Back in February, the Office of Naval Research (ONR) test-fired a prototype electromagnetic railgun that had been built by BAE Systems for the U.S. Navy. BAE isn’t the only game in town, however – this Tuesday, ONR announced that it is now evaluating a second railgun prototype, made by San Diego-based General Atomics.

As with the BAE device, the latest prototype has been installed at the Naval Surface Warfare Center in Dahlgren, Virgina.

Unlike conventional guns, railguns don’t use explosives such as gunpowder to propel their projectiles. Instead, they incorporate a sliding metal armature that sits between two conductive metal rails. Once the railgun is activated, an electrical current flows up one rail, through the armature, and back down the other rail. This accelerates the armature forward at great speed.

Depending on the design, the armature might actually be part of the projectile, or it may simply be used to push on the back of a separate projectile. In any case, that projectile exits the barrel at a speed of 4,500 to 5,600 mph (7,242 to 9,012 km/h), making railguns well-suited for use as long-range weapons. Ultimately, the Navy would like to see a ship-based device capable of shooting a distance of 50 to 100 nautical miles (57 to 115 miles/93 to 185 km).

There are currently no details available on the differences between the two prototypes, although program manager Roger Ellis has stated that the teams “are both delivering very relevant but unique launcher solutions.” Both BAE and General Atomics are said to be working on increased firing rates, which entails automatic projectile-loading systems and thermal management systems for the barrel.

ONR plans on evaluating the merits of both prototypes at the end of the year.

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