It seems to me that you would set up whatever power required to cruise at
best L/D and that would necessarily give you best range. Brett



"JGalban via AviationKB.com" u32749@uwe wrote in message
news:79bea10122a88@uwe...
john wrote:

I don't have a 1974 POH, but I do have one for the 1978. It list the
green arc as 2200 - 2700, so as long as I keep it in the green I
should be alright. I'll check the 1974 POH next time I use that
plane, but I would be surprised if it is different since they have the
same engine.

That's simply the normal operating range. The POH will also have graphs
or tables that will give you power and fuel burn information for various
altitudes and temperatures. Use them.

I often hear pilots saying things like, "What rpm should I use for
cruise?
" and hardly ever hear the correct answer, which is : It depends. What
it
depends on is the amount of power you wish to generate, and the density
altitude at which you'll be flying. To make a given percentage of
power,
the rpm required will increase as the density altitude increases (in a
fixed
pitch plane like the 172). If you want to fly around at an economical
55%
power setting, the rpm you should set will be very different if you're
flying
low on a cold day, or high on a hot day.

Quick example : The rpm that I use in my Cherokee to fly 75% cruise at 6,
000 ft. on a hot day is very close to the rpm that I'd use to fly at 100%
power (not a good cruise setting) near sea level on a standard day.

John Galban=====N4BQ (PA28-180)

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