US Navy keeps electromagnetic cannon in its sights   Leave a comment


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A railgun is an electromagnetic projectile launcher based on similar principles to the homopolar motor. A railgun uses a pair of parallel conductors, or rails, along which a sliding armature is accelerated by the electromagnetic effects of a current that flows down one rail, into the armature and then back along the other rail.

Railguns are being researched as a weapon that would use neither explosives nor propellant, but rather rely on electromagnetic forces to achieve a very high kinetic energy of a projectile. While explosive-powered military guns cannot readily achieve a muzzle velocity of more than about 2 km/s, railguns can readily exceed 3 km/s, and thus far exceed conventionally delivered munitions in range and destructive force. The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry come as additional advantages.

In addition to military applications, NASA has proposed to use a railgun from a high-altitude aircraft to fire a small payload into orbit; however, the extreme g-forces involved would necessarily restrict the usage to only the sturdiest of payloads.

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The United States Naval Surface Warfare Center Dahlgren Division demonstrated an 8 MJ railgun firing 3.2 kg (7.1 lb) projectiles in October 2006 as a prototype of a 64 MJ weapon to be deployed aboard Navy warships. The main problem the U.S. Navy has had with implementing a railgun cannon system is that the guns wear out due to the immense pressures, stresses and heat that are generated by the millions of amperes of current necessary to fire projectiles with megajoules of energy. Such weapons, while not nearly as powerful as a cruise missile like a BGM-109 Tomahawk cruise missile that will deliver 3000 MJ of destructive energy to a target, will theoretically allow the Navy to deliver more granular firepower at a fraction of the cost of a missile, and will be much harder to shoot down versus future defensive systems. For context another relevant comparison is the Rheinmetall 120mm gun used on main battle tanks will generate 9 MJ of muzzle energy. An MK 8 round fired from the 16″ guns of an Iowa Class battleship at 2500 fps (762 m/s) has 360 MJ of kinetic energy at the muzzle.

Since then, BAE Systems has delivered a 32 MJ prototype (muzzle energy) to the U.S. Navy. The same amount of energy is released by the detonation of 4.8 kg (11 lb) of C4.

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The Navy may eventually enhance railgun technology to enable it to fire at a range of 200 nmi (230 mi; 370 km) and impact with 64 megajoules of energy. One shot would require 6 million amps of current, so it will take a long time to develop capacitors that can generate enough energy and strong enough gun materials.

Posted June 27, 2016 by markosun in Weapons

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