DLR high altitude balloon launched experimental glider (HABLEG): System design, control and flight data analysis

In this paper the autopilot setup and the lessons learned from a successful balloon launched high altitude glider mission will be presented. Flying an unmanned aerial vehicle inside the stratosphere means operating it outside visual line of sight, in low pressures and cold temperatures. These environmental conditions pose many challenges to the UAV aerodynamic design, the autopilot system and the ground infrastructure. In May 2015 the HABLEG airplane was carried up to an altitude of 20km by a balloon. When the target altitude was reached it automatically transitioned to horizontal flight and landed back at the landing site where the balloon was released 145 minutes earlier. We will present and analyzed flight test result from every phase of the mission and summarize the lessons learned.