Experimental Measurement of Turbulence at UAM Operational Altitudes Using an Aircraft-Mounted Accelerometer

Urban Air Mobility(UAM) is gaining attention as an innovative solution in transportation systems and is expected to alleviate urban traffic congestion. However, UAM aircraft are smaller and lighter compared to conventional airplanes, making them more vulnerable to various weather conditions. Specifically, UAM operates at altitudes ranging from 1,000 ft to 2,000 ft, which fall within the Planetary Boundary Layer(PBL). This layer is highly active with weather phenomena such as turbulence, potentially posing significant challenges to safe UAM operations. Furthermore, the absence of commercialized UAM aircraft limits direct analysis of turbulence and other weather factors. To address this challenge, this study proposes an alternative research method using light aircraft (defined as having a Maximum Take-Off Weight(MTOW) of 5,670 kg or less), specifically a Cessna, which shares similar size and operational altitude characteristics with UAM.

In this study, a Cessna aircraft was equipped with portable 3-axis accelerometers (x, y, z) to analyze the impacts of turbulence and weather effects at UAM operational altitudes over the Taean Peninsula on Korea’s western coast. The accelerometers recorded turbulence-induced vibrations(aircraft bumpiness) at a high sampling frequency of 100 Hz. These data were then compared and validated against Pilot Reports(PIREPs), which document unusual weather conditions during flights, to assess the sensor data's reliability and accuracy.

The analysis of the accelerometer data revealed stronger fluctuations over mountainous regions and land-sea boundaries, such as coastal areas. This finding was supported by PIREPs, which confirmed turbulence in similar regions. These results indirectly confirmed the impact of terrain features on turbulence at UAM operational altitudes. Consequently, this study demonstrated an alternative research method using light aircraft and portable accelerometers to measure and analyze turbulence at UAM operational altitudes. This research is expected to lay the groundwork for the future development of UAM aircraft and the establishment of weather support systems.