Small multirotor unmanned aerial systems (UAS) have great potential to effectively investigate the urban boundary layer. Their ability to launch and recover vertically in tight urban spaces, along with their ability to be precisely controlled, including hover, makes them an especially attractive investigation tool for obstacle laden environments. These aircraft characteristics are also conducive to obtaining measurements with both high spatial and temporal resolution. With the motivation to obtain high-resolution measurements, a small multirotor UAS was meteorologically instrumented with both thermodynamic and kinematic sensors. This work details the development and subsequent verification of two orthogonally mounted acoustic resonance ultrasonic anemometers that provide a 3 dimensional solution suitable for measurement of the mean wind and its fluctuating component (i.e. turbulence). Comparison of the geo and time-stamped wind speed and direction measurement was made against a surface mounted anemometer during both indoor and field testing. The system will be deployed in upcoming urban field campaigns in the summer of 2020 and beyond.