Abstract: An airfoil temperature control arrangement includes a resistive heater element. A plurality of detectors allow a controller to gather resistance information at various intervals along the resistive heater element. Determining the resistance of the corresponding portions of the heater element allows the controller to utilize a known relationship between resistance and temperature for the material selected to make the resistive heater element. In one example, a nickel alloy or other material having a high coefficient of resistance is chosen to provide the controller with the ability to determine a temperature for each portion of the heater element. The determined temperature information is used, for example, to monitor whether any portion of the heater element has become delaminated from the airfoil surface.

Abstract: A system for providing power and communication signals to a device associated with a rotating component on an aircraft includes a communication strategy that allows power and command signals to be propagated along the same conductors. A stationary controller provides power and command signals to a controller that is supported for rotation with the rotating device. Only two slip rings are required to communicate power and command signals between the stationary and rotating controllers. Synchronous modulation preferably is used for sending the command signals to avoid interference from noise inherent in slip ring electrical couplings. A multi-zone propeller deicing heater is one example device that is controllable using the inventive approach.

Abstract: An airfoil temperature control arrangement includes a resistive heater element. A plurality of detectors allow a controller to gather resistance information at various intervals along the resistive heater element. Determining the resistance of the corresponding portions of the heater element allows the controller to utilize a known relationship between resistance and temperature for the material selected to make the resistive heater element. In one example, a nickel alloy or other material having a high coefficient of resistance is chosen to provide the controller with the ability to determine a temperature for each portion of the heater element. The determined temperature information is used, for example, to monitor whether any portion of the heater element has become delaminated from the airfoil surface.

Abstract: A system for providing power and communication signals to a device associated with a rotating component on an aircraft includes a communication strategy that allows power and command signals to be propagated along the same conductors. A stationary controller provides power and command signals to a controller that is supported for rotation with the rotating device. Only two slip rings are required to communicate power and command signals between the stationary and rotating controllers. Synchronous modulation preferably is used for sending the command signals to avoid interference from noise inherent in slip ring electrical couplings. A multi-zone propeller deicing heater is one example device that is controllable using the inventive approach.

Abstract: A messaging system for a rotating airfoil system is provided that includes a stationary structural member supporting a shaft that is rotatable about an axis. An airfoil assembly is supported by the shaft. A first arcuate coil assembly is supported on the structural member and is arranged at least partially about the shaft. A second arcuate coil assembly is supported on the airfoil assembly adjacent to the first arcuate coil assembly and is rotatable relative thereto. One of the coil assemblies provides a magnetic field having an inductance with an electronic message. The inductance of the one coil assembly produces a voltage containing the message in the other coil assembly. The message may be demodulated from the voltage. In this manner, messages may be sent to and from airfoil assembly systems such as blade heaters and blade pitch actuators.

Abstract: A rotary switch for providing deicing power to the heaters of a helicopter rotor includes a conductive rotor with conductive protrusions located thereon. Conductive fingers are arranged such that a pair of conductive fingers are in electrical communication with a pair of conductive protrusions for a given position of the conductive rotor. The pair of conductive fingers are in electrical communication with the heaters of a helicopter rotor such that if one the pair of electrical fingers fails to make electrical contact with its respective conductive protrusion electrical power is still delivered to the heater.

Abstract: A de-icing blanket and method of ice-removal from a moving object such as an airfoil comprises a center portion including a heater, and side portions flanking the center portion, each side portion including an electro-expulsive de-icing system (EEDS). The center portion is placed on the leading edge of the airfoil forwardly with respect to the side longitudinal portions such that when the airfoil is in motion, an airflow impinging on the airfoil forces water contacting an exposed surface of the center portion to flow rearwardly and to freeze on accreting surfaces of the side portions where the ice is subsequently removed by energizing the EEDS. The blanket may include a leading edge cap made of a highly polished impervious material to protect the blanket from atmospheric weathering.

Abstract: A composite fabric electro-expulsive blanket is provided for shattering and removing ice and other fungible material from an accretion surface such as an airfoil. The blanket includes composite fabric upper and lower layers having a modulus of elasticity approximately between 10 to 100 million psi. Upper and lower conductor segments are positioned within the blanket so that when electrically energized, they repel one another so as to rapidly set the outer ice-accreting surface into motion. Bowed or loose stitches connecting the outer and inner layers become taut during the motion of the ice-accretion surface, thereby rapidly decelerating the surface and shattering accumulated ice thereon. Slits in the outer layer limit undesired hoop stress.

Abstract: A method and apparatus for detecting the formation and build up of encrusted matter upon the outer surface of an electro-expulsive blanket utilizing the principles of stress and strain.

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 restoring means for returning the separated conductors to rest position and a method of expulsing solid or frangible material.

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 cordless communications system wherein transmission is made and received via magnetic lines of induction comprises a base station and at least one mobile station wherein the base station receives and transmits voice or data signals at different frequencies. A PIGLER unit is selectively disposed between the base station and mobile station so as to extend the range of the communications system.

Abstract: An atmospheric probe for detecting the occurrence and measuring the extent of ice accretion upon the probe.

Abstract: A cordless communications system wherein transmission is made and received via magnetic lines of induction comprises a base station and at least one mobile station wherein the base station receives and transmits voice or data signals at different frequencies. The base station employs at least two magnetic loop antennas for transmission and reception, respectively, oriented so as to provide a toroidal magnetic field which allows 360 degree transmission and reception in the planes of the antennas. The components of the at least one mobile station are mounted in an article of clothing. The mobile station is arranged in the article of clothing in such a manner as to insure a substantially constant effective coupling area with the base station antenna.

Abstract: Sensor and reference wires are directly exposed to the airflow past a vehicle. The wires are electrically conductive, and each has a resistance varying with its temperature. A continuous fixed voltage is passed through the reference wire. A short pulse of greater constant voltage is passed through the sensor wire, the voltage of sufficient magnitude to cause the rapid heating of the sensor wire during the pulse. The resultant rate of heat of the sensor wire, and its final temperature at the end of the pulse, is determined by whether ice or water is on the sensor wire. Circuitry is provided to generate an ice present signal when the difference in current flow during the pulse through the sensor wire and through the reference wire is of such magnitude and sign as to indicate that ice was in contact with the sensor wire. Due to water's heat of fusion, the effect of ice on the sensor wire is readily distinguished from the effect of water.

Abstract: An automatic flight control apparatus for aircraft having the desired attitude of the aircraft in a balanced relation to the action speed of the aircraft and utilizing this reference signal to generate a difference signal which corresponds to the difference between the reference signal and a signal representing the actual attitude of the aircraft; this latter signal then is used as one of the control parameters. The difference signal is fed to a control system through a limiter having a limiting range to avoid feeding excessively large difference signals into the control system and thus preventing unstable flight.

Abstract: An automatic flight control apparatus for a rotary wing aircraft for controlling the flight condition by utilizing a signal representing the air speed of the aircraft which is added to a bias signal corresponding to the attitude of the aircraft in hovering condition, which added signal is used as a "trim value" signal representing the attitude of the aircraft in a balanced relation to air speed at every instance. A signal representing the difference between said trim value signal and the attitude signal is used as an attitude/speed error signal and is added with the signal representing the difference between the ground speed and the set speed for performing control of the aircraft condition.

Abstract: An automatic flight controller for rotary wing aircraft having a setting apparatus for setting the device for the distance from a starting distance signal, a speed signal, and a remaining distance signal corresponding to the remaining distance from the starting spot to the hovering spot whereby the flight of the aircraft can be controlled in accordance with the remaining distance signal. A ground speed signal from a ground speed detecting device is integrated to obtain a signal corresponding to the flight distance from the starting spot and a remaining distance signal is then produced which is equal to the difference between the starting distance signal and the flight distance signal, and, through a function amplifier, a reference speed signal is obtained which corresponds to the remaining distance to be flown at every instance. This reference speed signal is compared with the actual ground speed to provide a speed difference signal which is used as a control signal for controlling the speed of the aircraft.