PTH Sensor Siting on Rotary-Wing UAS

Rotary-wing unmanned aircraft systems (UAS) are well suited for collecting vertical profiles of pressure, temperature, and humidity (PTH) within the atmospheric boundary layer. However, measurement accuracy is sensitive to even small changes in the placement of PTH instruments on the aircraft. As with all platforms, suitable positioning requires (at a minimum) adequate sensor aspiration, protection from exposure to direct solar radiation, protection from cloud/rainwater, and insulation from sources of engine and electronic heat. Experiments supported by CLOUD-MAP (Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics) indicate that position suitability also depends on the direction and speed of the aircraft-relative 3D flow field and thus on the wind velocity, profiling speed and direction (e.g., ascent vs. descent), and aircraft orientation. While ultimately platform-specific, best practices for instrument siting on rotary-wing UAS can be crafted. In this presentation results from systematic testing/intercomparison of instrument siting on two rotary-wing UAS will be presented in an effort to contribute to these best practices.