Uncrewed Systems Technology 044 l Xer Technolgies X12 and X8 l Lidar sensors l Stan UGV l USVs insight l AUVSI Xponential 2022 l Cobra Aero A99H l Accession Class USV l Connectors I Oceanology International 2022

7 Platform one Researchers in Japan have developed a 3D-printed radiation shield to allow mainstream low-cost UAVs to be used to gather vital data on climate change (writes Nick Flaherty). Numerical weather predictions (NWPs) rely on mathematical models that use data collected by telemetry systems on weather balloons. However, the radiosonde networks are limited in polar regions and can be costly in terms of sensors, energy and human resources, and they can leave electronic equipment as waste over the land and oceans. UAVs could potentially fit the bill as a replacement but are limited in the quality of data they can collect by radiation effects from the Sun, the UAV’s body, precipitation and cloud droplets, as well as the position of the sensors relative to wind direction. To address that, the researchers investigated the possibility of collecting high-quality atmospheric data using a conventional low-cost UAV equipped with a radiation shield. “Sustainable observation networks for NWPs are essential for preparing for weather disasters in our warming climate,” said Dr Jun Inoue from the National Institute of Polar Research. “Since the number of radiosonde observations has hardly increased in a long time, because of the costs of resources, continuous observations with UAVs are a highly desirable alternative to achieving sustainable development as well as meeting the need for improved forecasts.” Working with Kazutoshi Sato, an assistant professor at the Kitami Institute of Technology, he used a DJI Mavic 2 Enterprise Dual UAV to assess the horizontal distribution of wind and heat exhaust below the craft to gauge the ideal location for the sensors. Then, using 3D printing and a heat-reflecting coating, they developed a radiation shield for the sensors that also maintained ventilation and prevented the deposition of precipitation on the sensor. The UAV was used as the main craft in the study. It costs less than $4000 including meteorological sensors, making it affordable for small research groups and local government. It has an intelligent battery self-heating function that helps it to operate in polar regions, warming the battery to its optimum operating temperature even in temperatures as low as -10 C. Because of the relatively small size of the UAV, it can be kept warm in a car just before the launch, which increases the probability of successful measurements in cold conditions. An onboard infrared camera is also available, making the system suitable for operation during the polar night. The official maximum duration of operation is 31 minutes, although the typical flight time in the study was about 15 minutes. The study used an aerosol counter from Alphasense to monitor the aerosol size distribution in the 0.34-0.40 µm range and an iMet-XQ2 sensor from International Met Systems to record the air temperature, relative humidity, air pressure and GNSS satellite position at 1 second intervals. Together, these weigh 200 g. The researchers found that the optimal location for the meteorological instruments on the UAV is just below the downwash from the propellers. That led to a radiation shield located about 5-10 cm below the propeller and at a distance of one-third of the length of the propeller from the propeller tip. A parachute system from Flyfire was installed on the top of the body for safety. The researchers tested the modified Mavic against two other UAVs specifically adapted for meteorological measurements, an ACSL-PF2- R-SWM and a Meteodrone MM-670, and against the existing radiosonde system. The Mavic with the radiation shield operated up to an altitude of 500 m and provided high-quality data equivalent to that of the two other UAVs and comparable to radiosondes. “Our findings demonstrate that it is possible to make the existing polar observational networks sustainable with UAVs. This could significantly boost their observation frequencies and spatial coverage through citizen science programmes,” said Dr Inoue. Airborne vehicles Anti-radiation shield Uncrewed Systems Technology | June/July 2022 The shield could allow low-cost UAVs to be used to collect atmospheric data in polar regions