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FROM FICTION TO FACT:
How Arnold Schwarzenegger made the railgun cool
There�s a scene in the 1996 movie �Eraser� in which Arnold Schwarzenegger
tries to protect then fictional railgun-type technology developed by the
U.S. government from the bad guys.
Biceps bulging, Arnold blasts away with not just one, but two prototype
electromagnetic pulse weapons�one in each meaty hand.
Railguns fire projectiles at immense rates of speed using electromagnetic
fields instead of gun powder.
Elizabeth D�Andrea, Office of Navy Research project manager for the
Dahlgren railgun project, laughed when asked about fictional portrayals of
handheld railguns.
She hasn�t seen any sci�fi or video game railguns that resemble the
reality that�s taking shape at Dahlgren.
Sci�fi portrayals of railguns apparently go back at least as far as 1920s
spaceman Buck Rogers.
D�Andrea said the Navy�s electromagnetic railgun will be �deep reach,�
capable of hitting targets 200 miles away.
It�ll be a booming monster delivering a quick and devastating punch deep
into enemy territory, not a shoulder-launched movie pop gun that merely
makes for a cool zapping sound and a light show.
�Eraser� seems to have sparked the current railgun craze in the video
game industry. An �Eraser� video game with railguns followed the film, and
now there are dozens of video games, including the �Quake� series, as well
as role playing games featuring the weapon.
But even Arnold would have
a hard time lifting Dahlgren�s laboratory testing version of the railgun. It
�s 30 feet long and weighs 56,000 pounds.
The tactical launcher, however, will be much different and far lighter,
and one artist�s conception of what the weapon would look like deployed on a
ship is reminiscent of railgun type weapons on science fiction space ships.
�Michael Zitz
IS THE NAVY'S RAILGUN SAFE? Electromagnetic field sensors monitoring test facility and U.S. 301
Because the gun uses electricity, not gunpowder, to fire projectiles, the
Navy expects its new railgun to be safer than conventional guns, reducing
the danger of explosions on ships and in the logistics supply process.
Even though railgun discharge only lasts about 1/100th of a second, what
about the massive electromagnetic field involved with the 64 megajoule
railgun expected to be deployed on ships between 2020 and 2025? Is that
safe?
Elizabeth D�Andrea, the Navy�s railgun program manager at the Office of
Naval Research in Arlington, said there�s �a very aggressive program� to
keep tabs on electromagnetic field levels.
�Every time we shoot the gun we�re collecting EM field information,� she
said. �As we build up in power, we are going to continue to collect and
analyze the data.�
D�Andrea said there are multiple sensors throughout the area to monitor
any possible EM field expansion, including some along U.S. 301 near the
railgun testing facility. She said those sensors have registered nothing in
over 20 tests so far, and are not expected to indicate any problems but are
established to ensure total safety.
�We�re casting a wide net to make sure we�re not putting anyone in harm�s
way,� she said.
She said the Navy is always concerned about �the health and welfare of
our sailors.� And, she said, �It�s not just humans� that would be affected
if there were a problem. Such a powerful EM field could also play havoc with
other mechanical systems on the decks of ships, she said.
And Jack Bernardes, Dahlgren�s pulse power expert said, that, due to the
opposing current flow in the launcher, �the large generated magnetic fields
add in the center of the launcher (behind the projectile) and cancel on the
exterior of the launcher.� He said calculations and measurements to date,
show that the EM-field environment is �within a reasonable distance of the
launcher are below personnel exposure limits.� Bernardes said EM-fields will
continue to be monitored throughout the development of the railgun, and, if
required, shielding techniques can be applied to reduce fields to acceptable
levels.
The electromagnetic railgun will be safer, Charles Garnett, who is heading
up railgun testing at Dahlgren said, because �You don�t need to carry
explosives.�
The lab version currently being tested at Dahlgren is an 8-megajoule
electromagnetic device. But lab output will be ramped up to 32 megajoules by
summer. And the one to be used on Navy ships will generate 64 megajoules.
Current Navy guns generate about 9 megajoules of muzzle energy.
A mega joule is one million joules. Joules measure quantity of energy.
An analogy for energy storage, according to Dahlgren�s Chester Petry, is
�How much water is in the bucket. As the bucket get more full, �energy
storage� increases.�
A watt is one joule for one second, with watts measureing the rate of flow,
as with water flowing from a garden hose, Petry said.
�Michael Zitz
HOW THE NAVY'S RAILGUN WORKS
Railgun projectiles travel so fast they are expected to be capable of
devastating buildings and penetrating bunkers without explosives. Instead
of gunpowder, a powerful pulse generator is used to propel the projectiles.
The lab version being tested
at Dahlgren is only an 8-megajoule electromagnetic device, but the one
eventually to be used on Navy ships will generate 64 megajoules. That’s
about the amount of energy
a typical American household uses in an entire day, engineers working on the
project said.
The Navy weapon is eventually expected to be capable of firing 10 rounds a
minute. Projectiles are likely to eventually have fins so the global
positioning system can be used for guidance.
The concept of the railgun was born in the 1970s, then promoted two decades
ago when President Ronald Reagan proposed the “Star Wars” Strategic Defense
Initiative to shoot down incoming ballistic missiles.
Now the plan is for the technology to provide ground cover for Army troops
and Marines, to take out anti-aircraft weapons and to increase precision in
strikes to avoid collateral damage.
It will allow Navy ships to stay farther away from shore, decreasing the
chances of being hit by enemy fire.
Immense projectile speed is expected to increase the lethality of impacts
and allow projectiles to punch through bunkers and through many floors of a
building.
The range for 5-inch guns now on Navy ships is under 15 miles. The railgun
will extend that range to over 200 miles. Because munitions are to be fired
at seven times the speed of sound, or Mach 7, and impact at Mach 5, they’re
expected to reach targets in one-third the time it takes conventional
munitions to do so.
Fired at a distant target, projectiles are traveling at such great
velocity, they reach altitudes that cause them to leave the Earth’s
atmosphere for up to five minutes.
One of the engineering problems to be overcome, according to Dahlgren’s
Charles Garnett, is that re-entering the atmosphere at such speed, friction
will cause the skin of the projectile to heat up to 1,000 degrees, and that
could affect the guidance system.
The range and velocity are important to Army troops and Marines waiting for
cover when every minute could make the difference between life and death.
—Michael Zitz
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