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Registered Member #1119
Joined: Wed Nov 14 2007, 09:15PM
Location:
Posts: 9
Hey, im currently a high school senior and my friend and i want to make a rail gun for our science project. We have done a fair amount of research and have collected alot of our materials. I just have a question on the power supply. We were going to use a compulsator, but since that is a little out of our range as far as technically speaking, we've decided to use capacitors. Now as i understand it, i can connect the capacitors in series, charge them probably by using a wall plug and bridger, then discharging them through the rails. One question i have is what kind of capacitor would work best, and what is the best method of discharging the energy? A switch or injecteing the projectile into the "hot" rails? Sorry if this may sound naive, im trying to learn as much as i can, and any help is appreciated.
Registered Member #1106
Joined: Thu Nov 08 2007, 01:15AM
Location: Seattle, Washington
Posts: 25
im not a pro or anything, but for caps, electrolytic type caps seems to be the best due to their small size and availability/affordability. yes you would need a switch. i think railguns, just like coilguns use scr switching devices to act as a swich.
one question: what made you choose rail over coil?
Registered Member #1119
Joined: Wed Nov 14 2007, 09:15PM
Location:
Posts: 9
at the time it seemed easier, which we both recognize as wrong now.Also we figured we could get more performance out of a rail gun. But i like a challenge and i want to finish this, so its either do or die. But not literally die of course
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
A coilgun or ring launcher would be MUCH easier to build. Railguns are tricky, what with the projectile wanting to weld to the rails and all. I'm a senior too, and I will tell you that once you have the materials, you can throw together a single stage coilgun in a day.
If you are convinced on making a rail gun, you will need a bunch a fairly high-voltage high-energy capacitors, a BIG SCR to fire it, and a proper HV charging supply.
Rectified mains only gives 170V (on 120V mains), which will probably not do for a railgun. Think at least 400+.
Registered Member #1056
Joined: Thu Oct 11 2007, 11:15PM
Location: CT, USA
Posts: 27
Shaun wrote ...
A coilgun or ring launcher would be MUCH easier to build. Railguns are tricky, what with the projectile wanting to weld to the rails and all. I'm a senior too, and I will tell you that once you have the materials, you can throw together a single stage coilgun in a day.
If you are convinced on making a rail gun, you will need a bunch a fairly high-voltage high-energy capacitors, a BIG SCR to fire it, and a proper HV charging supply.
Rectified mains only gives 170V (on 120V mains), which will probably not do for a railgun. Think at least 400+.
You can use a Full Wave Voltage Doubler On the Mains which would give 340V, Although I recommend some kind of isolation transformer between you and the mains. 2 Transformers Connected back to back can do this.
Registered Member #222
Joined: Mon Feb 20 2006, 05:49PM
Location:
Posts: 96
Shaun, the projectile never welds to the rails in a working railgun design. If it welds, then that means that the railgun will never work even with near zero friction.
Welding indicates that the projectile has not traveled far or at all along the rails, meaning that the action integral of the energy pulse is too small. It also means the barrel is too long.
I would suggest a plasma armature railgun if building one is absolutely necessary. It has much better performance for small energies than solid armatures. Getting 250m/s+ speed with a .5g projectile with 5kj is easy with plasma. The same gun might only do 0-40m/s with a solid armature.
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