Electromagnetic gun (coilgun), which is a particular type of gun that uses electromagnetic forces, is a project that I and my friend started in the summer of grade 9. This project placed first at the 26th Seminar of Science and Technology of Allameh Helli High School and was selected as the top 40 physics project from the Physics Society of Iran. We were introduced to this idea by our physics teacher at the time. After doing some research and assessing the capabilities of the idea, we decided to design a coilgun with the goal of achieving maximum bullet speed, considering our knowledge, resources, and budget. The built prototype utilizes 2 switches, 1 AC to DC transformer circuit, a series or parallel connection of capacitors, a diode, a coil, and a nail functioning as the bullet. When the switch is closed, the transformer circuit converts city’s AC signal to DC, which is then stored in the capacitors. When the capacitors are charged, the first switch is opened and the second switch is closed. Now, the capacitors get discharged and all the current passes through the coil. The passing current, in turn, produces a significantly strong magnetic flux which accelerates the bullet forward with a relatively high speed.
 

At the time of doing this project, we did not have the sufficient mathematics and physics background to calculate the effect of each component of the device on the speed of the bullet. As a result, we were unable to theoretically determine the best combination of various factors, such as the number of capacitors, capacitance of each of them, number of coils, the internal and external diameter of the coils, etc.. Hence, we approached the problem in a rather empirical manner. We performed numerous trials with each having a different combination of the components and from that observed a pattern and estimated the best combination to result in highest bullet speed.
 

Moreover, since this project was just for our own learning experience, we had no funding available. This restricted us in terms of spending large amounts of money for different configurations. As a result, we devised a plan for the project ahead of even starting any experiments. Furthermore, we optimized the number of components, the way they were assembled together, and the way they were used. For example, we were able to come up with an interchangeable connection for the capacitors, such that they could readily be converted into series or parallel.



A number of photos and documents of the project have been attached below. Please note that the project was done in Farsi language at the time and hence, the documents are in Farsi language as well.