Abstract: A deicing system for an aircraft engine (4) having blades (14, 16) fixedly attached to rotating propulsors (6, 8) has emitters (22, 28) which irradiate microwave beams (24, 26, 30 32) onto coatings (18, 20) which are fixedly attached to said blades (14, 16). Substantially more of the energy of the beams (24, 26, 30, 32) is absorbed by the coatings (18, 20) than by any water or ice on the blades (14, 16) causing any ice which is on the blades (14, 16) to be thrown off by the centrifugal force of the rotating propulsors (6, 8).

Abstract: A deicing apparatus includes a heat source for producing deicing heat at one location on the body of an object and a heat distributing arrangement for distributing the deicing heat to one or more surface areas to be deiced. The heat distributing arrangement comprises thin strips or channels of heat distributing material having a heat conductivity greater than that of the material from which the remainder of the object is formed. One end or a portion of each strip or channel of the heat distributing material is in contact with the heat source itself or in contact with a highly heat conductive potting material in which the heat source is set. Another portion of each strip or channel of heat distributing material preferably forms a portion of one of the surface areas to be deicd.

Abstract: An electro-expulsive boot comprises two peripherally-interconnected and juxtaposed elastomeric members and an electrically-conductive element helically and/or spirally wound between the two members and embedded in the elastomeric material which comprises the members and an electrical current pulse applied to the conductive element generates a force in one member which opposes a force generated in the other member and the members are expulsively separated by the existence of the current pulse.

Abstract: A multiple blade aircraft propeller hub has a bulkhead supporting concentric slip rings connected by slide blocks to the aircraft electrical system. Electrical conducting flexible leads connect the slip rings to electrical heating elements or de-icing boots carried by the propeller blades. Each of the leads includes an elongated flexible braided copper tube for conducting electricity and which loosely surrounds a flexible multiple strand stainless steel cable, and an extruded flexible vinyl insulating tube loosely surrounds the braided tube. The leads provide for minimizing stresses and metal fatigue in the electrical conducting braided tube with changes in blade pitch and thereby provide for a substantially extended service life.

Abstract: A modular, electromagnetic de-icing system, useful for aircraft, each module being self-contained and including an actuator coil which has a surface configuration which is substantially the same as the shape of the aircraft surface to be de-iced. Each module further includes an electrolytic capacitor which, when discharged, produces a current pulse through the actuator coil, as well as a power supply connected directly to the aircraft-voltage supply for charging the electrolytic capacitor to a selected level, and an electronic switch for selectively connecting the capacitor to the coil when the voltage on the capacitor reaches a selected level. The current through the coil results in a magnetic force pulse which acts on the metal skin of the aircraft to debond and shatter the ice therefrom.

Abstract: An electro-expulsive apparatus including at least two superposed, flexible flat, separately jacketed continuous ribbons of metallic electrical conductor disposed within a sealed outer jacket so that portions of said separately jacketed electrical conductors are separable within said outer jacket to create a void when said conductors are energized simultaneously by an electrical current. The disclosure also includes the method of manufacture.

Abstract: A method is provided for producing a heated laminated windshield construction. Initially, a transparent material to be provided as the outer layer of such a laminated windshield is selected. A transparent basecoat is applied on the inner major surface of the outer layer. A quantity of electroconductive metal is deposited onto the basecoated surface to form a metal strike coat. A portion of the metal strike coat is masked so that unmasked portions of the strike coat comprise the pattern of the electroconductive metal film runs to be formed on the inner major surface. An electroconductive metal is electroplated onto the unmasked portions of the strike coat. Portions of the strike coat onto which no metal was electroplated are removed to thereby leave on the inner major surface of the layer a plurality of spaced apart electroconductive metal film runs comprising electroplated metal and the portion of the metal strike coat beneath the electroplated metal.

Abstract: An electroexpulsive separation apparatus suitable for deicing of the leading edges of aircraft includes a pair of sheet-like arrays each containing in spaced-apart relationship a plurality of parallel ribbon-shaped electrically conductive members. The electrically conductive members are electrically interconnected such that any electrical current flowing in the conductive members flows in the same direction in adjacent electrically conductive members in the first sheet like member and also flows in adjacent electrically conductive members of the second sheet-like array in a direction opposite. The first and second sheet-like arrays are coextensive and superposed proximate to each other such that the electrically conductive members of the first and second sheet-like members are substantially parallel. The electrically conductive members are electrically insulated from one another.

Abstract: Uniform electrical heating of a circular, single crystal germanium window (18) uses its bulk resistance and pairs of electrodes (20) equally spaced about the window's periphery. The electrode pairs are sequentially switched at a rate high enough to avoid thermal switching transients.

Abstract: An all solid state timer-controller for the timed, sequential application of electrical current to loads within a circuit at high amperage, the circuit finding utility in the application of electrical current to de-icers employed aboard aircraft.

Abstract: Ice detection apparatus for use with aircraft having an EIDI solenoid mounted in proximity to the aircraft skin includes a current pulse generator selectively supplying the EIDI solenoid with current pulses of first and second levels, the second level being effective to generate force upon the skin to remove ice from the skin, and the first level being less than the second level. An accelerometer mounted on the interior surface of the skin produces an output signal in response to force imposed on the skin by current pulses of the first level. The output of the accelerometer is a function of both the current pulse level and of the presence of ice. A comparator is provided to generate an output signal indicative of the presence of ice when the accelerometer output signal reaches a predetermined level.

Abstract: A plurality of electrically conductive wires is connected between two terminals and cross over each other at crossover points. Wire segments connect adjacent crossover points. All such adjacent connected crossover points have different potentials when a voltage is connected between the terminals. This forms a screen which protects an engine from damage caused by foreign objects carried into the engine intake. When a power source is connected to the terminals, the screen is heated to prevent the accretion of ice.

Abstract: Apparatus for the prevention of the formation and the removal of previously formed ice from the surface of various articles. A piezoelectric material is applied to environmentally exposed surfaces which are meant to be kept ice free. An available power source is adapted so that whatever the source, it is converted into an alternating current. A microprocessor is provided that, in accordance with the type of material used, its thickness, its currie point, and any other parameters of the specific piezoelectric material necessary for consideration, that it receives a current of the proper amplitude, duration, wave length, and shape which will realize the amount of movement or deformation of the piezoelectric material necessary to prevent ice formation. Further, the piezoelectric material is applied in a grid formation which enables the microprocessor to magnify the deformation of the material and to receive feedback information from specific areas as to the temperature, pressure, density, size of raindrops, etc.

Abstract: An electro-expulsive system 20 has one or more overlapped conductors OC1-OCN each comprising a flexible ribbon conductor 32 which is folded back on itself. The conductors are embedded in an elastomeric material 33. Large current pulses are fed to the conductors OC1-OCN from power storage units 1-N. As a result of the antiparallel currents I and I', the opposed segments of a conductor 32 are forcefully separated and the elastomeric material is distended. Void 34 in the elastomer aids the separation of the conductor segments. The distention is almost instantaneous when a current pulse reaches the conductor and the distention tends to remove any solid body on the surface of the elastomeric material.

Abstract: What is proposed is an electro-impulse de-icing device for use in an airfoil of an aircraft that includes a system having an energy storage device connected via a triggering device to a set of coils each embodying a coil construction in the form of a spirally wound ribbon coil member whose planar dimension is pressed against an interior surface in the leading edge of the airfoil, and wherein the coil sets are arranged in a linear manner along the long axis of the airfoil and are energized simultaneously and sequentially via an interlocking pattern from the wing tips or from the fuselage of the aircraft with each coil set being triggered twice from about three to five seconds apart.

Abstract: This invention provides for heating a brake assembly electrically to prevent it from freezing. More specifically this invention provides for heating electrically an aircraft multi-disk brake assembly.An electric resistance heating element 12 is adapted to form a heater 10 to provide heating to a brake stack 44. Heat may be transferred either directly to the brake stack 44 or indirectly by first heating a member of the brake assembly 36. This member in turn transfers heat to the brake stack.The heater 10 may be formed to fit within the cavity formed by a torque tube 26 wherein the heater abuts a substantial portion of the torque tube 26.Signals from a thermocouple may be used for activation and deactivation of the heater 10.

Abstract: A method of determining the temperature, preferably the ice boundary temperature, of an electrical resistive heating element of a de-icing system for airplanes, helicopters, and the like, preferably for a fully automatic control of the heating times of the heating elements. Additional temperature sensors are avoided and circuitry costs are substantially reduced by using the resistive heating elements themselves for determining the temperature. The resistance variation due to temperature variations of an element is ascertained by a current-voltage measurement, and a temperature variation of the element is determined from the resistance variation while using the temperature coefficient. The current-voltage measurement may be based on Ohm's law with a following analog or digital processing of the signal.

Abstract: A fast voltage pulse is applied to a transducer which comprises a composite of multiple layers of alternately polarized piezoelectric material. These layers are bonded together and positioned over the curved leading edge of an aircraft wing structure. Each layer is relatively thin and metallized on both sides. The strain produced in the transducer causes the composite to push forward resulting in detachment and breakup of ice on the leading edge of the aircraft wing.

Abstract: Electrical circuitry for monitoring the current flow through resistance elements on the leading edge of an aircraft wing or horizontal stabilizer. The resistance elements are individually and sequentially activated for heating to thereby effect a de-icing or anti-icing function. The non-activated elements are sensed by the circuitry to determine inferentially if there is a predetermined current flow through the heating elements to achieve the intended de-icing or anti-icing function.

Abstract: A system for indicating ice thickness and rate of ice thickness growth on surfaces is disclosed. The region to be monitored for ice accretion is provided with a resonant surface waveguide which is mounted flush, below the surface being monitored. A controlled oscillator provides microwave energy via a feed point at a controllable frequency. A detector is coupled to the surface waveguide and is responsive to electrical energy. A measuring device indicates the frequency deviation of the controlled oscillator from a quiescent frequency. A control means is provided to control the frequency of oscillation of the controlled oscillator. In a first, open-loop embodiment, the control means is a shaft operated by an operator. In a second, closed-loop embodiment, the control means is a processor which effects automatic control.

Abstract: An electrically heated glass pane includes a plurality of heating conductors (2) comprising a family of parallel conductors extending between a pair of power supply conductors (3) both disposed on and burnt-in a surface of a glass pane (1). A strip (4), of non-conductive material, covers conductors (3) and extends laterally from the edges of the conductors. The conductors (2) merge into the conductors (3) at a transitional region (7) broadened by an increasing flare so that the cross section of the region, determining the electrical resistance, is greater than the cross section of the conductors (2) providing resistive heating. A layer (12) which covers the same area as the strip (4) may be disposed below each conductor (3), directly on the surface of the glass pane (1). An opening (16) is recessed in layer (12), so that the conductors (3) are connected directly with the surface of glass pane (1).

Abstract: A device (10) for isolating from vibrational and impulse loads a power transfer unit (14) that transfers power from a helicopter electrical system to a plurality of deicing segments on the rotor blades includes a distributor (13) rotating with the rotor blades for distributing power from the power transfer unit (14) to the deicing segments, a housing (11) having an upper cylinder (24) and lower cylinder (23) the latter of which is flexibly secured to the helicopter as by a joint including ball (40), housing 11 substantially isolating the power transfer unit (14) from such loads, and a shaft (12) rotatably engaging the upper cylinder (24) for carrying the distributor (13) in rotation with the rotor blades.

Abstract: A switching system for sequential connection of a plurality of loads to an alternating current supply comprises a computer for generating switch selection data in the form of serial bits along a single line to a distributor arrangement which decodes the selection data and provides control signals to switch devices which connect the loads to the supply. The distributor arrangement includes a circuit for inhibiting supply of the control signals to the respective switch devices unless the voltage of the supply phase connected by the device is substantially zero. Additionally the control signals are time-advanced with respect to the zero voltage conditions so that the switch devices can be placed in states in which they can connect a load before disconnection of a preceding load.

Abstract: A novel solderless connection between a bus bar and an array of electroconductive wires avoids cracks in plastic window elements, particularly the outer component of curved lightweight heated windows, particularly those used in aircraft.

Abstract: A heating glass plate (15, 20, 27, 34) has a heating network (17, 24, 31, 36) made up of wires embedded in a thermoplastic layer following curved directrices. A device for making a heating glass plate having a plate (39) for supporting thereon a plastic sheet. A bridge (44) is slidably supported on the plate and has thereon a sliding carriage (45) carrying wire-laying members (46). Means are provided for imparting reciprocal motion to the carriage. A rod (51) connects the carriage to a vertical spindle (52).

Abstract: A deicer for use on the propeller of an aircraft wherein the heating elements or elements of the deicer which are embedded in an electrically non-conductive material adhered to a propeller blade provide a gradient type of heat distribution pattern having the greatest heat concentration at the area of the propeller closer to the shank end and a lower heat concentration at the area of the propeller further away from the shank end.

Abstract: A system which prevents the formation of ice on the external surfaces of aircraft structures by heating impinging atmospheric supercooled water droplets to above the freezing point by the transmission of microwave electromagnetic energy to the droplets which if unheated would freeze upon impact and adhere to the aircraft structures. The frequency of the microwave electromagnetic energy is such that it is strongly absorbed by the liquid water droplets but weakly absorbed by ambient air, frozen water or the aircraft structures, thus resulting in very efficient heating of the supercooled water droplets.

Abstract: A controller system using high frequency switching by providing a bilateral switch gated on and off at a frequency about ten times the source frequency and the duty cycle determined by pulse width modulation of the high frequency waveform in accordance with window heater temperature.

Abstract: A helicopter deicing control system (10) is provided for selectively distributing D.C. electrical power to a plurality of deicing segments (80, 90) on main and tail rotor blades with only two slip-ring assemblies (60 and 61, 62 and 63) for each rotor drive shaft. A power distribution controller (20) receives electrical power from the helicopter's onboard, fixed electrical power system and provides an output signal including power and control D.C. electrical signals of opposite polarities. A distributor (70) receives the output signal from controller (20) and increments a rotary switch (74) upon receipt of a D.C. electrical control signal, and distributes power to the main rotor deicing segment (90) connected to the rotary switch (74) contact then engaged upon the receipt of a D.C. electrical power signal so as to sequentially deliver D.C. electrical power to the desired main rotor deicing segment.

Abstract: A brush assembly for use with rotating slip rings wherein a plurality of brush modules composed of flat separate elements with brushes therein are assembled in a stacking order with spacers selectively placed between modules to facilitate the positioning of the brushes opposite the slip rings. Each module is molded separately to provide ease of molding, assembling and maintenance.

Abstract: A transparent plastic window containing embedded therein a novel static electricity dissipating circuit (hereinafter referred to as an anti-static circuit), which may also contain a heating circuit insulated therefrom, and a method of producing such windows.

Abstract: A system for effecting the removal of ice from external surfaces of aircraft, and particularly from helicopter rotor blades, by the transmission of microwave electromagnetic energy into the ice so that it functions as a surface waveguide. The system includes a permanent surface waveguide with a dielectric constant close to that of ice, so that a composite surface waveguide is formed. The permanent surface waveguide is formed from a characteristically low-loss material, so that the microwave energy is dissipated as heat primarily in the ice layer, thereby very efficiently melting or heating the ice.

Abstract: In a method for de-icing aircraft surfaces by means of a plurality of electrical resistance heaters which are sequentially supplied with heating current, the delivery of current to each heater being effectuated during a succession of cycles each constituted by a heating period during which heating current is supplied to the heater and a nonheating period during which no current is supplied to the heater, thereby controlling the average current supplied to the heater, the range of ice accumulation rates to which the de-icing process can adjust is enlarged by controlling the duration of the heating periods in dependence on the temperature at the resistance heaters and by controlling the duration of the nonheating periods in dependence on the water content of the atmosphere surrounding the aircraft.

Abstract: A device for preventing ice formation on parts of aircraft-support surfaces (wings or aerofoils), propellers, rotor blades or the like-comprises electrical resistance heaters embedded in a shell of thermally conducting material (e.g. aluminium sheet or moulding) sheathing the aircraft part. Thermally insulating, thermally conducting and electrically insulating layers may be provided within the shell. The heaters, or some of them, may be controlled by a temperature sensor in or on the shell.

Abstract: An axial flow elastic fluid turbine apparatus includes a rotor having an annular array of circumferentially spaced blades. A casing encircles the rotor and an annular array of circumferentially spaced stationary nozzle blades is fastened the casing and arranged to direct the elastic fluid against the blades of the rotor. An outer covering is disposed over the radially outermost half of at least one blade of the stationary array and a thermal insulating member is disposed between the surface of the blade and the outer covering. Electric heating means are provided for raising the temperature of the outer covering to the Leidenfrost point, i.e., the point at which the temperature of the covering exceeds the vaporization temperature of the elastic fluid corresponding to the prevailing ambient pressure by more than 200.degree. C., to evaporate water droplets which collect on the stationary blade and to prevent the accumulation of relatively smaller water droplets on the stationary blade.

Abstract: An electrically heated window system having at least two independently heatable zones wherein each zone includes its own independent resistance heating element which provides a path for the flow of electric current. A selected region in one of the zones includes a secondary heating component which produces a relatively high temperature in this region of the zone which controls a thermostat in thermal contact therewith. The thermostat initially connects an electrical potential to the one zone and then automatically cycles the electrical potential between the two zones in accordance with the rise and fall of the temperature in said selected region.