Connell 6

The Railgun Build Part 1:The Capacitor Bank

Pierce ConnellPedek-7December 23, 20131) AbstractThe purpose of this build is to construct the most critical part of the railgun itself: the capacitor bank. The purpose of the capacitor bank is to act as an energy reservoir that, unlike a battery (another form of energy storage), can discharge all its energy in a mere fraction of a second. This allows the energy running through the rails of the railgun to reach much higher voltages with less energy because it only requires a short discharge time.2) IntroductionEver since man discovered fire he has constantly tried to improve things. Be it making things better, faster, stronger, more efficient, etc. improving things has always been sciences goal. This drive spawned the creation of the railgun. This powerful tool has uses that far surpass the military. It can be used as a cheap way to launch satellites and other devices into space, easily start a fusion reaction, or help alter the velocity of a meteor. Although this technology is powerful it is not without faults. First of all the energy required to fire a large projectile from railgun is astronomical. Also because of the expended energy becoming heat and the electricity arcing between the rails they are limited to one or two shots before the railgun must be repaired and the rails replaced. This significantly limits its military uses, though it does not have as significant of an impact on its peacetime uses.a) PurposeThe purpose of this project is to build a capacitor bank that can successfully hold a charge at 330 volts in order to charge a railgun in the future.3) Materialsa) 62 disposable camerasb) Spool of Red and Black Copper Wirec) Spool of Rosin Core Solderd) Soldering Irone) Soldering Toolf) Aluminum Foilg) Wire Cutterh) Wire Stripperi) Electrical Tapej) Electronic Multimeterk) 4 Alligator Clipsl) AA and AAA batteriesm) High-voltage Glovesn) Goggleso) Flathead Screwdriver4) Procedurea) Preparationsi) Open the disposable camera casing and remove the circuit board.ii) Locate capacitor on the board and discharge it by placing flathead screwdriver on both positive and negative prongs.iii) Repeat steps i) and ii) until all circuit boards are removed and discharged.iv) Desolder the capacitor from the board by using the soldering iron.v) Repeat step iv) until only 2 capacitors are left on their respective boardsb) Building the Capacitor Banki) Cut 12, 9 inch strands of both the red and black copper wires.ii) Measure 2 inches on each end, and begin stripping each wire in 1 inch segments, so there are only 5 capacitors on each strand.iii) Using the soldering tool, create a hole in the stripped portions of the wire to insert the capacitors.iv) Insert the capacitors, such that the negative prong is inserted into the black wire, and the positive prong in the red wire.v) Solder the capacitors into the segments by heating each prong with the soldering iron and touching the rosin core solder to the heated section covering the open area of the wire with a layer of solder.vi) Strip 1.5 inches at the ends of each segment.vii) Once all the capacitors are soldered onto the strands, attach the strands together by soldering by soldering their exposed 1.5 inch ends together.viii) Cover the soldered joint with electrical tape to hold them together, and prevent future arcing.c) Building the Chargeri) Cut a 4 inch segment of both the red and black wires. ii) Strip half-inch on each end of both wires. iii) Take the 2 boards with their capacitors still attached.iv) Expose the charger on the board by removing the semi-triangular sheet of metal covering it.v) Solder the black wire to the cathode of the charger, which appears as a small circle in the middle.vi) Solder the red wire to the anode, which appears as a small semicircle surrounding the cathode.vii) Make sure both the wire and the solder arent touching, or it wont work.viii) Using the same wires repeat steps iv) through vii) on the other board to connect them.d) Charging the Capacitor Banki) Use two Alligator Clips to connect the Capacitor Bank to the Electronic Multimeter, positive to the red wire, and negative to the black wire.ii) Use the other two clips to connect the bank to the charger by attaching the negative prong of the capacitor on the leading board to the black wire, and the positive prong of the capacitor on the leading board to the red wire.iii) Insert batteries into both boards, and the bank will begin charging automatically.iv) Allow the bank to charge until the multimeter reads 330V.e) Discharging the Capacitor Banki) Use the flathead screwdriver to remove the batteries from the charger.ii) Carefully remove the alligator clips from the multimeter.iii) Get a piece of aluminum foil and fold it four times.iv) Attach the negative clip to the piece of aluminum foil.v) Touch the positive clip to the aluminum foil, causing a large discharge.vi) To ensure a fully discharged bank, touch each capacitors two prongs with the flathead screwdriver.5) Dataa) We were successfully able to charge the capacitor bank to 332v which is over our goal of 330vb) Electricity started arcing around 120vc) This caused a slight drop in charge at that moment but did not impede charging.6) AnalysisThe independent variable of the project was the amount of capacitor we attached in the bank and in what arrangement. The dependent variable was the amount of charge the multimeter detected and whether it discharges or not. The bank held 332 volts which is over the marked limit of 330 volts. This could be because of the inaccuracy of the multimeter or the marking on the capacitors. The arcing between the capacitors was because the amount of energy in them was enough to force its way through the air between capacitor prongs.

7) ConclusionThe capacitor bank build was successful. It achieved its purpose of being able to hold 33v of electrical energy then discharge it when we wanted it to. This means we could adapt it for use with a future build of a railgun body.To make our bank more effective there are two things we could do. First of all we could have added a dielectric, like wax, in between the capacitor prongs to prevent the arcing of energy between the prongs. Secondly we could have added more charging circuits in order to improve the speed at which our bank charged.This was a good first step towards building a railgun. We were highly successful and did not have to spend excessive amounts of money in order to complete it. Future projects for our capacitor bank will be the building of a railgun, the adding of an initial propulsion system, and the firing of the railgun into jell-o to analyze deviation patterns.