Focus on Science: Caleb Gaithright's project 'an excuse to build a coil gun'
By REBECCA LEFTWICH
Caleb Gaithright of East Coweta High School was pleased to win third place in the Georgia Science and Technology Fair for his entry in the Senior Electrical and Mechanical Engineering category, but his secret desire to build a pulse accelerator – commonly known as a coil gun – was the real driving force behind the project.
“Caleb has worked hard so hard on this project, more than any other student I advised for the science fair,” said mentor Katie Lowrie, who taught Gaithright in her Advanced Physics class last semester. “Most importantly, Caleb is passionate about the subject matter.”
“He was top of his class and always asking questions, wanting to know more about everything we discussed,” Lowrie said. “Caleb took his passion for creating things and constantly striving to understand how the world works and developed a science fair project with sound scientific methods that was interesting and creative.
“I am so proud of Caleb and his efforts on this project,” Lowrie added. “(His) hard work over the last year has shown me that he is going to be successful at anything he attempts in the future.”
Following is a Q&A with Caleb Gaithright on the birth of his science project, “Magnetic Pulse Accelerator: Capacitance Effects on Distance.”
Q: Will you describe your project?
CG: My project was based upon how the amount of capacitance would affect the distance of a ferrous projectile launched from what is essentially a large solenoid with a free moving core.
When a large amount of current is momentarily run through the solenoid it produces a very intense magnetic field that causes domains in the ferrous projectile to align and attract to the magnetic field. The attracted projectile then rapidly moves toward the center of the magnetic field in attempt to stabilize, but in that brief moment the stored electrical energy provided by the capacitor bank runs out, releasing the projectile from the clutch of the magnetic field and allowing it to travel using its previously obtained during the attraction.
Now capacitance comes into play as it completely dictates the period at which the magnetic field remains on and directly affects the distance at which the projectile can travel. During the actual testing I manipulated the capacitance by adjusting the amount of a set value capacitors and charged them to a constant voltage to ensure the amount of current was also constant.
After manipulating the capacitance I would launch the projectile from a fixed point – elevated at about three feet to prolong the unwanted effects of gravity – then measured the distance at which it would land. I continued to add capacitor until my testing was completed, and I felt my experiment was thoroughly investigated.
Q: Why did you choose this project?
CG: I chose this project as an excuse to build a pulse accelerator, commonly known as a coil gun. The science behind what was actually going on fascinated me, and a larger interest was sparked when I would watch videos of them in action. Just thinking of possibilities they could achieve aroused my imagination, allowing all sorts of practical applications for future use of this technology to form.
Q: How long did it take?
CG: The final version of my project took one month of continuous research and building.
Q:What was your inspiration?
CG: Inspiration arose from my curiosity about electromagnetism and my need to know if there were more practical or useful applications than just lifting metal objects at a junkyard. I have an interest in alternative means of propulsion to help our space programs continue to thrive and flourish, and I saw a pulse accelerator as a viable means and continued to look into the subject.