Week 4

Week 4

Final Prototyping

Prototype 3

          The first thing we did during the fourth week was obtained the parts we would need for our next attempt at a prototype. Once we obtained the material, we built the prototype and set to figuring out a projectile delivery system. To determine whether the rail itself functioned as it should, we started with a simple pneumatic system where compressed air was blown through a straw onto the projectile into the rails. Spot welding was still an issue, so our initial thought was that we weren't providing enough initial velocity, so we disconnected the system and practiced delivering the projectile into the system while it was off and we didn't have to worry about arc welding.

     The projectile was still getting stuck, and we figured this reason was because the rails were not perfectly aligned. Irritated that it required such specific and precise measurements, we decided for the next take, we would laser cut rows for the rails to sit in so that it was perfectly parallel since that was apparently what it requires.

     We spent some time getting the rails as parallel as we could without a computer, and then had some success getting it to launch the projectile. This prototype had more success than the prior two, but the delivery system was still very inconsistent. We figured the shape of the projectile might be the limiting factor now. We made several aluminum balls out of foil and had slightly more success with these. It was evident that the projectiles also would have to be computer created, whether by lasers or 3D printed with a conductive material -- it has to fit perfectly into the barrel of the rail gun so ensure consistent contact with each rail. Many hours were spent trying to create the perfect projectile. 

Week 3

Week 3

Initial construction of prototype

Capacitor bank 2

     The third week of the project we sat down and began construction of our prototype. We bought copper wire, and laid it down upon the toy train track. We only used a single 'block' of the track for the first attempt, for simplicity. With the rails in place, we connected our new bank of 10 4400 microfarad capacitors in parallel and obtained a 25V power supply to charge them. Since we were just trying to get the rail to do something, our projectile for testing was another piece of copper wire, rather than the train. The singular copper wire would have considerably less mass than the train and would serve as a better starting point to get the ball rolling.

Prototype 1

Prototype 2

     We had limited success with this prototype. We learned rather quickly that unless the projectile had initial velocity, it would become welded to the rails due to the large amount of current. So, we extended the system and added a drop-ramp such that gravity would provide ample initial velocity. This yielded a little bit more success, but "dropping" it onto the rail introduced too many variables for human error; unless it was dropped perfectly, the projectile would roll off one of the two rails and break the circuit. 

     We needed to revise our design. We decided it would be detrimental to pursue the train rail system since it would have been too difficult to devise a consistent launch mechanism in the limited time we had, and the train itself was much more massive than the wire projectile. We decided that perhaps just a gun would suffice, seeing how the only modern use of rail technology is for guns. We returned to YouTube and came up with a new prototype design, using two manufactured aluminum bars for the rail, seated in an acrylic housing. This new design addressed one of the two problems we were experiencing. We no longer had to worry about the projectile losing contact with the rails, but we still didn't have a reliable delivery system of the projectile into the system.

Week 2

Week 2

More research and calculations

     Throughout the second week, our time was devoted to furthering our understanding of the underlying principles of rail gun technology. We amassed various equations defining the movement of the projectile and various properties of the rail system, and even more equations to connect the former ones. More YouTube videos on successful rail guns were watched.

     With the equations in hand, we defined what mass we were going to try to project. Since we want to use rail guns for transportation, we decided that we wanted to build the rails on a toy train track and have it move a train from the set down the track. So, we measured the mass of the train and set off to figure out what kind of current we would need for such a task.

Calculation of desired current and potential capacitance (was ultimately incorrectly calculated)

      Once we determined the amount of current we would need to send through the rails to get the train to move, we started looking at methods of getting such large amounts. Ultimately, we decided upon using an array of capacitors for rapid discharge.

      We obtained four 53000microfarad capacitors that ran at 25 volts, and ran several tests and calculations to determine the viability of these capacitors. For equipment deficiencies, we weren't able to see the exact amount of current that they discharged; we didn't have a ammeter that would withstand 100+A of current. We charged the capacitors, and let them gradually lose charge as opposed to discharging them, and used the voltage at specific times data to calculate the internal resistance of the capacitors, and to check the capacitance. It turned out that these capacitors were defective due to their age, and we scrapped them.

Calculation of internal resistance and capacitance of capacitor bank 1

Week 1

Week 1 

Definition of concept and initial research.

     We spent the first week deliberating on what exactly we were going to do. We knew, because this project was to be for another competition as well, that we wanted to explore a theoretical problem for a prototype, and decided upon the technology behind rail guns as our core concept. With the main idea of our prototype in mind, we talked about what we would do with it. We wanted to investigate the technology so that a basic understanding of the physics and limitations of rail guns was understood. The idea was that in 20 years, when the limiting parts and materials of current rail guns had progressed enough to eliminate these limits, we would have enough understanding and a far enough along "prototype" (this is a hypothetical 20 years from now) that we would be at the front of the investigation into the utilization of rail gun technology in long distance transportation, such as trans-continental/oceanic rails/trains and space elevators.

     With our core idea and vision established, we began initial research into the technology behind rail guns, to gain an understanding of how they work, what makes them successful, and what makes them not work at all. We spent most of our time on YouTube for videos demonstrating these things.