STARSHIPS i7i
featured in their science fiction tales, and which is also being seriously
examined as part of the Star Wars missile shield.
Instead of using rocket fuel or gunpowder to boost a projectile to
high velocity, a rail gun uses the power of electromagnetism.
In its simplest form, a rail gun consists of two parallel wires or
rails, with a projectile that straddles both wires, forming a U-shaped
configuration. Even Michael Faraday knew that a current of electricity
will experience a force when placed in a magnetic field. (This, in fact,
is the basis of all electrical motors.) By sending millions of amperes of
electrical power down these wires and through the projectile, a huge
magnetic field is created around the rails. This magnetic field then
propels the projectile down the rails at enormous velocities.
Rail guns have successfully fired metal objects at enormous velocities over extremely short distances. Remarkably, in theory, a simple
rail gun should be able to fire a metal projectile at 18,000 miles per
hour, so that it would go into orbit around the Earth. In principle,
NASA's entire rocket fleet could be replaced by rail guns that could
blast payloads into orbit from the Earth.
The rail gun enjoys a significant advantage over chemical rockets
and guns. In a rifle the ultimate velocity at which expanding gases can
push a bullet is limited by the speed of shock waves. Although Jules
Verne used gunpowder to blast astronauts to the moon in his classic
tale From the Earth to the Moon, one can compute that the ultimate velocity that one can attain with gunpowder is only a fraction of the velocity necessary to send someone to the moon. Rail guns, however, are
not limited by the speed of shock waves.
But there are problems with the rail gun. It accelerates objects so
fast that they usually flatten upon impact with the air. Payloads have
been severely deformed in the process of being fired out of the barrel
of a rail gun because when the projectile hits the air it's like hitting a
wall of bricks. In addition, the huge acceleration of the payload along
the rails is enough to deform them. The tracks have to be replaced regularly because of the damage caused by the projectile. Furthermore,
the g-forces on an astronaut would be enough to kill him, easily crushing all the bones in his body.
featured in their science fiction tales, and which is also being seriously
examined as part of the Star Wars missile shield.
Instead of using rocket fuel or gunpowder to boost a projectile to
high velocity, a rail gun uses the power of electromagnetism.
In its simplest form, a rail gun consists of two parallel wires or
rails, with a projectile that straddles both wires, forming a U-shaped
configuration. Even Michael Faraday knew that a current of electricity
will experience a force when placed in a magnetic field. (This, in fact,
is the basis of all electrical motors.) By sending millions of amperes of
electrical power down these wires and through the projectile, a huge
magnetic field is created around the rails. This magnetic field then
propels the projectile down the rails at enormous velocities.
Rail guns have successfully fired metal objects at enormous velocities over extremely short distances. Remarkably, in theory, a simple
rail gun should be able to fire a metal projectile at 18,000 miles per
hour, so that it would go into orbit around the Earth. In principle,
NASA's entire rocket fleet could be replaced by rail guns that could
blast payloads into orbit from the Earth.
The rail gun enjoys a significant advantage over chemical rockets
and guns. In a rifle the ultimate velocity at which expanding gases can
push a bullet is limited by the speed of shock waves. Although Jules
Verne used gunpowder to blast astronauts to the moon in his classic
tale From the Earth to the Moon, one can compute that the ultimate velocity that one can attain with gunpowder is only a fraction of the velocity necessary to send someone to the moon. Rail guns, however, are
not limited by the speed of shock waves.
But there are problems with the rail gun. It accelerates objects so
fast that they usually flatten upon impact with the air. Payloads have
been severely deformed in the process of being fired out of the barrel
of a rail gun because when the projectile hits the air it's like hitting a
wall of bricks. In addition, the huge acceleration of the payload along
the rails is enough to deform them. The tracks have to be replaced regularly because of the damage caused by the projectile. Furthermore,
the g-forces on an astronaut would be enough to kill him, easily crushing all the bones in his body.