About the thinner air... I regularly fly a hexacopter at 7500' (MSL here in the mountains).
With all other things being equal, the thinner air means you have to run the motors at much higher speeds to appreciate the same lift, and the resulting loss in battery life is pretty significant. The same configuration that gets a 30 minute flight a 1000' MSL will only do about 12 minutes at 7500'.
About the thinner air... I regularly fly a hexacopter at 7500' (MSL here in the mountains).
With all other things being equal, the thinner air means you have to run the motors at much higher speeds to appreciate the same lift, and the resulting loss in battery life is pretty significant. The same configuration that gets a 30 minute flight a 1000' MSL will only do about 12 minutes at 7500'.