Glider pilots harness upward-moving thermal air currents to keep them aloft for hours, while soaring birds use them to save energy. Uncrewed aerial vehicles may soon borrow the same technique to save precious fuel, using software that identifies regions of rising air.
"It could increase the vehicles' endurance during surveillance missions," says Rhys Watkin of Roke Manor Research in Hampshire, UK, a member of the team that developed the system.
To seek out nearby thermal currents, the software first analyses video of the sky taken by an on-board camera. It searches for the telltale grey, dome-shaped clouds that are formed by rapidly rising hot air. The system combines this with real-time weather forecasts and computer simulations of air flow across the local terrain to predict the locations of further thermal currents. The team also fed the software information from anecdotal reports by expert gliders, highlighting areas of rising air in specific locations and in various weather conditions.
During a mission, the software uses all of this data, together with the aircraft's GPS coordinates, to plan a route that passes through as many thermals as possible. So far, the system has only been used to suggest the path for a glider pilot to follow, but the team is developing software to enable an autonomous vehicle to fly solo.
In the future, Watkin hopes to add further software that will analyse maps of the local area and estimate how well ground surfaces emit heat, which also helps predict the location of thermals.
