Exploiting meteorology to enhance the efficiency and safety of UAV operations

Abstract

The meteorological and topographical conditions in Norway (and in many other parts of the World) represent severe challenges for UAV operations. However, these conditions also provide opportunities that can be exploited to improve performance and safety. Aircraft can gain energy by using up-winds, and conserve energy by avoiding headwinds, strong turbulence and sinking air. The main atmospheric energy sources that are discussed in this report are slope wind, thermals and mountain lee-waves. Slope lift effects occur at low level, thermals are found from ground level up to intermediate altitude levels, whereas mountain lee waves occur from intermediate levels up to extreme altitudes. UAVs may use these energy sources to fly great distances, and to remain airborne for long durations without the use of engine power. It is suggested to use advanced atmospheric and topographic models, practical sailplane pilot experience and flight track logs to develop unmanned soaring capabilities. A UAV simulator will utilise prediction models for wind, up-lift, downdrafts and turbulence fields for flight path optimisation. This will enable more energy efficient and safe UAV operations. Sensor or other payload use may also be improved by the availability of more detailed weather predictions. A “Soaring UAV” concept is presented, with an airframe type that can effectively benefit from the atmospheric energy sources mentioned above. Several designs, following the same basic layout, with maximum take-off weight between 25 kg and 750 kg are envisaged.