From time to time, I get
into a discussion about how I operate my aircraft in the cruise
configuration.
Lycoming rated the IO-360-A1A at it's full 200hp, so
theoretically, you could keep the throttle firewalled the entire
time you're flying. Is that a great idea? Well, no, not
really. If you did that at lower altitudes, say below
4,000 feet, you'd just send money (aka fuel) through the
injectors at a faster rate with little to any performance
increase.
Take-off: After
rotation, I climb out at 100 mph until reaching pattern
altitude. I also pull the RPM back to about 2600 to help
cut back a little on the noise. Once at 1,000 ft agl, I
pitch the nose down a little and accelerate to 120 mph where I
will remain until I get to my final cruise altitude.
Cruise: On a normal
flight (i.e., when I
want to go somewhere), I won't touch the throttle between
the takeoff roll and descent to landing--it's full throttle the
whole time, with the ram air door open if conditions permit. Prop is usually
set at 2500 RPM; if I
really want a little more power I'll bump it up to 2600 RPM.
At 7,000 feet I see about 138 KIAS, which gives me 158-160 KTAS
depending on the outside temperatures and 10.5 gph fuel flow.
Sightseeing flights: If
I'm out for a simple joy ride and have nowhere to be in a hurry,
I like to cruise around at 19 squared (19" MP/1900 RPM).
This will yield about 120 KIAS on 5-6 gph fuel flow. Not
bad!!!
Always (always!) climb at max available
power and lean during the climb to keep your EGTs/CHTs about the same as
they were at
sea level, if desired.
Note: My aircraft has a
Hartzell 2-blade propeller that has a restriction on the RPM
settings. I cannot continuously operate the prop between
2100 and 2350 RPM. The 3-blade versions from Hartzell and
props made by McCauley have less restrictive operating limits,
but I find mine operates best between 2500 and 2600 RPM so I
don't really worry about it to much.
Best of luck and safe
flying!!
