Special UAV requirements for Nordic conditions. Nordic Drone Initiative White Paper. VTT-M-01038-21

The Nordic Drone Initiative project defined the urgent outdoor delivery mission as a key use case for Unmanned Aerial Vehicles (UAVs) in the Nordic countries. In this context, the successful deployment of drones in logistics missions requires an effort to quantify the special requirements for UAVs, with a focus on atmospheric icing and technologies for the power system based on fuel cells or batteries feeding the electric motors, versus internal combustion engines. This report presents an overview on the aforementioned topics, produced as part of Nordic Drone initiative project funded by Nordic Innovation (2020 - 2022). Atmospheric icing has been confirmed as a critical aspect to be addressed: when flying at 120m above ground level, the larger share of the territory in the Nordics already experiences icing 13 days per year, and the frequency of icing quickly increases in higher flight levels. In low level flight operations with smaller drones, the risk of icing will be mitigated with use of weather data during mission planning, and icing awareness (real time readings from airborne sensors, & aircraft metrics) and protection of critical flight sensors. Flying-wing UAV aircraft architecture seems well suited to minimize the effect of icing. In small helicopter-type UAVs ( ~200kg weight ), the power required for ice prevention seems largely proportional to the power in helicopters certified for flight into known icing conditions. The protection of such UAVs against icing seems realizable with currently available technology, at a cost of a noticeable reduction in payload and flight range. The power systems based on aviation fuel or fuel cell will likely be used for flight endurance over 30 minutes, whereas batteries continue to find its niche in the shorter missions. In both cases, low temperatures will limit operational capabilities. Fuel cell power systems are getting closer to the performance of aviation fuel, with the promise to integrate with the future hydrogen economy. Improved design of fuel containers capable of storing liquid hydrogen will help closing the gap. This work has been funded by Nordic Innovation, and performed under project “ Nordic Drone Initiative - An enabler for sustainable cross-border goods and passenger transport with drones” (ID 104335).