Temperature/Humidity Sensor Housing for Multirotor UAS

A new housing for temperature and humidity sensors on multirotor UAS is introduced. The housing has been designed to shield sensors from insolation, external (conductive) heat sources, and precipitation (artificial wet-bulbing) while maintaining sufficient sensor aspiration. The structure has also been designed to minimize turbulence in the aspirating flow and to sample air from a source as far removed from the strongly-mixed rotor wash as possible. Like many other multirotor UAS, the design exploits the rotors for aspiration. However, unlike systems that are mounted below the rotors, this system is mounted above the rotors and relies on rotor-induced pressure deficits to With an intake directed away from the aircraft body, the source of air passing across sensors within the housing is less likely to be affected by rotor wash than when sensors are mounted directly underneath the rotors. The entire housing is also modular, and a commercially available multirotor is used as the platform of choice, thereby making the setup generic and amenable to changes required for different UASs.

Results from CFD chamber simulations and field tests will be presented. Chamber simulations were designed to evaluate the sensitivity of flow rate through the housing to variations in housing geometry. Field tests using a hot-wire anemometer within the housing confirmed that aspiration was more than sufficient, though some sensitivity to aircraft orientation was seen. Extensive field experiments were also conducted during LAPSE-RATE (Lower Atmosphere Process Studies at Elevation – a Remotely-Piloted Aircraft Team Experiment), and were designed to quantify the sensor response within the housing, and to assess the impact of the induced wake on observations.