Exploring the history and fundamental principles of railguns, this article examines the differences between sci-fi depictions and real-world railguns, details their technological evolution, and investigates their current practical application potential.
A colossal monster robot formed by multiple cars merging climbs a pyramid. Far out at sea, U.S. forces observe the situation and fire a massive weapon resembling a laser cannon from their ship. Instantly, the monster is struck by the laser, stumbles, and collapses. Anyone who has seen the movie ‘Transformers: Revenge of the Fallen’ will likely remember this scene. The weapon depicted in the film, resembling a laser cannon, is actually a railgun. Anyone familiar with sci-fi movies or games has likely heard of it, but most media often depict railguns differently from reality. Let’s examine how railguns were developed and what they actually do.
The history of the railgun is very long. It began around 1920, about 100 years ago, when an American named Villers filed a patent related to railguns. At the time, it was merely an idea proposed; technical challenges prevented its practical application. Later, during World War II, the Nazis actually developed weapons utilizing railgun technology, but the war ended before they could be deployed. Development continued thereafter, and relatively recently, the U.S. military announced successful test firings, indicating plans for operational deployment. Thus, the railgun has long symbolized innovative advancement in military technology.
Given such extensive research over so many years, is the railgun based on incredibly complex theories difficult for the average person to grasp? Actually, no. Looking at the structure of the railgun Vilherp envisioned 100 years ago, the basic principle is simple enough that it differs little from modern railguns. Imagine a model you might see in a high school physics textbook. Two wires are placed side by side, each carrying an electric current flowing in opposite directions. What happens if you place a thin, free-rolling iron rod on top of these wires? To cut to the chase, the iron rod will roll along the wire rails. “
” This situation can be explained by electromagnetic induction. First, recall Fleming’s right-hand rule. Current flows through each wire, and according to the right-hand rule, a magnetic field is generated around each wire. At the center point between the two wires, a magnetic field perpendicular to the ground is formed. Furthermore, since current flows in opposite directions through the two wires, their magnetic fields at the center do not cancel each other out. Instead, they act in the same direction, increasing in strength. That is, a strong magnetic field perpendicular to the ground is generated between the two wires. Now, let’s place an iron rod on top of the two wires, using them as rails. A voltage difference exists between the two wires, causing current to flow through the iron rod. “
”It’s time to consider the Lorentz force. When the direction of the current is perpendicular to the direction of the magnetic field, the wire carrying the current experiences a force perpendicular to both the current and the magnetic field. This is the Lorentz force. In this situation, current flows through the rod, and the magnetic field from the surrounding wires acts perpendicular to the ground, meaning it also acts perpendicular to the rod. Therefore, the rod experiences a force perpendicular to both the current and the magnetic field, causing it to roll along the wire rails. The railgun operates on the same principle. The only difference is that the wires are replaced with very large rails carrying extremely strong currents, and instead of a rod, a massive metal projectile is used.
The principle of the railgun is simple, but its implementation presented numerous technical challenges. Handling high currents required advanced power management technology, and effectively controlling the heat generated when firing projectiles at high speeds was also a critical issue. To solve these problems, scientists researched new materials like superconductors and developed various methods to prevent arc discharges. This process involved repeated cycles of failure and success, ultimately leading to the railgun technology we have today.
Just over a decade ago, railguns were dismissed as fantastical tales belonging only to science fiction. However, they have now become sufficiently realistic that even the U.S. military is considering their deployment in actual combat. This signifies more than just the development of a new weapon. In fact, overcoming existing technological limitations to develop railguns required the application of diverse scientific and technological advancements, such as the use of superconductors and arc prevention. In other words, it signifies that scientific and technological progress can make our imagination a reality. Seeing the precedent set by railguns, we can hope that technologies currently dismissed as mere fantasy will one day become reality. Science and technology are constantly advancing, and through this, humanity will achieve even more astonishing accomplishments. Railguns are just the beginning.
