homemade Gauss pistol - pretty interesting

[olly_k]

That is neat! - It just goes to show what amatures are capable of well, bright amatures at least!.

 

[subzero349]

what happened to the relativety debate? Ron... why did you remove that portion... I was thinking about it :lol:

 

[Roff]

what happened to the relativety debate? Ron... why did you remove that portion... I was thinking about it :lol:

Well, I realized that Nostrafus was saying (I think) that C^2 is a constant, so, as he said, energy is proportional to mass. If you want to make up your own units of energy, I guess you could say E=M*K, where K is any arbitrary number, and the units of energy are Gribbles or whatever. However, if you want to have units that the rest of the world understands, the following argument holds (which I posted and then removed):

In whatever units you choose,
Energy=force*distance
Force=mass*acceleration
Acceleration=distance/time^2
Therefore,
Energy=mass*distance^2/time^2
The units of velocity (speed) are distance/time
Therefore the units of energy are:
Energy=mass*velocity^2

The point here is that the exponent is not arbitrary if you want to use conventional units (Metric, English, etc.).

Ron

 

[Nostrafus]

Okay, Ron got my point... Woohoo...

Sorry, it's just usually when I discuss physics, I end up with someone throwing a fit about how I'm wrong because some of my ideas go against modern science. Not saying anyone did it, really, I'm not, it's just that I've had to explain that several dozen times, so it gets a bit tiring.

Anyway, I'll have to dig up one of my old science books to get the push is more productive than pull thing.

I believe it was something along the lines of, if a pushing force can start behind an object and stay behind an object it is more effective than a pull, because at the end when you want to propel an object the pulling force must act like a slingshot to get the object to move in front of it, which requires more energy.

 

[Roff]

Nevertheless, the speed of light has everything to do with energy if you want units you can relate to (Joules, Btu, calories, ergs, etc.).
And you never did explain how an electromagnet can push a projectile. :?

 

[Nostrafus]

I haven't figured out how to make an electromagnet push yet, but a permenant magnet yes, Again, the slug must be of the same polarity as the poles closest to the barrel, the polls must be at an angle to give it forward motion, and become more angled toward the end of the barrel so it accelerates.

Sort of like a staged shaped explosives, the sharper the angle the more force is pushed toward the center.

Though I have been working on a slingshot like effect for pulling the round, by using a bolt action rifle, the bolt could place the round (In my case a 1/4" steel ball berring) about 1-2" inside the coils, so the electromagnet first grabs the round from behind and pulls it to give it a bit more forward motion to begin with.

I haven't had the time to build a full scale model, but right now it's the design that looks the most promising.

My friend and I are also working on a modular barrel using photosensors and high voltage capacitors, so if you wanted to make a rifle, you just add 5-10 modules, or 20 for those shots that absolutely cannot miss... :twisted:.

 

[Roff]

Sounds pretty cool. I was enamored with the concept of coil guns before I had ever seen plans for one (I'm old), but my attention span is too short.
Keep us posted on your progress!

Ron

 

[Nostrafus]

Yeah, I've been facinated by them since I saw the movie eraser, then I thought about it and laughed, as their weapon couldn't work... aluminum rounds don't move by electromagnetics. So I've been looking at them for....... Damn... 7 years... the movie came out in 1996 it's been that long!!!... man, I thought it was only about 4, but I guess it's been much longer than that.

 

[Nostrafus]

I've also got 2 bulk shipments coming in from EGM, miscellanous overstock/understocked items, maybe I'll get lucky, and find a few high voltage capacitors, or a fine wire spool, my monetary funding has been a bit tight this year, beings as how I'm trying to get a house and all, so I won't be able to actually build anything too expensive for a while.

 

[tansis]

Yeah, I've been facinated by them since I saw the movie eraser, then I thought about it and laughed, as their weapon couldn't work... aluminum rounds don't move by electromagnetics

Linear Induction Motors:
"The reaction plate is the equivalent of the rotor. This is usually a conductor sheet of aluminium or copper backed by steel, but any of these may be used alone"

Best link I could find a short notice.......
**broken link removed**

 

[arlin]

aluminum projectile

check this link out:

**broken link removed**

the so called "thompson coilgun" launches a nonmetallic (in this case aluminum) disc off the end of a steel shaft with a coil at the other end (i guess this is kind of like a "can crusher" turned inside out.)

Check out the rest of the site for some very cool stuff related to coil guns and the like.

 

[Nostrafus]

Okay, so it's kinda like a cyclotron, kinda like a coilgun, but uses the conductive property of aluminum.

Also, Okay, tansis I said aluminum isn't reactive to electromagnets, in the case of a linear motor, it also uses steel, which is magnetic reactive, and the aluminum is just there to lighten the load, if it was made of pure aluminum it wouldn't work.

It's the same reason recycling plants have a giant electromagnet on the side of the sorter. The aluminum passes through to the first conveyor belt, and the steel/tin cans (or sheets, or bails, whatever they're sorting) goes onto a seperate conveyor belt.

 

[tansis]

in the case of a linear motor, it also uses steel, which is magnetic reactive, and the aluminum is just there to lighten the load, if it was made of pure aluminum it wouldn't work.

I beg to differ and refer you to section 2.3 of the following document.
**broken link removed**
and the second paragraph of this page.
**broken link removed**


It is a popular misconception that arises because one cannot pick up a piece of aluminium with a magnet, but in can conduct an electrical current.
In the case of the linear motor this current is induced by a moving magnetic field, and current flowing through an inductor....

Finally for all you film buffs out there.

For many people, the word "railgun" simply refers to an advanced technological weapon only seen in movies, and therefore is theoretically impossible. In fact, railguns do exist, but not in the same way as depicted in sci-fi novels. For those completely unaware of railguns, see the movie Eraser, starring Arnold Schwarzenegger, to get a better picture of the power delivered by these devices. However, do not be fooled by the physics of the movie. Arnold shooting a slug at just under the speed of light implies his shoulder is enduring a momentum of approximately 29700000 N-s from the gun (assuming each bullet is 100g and neglecting the increase in mass which occurs as velocity approaches the speed of light).
Railguns are actually relatively simple devices consisting of two parallel copper rails with a groove cut into them. A small projectile made of either aluminum, copper, or graphite is fitted in the groove. The projectile must be at least semi-conductive in order to complete the circuit. The rails are hooked up to an enormous power source which sends an electric current up one rail, through the projectile, and down the second rail. The current up and down the raill causes magnetic fields that interact with the electrons (current) moving through the projectile. This interaction is known as the Lorentz Force and acts in a direction perpendicular to the magnetic field and the current. The effect of the force acting perpendicular to the magnetic field and current causes the projectile to accelerate down the rails. Therefore, using longer rails causes the projectile to reach a higher velocity before leaving the rails, due to the fact that the Lorentz Force will be acting on the projectile for a longer period of time.
**broken link removed**

This you have probably seen........................
http://www.powerlabs.org/railgunprogress.htm

 

[Nostrafus]

I THINK I'VE FIGURED IT OUT!!!

Aiight, here's the idea before I forget it.

In order to create a pushing linear accelerator you need a polarized piece of steel.

Now in order to polorize a cylindrical slug, you need to stroke it with a bar magnet, since it's cylindrical all parts must be evenly magnetized, by drilling a hole through the center of one poll of a bar magnet (Say positive simply because it's what is necessary for this demonstration) pass the slug though the hole making sure it touches the entire slug, this will straighten the polls and make the front of the slug positive, and the rear negative.

When an electromagnet is creates using an iron core and insulated wire, the postitive must be at the rear of the coil traveling forward, making the entrance a negative poll, and the end of the coil is positive.

If you use several stages of v-switches, you can create a constant forward motion.

But here's the kick, instead of the standard linear accelerator this one is made differently, with the electromagnets mounted on their ends, I'll show a demonstration of what the barrel may look like from the front.

FRONTAL VIEW

\|/
-o-
/|\

SIDE VIEW

| | | | | | | | |
-----------------
-----------------
| | | | | | | | |

Okay consider the o to be the barrel, and the 8 spikes being electromagnets precisely mounted around the barrel, making a design like this every 1/2 inch or so as seen in the side view.

So the beginning of the barrel would be an electromagnet powerful enough to drag the slug in front of it using a v-switch (since the front of the slug is positive, and the rear is negative, the slug will be dragged because the end of the electromagnets closest to the barrel are negative or south), and in front of the next electromagnet where it turns the electromagnet on behind it just long enough to activate the negative poll, thus pushing the negative end of the slug with a repelling force, then when the slug reaches the next magnet and gets just in front of it, the one behind it turns off, and the next one turns on, giving it a constant forward slide.

Since it is a pushing force there wouldn't be any drag to keep the slug inside the barrel, meaning there would be no need to turn off all the coils to keep from dragging the slug back, reducing speed.

Plus a design like this can be made modular, so each set of electromagnets can have it's own smaller power souce instead of one large one.

Did I describe that one right.