Navy begins tests on electromagnetic railgun prototype launcher

With a bang, Navy begins tests on electromagnetic railgun prototype launcher

February 28, 2012 Enlarge
This photo illustration shows the 32-megajoule prototype demonstrator, built by BAE Systems, top, which arrived at Naval Surface Warfare Center Dahlgren Division on Jan. 30, 2012, and is the first of two industry-built launchers to be delivered to the Navy. General Atomics is building the second launcher, bottom, scheduled for delivery in April 2012. ONR previously relied upon laboratory-built systems to advance the technology. Credit: US Navy Illustration
Engineers have fired the Navy's first industry-built electromagnetic railgun (EM Railgun) prototype launcher at a test facility, commencing an evaluation that is an important intermediate step toward a future tactical weapon for ships, officials announced Feb. 28.

The firing at Naval Surface Warfare Center Dahlgren Division (NSWCDD) kicks off a two- month-long test series by the Office of Naval Research (ONR) to evaluate the first of two industry-built launchers. The tests will bring the Navy closer to a new naval gun system capable of extended ranges against surface, air and ground targets.
"We are starting our full-energy tests to evaluate the barrel life and structural integrity of the prototype system," said Roger Ellis, program manager of the EM Railgun, part of ONR's Naval Air Warfare and Weapons Department. "It's the next step toward a future tactical system."

0The EM Railgun launcher is a long-range weapon that fires projectiles using electricity instead of chemical propellants. Magnetic fields created by high electrical currents accelerate a sliding metal conductor, or armature, between two rails to launch projectiles at 4,500 mph to 5,600 mph.

Enlarge
A high-speed camera captured the first full-energy shots from the Office of Naval Research-funded electromagnetic railgun prototype launcher that was recently installed at a test facility in Dahlgren, Va. The test shots begin a month-long series of full-energy tests to evaluate the first of two industry-built launchers that will help bring the Navy a step closer to producing a next-generation, long-range weapon for surface ships. The new launcher brings advanced material and high-power technologies in a system that now resembles a large-caliber gun. Credit: US Navy photo by John F. Williams/Released
The 32-megajoule prototype demonstrator, built by BAE Systems, arrived at NSWCDD on Jan. 30. One megajoule of energy is equivalent to a 1-ton car being thrust at 100 mph. The prototype-which now looks more like a naval weapon compared to previous lab-style launchers-is the first of two industry-built launchers to be delivered to the Navy. General Atomics is building the second launcher, scheduled for delivery in April. ONR previously relied upon laboratory-built systems to advance the technology.

After installing the BAE Systems launcher and outfitting it with a comprehensive suite of sensors, high-speed cameras and measuring devices, engineers fired successful low-energy test shots to prepare it for the evaluation. The team will conduct tests at 20 megajoules and 32 megajoules, shooting test projectiles similar to what was previously

fired through NSWCDD's laboratory launcher.

"The test series will characterize the gun's performance by shooting several rounds through the barrel at various energy levels to fully exercise the capabilities of the prototype," said Ellis.



When fully developed, the EM Railgun will give Sailors a dramatically increased multimission capability. Its increased velocity and extended range over traditional shipboard weapons will allow them to conduct precise, long-range naval surface fire support for land strikes; ship self-defense against cruise and ballistic missiles; and surface warfare to deter enemy vessels. The Navy's near-term goal is a 20- to 32-megajoule weapon that shoots a distance of 50 to 100 nautical miles.

Enlarge
Gary Bass, left, and Jim Poyner, from the Naval Surface Warfare Center, Dahlgren Division, take measurements after a successful test firing of the Office of Naval Research-funded electromagnetic railgun prototype launcher that was recently installed at a test facility in Dahlgren, Va. The test shots begin a month-long series of full-energy tests to evaluate the first of two industry-built launchers that will help bring the Navy a step closer to producing a next-generation, long-range weapon for surface ships. The new launcher brings advanced material and high-power technologies in a system that now resembles a large-caliber gun. Credit: US Navy photo by John F. Williams/Released
To achieve this, the Navy is moving ahead with the EM Railgun program's next phase: to develop thermal management systems for both the launcher and pulsed power to facilitate increased firing rates of up to 10 rounds per minute. Toward this end, BAE and General Atomics have been contracted to begin concept design of a next-generation thermally managed launcher.

"The next phase of the development effort is to demonstrate the ability to operate at a firing rate of significant military utility," Ellis said.


Additionally, ONR awarded contracts through Naval Sea Systems Command to General Atomics, BAE Systems and Raytheon Co. to develop a pulsed power system capable of meeting the firing rate goal.


Various new and existing ship platforms are currently being analyzed for future integration.



Provided by Office of Naval Research

 

found this today

How Rail Guns Work




Stuff You Should Know


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Inside this Article

1. Introduction to How Rail Guns Work
2. Rail Gun Basics
3. Problems with Rail Guns

1. Rail Gun Applications
2. Lots More Information
3. See all Devices articles

Rail Gun Basics

A rail gun is basically a large electric circuit, made up of three parts: a power source, a pair of parallel rails and a moving armature. Let's look at each of these parts in more detail.

The power supply is simply a source of electric current. Typically, the current used in medium- to large-caliber rail guns is in the millions of amps.

The rails are lengths of conductive metal, such as copper. They can range from four to 30 feet (9 meters) long.
T
he armature bridges the gap between the rails. It can be a solid piece of conductive metal or a conductive sabot -- a carrier that houses a dart or other projectile. Some rail guns use a plasma armature. In this set-up a thin metal foil is placed on the back of a non-conducting projectile. When power flows through this foil it vaporizes and becomes a plasma, which carries the current.
Here's how the pieces work together:


An electric current runs from the positive terminal of the power supply, up the positive rail, across the armature, and down the negative rail back to the power supply.
Current flowing in any wire creates a magnetic field around it -- a region where a magnetic force is felt. This force has both a magnitude and a direction. In a rail gun, the two rails act like wires, with a magnetic field circulating around each rail. The force lines of the magnetic field run in a counterclockwise circle around the positive rail and in a clockwise circle around the negative rail. The net magnetic field between the rails is directed vertically.


Like a charged wire in an electric field, the projectile experiences a force known as the Lorentz force (after the Dutch physicist Hendrik A. Lorentz). The Lorentz force is directed perpendicularly to the magnetic field and to the direction of the current flowing across the armature. You can see how this works in the diagram below.


Notice that the Lorentz force is parallel to the rails, acting away from the power supply. The magnitude of the force is determined by the equation F = (i)(L)(B), where F is the net force, i is the current, L is the length of the rails and B is the magnetic field. The force can be boosted by increasing either the length of the rails or the amount of current.
Because long rails pose design challenges, most rail guns use strong currents -- on the order of a million amps -- to generate tremendous force. The projectile, under the influence of the Lorentz force, accelerates to the end of the rails opposite the power supply and exits through an aperture. The circuit is broken, which ends the flow of current.
Usurping Power

Rail guns require tremendous currents to fire projectiles at speeds of Mach 5 or higher. This presents problems for a traditional battleship because power cannot be diverted from the ship's propulsion system. In the Navy's next-generation battleship, the all-electric DD(X), producing this kind of current will be possible. To launch a rail gun projectile, power would be diverted from the ship's engine to the gun turret. The gun would be fired, up to six rounds per minute, for as long as required. Then power would be shifted back to the engine.

 

great video I found of them test firing it check it out

[ame=http://www.youtube.com/watch?v=-uV1SbEuzFU&hd=1]BAE Electromagnetic Railgun - YouTube[/ame]