The Navy’s futuristic electric cannon, or railgun, received yet more hype this week for its ability to fire a shell at up to 5,600 miles per hour, and do it far more cheaply than a missile. But there’s a daunting reality behind the hype: the Pentagon is already looking past the railgun to a less power-intensive, more easily deployable alternative. The railgun rounds can be fired from more conventional cannons, giving the same capability sooner and cheaper.
Here’s how the railgun works: a sabot — a shell of tungsten inside a metal casing — is loaded into the gun. Instead of an explosive charge, the gun’s capacitors shoot an enormous amount of power, some 32 megajoules, into the shell and two long rails (instead of a barrel), creating an electromagnetic field that propels the shell down the rails at incredible speed.
The Pentagon loved the idea as a cheap alternative to missiles for targets 100 miles away and getting dangerous gunpowder off of ships. Over the course of a decade, the U.S. has spent more than a half a billion dollars on the program. The gun is supposed to be deployed on the new Zumwalt class destroyers since the Zumwalt is basically the only ship that generates enough juice, 78 megawatts, to power the gun. But the military is making just three of the ships.
In 2012, the Pentagon realized that they could fire the railgun’s projectile out of the 5-inch powder guns on existing ships. No, it wouldn’t hit speeds of Mach 7 (topping out closer to Mach 3), but that’s twice as fast as…