The principle behind railguns, which use an electromagnetic force to propel projectiles at high velocity, has been around since the First World War. Practical models are now under test, which could lead to systems being used in theatre in the next decade.
History
Railguns are an electric method of firing projectiles at a much faster speed than standard explosive methods allow. The idea goes back almost as far as the widespread use of electricity.
French inventor Louis Octave Fauchon-Villeplee invented an electric cannon in 1918, based on the principles of the linear motor. He was issued a US patent for his invention in 1922 as an “Electric Apparatus for Propelling Projectiles”. German scientists also designed, but never developed, an electric anti-aircraft gun during the Second World War.
Principle
Railguns consist of two parallel metal rails, between which a projectile, held in an armature, is loaded, completing a circuit between them. A massive electrical current of the order of one million amperes is applied, creating an electromagnetic field, which in turn produces a force that accelerates the projectile along the rails. A force also acts to push the rails apart, but they are held firmly.
As an acceleration force is applied to the projectile for the entire time the projectile is between the rails, much higher velocities can be reached than can be achieved through explosive forces, which, however powerful, have a limited duration.
Railgun projectiles are generally non-explosive, relying on their enormous speed to destroy the target, potentially reaching speeds of MACH 10 at sea level. This means they are comparatively small and lightweight, so more can be readily transported, and much safer than those containing explosive propellants.
Several technical problems still need to be overcome to make the railgun a viable weapon. A source of powerful electrical current is required, which limits its use to fixed locations. Furthermore, the current itself damages the rails every time the system is used, due to the enormous force between the rails and the arcing, which vaporises the surface. In addition, the friction between the projectile and the rails generates heat, which can make the railgun easy to detect and further damage the rails, as well as potentially leading to inaccuracy.
Blitzer test launch
To give an idea of the potential power of the system, General Atomics recently set a new world record during a test-firing of its Blitzer electromagnetic railgun. The projectiles, which were subjected to acceleration levels exceeding 60,000g, reached MACH 5 speed. High speeds mean projectiles are much less affected than conventional weapons by factors such as wind, allowing them to retain pinpoint accuracy over distance.
The force with which the projectiles left the muzzle was 33 megajoules — a single megajoule is roughly equivalent to a one-ton car travelling at 100mph.
General Atomics gained experience of powerful electromagnetic technology through work it carried out to support the nuclear industry. In the 1990s, the company worked with ITER (International Thermonuclear Experimental Reactor), where it helped develop electromagnets powerful enough to contain the superhot plasma needed to sustain nuclear fusion. The company has since worked on advanced electromagnetic technology for launching aircraft from naval aircraft carriers and maglev technology for public transit systems.
Future
Railguns have been a long time coming, but with developing technology coming together from defence and other industries to meet the requirements of a viable system, they could make the move from laboratory to launch sites within the decade.
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