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How to build a REAL rail gun (One way to wipe out those damn terrorists!)
Jengle and Fatro's Rail Gun Page ^ | Jengel and Fatro

Posted on 07/27/2003 1:18:25 PM PDT by mhking

Welcome to the newly redesigned haven for the rail gun enthusiast. This page covers some of the latest techniques in electromagnetic propulsion, but the construction of a rail gun is a perilous undertaking so use the information contained herein at your own risk. NOTE: In the interest of simplicity vector directions are ignored, it is assumed that the magnitude is as calculated and in the desired direction.


TOPICS: Culture/Society; Extended News; News/Current Events; War on Terror
KEYWORDS: techindex

1 posted on 07/27/2003 1:18:25 PM PDT by mhking
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To: Howlin; Ed_NYC; MonroeDNA; widgysoft; Springman; Timesink; dubyaismypresident; Grani; coug97; ...
And the decision is....Just damn.

HMB/Bizarre PING....

If you want on or off this list, FReepmail me!

FYI: This has fast outgrown it's original "charter" and become a home for the truly bizarre. An alternative saying/phrasiology is being sought (and suggestions are very welcome!). Also, like it's "cousin list" the B/C list, it has become a high-volume list.


I'm leaning toward "Just damn," on the suggestion of quite a few folks. I won't make a decision until Sunday. (And thanks to all of you for sending your suggestions!)

2 posted on 07/27/2003 1:18:43 PM PDT by mhking
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To: mhking
But vectors DO matter!

Hook up those magnets/wires the wrong way and the launcher might have the launchee for lunches.
3 posted on 07/27/2003 1:20:26 PM PDT by Robert A. Cook, PE (I can only support FR by donating monthly, but ABBCNNBCBS continue to lie every day!)
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To: mhking
Now I'm getting nostalgic for Quake II.

Hmm, wonder if I could persuade some of my students to build one as a project?

Of course I could. Let me rephrase that:

Hmm, wonder if I could persuade some of my students to build one as a project and still keep my job?

4 posted on 07/27/2003 1:26:04 PM PDT by Slings and Arrows (Decisions, decisions...)
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To: Robert A. Cook, PE
Kewl! I want the handheld version!
5 posted on 07/27/2003 1:28:54 PM PDT by Threepwood
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To: Slings and Arrows
How about a rail pumpkin gun?

Wonder what a pumpking hitting a target at 4,000 m/sec looks like?
6 posted on 07/27/2003 1:30:30 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: Threepwood
Funny you should mention that...Jane's Defense Weekly mentioned in early 2002 that the US Army was looking at manportable LASERS for air defense. A manportable railgun ought to be equally feasible...
7 posted on 07/27/2003 1:31:42 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: mhking

Sounds like a winner to me.

8 posted on 07/27/2003 1:33:36 PM PDT by Riley
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To: Poohbah
Sounds good to me. I wonder what the federal government here would say if I tried to register a electromagnetic railgun? I wonder if I'd even have to. Mind you, hitting an Elk with a projectile moving at 4km/sec might make the taxidermist's job a bit tricky...
9 posted on 07/27/2003 1:35:20 PM PDT by Threepwood
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To: mhking

A 10 minute railgun

A railgun is a device for accelerating an object by running electric current through it along a pair of rails. When large amounts of power are used, the railgun becomes a potent weapon. But the principles can be demonstrated safely by using a smaller amount of power, in our case, from a 9 volt battery.

When a small amount of power is used, the rails can be re-used many times. If larger amounts of power are used, the railgun becomes a one-shot device, as the rails are destroyed in the process of shooting the gun, due to arcing and flexing of the rails.

There are several types of rail gun, each with a different method of accelerating the object. This version is called a linear homopolar motor.

railgun

Click on image for an animated picture

What you need

railgun materials

Click on image for a larger picture

We start by spreading a thin layer of glue on the base, to hold down the foil strips.

railgun glue

Click on image for a larger picture

The foil strips are then placed on the base, about a half inch apart, and smoothed down with fingers to remove wrinkles. The extra 2 inches is left hanging over one side, to make it easy to clip on the leads for the battery.

completed railgun track

Click on image for a larger picture

Next we attach the battery with the clip leads. We won't worry about battery polarity at this time -- if the gun shoots the wrong way, we will reverse the battery.

filing railgun axle flat

Click on image for a larger picture

The nest step is to file the ends of the coathanger wire flat. This will allow the magnets to stick flat to the ends of the wire axle. If the filing is done carefully to make the flat ends perpendicular to the wire, then there will be less wobbling as the magnets travel down the rails.

railgun wheels

Click on image for a larger picture

Now the magnets are placed on either end of the wire axle. The magnets should have their poles facing in opposite directions. The magnets repel one another when aligned this way, but will still stick firmly to the steel axle. No glue is necessary, as the magnets are very strong.

Firing the railgun

To fire the railgun, just drop the wheels on the rails. They will start to accelerate immediately. If they don't move at all, the magnets are probably not pointing the same way. Lift the wheels, and flip one magnet, and try again. If it still doesn't work, check the battery and the connections.

If the wheels move in the wrong direction, you can either start them at the other end, or reverse the battery.

Click on the photo below to see the railgun in action.

railgun animation

Click on image for an animated picture

10 posted on 07/27/2003 1:35:28 PM PDT by Southack (Media bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: Slings and Arrows
Hmm, wonder if I could persuade some of my students to build one as a project and still keep my job?

I don't know, but I want to sign up for your class, whatever you're teaching.

/john

11 posted on 07/27/2003 1:37:03 PM PDT by JRandomFreeper (I'm just a cook.)
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To: mhking
Self ping: read later
12 posted on 07/27/2003 1:39:04 PM PDT by MalcolmS
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To: Poohbah
The Navy's looking into this as well.
13 posted on 07/27/2003 1:42:27 PM PDT by Tree of Liberty
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To: Poohbah
Did you see the pumpkin plunkin' contest on TV?

Elegant machines just cryin' for real-gourd railgun solution to throwin' pumpkins a long way.
14 posted on 07/27/2003 1:55:42 PM PDT by Robert A. Cook, PE (I can only support FR by donating monthly, but ABBCNNBCBS continue to lie every day!)
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To: Robert A. Cook, PE
How to make America great again:

Fire a pumpkin into orbit :o)
15 posted on 07/27/2003 1:56:33 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: JRandomFreeper
Seems like the right way to do it is to start the thing moving (with a spring ?) so the inital movement is assured BEFORE current is applied: the movement reduces the initial current surge when v=0 and simplifies the circuits.
16 posted on 07/27/2003 1:58:10 PM PDT by Robert A. Cook, PE (I can only support FR by donating monthly, but ABBCNNBCBS continue to lie every day!)
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To: Southack
Now isn't that cool.
17 posted on 07/27/2003 2:03:02 PM PDT by AdA$tra (Tagline maintenance in progress......)
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To: Robert A. Cook, PE
Before you become too enamored with a magnetic solution, consider not only my post above but also the magnetic acceleration factor.

How long would your magnetic rail gun have to be to get any substantial speed improvement in the projectile over existing technology?

18 posted on 07/27/2003 2:03:34 PM PDT by Southack (Media bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: Robert A. Cook, PE
I like the sabot approach with a large surface contact area so that current densities don't reach a level where welding occurs.

I have to wonder also about the relationship between voltage and velocity. 12 volts at 1000 amps (dc) = 12kw. So does 120,000 volts at 0.1 amp. Of course, arcing could be a problem.

But what do I know, I'm just a cook. ;>)

/john

19 posted on 07/27/2003 2:05:30 PM PDT by JRandomFreeper (I'm just a cook.)
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To: Southack
How long would your magnetic rail gun have to be to get any substantial speed improvement in the projectile over existing technology?

Barrel length isn't the issue: total acceleration is. The higher the acceleration imposed, the shorter the barrel must be for a given velocity.

20 posted on 07/27/2003 2:08:04 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: Poohbah
Is magnetic acceleration much the same as Gravitational acceleration (i.e. 9.8 m/s^2 on Earth)?

OK, so you can increase the magnetic field to improve acceleration somewhat, but won't that meager increase pale in comparison to the time spent on longer and longer rails (i.e. that whole "per second squared" thing)?!

21 posted on 07/27/2003 2:13:30 PM PDT by Southack (Media bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: mhking
And the decision is....Just damn.

LOL.

22 posted on 07/27/2003 2:21:18 PM PDT by Victoria Delsoul
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To: Southack
Is magnetic acceleration much the same as Gravitational acceleration (i.e. 9.8 m/s^2 on Earth)?

No.

OK, so you can increase the magnetic field to improve acceleration somewhat, but won't that meager increase pale in comparison to the time spent on longer and longer rails (i.e. that whole "per second squared" thing)?!

Magnetic field strength and barrel length are not tied directly to each other.

23 posted on 07/27/2003 2:23:39 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: Robert A. Cook, PE
Seems to me that you would enjoy this in view of your launchers for lunches remark.


Reasons why the English language is so hard to learn:

1) The bandage was wound around the wound.
2) The farm was used to produce produce.
3) The dump was so full that it had to refuse more refuse.
4) We must polish the Polish furniture.
5) He could lead if he would get the lead out.
6) The soldier decided to desert his dessert in the desert.
7) Since there is no time like the present, he thought it was time to present the present.
9) When shot at, the dove dove into the bushes.
10) I did not object to the object.
11) The insurance was invalid for the invalid.
12) There was a row among the oarsmen about how to row.
13) They were too close to the door to close it.
14) The buck does funny things when the does are present.
15) A seamstress and a sewer fell down into a sewer line.
16) To help with planting, the farmer taught his sow to sow.
17) The wind was too strong to wind the sail
18) After a number of injections my jaw got number.
19) Upon seeing the tear in the painting I shed a tear.
20) I had to subject the subject to a series of tests.
21) How can I intimate this to my most intimate friend?

By the way...there is no egg in eggplant nor ham in hamburger; neither apple nor pine in pineapple.

English muffins weren't invented in <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />England or French fries in France. Sweetmeats are candies while sweetbreads aren't sweet nor breads.

Quicksand works slowly, boxing rings are square and a guinea pig is neither from Guinea nor is it a pig. And why is it that writers write but fingers don't fing, grocers don't groce and hammers don't ham?

If the plural of tooth is teeth, why isn't the plural of booth beeth?

One goose, 2 geese. So one moose, 2 meese? Doesn't it seem crazy that you can make amends but not one amend. If you have a bunch of odds and ends and get rid of all but one of them, what do you call it? Is it an odd, or an end?

If teachers taught, why didn't preachers praught? If a vegetarian eats vegetables, what does a humanitarian eat? In what language do people recite at a play and play at a recital? Ship by truck and send cargo by ship? Have noses that run and feet that smell?

How can a slim chance and a fat chance be the same, while a wise man and a wise guy are opposites? You have to marvel at the unique lunacy of a language in which your house can burn up as it burns down, in which you fill in a form by filling it out and in which, an alarm goes off by going on.

English was invented by people, not computers, and it reflects the creativity of the human race, which, of course, is not a race at all.

That is why, when the stars are out, they are visible, but when the lights are out, they are invisible.

P.S. - Why doesn't "Buick" rhyme with "quick"?
24 posted on 07/27/2003 2:25:56 PM PDT by billhilly
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To: billhilly
bump
25 posted on 07/27/2003 2:29:34 PM PDT by Tribune7
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To: billhilly
"The tough coughs and hiccoughs as ploughs through the dough." --Spider Robinson
26 posted on 07/27/2003 2:34:00 PM PDT by Slings and Arrows (Am Yisrael Chai!)
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To: billhilly
"The tough coughs and hiccoughs as he ploughs through the dough." --Spider Robinson

D'OUGH!

27 posted on 07/27/2003 2:36:18 PM PDT by Slings and Arrows (Am Yisrael Chai!)
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To: Beelzebubba
geeky ping
28 posted on 07/27/2003 2:39:02 PM PDT by Henrietta
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To: Poohbah
"Magnetic field strength and barrel length are not tied directly to each other."

Not directly, but one would presume that magnetic field strength was proportional to the amount of electricity input to the rails, that acceleration was due to the magnetic field strength of the rails, and that velocity was a function of time on the rails (i.e. very tightly related to their length) multiplied by the acceleration factor of that particular magnetic field, no?!

29 posted on 07/27/2003 2:39:14 PM PDT by Southack (Media bias means that Castro won't be punished for Cuban war crimes against Black Angolans in Africa)
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To: Southack
Not directly, but one would presume that magnetic field strength was proportional to the amount of electricity input to the rails,

Correct.

Acceleration equals force divided by mass.

More electrical energy put into a given set of rails equals more acceleration.

that acceleration was due to the magnetic field strength of the rails, and that velocity was a function of time on the rails (i.e. very tightly related to their length)

This is A factor, not THE factor.

If I can crank ten times as much energy into my railgun, it's the same thing as giving the projectile ten times as much barrel length.

30 posted on 07/27/2003 2:44:02 PM PDT by Poohbah (Crush your enemies, see them driven before you, and hear the lamentations of their women.)
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To: Southack
Assume you want to launch something into orbit, or just get it to a high speed.

If you use a chemical "accelator" you've got a choice between an explosion-type or a rocket-type propulsion system. Both give you many, many problems:

Any explosion system (gun, cannon, mortar) requires the projectile be small diameter contained in a high-pressure short cylinder: the exploding/burning powder gives immense acceleration forces in a very short time that are all contained behind the projectile: this makes it very, very difficult to design internal components against the forces and stresses on the projectile itself. High short-term gas stresses give you very high stresses too on the barrel, chamber, and breech. So you have to limit yourself to "simple" mechanical things and small loads and VERY heavy gun barrels: less than 16" diameter limit for example and many hundred tons of mounting, aiming, and tracking machinery only give you 26 - 40 miles of range for just a few hundred pounds of "real" payload.

A rocket-type systems means you spend millions of dollars for lifting, guiding (and throwing away as exhaust) most of your expensive rocket as fuel and fuel tanks just lifting a very small proportion of the inital mass as payload. Worse, all that millions spent on rocket motors and pumps and guidance is wasted on the one shot.

Fire another rocket and you have pay for all that stuff you already built (motors, and tanks, and guidance packages) all over again.

Using a rocket is like buying a 120,000.00 dollar 18-wheeler tractor-trailer just to send one package cross-country once with a 100 pound cargo. The next day, you have to buy another 18-wheeler to send the next package cross-country.

The acceleration of a railgun can be adjusted to be slower and continuous over the length of the rail: thus there is much less "impact" of the explosion. The diameter of the projectile isn't limited by the "diamter" of a gun barrel (though there are limits of course!) and the thousands of psig "pressure" of the gasses behind a shell are not present. This means the aiming and tracking mechaism of the railgun can be less for the same weight projectile. The rail itself is the guiding mechanism, so you don't need to rebuild it for each shot - this sames on reload cost as well, because you only launch (throw away) the projectile.

Need more acceleration to make a faster projectile or get longer range? Make a longer rail. Use a higher voltage/current to get more magnetic thrust.

The limit of course is a miles-long railgun inclining "up" (from say a Colorado valley up the mountain side) into space. In a simpler shell-type system, you enclosure the launcher in a typical gun-type launcher, but don't need to store all the ammo casing and explosive gunpowder: think of the Hood, Arizona, and other "magazine explosions" that can destroy a ship with a single hit.

No magazines (smaller magazines for simpler projectiles) mean saving in space, weight, cost, manning, reload time, support time, support ship cost, and initial purchase cost.
31 posted on 07/27/2003 2:55:21 PM PDT by Robert A. Cook, PE (I can only support FR by donating monthly, but ABBCNNBCBS continue to lie every day!)
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To: mhking; JohnHuang2; MadIvan; TonyInOhio; MeeknMing; itreei; jd792; Molly Pitcher; muggs; ...
PiNgS
32 posted on 07/27/2003 2:59:18 PM PDT by ATOMIC_PUNK ("A conviction that we are right accomplishes half the difficulty of correcting wrong." --T Jefferson)
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To: ATOMIC_PUNK; *tech_index; MizSterious; shadowman99; Sparta; freedom9; martin_fierro; ...
This seems technical!

OFFICIAL BUMP(TOPIC)LIST

33 posted on 07/27/2003 4:26:36 PM PDT by Ernest_at_the_Beach (Recall The Governer and then recall the rest of the Demon Rats!!!)
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To: mhking
Methinks this might be a plan to blow theeself up!
34 posted on 07/27/2003 6:55:47 PM PDT by thegreatbeast (Quid lucrum istic mihi est?)
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To: Slings and Arrows
i'll build one just for fun
35 posted on 07/27/2003 8:08:06 PM PDT by Mr. K (VEY series about everything)
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To: JRandomFreeper
Hmm, wonder if I could persuade some of my students to build one as a project and still keep my job?

I don't know, but I want to sign up for your class, whatever you're teaching.

Computer science. This semester, Database System Design. Not much opportunity there.

Maybe I could offer to teach a course on digital circuitry. The rail gun would be a test to demonstrate...embedded controllers. Yeah, that's the ticket...

36 posted on 07/27/2003 8:20:25 PM PDT by Slings and Arrows (And at 4 km/s, they're going to be embedded but good.)
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To: Southack
"This version is called a linear homopolar motor."

I don't want any more talk about queer eskimos!

--Boris

37 posted on 07/28/2003 1:54:53 AM PDT by boris (The deadliest Weapon of Mass Destruction in History is a Leftist With a Word Processor)
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To: billhilly
the nastiest letter group in the English Language is "ough"
38 posted on 07/28/2003 3:08:36 AM PDT by King Prout (people hear and do not listen, see and do not observe, speak without thought, post and not edit)
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To: billhilly
Jerry Seinfeld?
39 posted on 07/28/2003 3:27:00 AM PDT by Bullish
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To: Slings and Arrows
I would make sure that the one they built was small enough that a student could not get on a carrier and launch him/her self.
40 posted on 07/28/2003 6:15:46 AM PDT by Blood of Tyrants (Even if the government took all your earnings, you wouldn’t be, in its eyes, a slave.)
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