Questions about density and being in the air

[Ariel24K]

How much lift do you think a helicopter could generate on the moon where the air density is zero?

Density is not a force, so it can't generate lift. Pressure, or rather pressure differences, generate lift. This is a force.

Chet

Ah sorry I got the density and pressure difference mixed up after reading the original post, thanks for clearing up

 

[Howardb]

Some people here are making this way too complicated. Air flow around helicopter blades is approximately incompressible. You can assume incompressible flow and get very close to the right aerodynamics, good enough unless you are actually designing a high performance helicopter blade, in which case you wouldn't be asking this question.

Incompressible means density doesn't change. Lift derives from the difference in pressure, in simple terms the Bernoulli equations with constant density (rho).
https://en.wikipedia.org/wiki/Bernoulli's_principle

Compressible flow occurs as the flow approaches the speed of sound, so don't worry about it, and it doesn't change one's understanding of the answer. For buoyancy to matter you need something the size of a blimp, not a blade.