Slashdot Mirror
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.
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"
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
...but it had to be texans, didn't it?
Find funky gifts
Oh man! Do you reckon they could get it to produce those curly blue trails a la Q2 ?
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.
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!
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
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.
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....
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?
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
Problem with firing stuff from space to ground is that you need a REALLY big projectile to have anything left when it hits the ground. You might have better luck with high altitude balloons and/or self piloting drones firing target aquiring ammo.
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 first rail gun is of course not from QuakeII or the movie Eraser.
I can remember that my Physics textbook at university had a piece in about rail guns. The idea was to shoot down enemy missiles. Normally you would need another (expensive) missile with a complicated guiding system to intercept a missile. Theoretically you could use a rail gun to accelerate a projectile to such a high speed that the target would not have time to move out of the way while the projectile is in the air. So you can just point the gun straight at the target and fire away.
Movies and video games aside, it will never be practical to have a handheld rail gun. Apart from the portable nuclear reactor that you would need to supply enough energy, the recoil would rip your arms off.
PS. The first handheld rail gun I can remember was in the game Shadow Warrior.
siener's youtube channel
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.
---
This sig has been temporarily disconnected or is no longer in service
Can we mount this on a robot and use it to propell stealth nuclear warheads from places off the world's nuclear strategy map?
----
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?
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!
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
(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...
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).
--
Fuck Censorship.
News for Geeks in Austin, TX
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
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.
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