Field Measurements of the Airflow in the Urban Environment: An RPAS Use-Case in Montréal, Canada

A use-case was conducted in Montréal in the summer and fall of 2023 to measure urban airflow characteristics using a small Remotely-Piloted Air System (sRPAS). The goal of the study was to acquire urban airflow data in a real environment in order to validate urban airflow characteristics from laboratory-scale testing conducted previously. The use-case took place in the downtown core of Montréal and involved flights from two hospitals to a variety of other buildings. The sRPAS was instrumented with an airflow measurement system. Fixed rooftop anemometer stations were also installed on top of buildings along the flight paths to measure urban airflow at altitudes within close proximity to rooftops. The study generated a valuable data set for characterizing sRPAS operations in urban environments. A number of operational challenges were experienced including the difficulty associated with visual line of sight operations with an urban backdrop, avoiding conditions that could lead to loss of command and control link, and the need to monitor electromagnetic interference during flight operations. The use-case produced evidence of the impact of urban airflows on the stability and response of sRPAS. High wind speeds and turbulence intensities were found in the urban flow field of Montréal. The sRPAS use-case results were used to validate wind-speed and turbulence characteristics from laboratory-scale testing on Canadian cities.