This invention relates generally to Gatling type machine guns and, more specifically, to the class of such guns known as 7.62 miniguns and an improved rotor assembly for use therein that serves to vent high pressure gases and shrapnel that result from over-pressure situations and hang fires.
The 7.62 mm minigun is a six-barreled electric driven Gatling type machinegun originally designed and built by General Electric Company in the mid 1960's for the U.S. military. The minigun has been in use since its inception by both U.S. and foreign military forces.
The 7.62 minigun fires a conventional 7.62 NATO cartridge that includes a bullet, a cylindrical cartridge case, a primer, and powder. The bullet is seated in the open end of the cartridge case; the primer is seated in the center of the base of the cartridge case opposite the bullet; and the powder is located inside the cartridge case between the bullet and the primer. The cartridge is fired by first detonating the primer, which ignites the powder and, in turn, causes pressure within the cartridge case to increase to the point that the bullet is forced out of the cartridge case and down the barrel of the gun.
The 7.62 minigun includes a main housing enclosing and supporting a main rotary body known as the rotor assembly. Inside the main housing, cartridges are handled by bolt assemblies, of which there are six, one associated with each of the six barrels. Each of the six bolt assemblies is aligned with respective ones of the six barrels. The six bolt assemblies are attached to and positioned around the rotor assembly. The rotor comprises the core axis of the minigun. The six barrels are connected to the forward portion of the rotor and are arranged for rotation as a cluster around the core axis of the minigun. As the rotor rotates, the bolt assemblies are driven forward and rearward by a helical cam incorporated within the main housing. The helical cam operates to cause cartridges to be delivered to the bolt assemblies, chambered in a barrel, and then fired. The empty cartridges are extracted from the chambers and ejected. The rotor is rotated by means of a series of gears driven by an electric motor.
The majority of the high-pressure gases and shrapnel generated by a hang fire or overpressure situation are directed into the area between the rotor assembly and the main housing. The high-pressure gasses and shrapnel are then forced to escape at high velocity through various openings in the housing, thereby subjecting the operator to possible injury.
A hang fire refers to the firing, or detonation, of a cartridge that is out of battery. A cartridge is “out of battery” when it is not chambered and locked into the chamber of a barrel. Under normal circumstances, a cartridge is locked into the chamber of a barrel when it is fired. The chamber of the barrel contains the pressure created by the burning powder, thus forcing the bullet down the barrel. If the cartridge is fired out of battery, high-pressure gases and fragments of the burst cartridge case are directed into the area between the rotor assembly and the main housing that surrounds the rotor assembly. An overpressure situation results primarily from either an obstruction within the barrel or a cartridge having too much powder. In the event of an overpressure situation, high-pressure gases will blow out through the base of the cartridge case releasing these gases and shrapnel into the area between the rotor assembly and the main housing.
It would therefore be advantageous to provide an improved minigun design that will eliminate the hazards associated with hang fires and overpressure situations. In accordance with the illustrated preferred embodiment of the present invention, a vented rotor assembly serves to redirect and dissipate high-pressure gases and shrapnel forward through the rotor assembly and away from the operator.