|
|
|
|
|
 |
|
|
The
Power of Chain gun
A chain gun is a
type of machine gun or automatic cannon that uses an
external source of power, rather than diverting energy
from the cartridge, to cycle the weapon, and does so via a
continuous loop of chain similar to that used on a motor
or bicycle. "Chain gun" is a registered trademark of
Alliant Techsystems Inc.for a chain-powered weapon.
Reliability and controllability are the advantages of
chain-driven weapons over their recoil-actuated
counterparts. Instead of depending upon the sometimes
unreliable firing of a cartridge to power the cycle of
action, a chain gun uses an electric motor to drive the
chain that moves in a rectangular circuit via four
sprockets which apply tension to it; one link of the chain
is connected to the bolt assembly, moving it back and
forth to load, fire, extract, and eject cartridges.
As with all guns which do not use energy from a fired
cartridge to load the next, a misfired round does not stop
the weapon; it is simply ejected.
During each full cycle of four periods, two periods
(passage along the "long' sides of the rectangle") control
the time taken for the bolt to drive forward and load a
round into the chamber, and how quickly it extracts it.
The other two periods, when the chain moves across the
"short" sides of the rectangle, sideways relative to the
axis of the barrel, determine for how long the breech
remains locked while firing, and open to allow cartridge
extraction and ventilation of fumes.
Since the time taken for the chain to move around a
complete loop of the rectangle controls the rate of fire,
varying the motor speed allows chain guns in principle to
fire at a rate continuously variable from single rounds to
the maximum safe rate imposed by the pressure drop rates
in the barrel after firing a cartridge, mechanical
tolerances, and other factors; for example the 7.62mm NATO
version EX-34 was advertised to offer 570 rounds per
minute, and developmental work was underway for a 1000
rounds per minute version. In practice chain guns usually
have two or three set firing speeds.
The chain gun operating principle is inherently reliable.
An unclassified report on the EX-34 prepared by the Naval
Surface Weapons Center in Dahlgren, Virginia, dated
September 23, 1983, stated that:
29,721 rounds of endurance tests were fired with no parts
breakage and without any gun stoppages... It is
significant that during firing of 101,343 rounds not one
jam or stoppage occurred due to loss of round control in
the gun or feeder mechanism... [this] is in our experience
very unusual in any weapon of any caliber or type.
Examples
A commonly used chain gun is the M242 Bushmaster. Versions
of its 25 mm action are found on ships (the Mk38),
Infantry fighting vehicles (the M2 Bradley), and LAV-25
around the world. Others are the M230 30 mm Cannon, which
is standard equipment on the Apache helicopter, as well as
the Bushmaster II 30 mm, and the Bushmaster III 35/50 mm
Chain gun.
A 7.62x51mm NATO caliber chain gun is used on some armored
vehicles as a coaxial machine gun, because of the
inherently small amount of fumes from spent propellant
discharged inside of the vehicle. A developmental version
of this gun was named EX-34. It is in use as the L94A1
chain gun with the British Army
|
|
|
|
|
|
|
|
