Methods for altitude changes

On Apr 7, 11:00 pm, "BT" wrote:
It depends on the situation, but for your specific example, of a 4 to
6 kft climb, I would increase power to max, then pitch (and trim) for
about 90 kts. If I had the mixture leaned, I would go to full rich
first (above 75% power, full rich is required for proper engine
cooling). 90 kts is faster than Vy for my Cherokee (about 72-74 kts),
but is recommended for cruise climb since it results in a lower nose
and better forward visibility, and also better engine cooling.

For Mr Fly Cherokee.

A full rich climb at those altitudes can result in lower performance. If
your POH engine manual dictates full rich above 75% power.. then I cannot
recommend against following that procedure.

However, At 5Kft MSL, on a hot day at full throttle are you really getting
75% power? The Density Altitude.. ohh.. that bugger we live with in the
west.. could be well above 8Kft MSL. 5K Pressure Altitude, 30C, = 7779
Density Altitude

If you find that climbing through 5Kft MSL your RPMs are dropping off, then
lean to max RPM for max performance of the engine and then bump it rich just
a tad.

BT

Yes, you are quite right, density altitude is the key parameter. I
have one of those ancient Cherokees with the pamphlet-style POH.
There's not a lot in there, but they do say full rich over 75% power,
which as I recall, is about 8 kft density altitude at full throttle.

In any event, I've always been a bit conservative when it comes to
leaning, I tend to err on the too-rich side, thinking that I'm helping
the engine.