I fly standard quadcopters above 10,000ft ASL regularly. Soon I will be on a trip where I will be taking off from aronud 20,000ft. Increase prop size or pitch t

I fly standard quadcopters above 10,000ft ASL regularly. Soon I will be on a trip where I will be taking off from aronud 20,000ft. Increase prop size or pitch to compensate and you don't lose any thrust, but you do lose some efficiency, esp. if you go for higher pitch. On Erebus (~ 0.65 atm) I had about half my sea level battery life fully loaded. https://www.youtube.com/watch?v=gMh8kM4o6tk https://www.youtube.com/watch?v=gMh8kM4o6tk