Rosemount Aerospace Limited

Paul A Ice

Charles Ray Willcox

Kevin J Benning

Fred A Steffen

Total air temperature probe

A total air temperature sensor probe samples the air stream surrounding an aircraft in flight, and includes a duct carrying a fluid flow a portion of which is diverted to a primary chamber mounting a total air temperature sensor. A secondary chamber has a secondary sensor for sensing a different property of a sampled air stream. The secondary chamber is open to receive air flow from passageways in the total air temperature probe.

Total air temperature probe providing a secondary sensor measurement chamber

A total air temperature (TAT) probe for measuring TAT includes an inlet scoop which receives airflow from free stream airflow moving toward the inlet scoop from a first direction. A first portion of the airflow entering the inlet scoop exits the probe through a main exit channel. A second portion of the airflow enters a TAT sensor flow passage, which extends longitudinally along an axis. This axis is oriented to form an angle of less than 90 degrees with the first direction from which the free stream airflow moves toward the inlet scoop. A sensor assembly extends longitudinally in the sensor flow passage and measures a total air temperature of airflow through the sensor flow passage. By increasing the angle through which the internal air turns, better inertial extraction of ice and water particles is realized. As a result, sensor clogging from accreted ice is significantly reduced. A second improvement is achieved by repositioning the sensor element to be more in-line with the internal airflow direction. This helps lower DHE by minimizing heated boundary layer spillage onto the sensing element.

Total air temperature probe providing improved anti-icing performance and reduced deicing heater error

A total air temperature probe positionable on a surface of an aircraft for measuring total air temperature includes an inlet scoop which receives airflow from free stream airflow moving toward the inlet scoop from a first direction. A first portion of the airflow entering the inlet scoop exits the probe through a main exit channel. A second portion of the airflow enters a TAT sensor flow passage, which extends longitudinally along an axis. This axis is oriented to form an angle of less than 90 degrees with the first direction from which the free stream airflow moves toward the inlet scoop. A sensor assembly extends longitudinally in the sensor flow passage and measures a total air temperature of airflow through the sensor flow passage. By increasing the angle through which the internal air turns, better inertial extraction of ice and water particles is realized. As a result, sensor clogging from accreted ice is significantly reduced. A second improvement is achieved by repositioning the sensor element to be more in-line with the internal air flow direction. This helps lower DHE by minimizing heated boundary layer spillage onto the sensing element.

An active heater control circuit for a deicing heater on a probe mounted on an aircraft, such as a pitot pressure sensing probe, a pitot-static pressure sensing probe, a total air temperature sensor, or engine inlet probe, controls power to the heater through a switch. When activated the switch sends electrical power to the heater until the probe temperature reaches a desired set point. A feature of the invention is an override pulse, which independently activates the switch to provide power to the heater at a selected period and duty cycle such that the aircraft current monitoring circuit receives current sufficiently often to avoid triggering a false heater failure alarm even when the probe temperature has reached its control set point. This feature allows the use of probes incorporating active heat control on existing aircraft configured for older probes having simple nickel-based resistive heater control.

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Apple Valley, MN, United States of America

Paul A Ice