Abstract: A method of monitoring an ice protection system of a rotorcraft or an aircraft includes applying heat to rotating blades of the rotorcraft or the aircraft according to a heater duty cycle and determining an anticipated ice shed time for ice to shed from the rotating blades. Torque of the rotating blades is sensed, and an actual ice shed time for ice to shed from the rotating blades is determined based on the sensed torque. A status of the ice protection system is determined based on the anticipated ice shed time and the actual ice shed time, and the status of the ice protection system is output for consumption by a consuming system.

Abstract: A method of monitoring an ice protection system of a rotorcraft or an aircraft includes applying heat to rotating blades of the rotorcraft or the aircraft according to a heater duty cycle and determining an anticipated ice shed time for ice to shed from the rotating blades. Torque of the rotating blades is sensed, and an actual ice shed time for ice to shed from the rotating blades is determined based on the sensed torque. A status of the ice protection system is determined based on the anticipated ice shed time and the actual ice shed time, and the status of the ice protection system is output for consumption by a consuming system.

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 a system for detecting foreign object debris ingested into an aircraft engine. The system detects such foreign object debris by projecting a beam of light over an inlet of the aircraft engine. When foreign object debris is ingested into the aircraft engine, it intercepts the beam of light and scatters a back-scattered portion of the intercepted beam of light. An optical detector is configured to detect the back-scattered portion of the intercepted beam of light. A processor is configured to determine whether foreign object debris is ingested by the aircraft engine based on a comparison of a threshold value with a signal indicative of the back-scattered portion generated by the optical detector.

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: A system for correcting an air temperature (AT) reading can include a water content sensor configured to measure a water content in an airflow and to output a water content signal indicative thereof, an AT sensor configured to measure an air temperature and output an AT signal indicative thereof, and a correction module operatively connected to the water content sensor and the AT sensor. The correction module can be configured to receive the water content signal and the AT signal and to correct the AT signal based on the water content to output a corrected AT signal.

Abstract: Apparatus and associated methods relate to a system for detecting foreign object debris ingested into an aircraft engine. The system detects such foreign object debris by projecting a beam of light over an inlet of the aircraft engine. When foreign object debris is ingested into the aircraft engine, it intercepts the beam of light and scatters a back-scattered portion of the intercepted beam of light. An optical detector is configured to detect the back-scattered portion of the intercepted beam of light. A processor is configured to determine whether foreign object debris is ingested by the aircraft engine based on a comparison of a threshold value with a signal indicative of the back-scattered portion generated by the optical detector.

Abstract: An air data probe system can include a pitot static system configured to sense at least one total pressure value of a flow at one or more locations, at least one static pressure value of the flow at the one or more locations, and, directly or indirectly, at least one differential static pressure value of the flow at the one or more locations. The system can include an angle of slip (AOS) module configured to determine a local angle of slip (LAOS) value at each location based on the at least one total pressure value at each location, the at least one static pressure value at each location, and the at least one differential static pressure value at each location.

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 detecting cloud conditions from a distance by generating a polarized microwave-frequency electromagnetic pulse and evaluating various reflected wave parameters pertaining to a corresponding cloud-reflected microwave-frequency electromagnetic reflection. Various cloud metrics can be calculated using these collected wave parameters. The microwave-frequency pulses can be scanned over multiple dimensions, using a steered beam arrangement which will lead to the ability to scanning a conical sector of the space in front of the aircraft. These collected multi-dimensional wave parameters can then be used to generate multi-dimensional maps of cloud metrics. Such cloud metrics can include relative velocities of moving cloud conditions in the flight direction, particle density distributions, ice/water ratios, estimates of particle side distributions, etc.

Abstract: A system for correcting an air temperature (AT) reading can include a water content sensor configured to measure a water content in an airflow and to output a water content signal indicative thereof, an AT sensor configured to measure an air temperature and output an AT signal indicative thereof, and a correction module operatively connected to the water content sensor and the AT sensor. The correction module can be configured to receive the water content signal and the AT signal and to correct the AT signal based on the water content to output a corrected AT signal.

Abstract: An air data probe system can include a pitot static system configured to sense at least one total pressure value of a flow at one or more locations, at least one static pressure value of the flow at the one or more locations, and, directly or indirectly, at least one differential static pressure value of the flow at the one or more locations. The system can include an angle of slip (AOS) module configured to determine a local angle of slip (LAOS) value at each location based on the at least one total pressure value at each location, the at least one static pressure value at each location, and the at least one differential static pressure value at each location.

Abstract: Apparatus and associated methods relate to determining liquid-water concentration in a cloud atmosphere based on a frequency of resonance of a magnetostrictive resonator and/or a temporal variation of the resonant frequency of the magnetostrictive resonator. The magnetostrictive resonator is configured to resonate at a resonant frequency indicative of a measure of ice accumulation upon an exterior surface of the magnetostrictive resonator. When in liquid-water ambient, however, the magnetostrictive resonator has a resonant frequency less than a baseline resonant frequency. When in the liquid-water ambient, the magnetostrictive resonator also has temporal variations in resonant frequency that exceed one part in ten thousand. Using one or both of these resonant-frequency responses to liquid-water ambient, a signal indicative of liquid-water content can be generated.

Abstract: Apparatus and associated methods relate to detecting cloud conditions from a distance by generating a polarized microwave-frequency electromagnetic pulse and evaluating various reflected wave parameters pertaining to a corresponding cloud-reflected microwave-frequency electromagnetic reflection. Various cloud metrics can be calculated using these collected wave parameters. The microwave-frequency pulses can be scanned over multiple dimensions, using a steered beam arrangement which will lead to the ability to scanning a conical sector of the space in front of the aircraft. These collected multi-dimensional wave parameters can then be used to generate multi-dimensional maps of cloud metrics. Such cloud metrics can include relative velocities of moving cloud conditions in the flight direction, particle density distributions, ice/water ratios, estimates of particle side distributions, etc.

Abstract: Apparatus and associated methods relate to determining liquid-water concentration in a cloud atmosphere based on a frequency of resonance of a magnetostrictive resonator and/or a temporal variation of the resonant frequency of the magnetostrictive resonator. The magnetostrictive resonator is configured to resonate at a resonant frequency indicative of a measure of ice accumulation upon an exterior surface of the magnetostrictive resonator. When in liquid-water ambient, however, the magnetostrictive resonator has a resonant frequency less than a baseline resonant frequency. When in the liquid-water ambient, the magnetostrictive resonator also has temporal variations in resonant frequency that exceed one part in ten thousand. Using one or both of these resonant-frequency responses to liquid-water ambient, a signal indicative of liquid-water content can be generated.

Abstract: An ice detector for an aircraft comprises a strut and probe assembly, and it is positioned on the aircraft so that the pressure field around the ice detector causes a lower temperature region on the probe assembly compared to the aircraft. Ice will therefore form on the probe assembly before it forms on the aircraft to provide an early warning of icing conditions near freezing temperatures.

Abstract: An ice detector for an aircraft comprises a strut and probe assembly, and it is positioned on the aircraft so that the pressure field around the ice detector causes a lower temperature region on the probe assembly compared to the aircraft. Ice will therefore form on the probe assembly before it forms on the aircraft to provide an early warning of icing conditions near freezing temperatures.