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DIY Railgun Projects
Rhett writes: "Straight out of Quake it's a couple of EE projects for building railguns: Working railgun by Texas Tech students and a project by MIT Students." Now if only we can get enemy ICBMs to pass through Texas Tech on their way to dropping nuclear weapons on the U.S., we'll have a working missile defense system.
Still would be handy for dealing with those pesky Salesmen.
Leave it to slashdot to obliterate a webserver in less than 10 minutes. Someone post an RFC for the slashdot effect.
. . .a deployment method for Student Star Wars (g)
Let's go *shooting*!!!
Yes pranks taken to the next level with almighty rail guns.. I can see the headlines now.. "MIT rails Caltech" .."I OWNz J00" was the battlecry from MIT when the they opened fire from a mile away punching holes in Caltech. Caltech responded by saying "Oh yea just wait til we get our BFG10k working then we will have the last laugh." then caltech was railed again and responded once more.. HEY I WAS TYPING..
"I am a kernel in the linux army"
You mean the DON'T pass thru Tech?
Now the system platform needs to be connected to a very fast moving servo controlled aiming system controlled using the galvanic skin response/ musculatory pressure sensing sleeve Boeing is developing to fly aircraft - WITH the final assembly being connected to the most sophisticated, accurate weapons guidance system in the world: A thirteen year old boy with a case of Cherry Coke and Doritos.
When the fire test fails in front of the review board, perhaps he can yell "LAG!!"
THIS SPACE INTENTIONALLY LEFT BLANK.
Now this is a new development. Farming computer games for new weapons ideas is a splendid idea. The most creative people are those who are not professionally involved in the area they are creating for, and who have not been educated in that field. This frees their minds from dogma and rigourously straight and uncreative thought. They are free to innovate, and may not even realise they are doing so.
I think that there could be lots of ideas to be reaped from computer games, which are truly the preeminent artistic genre of the 21st century. Rather like CERN's recent project to scan SF books and films for good ideas they could use for Physics and futures scientific developments, there is a good case for the Army searching through computer games for better methods of implementing death, be those methods strategic, technological or social, computer games designers spend time thinking of little else.
The US Army should create a department for this purpose. I really think it could reap dividends.
They fuck you up, your mum and dad.
--Anticipation of a New Lover's Arrival, The
A missle defense system - perhaps. But no rail gun in the free world is powerful enough to withstand an attack of the /.
...but it had to be texans, didn't it?
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I was told here on /. that all Americans are "fat and dumb"...? If that's true, then why was this "railgun" made by Americans and not Europeans or Chinese or whatever...
Oh man! Do you reckon they could get it to produce those curly blue trails a la Q2 ?
I built a scale one in high school for a science project. It was just a simple glass tube with 5 hand rolled wire coils along it with one end connected to the neg. pole of a battery and the other ends connected to a series of copper plates. I then connected a nail to the positive terminal and could launch BBs by running the nail over the plates. A fun little experiment for any high schoolers out there.
I like lots of people. That doesn't mean I go carting them around the galaxy with me. --Dr. Who
There are a lot of useful links at the bottom of the Electromagnetic Propulsion homepage about this sort of thing, but the main thing that interests me is the idea of massdrivers.
Although they're not so practical for using from the surface of the Earth to get into orbit, they'd be great for moving payloads from the surface of the Moon into Earth orbit without the use of expensive launch vehicles. Although the railgun uses an awful lot of power a variant called the coilgun uses far less power, although it costs more, and may eventually be practical for this purpose.
I still want a BFG!
"Straight out of quake it's a couple of EE projects for building rail guns:"....... Actually the Railgun is from the movie eraser. The makers on Quake2 must have thought it kicked ass...
If this guy was betting that his server could withstand the slashdot effect, he was wrong. Cool project though. His site had a good presentation of the project parameters and the problems they encountered. I immediately started thinking of possible solutions and improvements.
1. Perhaps encase the rails in high-impedence ceramics to add rigidity and provide a method of heat-sinking.
2. Create a 'magazine' and utilize a weaker rail system to pump the projectiles into the main rail chamber just before a cycle. The timing on this would be very difficult I admit.
Oh well, I just might have to build my own now.
Ciao
nahtanoj
I was recently having a discussion with a friend about railgun (a mutual acquaintance has one mounted on the side panels of his car, aimed backwards), and our plans to publish Railgun Living Magazine, a lifestyle magazine
for railgun enthusiasts and their families to enjoy their hobby, and learn about new and enjoyable uses for railguns, railgun accessories, and the like. We were originally going to call it `Better Railguns and Rails' but we thought it was a little derivative...
Railguns don't kill people. People kill people. People will railguns just enjoy it more.
All the best railing for you and your family this railing season!
There are other ways to magniticly accelerate a projectile. Does theory allow this to be more efficient (than other ways)? Has anyone calculated?
" if x then... !x "
This is neat, but unless you'll be fighting in space, why?
Chemical weapons (ie: guns, rockets) are smaller, self contained, easier to maintain in battlefield conditions than something that needs it's own Mr. Fusion(TM) power source, and more reliable.
III.IIVIVIXIIVIVIIIVVIIIIXVIIIXIIIIIIIIVIIIIVVIII
Okay. They need to work on getting the size down so I can carry it around campus for Quake simulations.
On a more semi-serious note, does it come as no real surprise that this bad-boy was built in Texas?
Chas - The one, the only.
THANK GOD!!!
Chas - The one, the only.
THANK GOD!!!
An AK-47 gives about 2000 feet per second, it weighs about 15 lbs, and it is more than 50 years old design.
The new German G-3 punches about 10000 feet per second, which is enough to pierce about one foot of steel, and it should be about the same weight as an AK-47.
For infantry, railguns will never be better than the ordinary chemicallly powered ammunition.
OTOH, put a railgun in a submarine. It could be about the same length as the sub, of the order 100 meters, with not much extra weight added. Normal ships could also use this.
Sure, this could be used in missile defense, and it would probably be very effective. But I think a better use would be in space-based offense rather than defense.
Suppose you've got an army and some tanks gathering somewhere. Just reposition your satellite, obliterate the tanks (the shrapnel would be quite dangerous to the enemy troops near it) and then send in your ground forces. There you go. Quick, simple, and efficient.
The bottom line on these is that for dumb payloads the first shot or two will likely hit depending proper leading of the target. but dodging the shots is relatively easy, since even with projectiles going at ten miles per second, shooting at target one hundred miles up means that the target is at least ten seconds away. This is plenty of time for alarms and manual menuvering. (Take evasive action Sulu!) This depends on detecting the characteristic magnetic flux from a rail gun shot at the time the shot is fired. a little dicey, but not that impractical.
Given atmospheric turbulence, etc. We should probably have something like a rapid fire rail gun to be really effective - something like machine gun speed.
I can see the black budget people working on this now.
"It is a greater offense to steal men's labor, than their clothes"
- it was a COIL Gun.
Really the same basic idea as a rail gun, but they 'wrapped' the rails around the payload to get more efficient use of the electromotive force -- more 'bang for your watt,' so to speak.That, and it looked more like a gun barrel. It was so much cooler looking!
Google turns up some interesting things, from someone trying to sell handheld weapon plans, to science-museum, brick-destroying, 900 foot-per-second Coaxial Electromagnetic Mass Accelerators. The second one is rather small, too -- something like that should scale up without too much trouble...
God, that looks like fun. This brings back that feeling I had 10 years ago when I really wanted to build one of these things. Maybe now I'll pull my head out of the computer long enough...
Oh, wait. Jet boat first.
"...America's great minds of today, teaching America's great minds of tomorrow. Poor bastards." -- A Beautiful Min
I'd always assumed that a railgun was more solenoid-like -- a long coil with many windings, and a magnetized firing slug that pushes the projectile out. Maybe implemented as lots of smaller coils, computer-controlled to fire at just the right moments.
Granted, this design is way simpler and super-elegant, but does the math show this as being much more efficient? (I'm certain it must, or they'd be doing a different design). It just wasn't what I'd figured it'd be...
On a more specific note, what happens to the armature as it reaches the end of the gun? Does it fly off, trailing the projectile, or do they have some means of capturing it before it exits (sending the projectile off by itself)? If so, how do you keep it from vaporizing itself? Or is the armature itself the projectile?
Finally, does anyone have a mirror set up yet? I can read all the MIT pages, but the snakeden pages seem slashdotted....
Obviously the "coward" part applies to "Anonymous Coward" author. This is WAY off topic, but I must reply to assert that the Christian Bible contains no basis whatsoever for this assertion. It does mention a "mark" being put on Cain, but all of his decendants were killed in the Biblical flood. Noah descended from the third son of Adam and Eve, Seth.
" if x then... !x "
They invented the revolver, the machine gun, the atom bomb...and soon the rail gun.
They drop environmental and social expenses to build an obscure missile defense system.
You have to like them!
Just because I can imagine doing a hippopotamus, doesn't mean I'd like to do it.
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
Correct Google cached URL
Following of the links on the previous story led to the MIT hack web page; with the MIT link here it's now clear then that the vancouver students were merely hanging a suitable target for their railgun experiments; I imagine they've already got a series of devices mounted.
~~~~~ BigLig2? You mean there's another one of me?
Wouldn't it be more fun just to drop a ball bearing into a particle accelerator? Who's game to try it :-)
That's because it not a railgun, that page is about a golf putter called 'the railgun'. This thing can make dents in stuff, but only in close range compared to a *real* railgun :)
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Mabye I'll try to convince my science teacher to build one, we could shoot holes in plywood or something. My friend once asked the science teacher if he built a tesela coil if he could bring it in, she said yes! Unfortunately he didn't build a tesela coil, which would have aslo been very cool.
Don't call my crazy, that's what they called me back in the home!
Actually, I don't think Jerry invented thor, he just worked on it. I think he also worked on Orion. The spaceship powered by a-bombs. Both devices were explored in "Footfall" by Pournelle and Niven. Love that battleship taking off from, IIRC, Bremerton, with the bombs going off underneath it. And using the engines to fire x-ray lasers. Way Cool
Best Slashdot Co
Watch it, people! The above is a goatse.cx link...
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Slashdot didn't accept your submission? hackerheaven.org will!
Ok. that was just uncalled for.
The rail gun is a fine weapon. We souldn't use them to attack California though. They don't have the power grid to support a rail gun brigade.
I've hit Karma 50 and gotten a Score:5, Troll... I win!
MIT was railed by Texas Tech.
Texas Tech almost dodged MIT's rocket.
dynoman7
Blarf.
Aren't more powerful designs based on rapidly switching the magnetic field as the projectile moves through the gun (kindof like maglev trains work)
Just curious.
the scene... a bunch of engineering students sitting at their computers
engineer1:what do you mean our server is down?
engineer2:umm..its something called slashdot, it seemed to kill our server!
engineer1:thats not very nice, we should do something about that evil website
engineer2:yeah, but what?
all look toward prototype railgun
all engineers together: hmmmm.....
(define the-question (or (* 2 b) (not (* 2 b))))
Sure, on a smaller scale. 5 bored students, a couple cases of beer, and some, uh "creative" parts gathering.
Took us a weekend, but we built it. Teflon barrel was about a foot long. Shot a 1/4" by 1/2" magnet about 75 feet. Would have gone farther had the dorm hallway not had a door on the end.
OMG, these kids are building a weapon of mass destruction. I hardly find this amusing. Nor, I imagine, does the FBI or DoD (although I wouldn't be surprised to find out that DoD is funding this project in some way). How could anyone possibly think that this project is funny or cool? Railing your buddies in Q3 is one thing--it's a computer game, and it's fun. Building a railgun, which if it works could no doubt become the next favorite weapon of the world's militaries, will only contribute to the spread of war across this planet. It's not a game, and it's not funny.
The Texas boys have taken down the web site.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
About 14 years ago, I went to my girlfriend's father's work. This was in San Diego at a time when the defense contractors around there were numerous(I was 15). Anyway, he showed be a plastic projectile that was launched using a rail gun. I suppose it used some sort of metal launch 'thing' to get the plastic to go, and they used plastic because an actual depleted uranium projectile was too expensive for basic testing. This plastic projectile pierced a 2" thick steel plate and then around 3 San Diego County Yellow Pages books (about 5" each) and turned into a twisted, mangled piece of plastic with tiny bits of yellow paper stuck all over it. Very cool. Supposedly it was being developed as a tank killer that could fire from miles away. The other cool thing they had going was an "air mine". It was a land mine that would take out low flying aircraft like helicopters. If I remember correctly, it used directional laser detection to locate a target... I don't know what it did to destroy the target though. Only saw a picture of it firing, and he couldn't tell me about it.
The Texas Tech railgun is my site - and we had no clue this was coming. It's served off a linux box hanging off a cable modem at a friend of a friend's house in another state, and was instantly obliterated. yeehaw. Love that slashdot effect!!!
The closest man portable conventional firearm to a quake style rail gun is most likely the Barret 50 cal semi automatic and all it's cousins or possibly a converted Norwegian 20mm anti tank gun retrofitted to be shoulderable but it had to be dragged around on a sled when it was used during WWII times.
Now, with conventional weapons, you have a serious design problem. To fire a projectile you create a small explosion in the barrel. The larger the explosion, the faster the projectile, but at some point, the explosion is so large that you cannot design a barrel strong enough to contain it (or at least not one that you can tote around on the average tank).
With a rail gun, you have a big advantage in that the force applied to the projectile is applied over the entire length of the barrel. This reduces the stress on the barrel because you can apply the necessary force over a longer period of time. This allows you to achieve higher velocities with lighter barrels which provides two big benefits:
1) more destructive force
2) guns that can be rotated and aimed faster and more accurately
Now of course there are limitations with this too, but it does get you beyond the problems inate in more conventional explosives based ammo.
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This sig has been temporarily disconnected or is no longer in service
The best use I've heard of for this technology would be to launch satellites and such into space. I'm sure it would be much more efficent than liquid or solid fuel. Anyone else heard of this or have more info?
Is here.
Understanding is a three-edged sword. --Kosh
What a frightening thought.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
in theory, a rail gun can project a metal object to nearly the speed of light. Now imagine being in the office behind the target when you read this on /.
Can we mount this on a robot and use it to propell stealth nuclear warheads from places off the world's nuclear strategy map?
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ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
Not true.
A MIRV from a US ICBM or SLBM, isn't "REALLY" big. They are about 4 feet long.
"As the design of the Mk 5 reentry was developed, the change to a shape stable nosetip (SSNT) was established. The nose of the Mk 4 reentry vehicle was boron carbide-coated graphite material. The Mk 5 nose has a metallated center core with carbon/carbon material, forming the rest of the nosetip ("plug"). The metallated center core will ablate at a faster rate than the carbon/carbon parent material on the outer portion of the nosetip. This will result in a blunt, more-symmetrical shape change with less of a tendency to drift and, consequently, a more-accurate and more-reliable system."
There was some talk a while ago about some of the MIRVs in US Navy SLBMs not having nuclear warheads, would it be possible to remove the nuclear bits and use a warhead like this as a kenetic kill system? How much damage would a 200-300 pound warhead do if it was dropped from 700,000 feet?
People complain about 31337 script kiddies who launch denial of service attacks - but I think some websites are more likely to complain about Slash than DOS. Check out the host server of one of those links above (www.railgun.org has already put us in today's log :).
http://halluc.snakeden.org/ (something to the effect of being /.ed and trying to find a mirror).
Go Geeks!
While rail guns are cool, what really impressed me about the projects I've read about in the past are the power storage systems. About 3 years ago, there was a SDI-funded project at UT (their site is gone now) that built railguns capable of firing projectiles somewhere between 5 and 10 km/sec.
The really cool thing, though, was the way they stored and delivered power. They built these things called "compulsators" which were basically flywheels that could spin obscenely fast and rapidly convert their kinetic energy back into electricity. They had units that couild store something like 30MJ and release it in 6-5MJ bursts over the space of a second. Very impressive.
Of course, I'd hate to be standing near a tank that had a couple of those things when the bearings gave out. With that much energy, a 5 ton tank could do a pretty impressive tumbling routine.
Was mich nicht umbringt macht mich hungrig.
The short of it is any conductor carrying current procuces a magnetic field arround it. (conductive slug gets one from the large current) The copper rails do the same thing. They have large currents up to but not past the slug (it goes thru the slug from one rail to the other) Like magnetic fields repel. The slugs field repells the field on the rails behind it. Result, slug moves forward. High current = high magnetic field = high force. Note the rails also repell each other and must be solidly held in place, otherwise the rails as well as the slug will try to depart at high speed from each other. One very real demonstration that the power companies see all the time is lightning dammaged transformers. Not only is the insulation dammaged and the oil set on fire, but the windings in the transformer move violently making a birds nest of the wire in the transformer. (ask your local power company to see a sample)
The truth shall set you free!
Pfeh! "advanced armies"! The glory of this here U-S-of-A is that not only can a couple of apple-cheeked kids build an advanced electromagnetic slug-thrower, they have the Constitutional right to bear it. Now, if only we could get our hands on some depleted uranium, we'd get rid of that "The 2nd Amendment is irrelevant because the Army has tanks," argument.
Tom Lehrer rocks.
Bugrit! Millenium hand and shrimp!
At our school, we've had a home-made one for years in the nuclear engineering department. =)
The main problem with using the rail gun anywhere was the size of the capacitors needed to reach the extrmemely high voltage it required to fire.
I didn't see anywhere on their site that they managed to reduce this overhead, has anyone?
Too funny. Of course Google has their cache of the page, but navigating through the different cached pages can be a pain. Here's a few
Their main page in Google's cache
The Railgun Theory in Google's cache
Some difficulties they ran into in Google's cache
Just copy the destination link into a Google search and the results page should have an option to view Google's cache of that page. The images aren't coming up for me though, I don't use this technique often enough to know if this is just a limititation of Google, or if it's just me.
Steven
-- I have marked myself unwilling to moderate-- I don't have other accounts to artificially inflate the karma of
Battletech (first published 1985) had the gauss rifle which is functionally the same as a railgun.
The scientific principles behind the railgun have been know a lot longer than that. So no, Id didn't invent the railgun.
0 1 - just my two bits
01.02.06 - Railgun.org gets Slashdotted. People post a lot of asinine comments, etc. Mailing list membership triples in an hour.
I'm pretty sure Pournelle first described this, in his High Frontier polemic ca. early '80's.
Niven and Pournelle then used it in Footfall.
The precedent to this was the mass driver lunar launched cargo shells in Heinlein's Moon is a Harsh Mistress.
Seth
$5 / month hosted VPS on linux = awesome!
If they are going to recreate items from video games, why can't the recreate something really cool? Like the Super Mushroom or Fire Flower from Super Mario Brothers. It would give whole new meaning to flaming some one.
BigCat79
BigCat79
"The dead have risen and are voting Republican!" --Bart Simpson
this is a great overview of the different types of super velocity conventional rounds over the years:
e l. htm
http://www.users.globalnet.co.uk/~autogun/highv
the fact that a round over a half ton in size can sail at 6,000fps with conventional methods is sick
I've dealt with these people before to get some high voltage supplies and pieces. They sell all sorts of stuff from Information Unlimited - they're run as a mad-scientist like outfit, and they have all sorts of nifty stuff. If you like railguns, coil guns, EMP guns, water explosion, lattice cracking, etc etc.. this is the place for you. Some of the stuff isn't cheap, but everything that I've ordered from them has worked reasonably well.
Anyhow, there's lots of people working on this. Nobody's made one more efficient than a .44 magnum though :)
..don't panic
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www.scorbett.ca
WTF?!? Moderators on crack? Why the hell is this modded as a troll? That is a real link to Google's cache of the site(sure, just the front page, and no pics, but still).
I'm off to metamod, you better hope I don't get this one.
Steven
-- I have marked myself unwilling to moderate-- I don't have other accounts to artificially inflate the karma of
The link to the Texas Tech page now has the Google cached pages up. no pictures or movies.
This is all because I never thought something like this would happen, and didn't have a decent backup. The link should be fully functional by tonight.
This is a common misconception about rail guns, as opposed to coil guns. The way that a rail gun works, is that there are 2 metal rods, inside a large coil of wire (the rods run through the diamiter of the coil). So far most people get it. But the part most people dont get is that there is a thin wire running between the 2 wires, right behind the projectile. When the high voltage is applied to the coil and to the rods, the thin wire conducts the current for a short time, and then vaproizes. The electromagnetic foces propel the vaporized wire down the rods, which in turn propels the projectile, usually at an extremley high acceleration and velocoty. The distinction is small, but significant, because it's a pain in the ass to re-load a real rail gun.
The (Hopefully) Great Slashdot Blackout Apr 21-27
(pats whiny European on the head)
There, there, now.
Did that nasty Slobodan make you sad? We'll help you out - we always do. Oh? You want to have your own defense force? Isn't that cute - I suppose you can have a little something as long as you don't start getting airs about being independent from NATO or anything. Now go play...
When I went to the Texas page they talked about recovering their stuff as if the had a drive crash. Certianly, this doesn't have anything to do with the /. effect does it?
Lego Mindstorm's, man. That's the key. just need a few hundred sets to drive the weight of the gun, but it will work. later ~Rusty http://www.rustybongwater.com
~~May your Eyes be red and your Buds green!~~ Later ~Rusty
This may be an image of it right here. On the other hand, I just might be talking out of my ass.
IIRC the Russian WWII-era anti-tank rifle called the PTRSh-41 (or somesuch, basically a bolt-action rifle chambered to fire their 14.5mm round) is the largest-calibered weapon designed to be fired by an infantryman (excepting rockets, guided missiles, and grenade launchers). Apparently the firer usually received a substantial amount of blunt trauma from the recoil, including a high incidence of broken shoulders. But then since that one shot also typically neutralized a German tank and crew... (yeah probably not a Tiger but still the lighter armored vehicles as well as the weakly armored portions of heavier ones would have been vulnerable, the round also had a significant powder charge in addition to having a really big bullet).
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Fuck Censorship.
News for Geeks in Austin, TX
How about on a tank? The DoD's study for the next gen MBT for the US army finds that a railgun is the best choice of armarment. In fact, it specifies a 5-barreled rail-gattling-gun. The kinetic energy achieved by the projectiles is estimated to be over twice that of the current 120-mm cannon-launched DU penetrators....
...considering that during the gulf war, it was commonplace for these projectiles to go completely through a T-72 tank, with enough heat to catastrophically ignite the air inside the vehicle, you would have to admit that 2x the kinetic energy in a projectile so fast that the first shot would be very, very likely to hit (and thus destroy) a target IS A USEFULL APPLICATION.
"Chill, Orrin!"---Trent Lott
And, there ARE people out there who honestly need killing. . .terrorists come to mind, as to dictators who sponsor them, like Saddam Hussein or Moammar Khaddafi.
It would be nice if all of God's chillun would make nice and not fight. But it's only slightly more likely than Microsoft deciding to put every single thing they produce under the GPL. . .
Anyway, I'll be mirroring his site soon.
-mouser
railgun.org
Well, in order for a kinetic object to be moving fast enough to do the same amount of damage to a tank that a conventional explosive would do, it would have to be moving fairly fast. Faster than the speed of sound, for one thing, which means you get nice big shockwaves propagating all over the place, and if your goal is precision destruction, then huge shockwaves bouncing around doesn't seem like a desired side-effect.
Even if such an object were falling at 1200 ft/sec (which is faster than sound last I checked), though it would do considerable damage to something it hit, there's still the matter of guidance. Hitting a tank moving at 60 miles per hour with an object moving at 1200 ft/sec is not going to be particularly easy. Heck, at that speed, course corrections would be insanely difficult, especially should the tank turn at the last second. Any significant changes in direction to the projectile (and thus aspect of its cross-section) would cause a huge slowdown from friction. Now you've got the object falling at maybe 300-400 feet per second, which is still going to hurt -- if it manages to hit -- but not any more than a TOW missile fired from 500 feet away by a sniper.
If this is such a great idea, how come it's never been used before? Surely one of these heavy low-cross section thingies could be dropped from a plane at 30,000 feet and would reach the same terminal velocity as one dropped from orbit by the time it hit the ground. Yet no one has ever done this. Why?
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
This is even funnier when you consider the only other comment about the mailing list on that page was from last month stating that there were only two people on the list. Unless they grew in the last few weeks that means they're up to six!
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As a matter of fact, I am a lawyer. But I play an actor on TV.
this story is.
Those stupid Americans and their low unemployment rates...their fancy cars...their hot women....their lifestyle the world lusts after...their levi's....their hot women.... All this and they innovate military weaponry too.
Certainly every man at his best state is but vapor
Lot's of work for something that's as effective as a 70 dollar Kmart .22. The plain matter of the thing is that you will get recoil in direct proportion to the amount of energy imparted to the projectile.
No, this is the very point. The kinetic energy of a projectile is (1/2)mv^2, while the recoil is proportional to the momentum mv. So if you make a projectile that weights 1/4 of a bullet, and fire it at the double velocity, you can deliver the same amount of energy with only half the recoil.
...the most extreme case of this is of course to use massless photons for projectiles: lasers have almost no recoil compared with the energy they deliver.
Yes, you'll be happy to know that the list membership was 23 last night. Now it stands at 104.
:)
-mouser
railgun.org
It's probably much, much longer. It's not the time to toss in another slug that matters, but the time to recharge the capacitors -- for a hobbyist-grade power supply, I'd guess minutes to hours. If you owned a fusion power plant ;) you could get that down to under a second, but you also have to let the rails cool down.
The "Texas Site" which was originally found at http://halluc.snakeden.org/railgun/ and was killed ruthlessly by the slashdot effect hs now being mirrored here:
http://web.mit.edu/mouser/www/railgun/halluc/
Unfortunately, I was not able to include the movies of the gun firing as my disk quota is full.
-mouser
railgun.org
This depends on detecting the characteristic magnetic flux from a rail gun shot at the time the shot is fired. a little dicey, but not that impractical.
Didn't you see Eraser? The projectiles leave big, green displacement marks in the air as they pass, similar to that seen as a conventional bullet passes through water. Should be pretty easy to see, as light is much faster than the projectile. No need to scan for the magnetic flux at all!
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"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
A friend of mine for his project in the AP Physics B class last year was to build a "rail gun" that (ideally) shot a metal(aluminum or steel) ring to speeds close to mach 1. unfortuneately, the administration was not too happy and the school did not have the power requirements to charge up a bank of 50 or so 1kv 0.001 uf (i think....) capicators to power the coils. additionally it was a multistage device (or with multiple stages of coils fired in sequence) and timing the triggers was difficult and the scr (silicon controled rectifiers...almost like silicon/solid state relays but not quite) didnt fire at the same time. it was an interesting project something to go down in the Geek History of our school.
Really, this is nothing special. Seriously, I came up with a primitive, if completely non-effective, idea for the same thing in a high school science project. Essentially, it'd just be a series of solonoids powered up and down in order so as to propel a "bullet" forward through a barrel.
The operating principles for a true coilgun are a bit different from your standard nailgun. A coilgun of the kind you seem to be describing works on ferromagnetic projectiles, using more or less DC effects. Apply a field to a coil in front of the projectile, and let it pull the projectile along.
Among other things, barrel friction from the dragged projectile is a problem here.
The coilgun designs from this university group use the Lenz's Law repulsion between a conducting projectile and an _alternating_ magnetic field. The projectile doesn't touch the gun barrel, which gets rid of a lot of the problems that railguns have.
If I remember right (It's been few years since I worked on this), for higher rates of speed it's impossible to use a coilgun. Reason? It's less efficient. The coilgun might impart energy to the projectile better, but the coilgun wastes more energy getting to the projectile. As a result, at higher speeds, a coilgun will basically melt itself.
Nothing that I know of about coilguns would cause a fundamental limit to projectile velocity, and I've done the calculations fairly recently.
The only requirement is that your coil field alternate many times while the projectile is within interaction range of it. While this causes frequency to go up with projectile velocity for a fixed coil size, you can just use a larger projectile and bigger coils spaced farther apart to build a gun that can handle higher speeds at lower frequencies.
Railguns are horrible. I've done the calculations for those, too. You need truly, truly silly currents to generate a useful amount of force, which means that your rails will degrade rapidly and that spot-welding of the projectile will be a big problem. You'll also have the very difficult task of figuring out a way to keep your projectile in good, conducting contact with the rails while sliding along at a few km/sec. The only even remotely practical approach to this I've seen is to send current through a plasma arc behind the projectile instead of the projectile itself, but that'll degrade the rails even more quickly.
Coilguns are much nicer to deal with electrically, and tend to have much higher accelerations (thus making the gun much more compact).
As for inefficiency... I can't see where this comes from, either (perhaps you could post a link?). As long as the projectile occupies most of the area inside the solenoid, and you're operating at frequencies high enough to make inductive and capacitive effects dominate resistive ones, and you're operating at frequencies low enough not to radiate power into the environment, most of your energy should go to the projectile.
Finally, even an inefficient gun - rail or coil - wouldn't have much of a heating problem if active cooling was used. Even a very fast projectile has relatively little energy invested in it. Even if you waste as much energy as you send into the projectile (or more), your gun only heats up by a few tens of degrees per shot, at most (for orbital-velocity slugs).
I remember, years ago, during the (seeming) height of the US military's interest in rail guns (and Popular Science, etc., etc...) a small group of college students with a more efficient answer...
:)).
it was a COIL Gun.
Really the same basic idea as a rail gun, but they 'wrapped' the rails around the payload to get more efficient use of the electromotive force -- more 'bang for your watt,' so to speak.
Actually, the operating principle of the version I've heard of was quite different. Railguns use the "motor principle" that you learned about in high school. Coilguns use Lenz's Law repulsion between coils and a conducting projectile (which you probably also learned about in high school
That, and it looked more like a gun barrel. It was so much cooler looking!
I thought of a way to up the coolness factor:
The Gauss Nerf (tm).
Drew up schematics a year or so ago. I'll get around to building it Really Soon Now, honest...
(It would fire giant Nerf darts with 50g aluminum cylinders in them fast enough to be entertaining. The challenge is to keep it slow enough not to break windows.)
1. A 7.62mm Sov round doesn't have a velocity of 2,000fps. Closer to 2,300fps when fired from an AK.
2. An AK-47 weighs 9.5 pounds empty (a couple of pounds more with a mag), not 15.
3. A G3 is not a new weapon; it's nigh on fifty years old as well. It was the first major post-war German rifle design, heavily influenced by the Fabrique Nationale FAL and the Spanish CETME. If memory serves me right, it was first produced in '59.
4. A 7.62mm NATO cartridge fired from a G3 has a muzzle velocity of around 2,800fps. More in the longer-barreled versions, less in the -K versions.
5. The penetration of a 7.62mm NATO round is insufficient to fully penetrate an automobile (ref: US Army field manuals on urban warfare), to say nothing of "a foot of steel".
6. The G3 is considerably heavier than the AK-47 is; the empty weight is about a pound more, but the loaded weight is considerably more due to the heavy-as-a-bear 7.62mm NATO cartridge.
Plasma armature guns have some advantages, such as being able to fire non-conductive projectiles, and the projectile tends to stick to the rails less.
And I thought the external magnetic field was usually from permanent magnets, not a coil. A coil with the axis parallel to the rails would propel the projectile perpendicular to the rails and the coil, which would obviously not work too well. So the coil is in the same plane as the rails? Could be some design difficulty there, but it would work. Mebbe I should find some detailed design documents on these - I'm going mainly on freshman E&M textbook stuff.
Bugrit! Millenium hand and shrimp!
Nobody has ever used the orbiting steel rods because of a little treaty that strictly prohibits the use of space for offensive purposes. Passive measures like spy satellites are fine, but absolutely no weapons are allowed under the treaty. Don't ask me how Star Wars was supposed to get around this. Maybe they just planned to ignore the treaty, as is currently being done with a different missile defence scheme.
They don't drop steel bars from aircraft because
1) The terminal velocity of a properly shaped piece of steel can't be reached in 30,000 feet. They fail to realize their destructive potential when dropped from aircraft.
2) It's a lot more effective to drop streamlined steel tubes containing 2000 pounds or so of mixed TNT & RDX from aircraft at 30,000-50,000 feet. There are many aircraft designed to do this and nothing else. One prime example is the Boeing B-52. Accuracy still remains a problem.
Bugrit! Millenium hand and shrimp!
As I recall (its not my department) the main benefit is maximum muzzle velocity. Apparently, normal powder guns run out of speed due to some physics associated with the speed of sound in the expanding gas. In tank guns muzzle velocity is the name of the game!
Ours works, but is far from being a deployable weapon. The current one uses a capacitor bank the size of a small house. Its obviously too big to go on a tank, but it was cheap and readily available. I understood that the Americans are working on some sort of wacky rotating machine called a "pulsed alternator", which would produce enough current and fit in a tank.
The other big advantage seems to be one of logistics. Rail guns run on diesel, powder guns run on high explosive. Which one would you rather have to lug around a battlefield?
I was referring to re-entry at the speeds necessary for a kinetic weapon to do the kind of damage referred to. An orbiting satellite and a kinetic bomb would have very different initial trajectories.
Wouldn't accuracy be an even bigger problem for things dropped from space? And the Iridium satellites would have pieces survive, sure, but the uncontrolled atmospheric burning would introduce a great deal of unpredictability as to their final destination. Same for kinetic-drop weapons. I'm sure the technology could deal with it, I'm just wondering how something like this would be a better weapon than a Tomahawk missile flying nap-of-the-earth for 200 miles.
What would be the terminal velocity of a "properly shaped piece of steel", and how high of a drop would you need to reach it (assuming your target is at sea level)?
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
The hot calibre of the moment for long range is 6.5mm/.264 Inches usually launched from a necked down 30-06 class case. There are lots of variants on this theme but you can't beat the 6.5-06 or 6.5-284 loaded with heavy (for the diametre) 142 Sierra Matchkings or the Lapua 139 grain match bullet - A friend uses his to 1200 yards with incredible accuracy.
All the parts and reloading equipment can be bought at mom'n'pop's gunstore or ordered from a supplier (You'll need to reload if you're serious).
As for the launcher? Well...here's my ideal rig: RPA Quadlock action, Krieger 34" barrel, Nightforce 12-42 variable scope, McMillan stock. You are talking serious money though, about 3000 US bucks minimum for this kind of kit, although buying second-hand can get you very good kit at a reasonable price.
I understand that many are "slaming" this site with a number of Xfiles type replies, but I am working on a railgun through experimentation and scientific inquiry as you are. First, I would like to state that it must be fantastic to have the facilities you have. As well as the freedom to persue such an oblique project. On with the post...I have done some research and question the use of a conductive armature. I have found numerous examples which look specifically at a so called "plasma armature" to achieve projectile acceleration. This allows for use of composite projectiles as well as conical ballistic projectiles i.e. bullets. Another thing I work on is fuel cells, and would be interested in your application since they produce a significant (!!!) amperage, but at low voltages. Based upon my use of fuel cells I had an idea you may ponder...use H2 and O2 as a mix, ignited my the same pulse (obviously this one would be attenuated) to produce the acceleration of the projectile. Somewhat easilly achieving a 10 ATM detonation of H2 and O2 at the injector, and thereby increasing initial v and a concommitant reduction in kinetic resitance with no or little redidue (that which remains is either H2 or O2 or some small fraction of NOx's generated by the deltaH of combustion in the presence of N2). Additionally, the residual gasses would create a plasma pressure wave for the projectile as I have seen used in DoE and DoD testing. Contact me if you have any questions/concerns and I could give you my ideas on this injector system. Also, the mix could be doped with an inert gas to control the plasma composition... See Ya.
This could end up being as protable as the amount of H2 and/ or not O2 you could carry. I have been working on an H2 O2 injector for a little while and have worked with fuel cells for a longer while. Consider if the H2 and O2 mix is ignited as an injector to a fuel cell/capacitor(+induct) acelerator. Can you say Ti/dewar H2 O2 storage?
I'm sorry, but I had to include one more thing which is the fact that in a ballistically (SP?) fired round, the horizontal component is CRITICAL! Think about it! Therefore, the utility of such a device is limited to "direct fire" situations. I.E. Kinetic force is directly proportional to impact force at that distance and inversely proportional to the distance...hmmmmmmmmm sounds like a law I've heard before. CIAO.