Constant speed props

I think Deakin is worth reading, but some of what he says should be taken
with a grain of salt. His columns are mostly based on experiments with his
own highly modified Bonanza, a few high performance radial engines, and some
theory. In fact, a careful reading of his columns will show no test data for
the most common engine and propeller combinations in use today. The reasons
for this are fairly simple -- few airplanes have the instrumentation that
Deakin needs to test his theories. This is why Deakin's theories for running
lean of peak remain a minority view. Granted, it is a very noisy minority,
but remember that it is also a small minority. I think they have a point.
They may even be right. But they don't have nearly the evidence that they
think they have.

Deakin's remarks are mostly pertinent to running TCM engines, which are much
different than engines from other manufacturers. Not to put too fine a point
on it, some TCM engines are the only ones I know of that so consistently
develop cracks that the most part of an annual inspection basically consists
of measuring and cataloging the spread of these cracks. The engine used in
the early 70's Cessna T206 rarely made it to its 1400 hour TBO, for example.

Barring solid data to the contrary (and Deakin, remember, does not give you
solid data -- he only appears to do that), your airplane should be operated
in accordance with the manufacturer's recommendations. This will ensure that
you maintain your insurance coverage, if nothing else.

Keeping all that in mind, Deakin's columns are still probably the best
exposition on how to use a constant speed propeller. You will note right
away that everything is about power and performance. A fair number of people
think it is also about fuel economy, but that is at best a secondary
consideration. Fuel economy is a natural result of getting maximum power for
your fuel burn, but if that were really the goal there would be no
turbocharged engines.