In theory, rail guns are the perfect solution for short- and long-range firepower. In reality, they present several serious problems:
- Power supply:Generating the power necessary to accelerate rail gun projectiles is a real challenge. Capacitors must store electric charge until a sufficiently large current can be accumulated. While capacitors can be small for some applications, the capacitors found in rail guns are many cubic meters in size.
- Resistive heating: When an electric current passes through a conductor, it meets resistence in the conductive material -- in this case, the rails. The current excites the rail's molecules, causing them to heat. In rail guns, this effect results in intense heat.
- Melting: The high velocity of the armature and the heat caused by resistive heating damages the surface of the rails.
- Repulsion: The current in each rail of a rail gun runs in opposite directions. This creates a repulsive force, proportional to the current, that attempts to push the rails apart. Because the currents in a rail gun are so large, the repulsion between the two rails is significant. Wear and tear on rail guns is a serious problem. Many break after a few uses, and sometimes they can only be used once.