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DIY Railgun Projects 202

Posted by michael from the drilling-holes-through-your-neighbors-for-fun-and-profit dept.
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.
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DIY Railgun Projects More

DIY Railgun Projects

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  • But not very portable given its attached to a 10X4 wooden board...

    Still would be handy for dealing with those pesky Salesmen.

  • Yay! (Score:1)

    by iomud ( 241310 )
    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*!!!

  • This could be interesting (Score:4)

    by darkmayo ( 251580 ) on Tuesday February 06, 2001 @04:28AM (#453242)
    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..
  • You mean the DON'T pass thru Tech?

  • Ender's Game (Score:3)

    by Scot Seese ( 137975 ) on Tuesday February 06, 2001 @04:29AM (#453244)

    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!!"
  • And this is another reason why they do. In the UK, the army trains many of its soldiers, tank crews, pilots, etc etc, on computer games. They even use Microsoft Flight Simulator for training rookies.The same is starting to happen in America I see.

    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.

  • 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?
  • 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 ?
  • For that matter, why was the airplane, the transistor, the microprocessor, or the atomic bomb? Wonders never cease.
  • 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.

  • There are a lot of useful links at the bottom of the Electromagnetic Propulsion homepage [sover.net] 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 [nasa.gov] 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

  • Yes pranks taken to the next level with almighty rail guns.

    I was thinking more along the lines of those Texans meeeting up with those Canucks, so that next year they'll be shooting a beetle off the Golden Gate with a rail gun.

    Stefan.
    It takes a lot of brains to enjoy satire, humor and wit-

  • 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!
  • You seem to think that rail guns were invented by id Software. You are joking? They popularised it, as did a number of science fiction authors, but this is an idea that came out of scientific research. I remember reading about them in one of those 'What will it be like to live on the moon' picture books when I was a child in the early 1980s.
  • There are other ways to magniticly accelerate a projectile. Does theory allow this to be more efficient (than other ways)? Has anyone calculated?
  • 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.

  • Okay. They need to work on getting the size down so I can carry it around campus for Quake simulations.

    Okay! There's Dean Whatshisname!

    *BOOM!*
    Now that is a frag my friends! Complete with blood mist and chunks no less!

    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!!!

  • Applications? (Score:3)

    by Caid Raspa ( 304283 ) on Tuesday February 06, 2001 @04:54AM (#453262)
    These are only toys, as this 200 feet per second the Texans get is a lousy projectile speed. Have they heard about gunpowder?

    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.

  • Railguns vs Orbital Platforms (Score:4)

    by Alien54 ( 180860 ) on Tuesday February 06, 2001 @04:55AM (#453264) Journal
    I once toyed with a story idea where some of the locals of a planet used rail guns against visitors from other systems. [Sort of like hillbilly geeks vs revenuers]

    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.

  • What about COIL Guns? (Score:4)

    by Raetsel ( 34442 ) on Tuesday February 06, 2001 @04:57AM (#453265)
    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.

    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 [hypermart.net], to science-museum, brick-destroying, 900 foot-per-second Coaxial Electromagnetic Mass Accelerators [resonanceresearch.com]. 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 [gas-turbines.com] first.

  • Physics Question (Score:3)

    by dschuetz ( 10924 ) <.gro.tensad. .ta. .divad.> on Tuesday February 06, 2001 @04:59AM (#453266)
    So, basically, these are self-acting/modifying magnetic loops? In a sense, it's a single-turn coil that collapses on itself, and the motion of the collapse is used to fire the projectile.

    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.
  • Although the link has already been slashdotted, what you're talking about is a coil gun, not a rail gun.

    The limitations of a coil gun is the speed of the switches that activate the coils. After the object attains a certain speed, the coils can't turn on fast enough to accellerate it any more.

    The rail gun is a different beast. It's therotical max speed is the speed of light. The object accelerates along the entire length of the rails. The US Navy has been looking into these to improve on their ship mounted guns. Using a demo mounted to a table, (Under the table was solid capacitor) they were able to fire an object with incredible force, they calculated it would of gone two miles.

    I've been looking into this, wondering if it could be used as an alternate way to move things into space. It seems that the best way to for a railgun to be used in that capacity would be as the inital boost, then use rocket engines to handle the rest of the flight. Otherwise, you're dealing with a VERY long railgun with EXTREME accelleration speeds.

    Ah, the link has come up. Yes, that's a railgun.

    It's difficult to find good links on this. The only people working on them are either government research labs, or weapons companies working for the government.

    A company developing a railgun for the Army. Prototype shown.
    http://www.uniteddefense.com/markets/defense/com ba t/vehicle/systems/advanced/emtech/index.htm

    Pages on the theory behind it.
    http://iml.umkc.edu/physics/sps/railgun/railgun. ht ml

    http://www.cmn.net/~molly/railguns.html

    Damn, half of my saved links on this have gone dead. I've got to start saving web pages.

    Later,
    ErikZ
  • Jerry Pournelle http://www.jerrypournelle.com invented a space weapons system called THOR in the 60s.

    It is basically a 20 ft metal rod in Earth Orbit with a small engine that has just enough power to take it out of orbit, some very simple guidance capability - small thins or moveable weights inside - and a small onboard computer.

    All you do is determin the target, fire the rocket, and drop it onto your target. It will be going at about 12,000 feet per second on impact; that is sufficient kinetic energy to destroy most hard targets, with minimum collateral damage and of course no fall-out.

    I think the problem with your plan is that the guys with Gravity on their side are bound to win.
  • 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!
  • Members of the University of maryland Scholars program also build a railgun as a semester project. They tested it out in Lot 4 (the largest and most distant parking lot) and were able to shoot a small projectile out of the lot to parts unknown. The second shot broke up in the launcher due to G forces and basically put it out of comission. The studenst then realized that hey, their first shot could have killed somone if it had landed, and hightailed it out of there along with the railgun. Location of the railgun is currently unknown, possibly sold to Iraq in exchange for free textbooks

  • All of your numbers are impressive, but you fail to mention that an arrow from a recurve bow has more foot-lbs of pressure behind it then both of the bullets from the guns that you describe. A compound bow has even more foot-lbs of pressure.

    This is why the military has continually attempted to create railguns over the last 100 or so years. A massive accelerated rail isn't going to be stopped like a bullet.

  • a loud booming voice sounds across the world, saying "TWO HITS - IMPRESSIVE".

  • The above link goes to railgun.com (they make putters!), not railgun.org

    Correct Google cached URL [google.com]

  • Following of the links on the previous story [slashdot.org] 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 [imdb.com].
  • Actually the problem with railguns is that they tend to melt when you get to high enough temperatures. Once the little link that goes across the rails gets enough juice going through it, Zap! no more metal. When the military was talking about making these thwy would use Plasma in place of a metal conductor in order to prevent this problem. Also youre right about the coils, A coil gun exists as well, and it doesnt have as much of a problem of overheating as the rail gun but its more complex.

  • 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 :)
    --
    Slashdot didn't accept your submission? hackerheaven.org [hackerheaven.org] will!
  • True. id wasn't even the first person to use the railgun in a video game..Turok was out before Quake2. And both Turok and Quake2 clearly modelled their idea of what a railgun would look/act like from the movie 'Eraser'.

  • 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.
  • 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
  • Watch it, people! The above is a goatse.cx link...
    --
    Slashdot didn't accept your submission? hackerheaven.org [hackerheaven.org] will!
  • The G3 has a V0 of about 780 m/s, which translates to about 2340 fps. Nowhere near 10k fps, but still plenty enough. Also, the M16 reaches the same speed as the G3 (using high speed ammo), but the G3 (and the AK-47) have 7.62mm, while the M16 only has 5.56mm. :-)

    Hope this helps.

    Cheers, Ulli

  • The US Army should create a department for this purpose. I really think it could reap dividends.

    Perhaps the Defense Modeling and Simulation Office [dmso.mil]?

  • Ok. that was just uncalled for.

  • 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

    Silly boy, if you're in orbit you don't need a railgun. Just drop things on 'em. Never heard of gravity?

    See N&P's "Footfall" for details.

  • OK I'm SEVERELY nitpicking, but Turok wasn't first with the railgun either. Shadow Warrior from 3d Realms had it first.

    Given SW only came out like 3 months before Turok, but like I said, I'm nitpicking :)

  • You also fail to mention the weight of the ammo itself which is a huge component of stopping power

    These military rifles have bullets with incredibly small profiles which are very light. Some of the heaviest bullets (on hand held weapons) never score above 200 grain. I believe this is 0.4 oz., where it looks like the rail-gun could loft a quarter pound (very conservative).

    At 200 vs 2000 fps the rail gun would still have 4 times the kinetic energy and a much larger profile.

  • 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.
  • And then the American Way Of Life will be everywhere!
  • I remember gauss guns (same theory) from the RPG Traveller circa 1978. Battletech and OGRE also had railguns a short time later. It's a fairly old concept.

    What these guys are doing is much more similar to the railgun in Neal Stephenson's The Big U (1988?).

  • MIT was railed by Texas Tech.
    Texas Tech almost dodged MIT's rocket.

    dynoman7
  • remind me, how does the coil gun accellerate a non-magnetic slug? Does the changing magnetic field somehow induce a current (and hence magnetism) in the slug?

    My last physics course was a Long Time Ago (in a Galaxy Far ...)
  • 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 tricky part, at least for a kid who was, at the time, in high school, would have been controlling the timing on the solenoids -- and getting enough power to do some damage. Of course, I'm sure that many of you out there had more talent for electrical engineering than I did/do.
  • Yeah, all invented like good old Edison : let others do the work, then steal it and claim you did it yourself. Nice.

    Other American variant : offer huge pile of money to foreign scientists (or "get out of jail free" if they are Nazi scientists) and then claim their work to be a pure American success.
  • But you'd be nowhere without the Chinese. They invented gunpowder centuries before America existed.


    Hacker: A criminal who breaks into computer systems
  • 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.

  • Railgun is a very old concept invented several decades ago (if not in the 19th century, since the effect itself dates from there). And I'm pretty sure most advanced armies have had at least some prototype of railgun for a long long time.
  • I admittedly didn't read the specs in detail, but it seems they are using a single step in the gun with a large pulse.

    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.

  • >Silly boy, if you're in orbit you don't need a railgun. Just drop things on 'em. Never heard of gravity?

    More Info for you non-niven fans

    Niven Described 6 foot bars of steal (very skinny) with small guidance fins to hold them upright. drop a couple thousand from orbit over a battlefield and they would decimate everything on the field. dropped from orbit they could go straight through a tank like butter.

  • Didn't the Engineer in Quake 1 Team Fortress carry a railgun? And didn't that come out before Shadow Warrior?

  • 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.....

  • Guns and rockets both need incredibly volitile fuels to function correctly; a bomb drop over a large amount of bullets would cause more fireworks than the fourth of July, plus cause a fair amount of damage to surrounding people/buildings. Rail guns, OTOH, don't have this drawback, so storage of the ammo is a lot easier. And remember, the early guns weren't very reliable/accurate either, it took time to get them as accurate as they are today.
  • These are definitely not designed to be hand-held. I think they would be more useful as a replacement for the big guns on battleships. They don't have a Mr. Fusion, but they do have a Mr. Fission to power it.
  • Bah ! Now that Junior is in the white house, everyone knows global warming is a lie invented by comies to subvert the familly-religion-guns values of America. I'm pretty sure those propagating these rumors will be fried somewhere in a Texas prison when the first amendment is dropped.
  • 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.
  • 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 .220 swift is one of the highest velocity [reloadbench.com] rifles around at 4110 fps. I have heard stories of people shooting rounds with a soft tip that leave a trail of vaporized lead.
  • 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.

  • Limits of conventional weapons (Score:4)

    by sterno ( 16320 ) on Tuesday February 06, 2001 @06:50AM (#453317) Homepage
    There is a major advantage to using a rail gun. Ultimately destructive force is measured by the mass and the velocity of the projectile. Thanks to the joys of physics, the velocity has a whole lot more to do with the amount of kinetic energy you can inflict on a target.

    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.

    ---

  • (I know, offtopic, but...) The Air Force has looked into it, but you run into a problem with backwards skill transfer: people's primary skillz become how to play the video game, not fly the jet. You get a much better learning rate with cheezy games that use the same visual-spatial skills, but not the exact motions needed to fly. The best program available for it (at least a few years ago when I was working on this) is a program developed by the Israeli Air Force called Space Fortress that uses ASCII graphics. Players have to pilot a ship with their right hands, fire weapons with a trigger, use their left hands to choose weapons, remember an IFF code and hit it on the keyboard, and tap a steady rythem with their feet. After that, flying a jet in combat comes naturally.
  • Can we mount this on a robot and use it to propell stealth nuclear warheads from places off the world's nuclear strategy map?
    ----

  • Droping In From Orbit (Score:3)

    by Wyatt Earp ( 1029 ) on Tuesday February 06, 2001 @07:31AM (#453329)
    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)
  • I think the problem with your plan is that the guys with Gravity on their side are bound to win.

    Agreed. If we are dealing with only the local population, such as here on Earth, that is one thing. If you have visitors from outside, that is another.

    also, for that matter you could just start dropping appropriate size rocks. But it depends on what you are aiming to do. For example, do you want to wipe them out, or just make life miserable?

    The planetary orbit story from the other day also has weapons potential, but you need to assess just how mad you are at the other guy. You do not waste a perfectly good planet unless you have plenty of spares.

  • These are only toys, as this 200 feet per second the Texans get is a lousy projectile speed. Have they heard about gunpowder?
    These are Texans. Gunpowder and alcohol are more familiar to them than air and water.

  • I've dealt with these people before to get some high voltage supplies and pieces. They sell all sorts of stuff from Information Unlimited [amazing1.com] - 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 :)

  • (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...
  • Do you guys even stop for a minute to think you are talking about more effective ways the government can kill people.

    I know how slashdotters love big brother and all, but really.
    -

  • 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.
  • I remember some work that some researchers were doing years ago in this area. It was in Dicover magazine, I have no idea which issue, but the idea was to fill the barrel with an explosive gas mixture that would burn/explode all along the length of the barrel right behind the projectile. I seem to remember they were lobbing several pounds of metal through thick steel plates with it, but it was far from portable.

    It kind of rememded me of the Nazi gun that had multiple chambers along the length of the barrel. That gun could shell the UK from german held territory. The allies bombed it all the hell before they could do too much damage with it. It was also huge and fixed in position, making it very easy to bomb once we knew it existed.
    -

  • What the idiots didnt have enough sense to fire it into a pile of sand?

    But shooting it straight up into the air makes the muzzle velocity calculations so much easier. :)
    -

  • 700,000 feet is 132 miles, which is just beyond the Earth's atmosphere. If you dropped a 300 pound warhead (explosive or not), it would either burn up on reentry, or if it didn't, friction would slow it down so that by the time it landed, it would be falling at a couple hundred feet per second. Last time I checked, objects falling at a couple hundred feet per second do very little damage to anything but themselves. (Like skydivers before they open their parachute, for example.) The only way to have kinetic damage from an object falling from space be significant is to have it travelling multiple miles per second *when it enters the atmosphere*. Depending on the size of the object, it will disintegrate and explode at a given altitude. A 200-300 pound man-made metal object is likely to be a few feet across, and moving at 1 mile per second would disintegrate within a few seconds upon hitting the *top* level of the atmosphere, to say nothing of reaching the ground. The object would have to be at least the size of a bus and moving at least 7 miles per second in order to even make it to the earth's surface.

    My numbers may be off a little but this should be generally accurate. Kinetic weapons from space are way harder to use and implement than regular self-guided conventional (or nuclear) weapons, and to a lesser (and much less controllable) effect. Unless you have a body with no atmosphere, in which case something like this would only work insofar as destroying whatever it hit directly -- remember, shock waves don't propagate without a medium. Drop a nuke on the moon, and all of the damage done would be thermal and radiation damage (which is 80-90% of the released energy anyway, but still); the kinetic energy released by the explosion would carry the bomb material itself outward at a high velocity, but there would be a tiny quantity of that material. In atmosphere, the overpressure shockwave caused by a nuke can do massive damage as well, but it needs the atmosphere to propagate the kinetic energy.

  • Have you ever built an AK-47 from raw metal?

    I'll pit your professionally-produced AK-47 against the DoD 5,000,000 Amp, 4 kilometers/second muzzle velocity, 5 kg projectile railgun any day.

    Alternatively, I'll pit my homebrew railgun against your homebuilt zipgun and homemade bullets and we'll see what's more impressive.

    -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?

  • Re:Limits of conventional weapons (Score:3)

    by jafac ( 1449 ) on Tuesday February 06, 2001 @11:35AM (#453399) Homepage
    Another advantage is the acceleration curve - you can vary it by varying the amount of power you feed as the projectile travels the length of the barrel. With a bullet, the acceleration curve is loaded very heavily at the front - which means more force is applied to recoil in a shorter amount of time. In an electromagnetic weapon like a rail-gun, mass driver or gauss gun, the recoil is distributed evenly (or any way you choose) along the entire acceleration of the projectile - which has a great potential for increasing accuracy.
    There's also the potential that the power-curve could be inversely wired to the reflexive muscle reaction of the firer, to provide dynamic feedback, and prevent over-compensation for recoil.
  • Rail-gun: projectile travels the length of the barrel, in contact with two conductive rails - propelled by elecromagnetic field produced by current from the rails. This would essentially be a high-velocity smoothbore type round, relying either on a spherical shape, or fin stabilization.

    Mass Driver: Projectile rides on rails (or is magnetically suspended) - Projectile contains natural magnets. The launching track contains electromagnets which switch polarity, alternately attracting and repelling the projectile as it travels past - tripping photosensors. The projectile is often called a "bucket" and is usually intended to be retrievable, and ejects the payload soon after launch.

    Gauss gun: (I believe this weapon first appeared in the "Stainless Steel Rat" Sci Fi book series). Simiilar to a mass-driver, projectile travels the length of the barrel, NOT in contact with anything other than air, the barrel is a wider diameter than the projectile, eliminating sliding friction entirely. Projective force is entirely provided by switched electromagnets along the length of the barrel. Spin is induced by magnetic bias, giving the projectile it's own gyroscopic spin stabilization (UNLIKE a mass-driver or rail-gun). This type of rifle technique would be far superior to the traditional type of gyroscopic spin stabilization induced by spiral "rails" machined into the inner surface of a conventional gun, because there would be no friction, none of the energy that would otherwise be put into forward motion would be lost to spin, so you would achieve smoothbore velocities (and energies) with a long-projectile (therfore, more mass for a given bore), with no worries of losing stability to atmospheric friction. (smoothbore rounds are usually either spheres - musketballs, or fin-stabilized - allowing a more efficient acceleration, with no loss of energy to rifling, but spheres do not allow for a more massive projectile without moving to a higher bore, and fins provide their own mass and storage inefficiencies.)

    Then there's Oni's Mercury Bow - which electromagnetically fires a confined "bolt" of liquid mercury at high velocities. I shudder at the environmental implications of such a weapon.
  • 7.62 mm NATO is a totally different round than 7.62 Russian that the AK-47 fires.

    7.62 NATO round is a longer, much more massive bullet, usually fired at higher velocities. It has roughly equivalent stopping power to a 30-06. It's one of those bullets that will splatter someone's head like a melon, even at long ranges. It's an excellent sniper round, and does decent damage to lightly armored vehicles (jeeps and stuff) - but firing this round results in high recoil - and without a bipod, or tripod mount, full auto is totally inaccurate.

    The 7.62 Russian is a short, stubby round, not as massive, usually has a relatively low muzzle velocity, which makes it much more stable when fired by a soldier in full-auto mode. It's great for close-range engagements, and jungle fighting. Not very accurate at long ranges (compared to the 7.62 NATO, and 5.56 NATO). The problem with the AK-47, is it does the same job as a submachinegun, while asking the soldier to carry a rifle. This is a pretty harsh assessment though, because in all fairness, 7.62 Russian IS a real rifle round. But only barely.

    The 5.56 NATO round used in the M-16 is a smaller, lighter bullet than the 7.62 NATO, but is also fired at relatively high velocities - which gives a potential for much higer accuracy at longer ranges (*not* with the M-16, but in sniper versions of the AR-15, it's pretty decent). The 5.56 NATO round has excellent penetration, plus the bullet is designed to destabilize or tumble, when it enters a substance the consistency of flesh (or ballistic gelatin). This tumbling causes the round to fragment, and otherwise cause a lot more damage than it would otherwise, for such a small round. The reasoning behind choosing a standard round that was 5.56 NATO instead of 7.62 NATO, was to allow a higher muzzle velocity, (which means better accuracy and stopping power at long ranges) but still keep the weapon relatively stable during auto firing. And also, 7.62 Russian (or NATO equivalent) was avoided because more 5.56 NATO rounds could be carried by a soldier, giving them more potential kill opportunities, less resupply burden.

    So what kind of ammo does the G3 fire? I'm assuming 7.62mm NATO - in keeping with the standard? or is it going to use something special?

  • Re:The Army loves computer games. (Score:3)

    by rjh ( 40933 ) <rjh@sixdemonbag.org> on Tuesday February 06, 2001 @12:13PM (#453406)
    1. Farming computer games for new weapons ideas is a splendid idea.

      Yep, except that in this case the computer games were farming Defense Department prototypes and SF literature. Railguns have existed for decades; they were even proposed as part of Reagan's Strategic Defense Initiative back in '84. So this is hardly life imitating art--art imitated life originally.
    2. The US Army should create a department for this purpose. I really think it could reap dividends.

      The Defense Department already does have a department for this, called the Defense Advanced Research Projects Agency (DARPA). In a previous incarnation it was simply the Advanced Research Projects Agency (ARPA), which developed the ARPAnet to connect ARPA research labs... and that, in turn, turned into the Internet.

      So your ability to post your opinion on Slashdot is due largely to the very agency that you think doesn't exist yet. :)
  • 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.
  • DERA [dera.gov.uk] (part of the UK MOD) have a large rail gun project. IIRC we have a 90mm calibre gun at a range in Scotland. The existance of the gun is not classified, but I haven't been able to find any URL's describing it.

    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)?

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