Abstract: A rescuer (1) is lowered at the end of cable (2) from a helicopter having a winch (4) on which the cable is wound. The rescuer is provided with a electric field sensor (20) which is downwardly directed and which is connected to a radio transmitter (22). The helicopter (3) has a corresponding radio receiver (24) which serves to actuate an active static discharger which is servo-controlled to the electrical magnitude supplied by the sensor (20). The servo-control is such that the potential difference between the rescuer (11) and the person to be rescued (10) is progressively reduced as the rescuer approaches the person to be rescued. Practically all risks of an electric shock on making contact are thus avoided.

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: This invention relates to a system for protecting an in-air vehicle from damage due to the craft sustaining a lightning strike. It is an extremely simple device consisting of a sacrificial graphite composite rod 40, approximately the diameter of a pencil with a length of about five inches. The sacrificial rod 40 is constructed with the graphite fibers running axially within the rod in a manner that best provides a path of conduction axially from the trailing edge of an aircraft to the trailing end of the rod. Sacrificial rod 40 is inserted into an attachment hole 32, machined into trailing edges of aircraft flight surfaces, such as vertical fin cap 31, and attached with adhesive in a manner not prohibiting the conduction path between the rod 40 and aircraft 10. The trailing end of rod 40 may be tapered for aerodynamic and esthetic requirements. This rod is sacrificial but has the capability to sustain several lightning strikes and still provide protection.

Abstract: An encapsulated metal bolt comprises a head portion having an encapsulating cap thereon with a plurality of conductive fibers therein electrically isolated from the head but electrically exposed to the surface of a complementary aperture.

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: A plurality of metal conduits for fuel for hydraulic fluids extend through an aircraft fuel tank made of non-metallic materials such as carbon-epoxy. The conduits are attached to wall portions of the tank at spaced apart locations. The conduits are spaced apart from each other and are each spaced away from such wall portion of the tank. A dielectric insulator such as teflon or polyimide is provided on each conduit.

Abstract: A fastener (36,58) attaches a composite material external skin (2) of an aircraft structure to another structure (4). Fastener (36,58) has a metallic head (44,62) and shaft (38,60) and a dielectric cap (50,70) covering a top portion of head (44,62). Head (44,62) and cap (50,70) are received into a countersink hole (6) in skin (2). Cap (50,70) is resilient and fills gap (16) between the top portion of head (44,62) and the inner sidewalls of hole (6). Cap (50,70) forms, with skin (2), an aerodynamic surface which is sufficiently continuous to receive and maintain a crack-free coat of paint having a uniform thickness. The top (52) of cap (50) of internally wrenching fastener (36) is an integral layer of uniform thickness. The top (72) of cap (70) of fastener (58) includes a uniform layer covering the head's top surface around a tool receiving recess (66) and a body of material (74) filling recess (66) and positioned therein after structures (2,4) are attached.

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: Conductive coating (20) is a thorough mixture of 0.03 parts per weight of carbon black together with 0.003 to 0.01 parts per weight of wetting agent and 20 parts of solvent, and further mixing in by low shearing mixing 1/2 to 1 part per weight of thermosetting resin. This is then sprayed into place on the substrate and thermoset. In this particular case, the substrate is exterior face sheet (12) of honeycomb structure (10) which may serve as part of a spacecraft, to electrically conduct away surface charges.

Abstract: A static discharger for discharging charge accumulation from the surface of the wing of an aircraft, comprises a generally flat layer of non-conductive material which is dimensioned and configured so that it can be secured to a portion of the wing surface and so as to conform generally to the shape of the wing surface. A generally flat base member is dimensioned and configured so as to be capable of being placed in conforming relationship with at least a portion of the surface of the layer of non-conductive material which insulates the base member from electrically contacting the surface of the aircraft. A plurality of strands formed of a discharging material are embedded in the base member. The plurality of strands are electrically connected to the wing surface of the aircraft so that charge accumulation may pass from the wing surface of the aircraft to the plurality of strands and be discharged at the trailing ends of the strands.

Abstract: A device for dissipating static charge collected on the surface of a laminated aircraft window having an outboard plastic ply includes a plurality of electroconductive static charge collecting wicks extending through the thickness of the outboard ply from the outboard surface of the ply to its inboard surface where the wicks are interconnected by wire runs adapted for connection to ground. The device may be laminated to additional transparent structural plies to form a composite aircraft transparency. The device is advantageously used to protect heating facilities in a composite transparency from static discharge damage, as well as to prevent damage to the plies of the transparency from static discharge through the plies.

Abstract: A conductive strip for attachment to an aircraft radome to provide protection against the effects of a lightning strike to the radome, wherein the conductive strip has a series of holes formed in it.

Abstract: A simple, nearly passive apparatus is disclosed that allows a spacecraft sensor to be driven to a potential close to that of a plasma where the ion concentration exceeds about 100 cm.sup.-3 even in the presence of a large vehicle potential. The apparatus includes a conductive reference surface insulated from all spacecraft elements. The reference surface is situated on the spacecraft such that it faces in the direction of motion, and collects ions thereon. There is developed on the surface a plasma potential. The reference surface is connected to the inverting input of an operational amplifier that is powered by floating voltages referenced to the potential at the noninverting input of the amplifier. Since the operational amplifier has to maintain equal voltages at both inputs, the amplifier will drive against spacecraft ground until the voltage at the noninverting input is substantially equal to the voltage at the inverting input.

Abstract: A method of providing lightning protection for non-metallic component structures, aircraft skins, etc. including sandwich-type skins on aircraft where fast removal and easy access is required between components of the lightning protection electrical circuit path. The electrical circuit path between aircraft structures utilizes a flexible clip not requiring fastener connection and removal when a component at the end of the circuit path is required to be replaced.

Abstract: A fiberglass fabric wherein a selected number and pattern of yarns have been coated with an aluminum coating is preimpregnated with epoxy or other resin system and laid up as an integral part of a composite structure of the type having a honeycomb core and a plurality of fiberglass plies. Multiple plies of fiberglass fabric which include the yarns coated with an aluminum coating may be utilized in edgeband fastener areas for increased electrical continuity without loss of mechanical strength of composite parts.

Abstract: Conductive coating (20) is produced by the process of first mixing by high shear mixing a mixture of 0.03 parts per weight of carbon black together with 0.003 to 0.01 parts per weight of wetting agent and 20 parts of solvent, and further mixing in by low shear mixing 1/2 to 1 part per weight of thermosetting resin. Prior to application this is then sprayed into place on the substrate. In this particular case, the substrate is exterior face sheet (12) of honeycomb structure (10) which may serve as part of a spacecraft, to electrically conduct away surface charges.

Abstract: The invention relates to a method and to a structural element for protecting an aircraft against the building-up, when flying, of electrostatic charges on the external metallic surface of the aircraft normally coated with a finishing dielectric paint.The structural element of the aircraft is subjected to a treatment consisting in applying on the external metallic surface of the aircraft, prior to the depositing of the finishing paint, a resistive electrostatic protection layer having a surface resistivity of between 1 and 100 M.OMEGA. per square and being connected to the reference electric potential (i.e., ground or mass) of the frame or body of the aircraft.The the protective layer is provided, for example, by applying at least a paint layer forming, once dry, a coating exhibiting the required surface resistivity.

Abstract: A first embodiment of an aircraft grounding receptacle (10) comprises a connector portion and a tubular portion (18). The connector portion (12) includes an external thread (14) and a hexagonal portion (16). The tubular portion includes a reduced diameter portion (40) and a hexagonal flange (24). Four slots (34) separate the tubular portion (18) into four tines (26,28,30,32) and intersect the flange (24) at locations spaced apart from four of the six points comprising the hexagonal shape of the flange. A bore (38) extends through the body for receiving an aircraft grounding plug (52) and includes reduced diameter portions (40,41) for mating engagement with the terminal groove (54) of the plug.A second embodiment of the aircraft grounding receptacle (60) comprises a plug receiving portion (62) and a collet portion (64).

Abstract: A carbon fibre or aramid fibre fabric in a matrix of thermoset plastic is coated first with a thin layer of nickel, then with a highly conductive second layer, and on the outside once more with nickel. If the metals are deposited under wet-chemical currentless conditions, the flexible fabric will be electrically highly conductive. The composite material is particularly suitable for lightning and NEMP protection.

Abstract: A lightning diverter strip is provided with button elements in the form of diamond-shaped conducting segments which arranged longitudinally on the strip in spaced-apart relation, with the sharp corners of each of the button conductive elements in longitudinal alignment with each other and with the opposite corners presented along the edges of the strip. The spacings of the conductive elements at the corners may be varied so that some of the elements are spaced more closely together than are other ones of the elements, to provide a lightning diverter strip having a lower break-down voltage potential.

Abstract: Method and structures for enhancing the conductivity of graphite composite materials for lightning protection and prevention of attachment of lightning to fasteners. The integral lightning protection for composite aircraft skins, including skins with fasteners penetrating into fuel tanks, utilizes metal coated or plated graphite fibers which are woven into the outer layer of tape or fabric of the structural component requiring protection.

Abstract: In a laminated structure, such as a structural component of an aerospace vehicle or the like, which is fabricated of layers of filament composite material, means is provided for protection against lightning strike damage and electromagnetic interference. In particular, the outer surface layer of the filament composite material is fabricated of conductive metallic-coated filaments to provide a conductive barrier to disperse the current from lightning or other electromagnetic sources. The filaments may be fabricated of a composite material such as glass which has an aluminum coating. The structure may be woven or filament wound with intermixed resin, and the metallic-coated filaments are cured simultaneously with the entire laminated structure of filament composite material.

Abstract: Method and structures for enhancing the conductivity of graphite composite materials for lightning protection and prevention of attachment of lightning to fasteners. The integral lightning protection system for composite aircraft skins, including skins with fasteners penetrating into fuel tanks, utilizes nickel-plated graphite fibers (24) which are woven into the outer layer of fabric of the structural component (10) requiring protection.

Abstract: An ionization-type lightning diverter strip structure having improved environmental edge and tip sealing. Semi-conductive particle edge configurations and particle distribution geometries for improved streamer formation include forward strip and conductive particle termination and particle distribution geometries having variation along the length of the ionization-type lightning diverter strip structures and multilayer particle distribution geometries to resist particle impact erosion (e.g. rain erosion).

Abstract: An ordinary lightning-accessible surface of an aircraft component consisting of a composite material such as a graphite epoxy composite includes one or more layers of dielectric material applied over the exposed composite surface portion of the aircraft, the outermost layer of dielectric material having a binder on the exposed surface thereof for holding a finely divided metal powder distributed uniformly over the surface of the outermost layer of dielectric material.

Abstract: A flush, zero drag discharger system for dissipating static electric charges from surfaces of high performance aircraft and similar vehicles which is capable of withstanding a severe lightning environment without substantial degradation of the system. The discharger system includes a configuration of the vehicle secondary structure into non-electrically conductive areas, conductive high corona threshold areas, and controlled low corona threshold electrostatic discharge areas which are protected from the detrimental effects of lightning by the utilization of ionization-type lightning diverters.

Abstract: A method of preparing an antistatic coating exhibiting a desired value of surface resistivity which is substantially stable with respect to time takes as its starting point a commercial antistatic product having a synthetic resin base and substantially free from metallic particles but of which the surface resistivity, measured after mixing with its hardener and drying, is very much below the desired value. A compatible insulating resin is added to this product so as to raise the surface resistivity, still measured after mixing with the hardener and drying, to a value much higher than the desired value. The resulting product is then subjected to an accelerated ageing treatment causing a reduction in surface resistivity with terminal asymptotic development to the level of the desired value. Such a coating may be applied to radomes and other aircraft surface elements, and has the advantage that its conductivity does not increase appreciably with age.

Abstract: A controlled dielectric barrier is created surrounding a fastener to isolate its sparking areas. The barrier is formed by creating a cap to define a desired cavity between the cap and the fastener and then dielectric isolation material is placed in the cavity and held in place by the cap until hardened. The cap may then be removed from the fastener as desired.

Abstract: A terminal for a high current lightning ionization channel is provided which has a truncated V-notch shaped end portion to which the lightning diverter strip is fastened by a bolt and dimpled washer arrangement. Electrical continuity of the diverter strip remains unbroken, thereby preventing the diverter strip from becoming a noise source during triboelectric charging conditions.

Abstract: A polyurethane-quartz laminate suitable for aircraft radomes. Controlled amounts of a mixture of unpolymerized 4,4 diphenyl methane diisocyanate (MDI) and 2,4 toluene diisocyanate (TDI) are polymerized with ethylene glycol at a preselected temperatures and periods to produce a polymeric resin of relatively few nonpolar isocyanate groups. The resin is impregnated and cured in layers of quartz cloth to form a relatively high strength composite or laminate having a low dielectric constant.

Abstract: A lightning protection system for advanced composite aircraft structures consisting of a sandwich structure including two layers of aluminum foil separated by a layer of dielectric material. The sandwich structure is applied to the surface of the composite aircraft structure desired to be protected from lightning strike damage thereby confining damage to the sandwich structure which can be removed and replaced.

Abstract: A member suitable for use at the exterior surface of an aircraft for structural or containment purposes includes a nonmetallic base or core and a thin electrical shield over that surface of the base that is presented outwardly. Preferably the base is a composite consisting of graphite fibers and a cured resin in which the fibers are embedded. The shield is tin or a tin alloy that is bonded to the surface of the base, preferably by metal spraying techniques. An electrical discharge, such as lightning, that attaches to the member is dissipated through the shield without impairing the strength or containment capabilities of the base.

Abstract: A method of spraying electrically charged particulate material to ground from a low flying airplane. The method includes the steps of imposing an electrical charge of given polarity upon an emitted primary spray of particulate material of sufficient magnitude to electrostatically enhance the deposition thereof and concurrently emitting a secondary spray of oppositely charged particulate material of selective character from said airborne source at a charge level of a magnitude to avoid material degradation of the charge on said primary spray intermediate its loci of emission and deposition.

Abstract: A dielectric film is provided with a metallic back layer for use as the outer layer in a multi layer "thermal blanket" employed as part of the temperature control system for a spacecraft. The dielectric film is repeatedly punctured from the metallized side in order to produce a plurality of small holes, which collect a disproportionately large current from the plasma and adjacent charged surface. The rough edges of these holes also act to initiate frequent, small, field emissions, thereby preventing large surface potentials from building up in the presence of a "hot" space plasma or electron beam environment.

Abstract: Passive and active devices reduce stored electrostatic charge levels on dielectric surfaces, while at the same time reducing electromagnetic interference due to streamer currents, by means of appropriately applied conductors, use of direct or alternating current power sources, ion flooding, fluid flooding and boundry layer control. In addition, the devices detect the presence, polarity and magnitude of triboelectric charging or stored charges on a dielectric surface for the purpose of signalling or of controlling active charge reduction devices. Moreover, the devices can be used to discourage lightning strikes. The devices can be applied with little if any impairment to optical or radio frequency energy transmission or reception.

Abstract: A grounding device for discharging a charged helicopter or the like comprs, in one embodiment, a nylon or Teflon.RTM. stringer having a metal weight at one end and a metal connector at the other. A plurality of spherical, graded resistance conductive ceramic beads and conductive points are strung on the stringer to form a flexible self-cleaning discharge device.

Abstract: An aircraft static discharger and mounting structure therefor is disclosed formed of non-metallic conductive material, such as carbon filled nylon, for mounting an aircraft static discharger onto a graphite and/or boron composite aircraft skin. The discharger includes a mounting structure formed as a sub-base having a lower surface provided with downwardly extending conical projections terminating in points which engage the underlying graphite composite surface and form electrical contact therewith, providing for the mounting of the sub-base to the composite surface by conventional non-conductive epoxy. A surface conductive to lightning currents is provided by bonding powdered aluminum to the outer surfaces of the discharger base and the sub-base which, together form a lightning diverter strip formed on the discharger, transfer lightning currents over the surface of the base and sub-base to the underlying aircraft structure.

Abstract: A voltage driven corona current sensing probe, utilized to sense electrostatic charge (such as on aircraft), is provided with higher positive operating voltage than negative operating voltage to compensate for the different electron emission threshold and mobility of electrons compared to positive ions. In an AC embodiment, the voltage difference is achieved by a polarity-asymmetric voltage divider on a high voltage AC source feeding a single probe. In another embodiment, separate DC power supplies drive respective probes with different voltages.

Abstract: Apparatus for removing electrostatic charge from an aircraft windscreen includes a conductive member arranged to be supported in contact with or in juxtaposition to the windscreen and connected to the aircraft "earth". If in contact, the member may be of conductive rubber. If juxtaposed, it may be of metal or other rigid material. The linkage supporting the member is arranged to allow it to be swept over the windscreen surface to clear an extended area thereof of charge.

Abstract: A lightning diverter strip for use on aircraft components has a polyester tape base onto which is bonded by an epoxy a coating or layer of uniformly dispersed powdered aluminum.

Abstract: A device for producing a gaseous stream carrying electric charges, particrly in view of influencing the electric voltage of a body, particularly of an airship such as a helicopter, comprising a metallic needle connected to a first pole of a high voltage electric source and having a point which is arranged in the neck of a metallic nozzle supplied with a source of compressed air to create a stream carrying the electric charges, the nozzle being arranged at one end of an electrically insulating hollow duct means for ejecting the stream towards the atmosphere, the ejection opening of the stream being surrounded by a massive hood made of an electrically insulating material.

Abstract: An electrostatic discharger has a stem of high electric resistivity faste at one end to an aircraft body and secured at its other end to an enlarged head provided with a sharp circular charge-emitting edge in a plane perpendicular to the stem axis. The edge, bounded by two annular surfaces converging at an acute angle with a radius of curvature of the order of 0.05 mm, may project radially or axially from the head and in either case has a diameter greatly exceeding that of the stem.

Abstract: Construction parts are protected against lightening by a layer which releases a cloud of ionized and ionizable particles to spread the area affected by the lightening flash and to fan out the current path. The layer may include additives which swell when heated to increase the volume and density of the cloud. An electrically and thermal conductive layer or two such layers each having predominantly one of these properties is provided underneath the releasing layer.

Abstract: The proposed electrostatic discharger comprises a corona electrode and a resistive element, which are secured in an insulating bush so that the corona electrode extends outward from the insulating bush, a mount electrically connected to the corona electrode and the resistive element, and an annular electrode enveloping the insulating bush, electrically connected to the corona electrode and defining an ionization gap between it and the mount. The proposed electrostatic discharger ensures reliable protection of aircraft structural elements against repeated lightning strikes and, as its basic purpose, reduces electrostatic interferences to airborne radio communication facilities.

Abstract: A static discharger for use on aircraft includes an elongated nylon body, and an internal resistance element is in the form of a fiber glass rod having conductive coating thereon received within an elongated opening formed in the body. The remote end of the conductive rod is mechanically and electrically bonded to a transversely oriented tungsten corona discharge needle, while the inner end of the rod is mechanically and electrically connected to a mounting base portion through a spring arrangement by means of which the differences in thermal coefficients of expansion between the body and the rod are accommodated. In one embodiment a stainless steel coil spring is used, and in another embodiment, the spring takes the form of a block of conductive rubber. A lighting diverter strip is formed along an outside surface of the nylon body.

Abstract: A device for suspending a raft from a transport such as a helicopter so that the raft can be lowered and raised into and out of the water without subjecting persons attending or occupying the raft to an electric shock from a static charge that may be carried by the transport. The device comprises a metal plate attachable to the transport having straps provided with snap fasteners releasably attachable to the raft. A ground wire connected to the plate is sufficiently longer than the straps so as to contact the water and ground the transport before the straps contact the raft.