A good pilot is always learning -- how many times have you heard
this old standard throughout your flying career? There is no truer
statement in all of flying (well, with the possible exception of
"there are no old, bold pilots.") It's part of what makes aviation
so exciting for all of us... just when you think you've seen it
all, along comes a scenario you've never imagined.
Aero-News has called upon the expertise of Thomas P. Turner,
master CFI and all-around-good-guy, to bring our readers -- and us
-- daily tips to improve our skills as aviators, and as
representatives of the flying community. Some of them, you may have
heard before... but for each of us, there will also be something we
might never have considered before, or something that didn't
"stick" the way it should have the first time we memorized it for
the practical test.
It is our unabashed goal that "Aero-Tips" will help our readers
become better, safer pilots -- as well as introducing our
ground-bound readers to the concepts and principles that keep those
strange aluminum-and-composite contraptions in the air... and allow
them to soar magnificently through it.
Look for our daily Aero-Tips segments, coming each day to you
through the Aero-News Network. Suggestions for future Aero-Tips are
always welcome, as are additions or discussion of each day's tips.
Remember... when it comes to being good pilots, we're all in this
In Aero-Tips 1/8/06 we learned
that the peak, or highest Exhaust Gas Temperature (EGT) is the
benchmark for all mixture leaning. But how can we use this
Engine horsepower follows a predictable curve in relation to
EGT. Maximum, or peak horsepower occurs at about 80°F rich of
peak EGT. That is to say:
- Carefully lean the mixture until you arrive at peak EGT
- Note the exhaust gas temperature at this point (Note: the
precise temperature of EGT isn’t important; you’re
looking for a temperature difference relative to peak)
- Carefully enrichen the mixture (add fuel) until the EGT drops
about 80°F below that indicated at peak (Note: most standard
EGT gauges are marked in 25°F increments... the horsepower
curve is fairly flat at this point, so three lines, or 75°F
rich of peak EGT, is very close)
No EGT gauge? You can approximate the same mixture
setting in smooth flight by leaning for maximum rpm (with a
fixed-pitch propeller) or maximum indicated airspeed (with either
fixed-pitch or adjustable propellers). These methods, of course,
are less precise.
You’re now at the mixture setting that provides the
greatest horsepower for the manifold pressure and/or rpm you have
selected. This is the mixture setting to select for maximum
airspeed so long as it meets engine limitations, provides adequate
cylinder cooling, and results in an acceptable rate of fuel burn
for a specific flight. Many sources call this the “Best
Power” mixture setting, but it is “best” only if
it meets the criteria I just listed.
For more information see www.advancedpilot.com.
Aero-tip of the day: Know what’s meant by
a “peak horsepower” mixture setting, how to achieve it
in the airplane you fly, and when it makes sense for you.