Started work on the railgun I'm making

[KnightElite]

So far we've got some 3D renders of the accelerating sections. Here be they:

This one is a view from the end, looking at the bore. You can see the projectile in the middle:


The next one is an oblique view of one end. You can see the bullet ready to enter the gun. The top and bottom part is 3/4" thick plexiglass, the brownish coloured part is the rails, which are 5/8" thick. The bullet itself is .50 Cal. The bolts along the side are what will hold it all together. They are Grade 5, 3/8" diameter bolts. They are spaced every two inches.


The last one is the entire "rail" portion of the gun. The whole thing is 32" long, 2 1/4" thick, and 3" wide.


For power, I am getting 110 2400 uF, 400V, 450Vmax electrolytic capacitors. Total energy of the power supply when fully charged should be ~20kJ.

Still working out the details, but suffice to say that if I fire a 10g bullet, and the railgun is only 5% efficient, it will go at ~Mach 1.5 I should be able to get more efficiency than that (or so I hope).

There will also be a compressed air injection system (hopefully injection speeds will be upwards of 100 m/s).

[isp]

Hmmm that's a little over my head... the only thing that comes to my mind when I hear "rail gun" is quake3

Just don't shoot me with it! :thumbsup:

[Smizack]

That is badass... Put me on the order list!

[sjohnson]

Now all you need is to find some depleted uranium to cast into the projectile(s)

How did you calculate the length? From what little I know of the physics the barrel has to be considerably long to allow for projectile accelleration. Else the armed forces would already be using these (or are they?).

[KnightElite]

Lol, actually, I think the barrel is longer than it needs to be, by a fair bit. If you look at www.powerlabs.org/railgun.htm , his railgun is only accelerating for about an inch of his barrel length. Ours will probably use lower current for a longer period.

[st0nedpenguin]

Holy crap, under no circumstances did I think you would actually be building a railgun after reading that title, I was expecting some kind of joke.

Well, anyway, when it's done, let me know, I know a few people, um, sorry, targets, you could test it out on.

Note to self, never, ever, under any circumstances piss off KnightElite...

[sjohnson]

OK, that read was awesome. I was laboring under the assumption that this design somehow still used "normal" electromagnetic induction.

I particularly liked the statement that the projectile melted and fused to the rails on one of the first tries. Massive amounts of power lol.

An xtreme project if ever there were one. Good luck KnightElite

[antipop]

He's been talking a lot about it on IRC, i hope the project will go well

ps stop playing quake3, it's starting to mess up with your brain

[KnightElite]

Lol... the funny thing is I've only ever played quake3 about 3 or 4 times in my life, at LAN parties.

[Stang_Man]

wtf is a railgun??

[KnightElite]

A railgun is an electromagnetic device that propels the projectile forward by means of the Lorentz force.

Basically, it's a linear motor. It functions exactly like a normal DC motor.... except that it goes straight instead of spinning around.

[Teus]

cool stuff over there, but please watch out with those arms. I hope you can fire it remotely?

[KnightElite]

Got the capacitors today:
http://www.ocfaq.com/railgun/cap_boxes.jpg
http://www.ocfaq.com/railgun/cap_insidebox.jpg
http://www.ocfaq.com/railgun/cap_sizecomp.jpg
http://www.ocfaq.com/railgun/cap_label.jpg

[Paladin]

Hope you got someone to donate those caps. They get expensive! You figured out what to do about vaporization of the projectile and rail ends?

[Peckers]

If I understand correctly, your compressed air injection system will be used to create forward motion to the slug before it comes in contact with the rails and currents. This to decrease friction (kinetic friction is less than static friction). How will you get the timing right? optical gate?

Also, what material are you planning to use for the projectile?

very interesting project KnightElite, keep us updated

[KnightElite]

Well, we're not sure about material for the projectile yet. Right now I'm making a huge spreadsheet to calculate all that, and spit out lots of useful graphs.

As to timing, we may not bother, since the slug completes the circuit, so it triggers itself.

[wespwnzu]

who cares about the technical stuff? what kind of stuff are we talking about being blowed up here? what kind of damage?

[Iridium192_217]

Originally posted by st0nedpenguin
Holy crap, under no circumstances did I think you would actually be building a railgun after reading that title, I was expecting some kind of joke.

Well, anyway, when it's done, let me know, I know a few people, um, sorry, targets, you could test it out on.

same here!

[KnightElite]

I've started working on a spreadsheet to calculate all the relevant parameters. Here's what I have so far, if anyone is interested (~2.5MB):
http://www.ocfaq.com/railgun/railgun%20discharge.xls

The force formula must be off somewhere, because the results it is generating are much too low.

[Dr. 1337]

Can you shoot through walls with it?

[sjohnson]

With the right load, a railgun can shoot through tanks, banks, even Fort Knox.

Remember, the projectile can be ejected from the railgun travelling at speeds in excess of Mach 1

[Peckers]

Originally posted by KnightElite
As to timing, we may not bother, since the slug completes the circuit, so it triggers itself.

ah, ok I guess that should work.


sjohnson, as to military applications I found this read interesting.
edit: under Research Projects\Railgun Pulsed Power Program

[space-ghost]

wow... very wicked, keep us updated

[Dr. 1337]

How much does one of these cost? (all the random parts) What are you actually gonna use it for? Shoot it into the ground? Or are the projectiles so small (1gram in that site) that itll just bounce off a brick wall?

[KnightElite]

I'm currently planning on 10g for the projectile, though we will be able to experiment with any projectile weight, as long as it fits between the rails.

All the random parts, so to speak, will probably cost $300 or $400 CAD, plus the value of the capacitor bank (~$7K USD). We will also have machining costs, but they should be relatively low, given that the engineering department has a machine shop, and will do work for minimal charge (like $2, as compared to $60 for a normal shop).

Today I went and tested every one of the capacitors and determined their exact capacitance. Average is ~2150uF, with the highest at 2290uF and lowest 1950uF. So, about 12% under rated capacitance, like the CEO of CDE told me.