On 18-Aug-2003, "Wayne" wrote:

Still a little weired out about the CS prop though. Read what I could
find and it seems like everyone I talk to has a different opinion on what
is right and wrong. Some say climb at 24MP and 2400 RPM prop. Cruise at 23
squared. The teach has a red area marked and is noted that you shouldn't
run in that range for an extended period, it's around 1700-2000 RPM's I
think.
What's up with that? Vibration? Harmonics? I was also told to use full
prop if under 100MPH or under 15MP. Can anyone enlighten me on this?


The STC covering the engine change should have included a supplement for the
POH (actually, it's probably an "Owner's Manual" on an old Cessna). This
supplement should include a new set of performance charts that allow you to
figure, among other things, percentage of power at given MP/RPM settings.
Which to use? Well, for TO and max performance climb the prop should be at
max RPM. The prop control should also be put full forward after you retard
the throttle to land. (Do it earlier in the pattern and the sudden increase
in engine speed will likely give a start to your passengers.)

For cruise, any recommended MP/RPM combination is fine. You may find that
the engine runs smoother at some settings than at others. Of course, you
should avoid RPM settings in the red arc, which may cause excessive
sympathetic vibrations.

You have probably already been instructed that, in making power changes that
involve both throttle and prop controls, you should pull back on the
throttle first (for reducing power) and push forward on the prop control
first (for increasing power).

-Elliott Drucker