Abstract: Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.

Abstract: A system for determining parameters of a cloud atmosphere within a wind tunnel. The system includes: a light projector configured to project a pulse of light energy into a projection field of view; at least one light detector having a detection field of view that forms a range-limited intersection with the projection field of view, the range-limited intersection having a maximum sampling range so as to exclude wall structures of the wind tunnel, wherein the at least one light detector is configured to detect a backscattered portion of the projected pulse of light energy backscattered from within the range-limited intersection; and a cloud parameter calculator configured to determine parameters of the cloud atmosphere based on the backscattered portions detected.

Abstract: An optical ice detector and airspeed probe includes an ice detection module and an airspeed module. The ice detection module detects the presence or absence of ice, water, or ice and water particles, and the airspeed module determines a line-of-sight speed along a directional vector, each based on backscatter light returns emitted from a common collimated light source. An electronics module determines an airspeed of an aircraft based on the line-of-sight speed determined by the airspeed module and at least one aircraft parameter received from the air data system.

Abstract: A method of operating an optical icing conditions sensor includes transmitting a first light beam with a first transmitter and a second light beam with a second transmitter, thereby illuminating two illumination volumes. A first receiver receives the first light beam. A second receiver receives the second light beam. A controller measures the intensity of light received by the first and second receivers. The controller compares the intensities to threshold values and determines if either intensity is greater than the threshold values. The controller determines a cloud is present if either intensity is greater than the threshold values. The controller calculates a ratio of the intensities if a cloud is present. The controller determines, using the ratio, whether the cloud contains liquid water droplets, ice crystals, or a mixture of liquid water droplets and ice crystals.

Abstract: A system for determining parameters of a cloud atmosphere within a wind tunnel. The system includes: a light projector configured to project a pulse of light energy into a projection field of view; at least one light detector having a detection field of view that forms a range-limited intersection with the projection field of view, the range-limited intersection having a maximum sampling range so as to exclude wall structures of the wind tunnel, wherein the at least one light detector is configured to detect a backscattered portion of the projected pulse of light energy backscattered from within the range-limited intersection; and a cloud parameter calculator configured to determine parameters of the cloud atmosphere based on the backscattered portions detected.

Abstract: Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.

Abstract: A method of operating an optical icing conditions sensor includes transmitting, with a transmitter, a light beam and thereby illuminating an illumination volume. A receiver array receives light over a range of receiving angles. The receiver array is configured to receive light having the wavelength over a receiver array field of view which overlaps with the illumination volume. A controller measures an intensity of light received by the receiver array. The controller determines that a cloud is present if the intensity is greater than a threshold value. The controller calculates scattering profile data of the light received by the receiver array if a cloud is determined to be present, which includes an angle of a scattering intensity peak within the range of receiving angles and a breadth of the scattering intensity peak. The controller estimates a representative droplet size within the cloud using the scattering profile data.

Abstract: A method of operating an optical icing conditions sensor includes transmitting a first light beam with a first transmitter and a second light beam with a second transmitter, thereby illuminating two illumination volumes. A first receiver receives the first light beam. A second receiver receives the second light beam. A controller measures the intensity of light received by the first and second receivers. The controller compares the intensities to threshold values and determines if either intensity is greater than the threshold values. The controller determines a cloud is present if either intensity is greater than the threshold values. The controller calculates a ratio of the intensities if a cloud is present. The controller determines, using the ratio, whether the cloud contains liquid water droplets, ice crystals, or a mixture of liquid water droplets and ice crystals.

Abstract: An optical sensor for an aircraft includes two detectors, a light source, and a controller. The detectors are oriented along detector paths and have tilt angles and fields of view. The detectors are configured to detect light reflected from an illumination volume and to generate detector signals that correspond to intensities of detected light. The tilt angles are equal such that each detector is oriented in an opposite direction within a plane containing a light source path and the detector paths. The light source is oriented along the light source path and is configured to illuminate the illumination volume which overlaps with the fields of view within a predetermined distance range. The controller is configured to receive the detector signals, detect whether a cloud is present based upon the detector signals, determine a cloud phase, and calculate a density of the detected cloud.

Abstract: Apparatus and associated methods relate to determining metrics of a cloud atmosphere using time difference measurements. A light projector projects a pulse of light into a cloud atmosphere, and a light sensor detects a portion of the projected pulse of light backscattered by the cloud atmosphere. A backscatter coefficient is calculated based on peak amplitude of the detected portion. An optical extinction coefficient is calculated based on a time difference between a peak time and a post-peak time, which correspond to times at which the peak amplitude of the detected portion occurs and at which the detected portion equals or crosses a sub-peak threshold, respectively. In some embodiments, a logarithm amplifier is used to facilitate processing of signals of widely varying amplitudes. In some embodiments, the sub-peak threshold is calculated as a fraction of the peak amplitude of the detected portion.

Abstract: Apparatus and associated methods relate to determining an effective size, quantity, shape, and type of water particles in a cloud atmosphere based on differences in amplitudes of optical signals backscattered at different backscattering angles. Off-axis backscattering—backscattering at angles other than 180 degrees—is affected by the effective size, quantity, shape, and type of water droplets. Detected amplitudes of optical signals that are backscattered at different angles are used to indicate the effective size, quantity, shape, and type of water particles in the cloud atmosphere. In some embodiments, optical emitters and detectors are configured to measure amplitudes of optical signals backscattered at backscattering angles of both on-axis—180 degrees—and off-axis varieties.

Abstract: Apparatus and associated methods relate to determining health of an electrical heater of an air data probe based on a comparison between a calculated expected value and a measured value of an electrical property of the electrical heater. The expected value of the electrical property is calculated based in part on the electrical power provided to the electrical heater and further based in part on the aircraft flight parameters and/or environmental conditions. Such aircraft flight parameters and/or environmental conditions can include at least one of: electric power source status, airspeed, air pressure, altitude, air temperature, humidity, liquid water content, ice water content, droplet/particle size distribution, angle of attack, and angle of sideslip. These aircraft flight parameters and/or environmental conditions are received via an aircraft interface.

Abstract: Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.

Abstract: Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.

Abstract: Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.

Abstract: An optical ice detector and airspeed probe includes an ice detection module and an airspeed module. The ice detection module detects the presence or absence of ice, water, or ice and water particles, and the airspeed module determines a line-of-sight speed along a directional vector, each based on backscatter light returns emitted from a common collimated light source. An electronics module determines an airspeed of an aircraft based on the line-of-sight speed determined by the airspeed module and at least one aircraft parameter received from the air data system.

Abstract: Apparatus and associated methods relate to sampling a large volume of a cloud atmosphere so as to obtain a large signal response from even a sparse distribution of water droplets in the cloud atmosphere. Such a volume can be probed by projecting an uncollimated optical beam into the cloud atmosphere and sampling the signal backscattered from the water droplets located within the probed volume. The uncollimated optical beam can be generated by projecting a diverging pulse of light energy from a polished end of a first optical fiber. A second optical fiber can be used to receive the optical signal backscattered from the cloud atmosphere. The second optical fiber can also have substantially the same field of view as the first optical fiber, so as to receive signals from a volume of the cloud atmosphere that is substantially commensurate with the probed volume.

Abstract: A system for determining parameters of a cloud atmosphere within a wind tunnel. The system includes: a light projector configured to project a pulse of light energy into a projection field of view; at least one light detector having a detection field of view that forms a range-limited intersection with the projection field of view, the range-limited intersection having a maximum sampling range so as to exclude wall structures of the wind tunnel, wherein the at least one light detector is configured to detect a backscattered portion of the projected pulse of light energy backscattered from within the range-limited intersection; and a cloud parameter calculator configured to determine parameters of the cloud atmosphere based on the backscattered portions detected.

Abstract: Apparatus and associated methods relate to determining an effective size, quantity, shape, and type of water particles in a cloud atmosphere based on differences in amplitudes of optical signals backscattered at different backscattering angles. Off-axis backscattering—backscattering at angles other than 180 degrees—is affected by the effective size, quantity, shape, and type of water droplets. Detected amplitudes of optical signals that are backscattered at different angles are used to indicate the effective size, quantity, shape, and type of water particles in the cloud atmosphere. In some embodiments, optical emitters and detectors are configured to measure amplitudes of optical signals backscattered at backscattering angles of both on-axis—180 degrees—and off-axis varieties.

Abstract: Apparatus and associated methods relate to determining health of an electrical heater of an air data probe based on a comparison between a calculated expected value and a measured value of an electrical property of the electrical heater. The expected value of the electrical property is calculated based in part on the electrical power provided to the electrical heater and further based in part on the aircraft flight parameters and/or environmental conditions. Such aircraft flight parameters and/or environmental conditions can include at least one of: electric power source status, airspeed, air pressure, altitude, air temperature, humidity, liquid water content, ice water content, droplet/particle size distribution, angle of attack, and angle of sideslip. These aircraft flight parameters and/or environmental conditions are received via an aircraft interface.