A high-speed camera captures the Office of Naval Research Electromagnetic Railgun firing a world-record setting 33-megajoule shot Dec. 10 at Naval Surface Warfare Center Dahlgren Division. The demonstration breaks the previous record established Jan. 31, 2008. (U.S.Navy photo) |
Scientists
at the Naval Research Laboratory (NRL), Arlington, Virg., hit a
materials research milestone in the Office of Naval Research’s (ONR)
Electromagnetic Railgun program when they fired a laboratory-scale
system for the 1,000th time Oct. 31.
“A
significant amount of development has been coming out of NRL to support
the program,” said Roger Ellis, ONR’s Electromagnetic Railgun (EMRG)
program officer. “It’s a key piece of making railgun successful.”
The
EMRG is a long-range weapon that launches projectiles using electricity
instead of chemical propellants. Under development by the Department of
the Navy (DON) for use aboard ships, the system will provide Sailors
with multi-mission capability, allowing them to conduct precise naval
surface fire support, or land strikes; cruise missile and ballistic
missile defense; and surface warfare to deter enemy vessels.
“The
weapon does all its damage because of its speed,” said Dr. Roger
McGinnis, program executive for ONR’s Naval Air Warfare and Weapons
Department, which oversees EMRG. Launched at 2 to 2.5 km per second
(4,500 to 5,600 mph) without using explosives, the projectile reaches
its target at speeds that require only a small charge similar to that
found in automobile airbags to dispense its payload, eliminating the
objective through the inherent kinetic energy.
“EMRG
will provide the Department of Defense with an advantage in future
conflicts by giving troops the ability to fire weapons inexpensively
against targets,” McGinnis said.
As
part of the EMRG development program, ONR and NRL co-funded scientists
at NRL to build and operate a 6-m long, 50-mm diameter railgun as a
subscale experimental lab at the Materials Testing Facility (MTF).
Researchers fired the first shot in March 2007. After improving the
gun’s sliding armature and rails, the lab has fired an average of 300
shots per year since 2008.
A
railgun launches projectiles by generating magnetic fields created by
high electrical currents that accelerate a sliding metal conductor, or
armature, between two rails.
“The
1,000th shot is testing new ideas of how the armature interacts with
the rails,” said Dr. Robert Meger, head of NRL’s charged particle
physics branch, which conducts about 30 experiments annually on the
railgun. Following each test firing, researchers dismantle the gun to
examine all the components. They slice up the rails for further analysis
under a microscope to reveal surface damage.
During
the course of firing all 1,000 shots, NRL scientists have experimented
with a variety of materials and geometries to determine which ones can
withstand the metal-melting temperatures and pressures of shooting a
1.5-megajoule energy weapon. One megajoule of energy is equivalent to a
1-ton car traveling at 100 miles per hour.
“We’ve
really explored a lot of territory,” ONR’s Ellis said. “When you couple
what we’re seeing in testing with what we’re seeing in modeling and
simulation, it results in some interesting barrel shapes that you
wouldn’t intuitively think about. Railgun barrels don’t necessarily have
to be round as in most conventional gun designs.”
Since
2005, scientists have been working to increase the railgun’s barrel
life, muzzle energy and size. Ultimately, their work will help to
produce a 64-megajoule railgun with a range of about 220 nautical miles.
“You
really have to look at the course of our understanding from the first
day they shot to the 1,000th shot today, and how much our understanding
of the rail life has dramatically increased, and how much science we
have applied to ensure that we’re on the path toward a future fieldable
system,” Ellis said.
Materials
science breakthroughs resulting from the test firings have given
researchers confidence to transition new technologies to a scaled-up
experimental launcher at Naval Surface Warfare Center Dahlgren,Va.,
which fired a world record setting 33-megajoule shot in December 2010.
