DLR HABLEG – High Altitude Balloon Launched Experimental Glider

The group Flying Robots at the DLR Institute of Robotics and Mechatronics in Oberpfaffenhofen conducts research on solar powered high altitude aircrafts. Due to the high altitude and the almost infinite mission duration, these platforms are also denoted as High Altitude Pseudo-Satellites (HAPS). This paper is about the design, building, integration and testing of a flying experimental platform for high altitudes. This unmanned aircraft, with a wingspan of 3 m and a mass of less than 10 kg, is meant to be launched as a glider from a high altitude balloon in 20 km altitude and shall investigate technologies for future large HAPS platforms. The aerodynamic requirements of high altitude flight were investigated and a design solution to allow for stable flight in the low-density atmosphere was derived. This includes the development of a launch method allowing for a safe transition to horizontal flight from free-fall with low control authority. Due to the harsh environmental conditions in the stratosphere, the integration of electronic components in the airframe is a major effort. Considering thermal suitability and the usage on future HAPS platforms, a concept of housing all major avionics in a single container was devised. For regulatory reasons a reliable and situation dependent flight termination system had to be implemented. A mission simulation and various system tests were developed and used for crew training as well as qualification of the system. Results of flight testing the aircraft will also be presented