think they're similar to coil guns.

Anyway, a rail gun has two parallel rails, which are electrically connected by the projectile. When the current flows, the magnetic fields produced by the electric current combine in such a way that they push the projectile along the rails. Actually, the power requirements for a small railgun aren't really that large. They are currently associated with large power requirements because the research being done currently is in large applications (naval destroyer mounts and such). But people build small rail guns at home, as well. I'd imagine the power requirements are similar tot his coil gun...1.25kJ of capacitor output for about 37J of projectile energy.

A coil gun, on the other hand, uses a coil of wire to produce a magnetic field that then acts on the ferrous component of the projectile to pull it through the coil and accelerate it.

I think (but I'm not sure, others can check me if I'm incorrect) a guass gun is similar to a coil gun but instead uses a series of electromagnetic rings that fire in a carefully timed sequence, so each pulls the projectile along from teh one before.

They're all using magnetic acceleration, but it's how they accomplish it that is different.
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Sorry I was using the 'Gauss' term in the generic sci-fi sense, to cover any magnetic acceleration weapon. The weapon in question is, I believe, a coilgun.

And yes 37J isn't much (around the CB cap level if I remember) but it's cool.
Just wait for room temperature superconductors.:D
 
catsmate1 said:
Sorry I was using the 'Gauss' term in the generic sci-fi sense, to cover any magnetic acceleration weapon. The weapon in question is, I believe, a coilgun.
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That may be right, I can't remember. It's either the general term for magnetic weapons or it applies to the seqential loop type, I can't remember (the loop ones may be included in coil guns).

In any case, I was responding to Bikewer's comments, not your OP :)

And yes 37J isn't much (around the CB cap level if I remember) but it's cool.
Just wait for room temperature superconductors.:D
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ETA: On further research, it appears "guass gun" and "coil gun" are interchangeable, with rail guns beign a seperate category of magnetic weapon.
 
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I saw a video of a home made railgun, it emited quite a lot of sparks and smoke along with the projectile. It must be the rails and projectile charring by the current.

I believe one set of drawings have small photo detectors to trigger each coil/capacitor as the projectile comes along.
Cool build, but not practical. :)
 
I have quite a bit of info on the Navy's railgun project. Was a topic for a brief I did in one of my military training courses. The terst was done at Mach 5, but the system is capable of firing at about 3 times that speed, with a range (projected) of about 200 nautical miles, and an accuracy of 5 foot at that range. Kinetic damage from inpact is roughly equivalent to the explosive load on a Tomahawk cruise missle (conventional warhead).

It's designed to be mounted on a destroyer, and the vessel is reduced to 75% speed due to the power needed to operate the railgun.

The biggest issue they're having is materials for the rails. The enormous currents and friction forces warp and damage the rails, and can lead to misfires and such (especially at higher power levels). Which makes this somewhat impractical comapred to conventional weaponry.
 
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Hellbound said:
I have quite a bit of info on the Navy's railgun project. Was a topic for a brief I did in one of my military training courses. The terst was done at Mach 5, but the system is capable of firing at about 3 times that speed, with a range (projected) of about 200 nautical miles, and an accuracy of 5 foot at that range. Kinetic damage from inpact is roughly equivalent to the explosive load on a Tomahawk cruise missle (conventional warhead).

It's designed to be mounted on a destroyer, and the vessel is reduced to 75% speed due to the power needed to operate the railgun.

The biggest issue they're having is materials for the rails. The enormous currents and friction forces warp and damage the rails, and can lead to misfires and such (especially at higher power levels). Which makes this somewhat impractical comapred to conventional weaponry.
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What, they're not using plasma to conduct to the projectile yet?

What've they been doing with all that research money? ;)


Dave
 
Hmm ... staged acceleration through staggered coils, each triggered by the projectile breaking an optical beam before each stage ... I wonder ...
 
Hellbound said:
I have quite a bit of info on the Navy's railgun project. Was a topic for a brief I did in one of my military training courses. The terst was done at Mach 5, but the system is capable of firing at about 3 times that speed, with a range (projected) of about 200 nautical miles, and an accuracy of 5 foot at that range. Kinetic damage from inpact is roughly equivalent to the explosive load on a Tomahawk cruise missle (conventional warhead).

It's designed to be mounted on a destroyer, and the vessel is reduced to 75% speed due to the power needed to operate the railgun.

The biggest issue they're having is materials for the rails. The enormous currents and friction forces warp and damage the rails, and can lead to misfires and such (especially at higher power levels). Which makes this somewhat impractical comapred to conventional weaponry.
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Very cool. Any pictures?
 
Olowkow said:
Very cool. Any pictures?
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BeAChooser's first link is to some of the Navy's research. They did (IIRC) a 10MJ test so far, haven't heard of anything stronger yet (note, the article claims it is a 32MJ weapon, which is correct...but the test shot they show is only at either 5MJ or 10MJ...it's been a while and I can't recall the exact details). Useful search terms are Navy, rail gun, BAE (they are the contractor that developed it), and Surface warfare Center.

The Navy lab that is working on this can be found at http://www.navsea.navy.mil/nswc/dahlgren/default.aspx; they have a link there (second from the right in the top row) to their rail gun project, but it appears to be down right now.
 
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