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Registered Member #1451
Joined: Wed Apr 23 2008, 03:48AM
Location: Boulder, Co
Posts: 661
This is going to be a thread to help plan my next big project.
What I'm planning on building is a four stage optically (or something else?) triggered inductance gun using four 1200v 320uf caps. This will be charged using a SLR inverter and discharged with a 1200v 3.5kA pulse rated SCR per cap. I want to get as high of a rate of fire as possible so the charger will be beefy. I want to add some sort of gyroscopic stabilization to the projectile using either a motor and bearing setup or a pneumatic system. I also have 14 pnumatic actuators with valves that I scored from a scrap yard and it would be cool to incorporate them somehow... hehehe They're 3/4 diameter and have a 1 in travel. The whole setup will be PIC controlled too.
So here are some things I'm contemplating
* Barrel material (Leaning towards Brass but can also machine a PVC one with coil forms) * Coil inductance (Should I go for the highest current and fastest pulse that my SCRs can handle?) * Projectile material (Thinking Brass. Would the coefficient of friction be better with a brass barrel or PVC barrel?) * Triggering (Optical most likely but maybe some sort of Magnetic trigger?) * Stabilization (Motor or pneumatic, maybe some sort of inductance motor with the projectile being the stator?) * Some fun way to use the pneumatic actuators * I want to use an injector for the first stage. I'm thinking a solenoid kicker but any other ideas? * Water cooling of the coils or just forced air? I know I'll need some sort of cooling if I have repetitive firing * Any other cool ideas?
I wanna have fun with this one and make it look good as it is my last summer before college so any wild ideas are welcome! Thanks!
Registered Member #2317
Joined: Thu Aug 27 2009, 01:45AM
Location:
Posts: 27
I was planning a big coilgun project recently and gathered a few things I think you might be able to use.
One area of losses of efficiency in a coilgun is the eddy current losses that are produced in the projectile. One known way to mitigate eddy currents is to break up the conductor into smaller parts. So, what I was planning to do is make my own projectile out of thin iron rods that are glued together with epoxy. Using this method, I was going to cut off a piece of my barrel material the same length that I wanted my projectile and coat the inside of it with some type of oil. Then paste epoxy on the iron rods and place them inside the form. I'd fill any spaces in between the rods with more epoxy. When it dried, it would be a projectile that fit the ID of the barrel perfectly and also eliminates most eddy currents.
For your barrel material, I was going to use brass so that I could have a very thin barrel wall (.014"), then slit it to reduce eddy currents. With plastic, you can't go nearly as thin without losing a lot of strength.
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Plans for a new 900J inductance coilgun!!!
