Abstract: Two composite structures are fastened together using an electrically conductive, threaded fastener. The composite structures have insulating surface regions and inner regions which contain conductive fibers. The threaded fastener is provided with large contact areas through the inner regions to facilitate discharge of high curent densities from the composite materials while minimizing localized heating. This significantly increases the life of the composite material.

Abstract: A volume of gas is enclosed by a cap around a fastener that is through a composite structure on an aircraft. The gas provides spark suppression for arcing that may occur between the composite structure and the metal fastener during a lightning strike. The volume of gas is sufficiently large to absorb the energy of small, very hot particles of graphite, epoxy, etc., that may be present resulting from arcing. High-pressure gas regions between the fastener and composite member vent to the larger volume of gas and are absorbed. This provides effective spark suppression for particular areas in an aircraft, such as a fuel tank, etc.

Abstract: A method for conditioning a composite structure to have an increased sparking current threshold. The method calls for the treatment of the joint in a composite structure by injected currents for predetermined periods of time at a sequence of voltages which are initially less than the present sparking voltage threshold of the structure. The voltage levels can be increased during the treatment to be greater than the sparking voltage threshold of the original structure. If the composite structure contains fasteners, the sparking voltage threshold can be conveniently increased by injecting the current from a timed voltage source through a variety of pairs of the fasteners.

Abstract: In a method for plating one side of a woven fabric sheet, a backing layer is applied to one side of the sheet. The sheet and backing layer are wetted in an electrolytic solution containing metallic ions to be deposited on one side of the fabric sheet only. Air bubbles trapped in interstices of the fabric weave and beneath the backing sheet prevent the electrolytic solution from soaking through the fabric sheet. Electrodes bond the metal ions on the wetted fabric thereto. The backing sheet is then removed. The resulting fabric is coated only on one side and the interstices are not filled in by plating material. The fabric is useful as the outermost layer in a composite laminate for an aircraft skin.

Abstract: A method for providing a junction between metal fittings in a composite structure is disclosed which reduces susceptibility of the junction to electrical arcing during a natural lightning strike. A bore is formed in the composite structure which has a diameter approximately equal to a portion of the metal fitting. In a first embodiment, the bore is provided with internal threads. The metal fitting is provided with cooperative threads which engage the bore to form an interference fit. The metal fitting is continuously rotated into the bore to generate substantial heat therebetween until the metal fitting is fully seated. A substantially void-free interface between the metal fitting and the composite structure results which is preconditioned to a lightning strike. The junction is capable of withstanding current flows of up to 30 kA for the particular part described without the occurrence of electrical arcing.

Abstract: An improved composite structure is disclosed for a lightning protective skin member of an aircraft vehicle surface. The skin member includes first and second graphite panels separated by a wire grid. The grid enhances the strength and elasticity of the skin member while also providing a conductive path for lightning current. Each of the graphite panels includes a plurality of graphite plies laminated with an adhesive, preferably epoxy.

Abstract: A method for protecting composite structures from electrostatic discharge. This method includes limiting resistive heating in conductivity enhanced layers of composite material to prevent delamination due to pyrolytic reactions. Only sufficient metal is used in external conductivity enhanced layers to cause dielectric breakdown to occur before delamination due to pyrolytic reaction results.

Abstract: A first and a second conduit section (10, 12) each have end portions (11, 13) which are covered by a dielectric insulating material (14, 22). The dielectric material (14, 22) covers an outer side surface (16, 24), an end surface (18, 26), and an inner side surface (20, 28) of each end portion (11, 13). The conduit sections are connected together at their ends to form a continuous conduit. Each section is grounded, which in combination with the dielectric material, prevents an electric spark from arcing between their ends.

Abstract: An electrically conductive metal fastener (14) is positioned through an opening (22) in a first surface region (20) of a composite material (10). The first surface region (20) has a relatively low electrical conductivity. A conductive second surface region (32) of the composite material (10) is adjacent the first surface region (20) and is grounded. A film of dielectric material (30) covers the metal fastener (14) and an area immediately surrounding the fastener opening (22). The material (30) diverts a lightning strike away from the fastener (14) and to the conductive second surface region (32).

Abstract: Sabot adapters are provided for mounting along the outer periphery of a ret on opposite sides of the center of gravity with the sabot adapters at each location including inner and outer ring shaped structures that are made of segments and telescoped together with tapering surfaces so that as the two ring structures are moved together they expand radially to fill the radial spacing between the rocket and a rocket launch tube to provide support for the rocket and cause accurate firing of the rocket.