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Plasmaarc452

Mon Sept 28 2009, 04:16AM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

Alright so I was talking with my brother about building a very cool coilgun and he thought it was a very cool idea and that if I could produce a working model that he may fund it.

So I don't have the full model yet, that will take at least a week for me to make but here is what I am modeling it on.

The basic idea is to have a 6 round rotary magazine like a revolver with 2 pneumatic pistons and a stepper motor. The first pneumatic piston loads rounds into the 6 round magazine. The second piston pushes the rounds out of the magazine into the barrel which initiates the triple coil firing sequence. The stepper motor spins the rotary magazine to a new fresh round each time. Now the ammo is gravity fed into the loading chamber for the first piston to push in so the gun would be able to load and shoot a round at the same time. Now the coils would have a metal casing around them to absorb heat and the casing would be filled with ice water that would be circulated constantly by a small pump. So this gun would be able to shoot 12 rounds per minute with a mot charging the capacitors. I am sure that it could shoot more but that's pushing the limits.

There will be a full multi minute animation about this coilgun, it will go through the loading, revolving, and firing. This will take quite some time to make, modeling it will take a week from now but actually rendering it will take a few days because I want it at 1920 X 1080 resolution at 60 fps so it will take a good deal of time!

Tell me what you guys think about this!

Even if I don't get to build it because it would be hard to make some of the parts it would still be a cool concept model!

PYLEMET-mk2

Mon Sept 28 2009, 09:50AM

Registered Member #1513 Joined: Sat May 31 2008, 12:08PM
Location: Russia Klin
Posts: 48

wrote ...
So I don't have the full model yet, that will take at least a week for me to make but here is what I am modeling it on.

I think it is a bad idea - to model coilgun than to build it in practice

wrote ...
This will take quite some time to make, modeling it will take a week from now but actually rendering it will take a few days because I want it at 1920 X 1080 resolution at 60 fps so it will take a good deal of time!

Nobody would be interested

Plasmaarc452

Mon Sept 28 2009, 05:35PM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

Llevellyn wrote ...

I think it is a bad idea - to model coilgun than to build it in practice

wrote ...

Nobody would be interested

Now the first thing you said is utterly stupid, modeling and designing something before building it is crucial. Do you know anything about engineering? Obviously not ...... Do you think the guys at NASA just decided to slap together parts and build a space shuttle? NO they spent years designing, modeling, planning, and testing. Do you think the engineers that built the huge railgun for the navy just slapped together parts? NO they spent a long time designing, modeling, planning, and testing. I am not saying that I am an expert engineer, its a hobby but those are really basic things to do.

I am basically creating a blueprint for the hardware side of the gun. Once its modeled all I have to do is send the models away to a fabrication house to have them built or do it myself (it also creates standard technical drawings). I am working on the electronics side separately.

If you seriously just build crap before planing it then eventually you are going to hurt/kill yourself.

Now the second thing you said is just like WTF? You guys may not be interested at the moment because I haven't produced anything worth taking an interest in yet but I can assure you that when I am finished it will be well worth looking at.

If you don't have anything positive to say then keep it to yourself.

Here is part of the rotary magazine that I have right now, its no where near done MANY things are missing (not yet modeled). The two rings on the bottom hold the first piston which loads rounds into the magazine (in front of it is the loading dock I guess you could call it). The upper two rings hold the second piston which pushes the round out of the magazine into the barrel to be fired. BTW there are rare earth magnets within the rotary magazine to hold the projectiles in tight so they will not fall out.

rp181

Mon Sept 28 2009, 11:02PM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

It does look like a good plan.
What software are you using? It should take more than a couple of days to render at that high res and frame rate, what kind of computer is it on?

Plasmaarc452

Mon Sept 28 2009, 11:48PM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

I am using Inventor professional 2010 to model it and Inventor studio to animate it. I wish I could learn 3ds max to animate it but I couldn't take the class this year and for some reason I can't get an educational version of it (well I can but its a 30 day trial go figure).

The computer that it will render on will be a lenovo t61p laptop, 2.5ghz intel core 2 duo, 4gb of ram, nvidia quadro fx graphics. Its going to take a while because its a laptop now if I could only get my brothers i7 quad core with 8 gigs of ram and a nice big graphics card. Now that would considerably speed things up but I don't think he's going to let me "borrow" that.

doctor electrons

Tue Sept 29 2009, 01:55AM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

I say if your interested than you should go for it! Any time you build something different or interesting some people will criticize.
Don't listen to any of it unless it is constructive! Even if you don't get to build it you should have some fun doing the modeling! (which by the way like stated here already, IS PRETTY MUCH A REQUIREMENT!) Go for it man! Best of luck! Above all have fun and learn new things

ZapHappyPrimate

Tue Sept 29 2009, 03:17AM

Registered Member #2393 Joined: Sun Sept 27 2009, 07:36AM
Location: Central Victoria, Australia
Posts: 7

Sounds pretty sweet (and interesting). what size are your projectiles to be?

Myke

Tue Sept 29 2009, 04:14AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Looks nice.

What material is it going to be made from?

How close are the magnets going to be to the coil? If they are too close to the coil, they might get demagnetized or pulled from the frame. Just wondering because I know rare earth magnets have been tried for projectiles and have been either remagnetized or completely reversed in polarity.
What trigger method are you going to use for each stage of the gun? What stored energy are you thinking of? Where are the capacitors going to go?

Plasmaarc452

Tue Sept 29 2009, 04:40AM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

The main revolving magazine would be constructed from abs plastic, the pistons would be either generic (much cheaper) or ordered custom if I cannot get the specifics that i want. I should be able to create the main parts just fine if I am very careful at cutting them and drilling the plastic. The magnets are in the magazine so they would be about 5 inches away from the first coil.

The projectiles are half inch wide 2.5 to 3 inch long metal spears. For each stage I will use a large SCR that would be controlled via a computer program. The capacitors will be 6 x 450v 2000 something UF capacitors (I have to go read the specs again). We got them off ebay for like $40 plus shipping so it was a good deal. In total it should be around 2kj of total power. The capacitors will go in a nema 3 enclosure (sorry if I didn't spell it right) which we also got off ebay (its water proof, acid resistant, non conductive, and heat resistant) which makes a great candidate to house the dangerous high voltage mots and capacitors.

kromsson

Tue Sept 29 2009, 04:59AM

Registered Member #1444 Joined: Tue Apr 15 2008, 06:55AM
Location:
Posts: 20

The energy of your capacitors is 1/2 x 6 x 2.000/1.000.000 x 450 x 450 = 1.215 J = 1.2kJ

Assuming efficiency of 0.2 (which is VERY difficult already) you have 1.2 x 0.2 = 0.24 kJ of kinetic energy to the projectiles.

A projectile will have a volume of (converting inches to cm) : 1/2 x pi x 1.27 x 1.27 x 6.35 = 16 cm3

I assume you will use iron (induction coilgun) with a weight of about 8.000 kg/m3. This means your projectiles will weigh
about 0.13 kg each.

E = 1/2 x m x u2 ===> u = 2 m/sec = 6 fps.

For this matter you need greater capacitance, and a LOT smaller and lighter projectiles.

On the other hand, the auto loading of the magazine and the revolving and the cooling of the coils sound VERY interesting, good luck and I would be VERY interested to see the final project!

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