Practical Manportable Railguns


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Nightcrawler
February 19, 2003, 01:54 AM
Many technobuff TFLers were proponents of the Rail Gun as the next generation of small arms. They're certainly more plausible and less complex than, say, plasma weapons, and don't suffer from the numerous drawbacks of lasers. If properly designed, they'd be mechanically VERY simple, albeit relying on a power supply.

The lack of an appropriate power supply, of course, is why we don't have them now, but imagining better battery and capacitor technology in the future doesn't seem much of a stretch.

For those who are unfamiliar with the term, a "rail gun" is a device that uses electromagnetic rails (or coil, then called a coil gun) to accellerate a projectile. They are sometimes referred to as "gauss rifles" or "gauss guns", though I don't know why. Anyway, a magnetic pulse is sent down the rails, basically dragging the projectile with it. No chemicals required, few moving parts. Conceivably, the most complex part of a rail gun would be the feed device.

Most seem to imagine a weapon firing a tiny projectile at ultra high velocities. This is doable, but projectiles can be of any size, and their velocity is limited only by the power of the "barrel" (the electromagnetic coil).

Another advantage is the lack of sound; while the power source might make some noise (perhaps a hum or something), a coil gun would not rely on chemical combustion; in other words, the actual firing wouldn't make any noise. There would be, of course, a sonic "crack" if the projectile broke the sound barrier. The neat thing is that you could adjust the power to control muzzle velocity. Turn the knob, instantly subsonic and virtually silent weapon.

Also, if my understanding is correct, the projectile could be made of any material, not just metals. Plastic. Rubber. Heck, wood, even. It could also be any shape. You could even make shotgun rounds.

I'm not positive, but I think the projectile needn't be the diameter of the weapon's bore, either. Imagine firing high velocity, 6mm bullets and roughly 10 gauge buckshot loads out of the same weapon!

The coil gun would, of course, have recoil, just like a normal weapon. And it would rely on a power supply, which could be a disadvantage.

Also, I don't know if the projectiles could be caused to rotate, so I'm unsure of what kind of accuracy you'd get out of a railgun.

I'm interested in using practical railguns as small arms in a story I'm writing, so if any technobuffs could chime in and fill me in, I'd appreciate it. Any ideas on designs for rifles, handguns, and other weapons would be appreciated as well.

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Skunkabilly
February 19, 2003, 02:24 AM
Anti's 50 years from now:

"I can't see why anyone would need a railgun. With a firearm, you need some skill to kill someone, but with a railgun, you can just go out and kill a bunch of people with just moving your finger!!"

Airwolf
February 19, 2003, 02:25 AM
I believe the current experiments are using a sabot type round where projectile is surrounded by 2 piece shoe which is split aerodynamically as the round leaves the muzzle.

The projectile is spin stabilized by fins at the rear.

Saw this on History Channel/TLC show awhile back.

Problem is, as you pointed out, power. It takes a hell of a lot to accelerate a projectile to adequate velocity. In the experiments I've seen the charge is collected in a capacitor bank and it takes some time to charge the bank before each shot.

I agree if the power supply issue can be solved a rail gun would be a awesome and versatile weapon.

As for the look of the gun for a story....

http://flymeaway.net/images/cx4storm.jpg

http://flymeaway.net/images/cx4storm2.gif

http://flymeaway.net/images/fn%20f2000.jpg

Nightcrawler
February 19, 2003, 02:40 AM
Well, a quantum leap in batteries would be required, but it's hardly unbelievable. If you think about it, our current batteries are technology that is literally thousands of years old. They've found ancient batteries in dig sites. They were made from clay jars and all, but bascially the same concepts that we use today.

No reason to believe that we won't eventually develop something better.

UnknownSailor
February 19, 2003, 03:47 AM
Really, for man portable rail guns to work, room temp super conductors are needed.

I do see large style weapons being introduced relatively soon, like ship-board systems, and large, mobile type set-ups, where power generation and size don't matter so much.

PenHolder
February 19, 2003, 04:00 AM
There's a guy in Brazil who's playing with several projects along these lines. The URL for his web page is http://www.powerlabs.org/ , though it seems to be down at the moment. He's got pictures of various coil-guns and rail-guns, along with animations of them firing.

They're not practical to tote around yet, but they're still neat to watch.

Something tells me his brand of garage-inventor tinkering would get him a stern visit from the Feds if it was conducted in the US.

Individual experimentation with weapons is pretty much outlawed now, isn't it? If so, that's a shame. Weren't folks like JMB and Kalashnikov just "regular civilians" before their designs were adopted?

4570Rick
February 19, 2003, 06:04 AM
I can remember many years ago reading in popular mechanics or popular science about the rail gun testing. It seems to me that they used a plastic cube aprox. 3 inch square and drilled like swiss cheeze. With a muzzle velocity of something like 15,000 feet per second:what: they drilled this cube through, I don't know, a whole bunch of armor. The article also talked about the huge power supply.

illuminatus99
February 19, 2003, 06:41 AM
I made a coilgun in highschool, they're not very complex but it had to be plugged into a wall socket to get enough power. it had no problem putting a ball bearing clean through a 1/2" sheet of plywood. one of these days I'll have to get some more pinball machine solenoids and build another one, maybe I could use capacitors for the power source and design some sort of feed system.

Keith_Yorktown
February 19, 2003, 09:21 AM
How about a car mounted gun ala "Mad Max"... :evil:

DMK
February 19, 2003, 10:26 AM
They are sometimes referred to as "gauss rifles" or "gauss guns", though I don't know why. Carl Friedrich Gauss did much research on magnetism and electricity. We use the Gauss' Magnetic Law to explain what magnatism is and it's effects.

Magnetism is also measured in units known as gauss. To de-magnetize something, you degauss it.

http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Gauss.html

ahenry
February 19, 2003, 10:32 AM
Given how little we actually know of magnetism (we know a lot, but there is a lot more we don’t know), it seems to me that it is entirely possible for rail guns to be portable in the near future.

BenW
February 19, 2003, 10:44 AM
Gaussian because I believe most experiments use the Gaussian waveform for current distribution because of its efficiency in beam velocity distribution compared to other waveform models. Not a physics expert, just recalling what's left over from college.:)

dav
February 19, 2003, 12:56 PM
Keith_Yorktown,

Good idea. I drive an Electric Vehicle... now all I need to do is mount a .50 caliber rail gun on top and I'll be all set! With remote control and video aiming, of course.

Don't get me wrong, this is *not* for drive-by shootings, this would only be used for important things... people cutting me off on the freeway, or taking my parking spot at the mall... :p

Skunk, your sig line implies you are thinking of leaving the Glorious People's Republik of **********! Say it ain't so! Where will we poor souls go to learn to become properly Tactical?

David

QKRTHNU
February 19, 2003, 01:01 PM
As far as power needs go, two words.

FUEL CELL.

Nightcrawler
February 19, 2003, 01:56 PM
You're right; electrochemical fuel cell technology is in the works as I type this. Within ten years they say it'll be viable.

That assumes, of course, the oil companies don't manage to suppress it, and I'm sure they'll try. Imagine if they failed, though, and all of a sudden, our cars were powered by and our homes were heated by these fuel cells.

You'd still need jet fuel, though; you can't make an electric jet. You can, however, make electric helicopters, prop aircraft, ducted-fan aircraft, etc.

As a bonus, we could tell OPEC to go piss up a rope, and they'd have no more sway over us. Countries like Saudi Arabia would probably be back to sticks and stones overnight, since they don't have any infrastructure or economy, except for the state-run oil industry.

Plus, it'd make the environmentalists happy, until they found something else to complain about.

Anyway, another advantage of the gauss rifle as I imagine it would be very high capacity. The magazine need only contain the projectile; no case, no propellant, no primer. Imagine how many .308 bullets you could fit into something the size of a 20-round FAL magazine? I imagine a very high capacity box magazine, that has a little conveyor inside, and the rounds are stacked in an "N-bend". You could have a hundred rounds or so in something that protrudes down only about as far as a normal 20 or 30 round magazine.

Pistols would benefit, too, though likely less so since fewer pistol cartridges are bottlenecked like rifle cartridges.

You could, however, have bullets that are very long, without having an overly long action. Bullets that are very long have good sectional density, penetration, and tend to tumble in soft media (like a person). Put an air pocket in the nose and you can improve this.

Plus, having adjustable muzzle velocity without having to change ammunition could really come in handy. It'd certainly make "handloading" easier, wouldn't it?

And, reloading ammo wouldn't be necessary. Ammuntion wouldn't cost anymore than bullets do now, and like now there's no reason you couldn't make your own. And they wouldn't have to be traditionally bullet shaped, either. I suspect a large, cube projectile would be very unpleasant over short ranges, though long range accuracy would probably suffer.

Just throwing out ideas here. Of course, on large scale, you can build railguns as big as you want. They're limited only by the power source. Very large rail guns are also called "mass drivers" and could, conceivably, be used as a weapon of mass destruction. Orbital bombardment, and all.

On the other hand, very large railguns on the surface would probably be able to shoot a satellite down without too much trouble, provided a decent targeting computer. It is, after all, very hard to hide things in space.

Airwolf
February 19, 2003, 02:06 PM
That’s an interesting point about bullets only, no cases.

Given the acceleration potential of a rail-gun the projectiles could be made of something other than lead. You could make up the loss of mass through higher velocities.

That would make that mag stuffed with projectiles very light indeed.

The weapon could be designed with multiple mags with different ammo (both shape and mass). Between on-the-fly ammo selection and variable acceleration you could precisely tailor the round delivered for each and every shot.

Couple that with other weapons in the same package and you have a one person assault team.

http://flymeaway.net/images/PDVD_000.jpg

UnknownSailor
February 19, 2003, 02:06 PM
Yes, I'd like to see money put into a rail-gun system for a limited anti-missle system. Why hit a missle with a missle, when you can rail it? :D (shameless Quake III joke)

hso
February 19, 2003, 02:17 PM
DMK is correct about the gauss gun question.

Electromagnetic guns will have the same recoil properties as todays weapons, but they will have the advantage of reduced impulse. In other words, the momentum will get conserved over a longer period of time (the time for the round to be accelerated up the barrel), even if it's still brief.

Power for man portable weapons will come about after practical room temperature superconductors are developed and will initially be provided by backpack power supplies or electorchemical impulse systems. You might think of the first weapons as being squad support or anti vehicle/armor systems. Development of better power storage/discharge systems will allow personal weapons to be developed.

For those of you that envision a world where OPEC is relegated to the same international significance as Bolivia's bauxite mining by the development of fuel cells you may be forgetting that fuel cells operate on hydrogen (some very few on natural gas) and that hydrogen is evolved by use of electricty and electricty comes from oil fired, coal fired, gas fired, hydroelectric, wind, solar electric generating facilities (in that order). Without conservation, alternative/renewable fuels, nuclear power, etc. we will continue to be in the thrall of the oil producing countries.

illuminatus99
February 19, 2003, 02:37 PM
UnknownSailor, the navy has been testing railgun based anti missile systems on a few ships for quite some time, from what I've heard they work really well since the round doesn't start dropping for quite some distance and because of the speed you don't have to lead the target nearly as much

Nightcrawler
February 19, 2003, 04:18 PM
To eliminate the neat for sabot shells to cause the projectile to rotate (for stability in an atmosphere), simply make the projectiles like flechettes, with little fins on them, like an arrow. Everyone assumes for some reason (at least amongst science fiction circles) that future gauss rifles will automatically use very small bore, extremely high velocity ammuniton. Many scifi buffs aren't shooters, though, and even some that are up on their physics don't fully understand ballistics, especially in how it relates to wounding patterns and penetration of various hard and soft media.

A gauss flechette can be as big or as small as you'd like. I'd prefer something larger than 4mm, myself, for the benefit of being able to make your shots subsonic and, thusly, silent. I mean, a 20 grain 4mm flechette isn't going to do much damage at 950 feet per second, and with projectiles that small you could only make them so heavy (without getting into really heavy metals that are difficult to acquire).

I think a six to seven millimeter projectile, long and nail-shaped, with four fins that will cause it to rotate in an atmosphere, would be very versatile. It would have a good ballistic coefficient, and thusly good penetration of soft and hard covers, as well as be able to do high velocity without a huge jump in recoil. Projectile weights could vary from fifty to two hundred or two-fifty grains, depending on what it was made out of and what you were trying to accomplish with it.

The bore diameter could be roughly 12 gauge, though, giving you the option for larger projectiles including buckshot clusters and small grenades. The only trick would be making the feed device in such a fashion that it efficiently fed the projectile into the weapon's "breach" when the projectile wasn't necessarily the same diameter as the breach itself.

This is just my idea for a versatile, jack-of-all-trades longarm that could perform the functions of rifle, shotgun, or light repeating grenade launcher, depending on the ammunition. Other designs of a more specialized or more versatile nature could easily be developed.

I have in mind, for instance, a special, large, long ranged sniper type weapon. It'd have a long electromagnetic coil, capable of pushing even heavy projectiles to high velocities. It'd probably need a very effective recoil buffer, as well as a bipod for stability.

It'd fire a roughly 9mm (though you could make bigger ones) flechette like projectile, with weights varying from 200 grains to 300 grains (or whatever, just a thought) at velocities ranging from subsonic to really freaking fast. It'd have pretty healthy recoil at the latter setting, but between the high velocity and the heavy weight of the projectile, you would have a weapon that could easily put the hurt on people at a thousand meters and beyond. Combine the weapon with a sophisticated electronic multi-spectral, night-vision-capable scope and you're all set. Heck, you could probably even take big game with it...

Owen
February 19, 2003, 05:41 PM
im going to ask the guy that sits next to me tomorrow, (used to design artillery and tank projectiles) but I think as soon as you add fins to anything, the BC goes to hell.

Fuel cells are great, but i think it will be a VERY long time before they are light and powerful enough to be used in a manportable weapon with respectable rates of fire, and sustainability. I can see them being used in tanks and artillery in 10 or 15 years, but those are relatively weight insensitive compared to small arms.

UnknownSailor
February 19, 2003, 10:15 PM
UnknownSailor, the navy has been testing railgun based anti missile systems on a few ships for quite some time, from what I've heard they work really well since the round doesn't start dropping for quite some distance and because of the speed you don't have to lead the target nearly as much.

Thus, the reasoning behind the DD-21 project using electric drive. For power reasons (i.e. feeding juice to those rail guns).

Billll
February 19, 2003, 10:35 PM
There are a number of amaturs working on railguns. Google railguns to locate them. I built a very small one (size of a shoebox) that would toss a split shot sinker aceross my garage. Took about 30-40 sec to recharge, plugged into the wall. Friend of mine is working on a 1 meter x 1 cm job, but that one will be about the same size and weight as an office desk full of bricks.
Fun physics, though.

PaladinX13
February 20, 2003, 01:07 PM
One thing to be careful about with SciFi (if you want your writing to be smart) is to consider the implications of any technology you're introducing and how it ripples throughout the rest of the world. If we've mastered room temperature super conductors and massive portable power sources, I think a railgun is possibly much less relevant. The very same technology used to make the gun can be used to create defenses.

Yes, it would take a quantum leap in technology to get there, and mostly likely computers will have advanced quite a bit too. It's not out of the question to have vehicles and buildings track incoming projectiles and stop them with a repelling pulse.

Another one, I could imagine is a vest (somewhat bulky but light) that catches projectiles. The projectile would have already slowed down a lot compared to its muzzle velocity, so less force is involved, also the force needed to stop the bullet is less because you can have traditional armor behind it to stop it too. So basically, the instant a projectile breaks the self-healing "skin" of the vest, a pulse is sent against and around the bullet to bring it to almost a complete stop. If it has anything left, the carbon nanotube plate behind it should prevent penetration. Then, another pulse is given to eject the projectile from the vest and the material heals back over. It's just like Active Tank armor but taking advantage of advances in material science, computers, magnetics, and power.

Anyways, just be sure to not make technological leaps for the sake of a weapon while forgetting where else it can be used.... unless, I suppose, you're talking about a unique individual/weapon where the technology is not available at large.

Roadkill Coyote
February 20, 2003, 02:05 PM
I suppose you would also have to address what effect all these electromagnetic hijinks would have on the wireless computer and communication capacity that will probably be integrated into our clothes (and everything else) by then. Will you need a hardened cell phone / PDA to call 911 and log on to THR?:evil:

DJJ
February 20, 2003, 02:16 PM
The weapon could be designed with multiple mags with different ammo (both shape and mass). Between on-the-fly ammo selection and variable acceleration you could precisely tailor the round delivered for each and every shot.

Make it voice-activated, and you'd be Judge Dredd!

"Double Whammy." :D

Not that I actually watched that. :uhoh:

QKRTHNU
February 20, 2003, 02:25 PM
For those of you that envision a world where OPEC is relegated to the same international significance as Bolivia's bauxite mining by the development of fuel cells you may be forgetting that fuel cells operate on hydrogen (some very few on natural gas) and that hydrogen is evolved by use of electricty and electricty comes from oil fired, coal fired, gas fired, hydroelectric, wind, solar electric generating facilities (in that order). Without conservation, alternative/renewable fuels, nuclear power, etc. we will continue to be in the thrall of the oil producing countries.
There are already some pretty cool ways of gathering Hydrogen for fuel cells. Check this out.

http://www.fuelcells.org/fcfaqs.htm#hydro
Enzymes - Another method to generate hydrogen is with bacteria and algae. The cyanobacteria, an abundant single-celled organism, produces hydrogen through its normal metabolic function,. Cyanobacteria can grow in the air or water, and contain enzymes that absorb sunlight for energy and split the molecules of water, thus producing hydrogen. Since cyanobacteria take water and synthesize it to hydrogen, the waste emitted is more water, which becomes food for the next metabolism.

Solar- and Wind- powered generation - By harnessing the renewable energy of the sun and wind, researchers are able to generate hydrogen by using power from photovoltaics (PVs), solar cells, or wind turbines to electrolyze water into hydrogen and oxygen. In this manner, hydrogen becomes an energy carrier – able to transport the power from the generation site to another location for use in a fuel cell. This would be a truly zero-emissions way of producing hydrogen for a fuel cell.

M67
February 20, 2003, 03:58 PM
This isn't new. I have seen a reference to (but not read) an article in Scientific American from the 1840s about shoulder fired coil guns, and I don't think the idea was new then either. I do see large style weapons being introduced relatively soon, like ship-board systems, and large, mobile type set-ups, where power generation and size don't matter so much. Not new either. A Norwegian scientist filed some patents regarding large coil guns around the turn of the last century, I think 1901 or '02. His tests in his lab at the University of Oslo involved a 20 kg iron projectile fired into a wooden "bullet trap". I don't remember velocities, but he did say that he could have gotten more velocity if only he could have drawn more power from the city's main grid. In a later experiment he overloaded the main circuit board at a hydro electric power plant, and caused a fire. The plan was to build field and coastal batteries. For anti-shipping use he envisioned "torpedoes", huge iron shells with a payload of 500 kg of nitro glycerin... The guns were supposed to be powered by mobile generators with "huge flywheels". The main problem was to switch the coils on and off at the right time, this was before computer control, photoelectric switches and such. I think the plans for full-scale guns involved hundreds if not thousands of individual coils. If the coils were not switched on/off at the right time, the result was huge sparks and lots of noise. And a further digression: Even if the electro-magnetic artillery project never came to much, this way of making huge electric sparks lead directly to a new method for producing nitrogen-based fertilizer. For those interested in WWII history, one of the byproducts of this manufacturing process is heavy water.

During WWII there were German plans to build electromagnetic guns for shooting from Belgium to targets in Britain. I don't remember where I read about this, but it included drawings of huge contraptions that looked like something out of Jules Verne.

MrAcheson
February 20, 2003, 03:58 PM
A railgun projectile is accelerated by a lot of force on a small area for a relatively long length. To defend against it you need to be able to produce a lot more force in a much shorter distance on a much larger potential area. A shorter distance because a vest needs to stop the projectile in 2" instead of the 20" it was accelerated in. A larger area because the cross sectional area of a gun barrel is much smaller than to the cross sectional area of your whole chest. A lot more force because you have to overcome the distance and area problems with force.

Now you may be able to get around the area problem by using a good control system, but you cannot get around the length and force problem easily. As such defense will lag behind offense, if they are using the same physical principles. Besides who says the railgun nail needs to be conductive, what if the nail's ballistic sabot is conductive but the nail is not? If the nail is essentially inert (ceramic/polymer penetrator for instance) then no field is going to stop it because those physics don't apply anymore.

Also, carbon nanotubes are really really brittle and fragile. Makes them stink at impact absorption because they break down with multiple impacts. Your backplate would be trashed after the first impact. This is why some polymer framed guns have had problems with cracking.

Seriously though, railgun research has been dropped in many areas. Power supplies are ridiculously large (like a the size of a building) and the guns themselves are as heavy as conventional guns because of the spreading forces created by the e-fields used to propel the nail. Plus conservation of momentum means you don't get a free lunch on recoil either, gun pushes projectile and projectile pushes gun.

PaladinX13
February 20, 2003, 07:19 PM
There's no reason to power up the entire chest as you presume, just as active armor doesn't explode the entire surface of tank. Besides, that's just one means of doing it, another would be to have literal active armor... a plate of armor that, upon detection of incoming projectile, moves out a couple inches to meet it, this can handle whatever a bullet may be made of and solves the distance/force issues... essentially turns bullets into bean bags.

Don't limit your imagination. The point is that whether defense lags behind or not, a railgun isn't a magic sword. At any point that something becomes magic-sword like, the defensive side closes the gap. You can list all these advantages that a railgun has over present day technologies... but don't ignore the advantages that would go to defense along the way.

Brittle Carbon Nanotubes (http://thefiringline.com/forums/showthread.php?s=&threadid=141967) that's an old and incorrect misconception tackled in an old TFL thread. Perfect carbon nanotubes are nothing like fiberglass-type polymers and can be very elastic.

TexasVet
February 20, 2003, 11:57 PM
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Another advantage is the lack of sound; while the power source might make some noise (perhaps a hum or something), a coil gun would not rely on chemical combustion; in other words, the actual firing wouldn't make any noise.
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Actually, since the projectile is usually exceeding the speed of sound while still in the barrel, the experimental military railguns are EXTREMELY loud.

MrAcheson
February 21, 2003, 09:23 AM
Sorry Paladin, but I'm also a ex-composites engineer. I have handled carbon nanotubes, they're brittle like graphite at the macroscale. I also have been to conferences where their proporties (which are entirely theoretical for nanotubes longer than a millimeter or so) have been discussed. Carbon nanotubes are like every other nanotech wonder technology, full of promise but almost worthless for the foreseeable future until manufacturing in a usable form becomes possible.

Secondly, do not assume that defense will automatically close the gap with offense. For essentially two hundred years no one bothered to wear body armor to protect against bullets. Why? Because the armor would have been so heavy as to be utterly impractical. Offense in this area badly outstripped defense and people focused on mobility instead. It was only the advent of manmade fibers that allowed defense to catch up.

The point is that because of basic laws of physics anbd natural human tendencies, a soldiers defensive gear almost always lags behind his offensive gear. Railguns are not magic swords, but defensive garments are even less likely to be magic shields.

Nightcrawler
February 25, 2003, 02:24 AM
Actually, since the projectile is usually exceeding the speed of sound while still in the barrel, the experimental military railguns are EXTREMELY loud.

Well yes, but that's why you adjust your muzzle velocity down to subsonic speeds. That's why it's so versatile.

Nightcrawler
February 25, 2003, 09:34 PM
Many gauss rifle ideas I see on the internet (mostly on role playing game sites) involve a 4x20mm flechette. That's kind of on the small side.

What would you prefer? Tiny and super fast or bigger and not quite so fast?

Gauss rifles would have the disadvantage of requiring a power supply. They would have the advantage of having almost no moving parts and a perfectly clean method of operation; they wouldn't foul, even after thousands of rounds of firing, and parts breakage would be much less.

A recoil reduction/absorbtion device might be warranted, adding complexity, but nothing unworkable.

TexasVet
February 25, 2003, 11:40 PM
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Well yes, but that's why you adjust your muzzle velocity down to subsonic speeds. That's why it's so versatile.
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But then your cost/benefit ratio gets stacked WAY in favor of conventional arms. Silencers are very cheap to make.

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