Testing high altitude flying is very important to us, therefore we have tested drone in up to 10.25km altitude (33628ft in America).
Efficiency testing results are the following:
In 1km altitude: 22,4A at 14,8V = 331,5W for 13,1m/s climbrate
efficiency: 25,3W / m/s
In 5km altitude: 23,6A at...