High altitude and battery life

[Rubik]

Has anyone noticed that the batteries drain faster at high altitude? It make sense because of the thinner air, the motors must work harder. I was flying yesterday at about 6300 ft elevation. TH still flew fine but not as long.

 

[PatR]

A brief article in this month's AOPA magazine talks about the effects of density altitude on an aircraft. Most pilots are aware of those effects but the short version is everything has to work harder at higher density altitudes. If you are standing at an elevation of 100' with the aircraft at an elevation 400' above you with an air temp of 90*, the temperature alone will cause a density altitude of much, much more than 500'. If the humidity is elevated the density altitude further increases. Although the altitude mentioned was 6300' the density altitude might have been well over 10,000'. Flight time would be reduced. The one area that has no impact on an electric multirotor is the power unit. Electric motors do not require oxygen mixed with fuel to sustain a combustion process. Instead they use a more efficient direct power conversion via electricity obtained from a battery. That does not change lift equations though.

I'll suggest researching "effects of density altitude on aircraft" for more depth of understanding. There's a lot of useful stuff there to know.

Density Altitude - AOPA
Density Altitude Calculator - English/Metric
Density altitude - Wikipedia

 

[Rubik]

A brief article in this month's AOPA magazine talks about the effects of density altitude on an aircraft. Most pilots are aware of those effects but the short version is everything has to work harder at higher density altitudes. If you are standing at an elevation of 100' with the aircraft at an elevation 400' above you with an air temp of 90*, the temperature alone will cause a density altitude of much, much more than 500'. If the humidity is elevated the density altitude further increases. Although the altitude mentioned was 6300' the density altitude might have been well over 10,000'. Flight time would be reduced. The one area that has no impact on an electric multirotor is the power unit. Electric motors do not require oxygen mixed with fuel to sustain a combustion process. Instead they use a more efficient direct power conversion via electricity obtained from a battery. That does not change lift equations though.

I'll suggest researching "effects of density altitude on aircraft" for more depth of understanding. There's a lot of useful stuff there to know.

Density Altitude - AOPA
Density Altitude Calculator - English/Metric
Density altitude - Wikipedia

Thanks Pat. Very interesting. That explains my shorter battery life. I wonder if some drones would be unable to fly at that altitude. I could hear the TH working harder than usual.
BTW, here's the video from that day of flying:

 

[BobW55]

Would be interesting to put the H in a vacuum chamber where you could simulate higher altitudes. Could safely find out just how thin the air would have to be and the H no longer able to fly.
When I was a Student Pilot, you had to have the density altitude calculation shown on you flight planner or they would not let you go up. Really wanted to make sure you had it embedded in your brain.

 

[Dr Delta]

There has been another thread about flying and taking off at even higher altitudes.

H does the job and battery consumption is of course high, just like temperatures on motors and battaries.