Originally Posted by Gary Lager
However, at constant IAS (ignoring compressibility at the intake), the mass flow will be the same, since:
air mass flow rate = Intake area x TAS x actual density = Intake area x IAS x sea level density
...therefore air mass flow rate at constant IAS is the same, regardless of actual air density, but drag is also constant at constant IAS (ignoring compressibility, again), so density plays no part.
Er, is it so?
The mass flow rate is proportional to density and TAS.
The aerodynamic forces, drag and lift are proportional to density and, at low Mach,
square of TAS.
So, climbing at constant IAS, the density should fall faster than the TAS increases. The mass flow should decrease.