Unmanned aircraft in VORTEX-2

In the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX-2) autonomous unmanned aircraft were used for the first time to collect in-situ observations in close proximity to supercells. The use of unmanned aircraft to collect data significant to stormscale research has long been recognized. However, collecting these data requires aircraft operation beyond the visual line of sight of the controller which necessitates aircraft autonomy. An autonomous unmanned aircraft requires a significantly more complex command and control system and elicits more scrutiny by airspace regulatory agencies. Therefore, while the potential utility of unmanned aircraft systems (UAS, the unmanned aircraft along with the communications and logistics infrastructure required for their operation) for stormscale research may be obvious, the engineering and regulatory hurdles that must be overcome for their use are significant.

Surmounting these engineering and regulatory hurdles was the principle objective of the UAS component of VORTEX-2. Regulatory hurdles prevented UAS operations in the first year of VORTEX-2. However, the Federal Aviation Administration (tasked with regulating all UAS operations) granted the UAS group certificates of authorization (CoA) to fly for all of year-2 over northeast CO, southwest NE, and northwest KS. The majority of the engineering hurdles involved the communication system necessary to 1) command and control the aircraft through its on-board autopilot and 2) direct ground-based vehicles required to remain compliant with FAA regulations. Testing during both year-1 and -2 yielded a robust communication system. Lessons learned from interactions with the FAA along with an overview of the communication system will be presented at the conference.

Scientifically, the UAS in VORTEX-2 was tasked with collecting in-situ observations of the temperature and moisture above the surface across the rear flank gust front (RFGF) and within the rear flank downdraft (RFD). Despite the relatively small region approved for UAS operations, 6 flights were conducted in the vicinity of supercells during year-2 of VORTEX-2: 6 May, 26 May, 6 June, 7 June, 9 June, and 10 June. Of these flights, three (6 June, 9 June, and 10 June) collected observations across the RFGF and within the RFD. Results from the VORTEX-2 flights along with an outlook towards possible future applications of UAS for stormscale research will be presented at the conference.