A Simple, Small, Low Power Instrument to Measure Aircraft Icing Severity

Aircraft icing severity depends on two key cloud parameters, liquid water content and droplet size. Proposed is a simple instrument using multiple hot wire elements to measure cloud droplet size (median volume diameter) and liquid water content.The unit utilizes three hot wire sensor elements each of a different geometry, all exposed to the same airflow. By virtue of their different sizes/shapes, the elements have different measurment efficiencies with respect to droplet diameter.Liquid water content is determined by the total amount of water measured by all three elements. Droplet median volume diameter is determined by the response differences between the three elements. The range of droplet measurement includes super large droplets SLD).The proposed instrument has no moving parts, no optics and emits no electromagnetic radiation. It is a first principles device capable of complete calibration. Its response time is under one second.Total frontal area of the instrument is less than four square inches. Less than 500 watts of power are required for operation in continuous icing conditions. The operational airspeed range is compatible with operational jet and turboprop transport aircraft.Applications include icing research and operational cockpit warning for icing and SLD conditions.