Best Of: Railguns: The Fast, the Furious—and the Future?

Photo: General Atomics

For this year’s Fourth of July feature, The Cipher Brief revisits its coverage examining the concept of an electromagnetic railgun. Capable of firing projectiles at speeds of Mach 7 to strike targets over 100 miles away, electromagnetic railgun systems for the Navy and the Army are now reaching the final stages of development and could become operational for roles ranging from missile defense to naval surface warfare within the next few years. On the anniversary of American independence Cipher Brief takes a look at this revolutionary technology, and what it may mean for the future of U.S. defense.

With electromagnetic railgun systems (EMRS), “faster than a speeding bullet” takes on new meaning. The 32-megajoule – a measurement of power applied over a period of time, in this case equivalent to about nine kilowatt-hours – railgun in its second phase of testing by the Office of Naval Research (ONR) can fire a projectile at seven times the speed of sound (Mach 7), almost three times faster than an M16 rifle bullet. What’s more, the weapon achieves this blistering speed without the need for volatile, expensive, and heavy chemical propellants like gunpowder.

This technology has attracted U.S. military planners’ interest. ONR tests of the 32-megajoule railgun at the Naval Surface Warfare Center Dahlgren Site in Virginia are aimed at eventual deployment of the weapon on new vessels like the Zumwalt-class destroyer, which produces the energy necessary to power the weapon.

However, bringing this weapon of the future to the battlefield is not easy, and early hopes that the railgun could enter service by the end of this year now seem far-fetched. Given the progress made and the challenges ahead, what does the future hold for the military’s super gun?

The concept of EMRS is futuristic, but it is hardly new. French inventor Louis Fauchon-Villeplee filed the first patent for an “Electric Apparatus for Propelling Projectiles” nearly 100 years ago, and the idea has enjoyed periodic resurgences ever since. Most notably, during the 1980s, the Reagan administration’s “Star Wars” Strategic Defense Initiative hoped to use railguns to quickly intercept and destroy approaching ballistic missiles. However, until very recently, no one has been able to make the weapon practically viable.

Put simply, the railgun is a large electrical circuit made up of three parts: the power source, two metal rails, and an armature, which is a piece of conductive material that creates a circuit between the two rails. Once activated, the gun draws an electrical pulse from the power source, which then runs up the positive rail, through the armature, and back to the power supply through the negative rail. This circuit creates two magnetic fields around the rails, which exert a perpendicular force on the armature – encased in a “sabot” that guides projectile along the rails – and launches it out of the barrel.

In theory, this is all simple enough. However, getting this circuit to actually launch a supersonic projectile presents substantial challenges. First, keeping the railgun’s barrel to a manageable length requires pumping millions of amperes of electrical current into the rails to attain speeds of over Mach 5. This not only requires a large amount of power, it requires a system that can release megawatts of energy in a split second. As John Finkenaur, Director of Advanced Technology Programs at Raytheon’s Integrated Defense Systems tells The Cipher Brief, “it’s always a challenge to release that much energy at one time. Just getting to the point where you can fire once…is a real challenge.” Building a system that can store and deliver that power multiple times over, however, takes that challenge several steps further.

The second major challenge with implementing the railgun technology is simply building a weapon that can physically survive multiple shots. The barrel and rails, for instance, must be able to withstand the intense heat caused both by the electric current traveling through the rails, as well as friction from the armature traveling down the barrel at hypersonic speed. In addition, the magnetic fields surrounding the two rails conspire to exert enormous opposing forces and push the two rails apart.

Finally, creating a projectile with electronic guidance systems that can survive this intense environment is extremely difficult. This is the case not least because, unlike conventional projectiles, which lose acceleration from the moment they are fired, the railgun projectile speeds up as it travels down the rails. Perfecting this projectile is especially difficult because, as President of the General Atomics Electromagnetic Systems Group (GA-EMS) Scott Forney observes, the railgun “projectile” is “actually a hybrid missile.” As such, it contains a variety of microelectronics, navigation control, and other internal systems that must be shielded against this tremendously hostile environment.

For these reasons and more, many have begun to doubt theories that what Deputy Secretary of Defense Robert Work described as a “set of railguns that would be inexpensive but have enormous deterrent value” could form a key layer in the Pentagon’s new “Third Offset” strategy. They argue that the power needs for the Navy’s designs are so great that only the 78-megawatt electric Zumwalt destroyer could use it – only three of these ships are being made –  and that wear and tear could unreasonably limit the weapon’s use.

However, for those involved in the development effort, such criticism is shortsighted. First, as Finkenaur notes, the railgun is a very adaptable system that “can scale the firing velocity of the projectile just by how much of the system you charge up.” This means that, using a pulsed power system like the one Raytheon has begun delivering to the Navy, railgun operators decide how much energy to plug into the rails and how many shots to store up in their batteries, depending on need.

Thus, even if a 32-megajoule (or more) railgun optimized for offensive naval surface fire support at ranges of over 100 miles is not feasible in the near term, EMR systems can still be highly effective at the 5-, 10-, or 20-megajoule range for a number of different roles, including missile defense. Due to its high launch velocity, the railgun is ideal for missile interception, and indeed, General Atomics already demonstrated a mobile land-based missile defense-focused version of its Blitzer railgun for the Army this April. Packed with precise navigation hardware and what Forney describes as “essentially a tungsten shotgun shell at the tip of the projectile,” this system can accurately intercept speeding missiles with “a tungsten shield.”

At the end of the day, whatever the railgun’s power or range, its overriding advantage will always be cost. As Forney notes, when adversaries begin to threaten the U.S. with cheap missiles, possibly in swarms, “we will soon be able to respond with $25,000 hybrid missiles from a railgun rather than multimillion dollar conventional missiles.” Forney believes GA-EMS could field a system within three years, while Finkenaur guesses that five years is more realistic for a land-based system and ten years for the Navy.

Until then, the Pentagon is focusing on shorter-range defensive capabilities. However, given its scalability, adaptability to different missions, and cost-effectiveness, it is only a matter of time before the electromagnetic railgun becomes an operational reality.

Fritz Lodge is an international producer at The Cipher Brief. Follow him on Twitter at @FritzLodge.

Below is footage of an electromagnetic railgun being test-fired by the Office of Naval Research: