Leaning at higher altitudes

On Sun, 15 Apr 2007 16:15:40 +0200, Mxsmanic
wrote:

Am I correct in assuming that changes to mixture diminish with increasing
altitude? That is, a mixture change is more important and larger when going
from sea level to 5000 feet than when going from 10000 to 15000 feet?

Depends.

If you're talking about the amount of fuel needed for optimal mixtu

Density of dry air in standard atmosphere decreases almost linearly at
the altitudes you mention.
Normalized to density at sea level the numbers a
S.L. 1.0
5000' 0.86
10000' 0.74
15000' 0.63
20000' 0.53

So the change from 0 to 5000 is marginally larger than 10k - 15k. They
both decrease about 15% *relatively* to the starting point.


But if you're talking about the amount of movement of the mixture
control, you may be right, at least for some aircraft.
182 that I fly requires about 1.5" of movement of the mixture lever
for SL to 5000' climb.
Climbing another 5000' to 10k requires much smaller adjustment.

This may be due to the way the control is implemented and may vary
between aircraft.

- Tom