Lockheed Martin Robotics Seminar
Teaching Drones to Soar
Aerospace Engineering Department
Pennsylvania State University
Small unmanned aircraft (UAVs) suffer from limited capacity for on-board energy storage and sensing payload. There is often an explicit trade between fuel (for increased mission duration) and payload (for increased data collection). In addition, the low operating Reynolds numbers typical of small aircraft make it difficult to design a small vehicle with aerodynamic performance similar to its larger cousins. Small robotic aircraft, therefore, suffer both from reduced on-board energy capacity and from low aerodynamic performance. Together, these two factors greatly reduce the mission capabilities (and hence utility) of small robotic aircraft.
Large birds (such as hawks, vultures and eagles as well as sea birds such as pelicans and albatrosses) operate in a Reynolds number regime similar to that of small UAVs. They have developed flight techniques that exploit energy available in the atmosphere to remain aloft for several hours and fly hundreds of miles without flapping wings. Further, human sailplane pilots have developed soaring techniques that enable flights covering well over 2000 km without the use of engines. Soaring flight by small UAVs has the potential to significantly improve both range and endurance, and this has indeed been demonstrated by several research groups.
This presentation will present a (very) brief historic overview of soaring (the first intentional soaring flights were performed by Wilbur and Orville Wright in 1911) and discuss current progress in autonomous soaring flight. The main focus will be “static” soaring, where the aircraft exploits vertical air motion whose time scale is long compared with vehicle dynamics; however, there shall be some discussion of dynamic soaring.
It shall also describe the AutoSOAR platform and results of a flight test campaign at Aberdeen Proving Grounds that resulted in 7.8 hours flight time with the autonomous soaring system engaged, with three hours spent climbing in thermals. Several climbs of greater than 1000m occurred, with many shorter climbs. The presentation will also discuss observations of soaring birds: vulture and bald eagles were active during the test flights, and often flew in close proximity to the AutoSOAR aircraft.