The first test flight of the “SolarStratos” was successful. Test pilot Damian Hischier has flown at 7 minutes 300 m high. To the satisfaction of the pilot the flight ran perfectly and exactly after the planning of the “SolarStratos” team. The ultralight airplane has flown during the whole flying time solidly. Other tests are necessary at the flying time and height. In October, 2017 the pilot Raphëal Domjan already simulated an other test flight at 13000-m height in-55°C. The final flying time in the stratosphere is estimated currently at 5.5H.