Abstract: The present invention involve a method for severance of materials made of polycarbonate, polycarbonate laminate and aciylic/polycarbonate laminate, a canopy fracturing system and a conopy having the canopy fracturing system. The present invention utilizes a linear shaped explosive charge placed at a predetermined distance or stand off from the polycarbonate material to be severed. The coreload of the charge is determined such that the minimum coreload necessary to effect severance of a given thickness of polycarbonate material is utilized. A retainer is placed around the charge and affixed to the material such that the charge is at the proper stand off from the material. The retainer surrounds the back side of the charges but leaves open space between the charge and the material to be severed. Upon detonation, the charge creates an explosive cutting force, or jet blast, that severs the polycarbonate material.

Abstract: The present invention involves a method for severance of materials made of polycarbonate, polycarbonate laminate and acrylic/polycarbonate laminate, such as the materials from which many of today's military aircraft canopies are manufactured. A method of severing a section of an aircraft canopy so as to allow aircrew egress is necessary for aircrew safety. Past severance methods focused on fracturing materials using the shock waves created by explosive charges placed on, near or in the canopy material. These methods are effective for fracturing canopies manufactured from acrylic type materials, however, they are not reliable in severing polycarbonate type materials.

Abstract: A method for severance of materials made of polycarbonate, polycarbonate laminate and acrylic/polycarbonate laminate utilizes a linear shaped explosive charge placed at a predetermined distance or stand off from the polycarbonate material to be severed. The coreload of the charge is determined such that the minimum coreload necessary to effect severance of a given thickness of polycarbonate material is utilized. A retainer is placed around the charge and affixed to the material such that the charge is at the proper stand off from the material. The retainer surrounds the back side of the charges but leaves open space between the charge and the material to be severed. Upon detonation, the charge creates an explosive cutting force, or jet blast, that severs the polycarbonate material. Also, provided are methods for intersecting explosive charges about a pattern to be severed and methods for transferring detonation between such intersecting explosive charges.