Railguns: All you need to know about the weapon that uses electromagnetic force

• Railguns are some of the most technologically advanced methods of lobbing heavy projectiles over a great distance.
• They have a very high "muzzle velocity" and have been cited as potentially devastating future weapons.
• However, the U.S. Navy has recently mothballed its research into the technology. But why?

Recently, the U.S. Navy announced that it was pulling the plug on its planned railgun program, sending 15 years of development and $500 million in research and development (R&D) costs down the drain.

Per the Navy’s official statement, they intend to re-focus their R&D efforts toward developing hypersonic missiles and directed energy weapons, as these weapons are already seeing limited deployment worldwide today. 

However, this might not be the only reason the Navy decided to move on from their planned railgun. Throughout development, the Navy struggled with making its railgun prototypes energy and resource-efficient. Firing a single shot from one of these prototypes involved diverting massive amounts of power from the ship it was stored on.

The Navy’s railguns also suffered from another issue other railgun prototypes throughout history have gone through; poor reliability. Due to the sheer amount of force generated with each shot, the barrels, or rails, of a railgun wear out incredibly fast, making the gun less effective and less accurate over time without constantly replacing its parts.

So, what is a railgun anyway?

Rail guns use electrical power instead of chemical power to propel projectiles over long distances at hypersonic speeds. A linear motor device, this weapon typically uses electromagnetic force to launch its projectiles.

Such weapons will usually consist of two parallel conductors (rails) along which a sliding armature is sped up by the electromagnetic effects of a current that flows down one rail, into the armature, and then back along the other rail. A projectile is loaded in the armature, completing a circuit between the rails. It works on the same kind of ideas as the homopolar motor.

However, unlike present-day artillery shells, railgun projectiles are just that – projectiles.

They contain no explosives, relying on the kinetic energy imparted by the projectile, traveling seven or so times the speed of sound, which can rip through steel or concrete, destroying anything in its path.

After decades of research and development, railguns are still very much in the research stage, and it's still unclear if they will ever be used as real military weapons. Any trade-off analysis between electromagnetic (EM) propulsion systems and chemical propellants for weapons applications must also factor in the relative durability, availability, and economics of the weapons, as well as the novelty, bulkiness, high energy demand, and complexity of the pulsed power supplies that are needed for electromagnetic launcher systems.

As we've seen with the U.S. Navy's official decision to mothball railgun research, it seems this technology is not viable given the present technology and energy storage.

A brief history of the railgun

While railguns sound like very modern pieces of kit, they actually have a long and exciting history.

French inventor André Louis Octave Fauchon-Villeplée first introduced the concept of an electromagnetic railgun to the world with a functional, small-scale prototype of an electric cannon in 1918, and several weapons engineers worldwide took notice.

They began work on their futuristic railguns.

It wasn’t until World War 2 that we saw plans for a fully functional, combat-ready railgun laid out. German engineer Joachim Hänsler proposed creating what was essentially a railgun – an electromagnetically powered anti-air gun placement. This was to be an iteration of Villeplée's design decades earlier, a ‘cannon’ that utilized a charged current to propel its projectiles forward.

But that’s all Hänsler's idea ended up being: a design. Hänsler’s railgun was never built. Despite that, word quickly spread about this revolutionary new weapon design.

The catch? Despite the weapon being theoretically possible, its sheer energy cost and operational requirements ensured that weapons of this type would not see development for quite some time.

At the time, this hypothetical railgun would use enough energy upon firing a single shot to power half of Chicago at its proposed specifications. Since then, there have been multiple attempts by militaries around the world to get a working prototype out of the drawing board and into the battlefield.

Perhaps the most recent and high-profile example of a military attempting to introduce an actual working railgun into its arsenal would be the U.S. Navy’s $500 million railgun project. Although R&D had progressed enough to the point where several functional prototypes had been built, the U.S. Navy recently decided to pull the plug on its ambitious project.

How fast does a railgun shoot?

By design, railguns are intended to be among the most powerful projectile launchers in the world. An electromagnetic railgun is designed to launch projectiles toward their target at velocities several orders of magnitude faster than the speed of sound.

To illustrate, the U.S. Navy’s prototype railgun could launch its projectiles at Mach 6 - six times faster than the speed of sound. That’s roughly 4,603.6 miles per hour (7,408.8 kph), faster than just about any other weapon on the planet.

How far can a railgun shoot?

A railgun’s effective range is closely related to the speed at which it can launch a projectile. Land or ship-based railguns with Mach 6 capabilities are understood to have practical ranges of roughly 126 miles (202.8 km) or 110 nautical miles (177.03 km) at sea.

How does an electromagnetic railgun work?

As its name suggests, an electromagnetic railgun utilizes electromagnetic energy to launch its projectiles. This makes it closer in design to a large electric circuit than a gun.

A railgun has three main components: a power supply, rails, and armature.

The power supply is what delivers current to the railgun. This current consists of millions of volts of electricity. The millions of volts of electricity come from the power supply, which first gets sent to the positive rail.

The rails – where the railgun gets its name – are the lengths of highly conductive metal the current runs through to charge up the projectile. They’re essentially gigantic magnets and, as such, have a positive rail on one side and a negative rail on the other.

After the current passes through the positive rail, it moves towards the armature, which bridges the gap between the two rails. This is typically where the projectile is stored. The current can then move towards the negative rail and eventually back to the power supply. 

With all this current circulating throughout the system, a strong magnetic field and a magnetic force are formed. Like any other force, it has a magnitude and direction. In a railgun, this magnetic force is charged until it reaches critical levels and is used to launch projectiles forward with tremendous force.

Despite its massive potential in naval and surface-to-air combat, the Navy couldn’t contend with the railgun’s numerous drawbacks. Due to how electromagnetic railguns work, many of these drawbacks are sadly unavoidable.

These include the need for a source of powerful electrical current and enough room for the massive bank of capacitors needed to generate the charge. In addition, the current itself damages the rails every time the system is used, due partly to the tremendous heat generated and to arcing, which vaporizes the surface. The magnetic fields generated during launch can cause damage to nearby electronic equipment, so the ship must also be shielded, adding cost. It also takes some time to charge up between shots, reducing the number of rounds per minute that can be fired.

The potential future of railguns

Recent reports indicate that China intends to pick up where the U.S. Navy left off, with their own take on the railgun. They, too, have built and tested functional railgun prototypes out on the open sea. Now all that’s left is to make it strong enough to withstand operational requirements.

Chinese researchers have taken cues from previous railgun projects to develop a functional but also practical and efficient design. For instance, to circumvent the barrel wear faced by the Navy’s railgun, they’ve run experiments using liquid metal, a highly conductive cooling material, to significantly decrease the wear and tear on the railgun’s rails.

According to their reports, not only could their railgun be much more practical than the Navy’s, but it could also launch projectiles at higher velocities and at greater range, too. Their prototype launched a projectile well past Mach 7, hitting a target 155.3 miles (250 km) away. However, it is not known if they have been able to counter the other drawbacks.

Presently, news on the status of the Chinese railgun is thin on the ground, but their focus on hypersonic missiles may give us a clue as to the project's status.

And that's your lot for today.

Railguns could potentially be potent weapons of war if they are ever finalized. However, with recent high-profile railguns now effectively mothballed, militaries worldwide are seeking alternative and more reliable means of long-range devastation.

Whether this indicates that railguns are a technological dead-end or not is yet to be seen, but it doesn't look like we'll see them anytime soon on the battlefield.