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

[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.

[Southack]

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)?!

[Victoria Delsoul]

And the decision is....Just damn.

LOL.

[Poohbah]

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.

[billhilly]

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"?

[Tribune7]

bump

[Slings and Arrows]

"The tough coughs and hiccoughs as ploughs through the dough." --Spider Robinson

[Slings and Arrows]

"The tough coughs and hiccoughs as he ploughs through the dough." --Spider Robinson

D'OUGH!

[Henrietta]

geeky ping

[Southack]

"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?!

[Poohbah]

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.

[Robert A Cook PE]

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.

[ATOMIC_PUNK]

PiNgS

[Ernest_at_the_Beach]

This seems technical!

OFFICIAL BUMP(TOPIC)LIST

[thegreatbeast]

Methinks this might be a plan to blow theeself up!

[Mr. K]

i'll build one just for fun

[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.

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...

[boris]

"This version is called a linear homopolar motor."

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

--Boris

[King Prout]

the nastiest letter group in the English Language is "ough"

[Bullish]

Jerry Seinfeld?

[Blood of Tyrants]

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.