It seems like sometimes that is the only way to keep that 150/152 in
the air and flying faster than 85kts. I would suggest you consult the
POH for your particular aircraft. Most manufacturers don't recommend
more than 75% power now that is not the same as 75% of your rpm which
would for your normal small trainer would be like 1850 rpm which is not
correct by any means. To answer another of your questions yes the
engines are designed for that higher rpm because they do often turn
2300-2400 rpm in curise for long periods. Another consideration
especially if you are borrowing/renting an airplanes is what the
owner's wishes are for operations. They may request a lower cruise
power setting such as 65% or 55% to help prolong engine life.
Truthfully in my experience though this really doesn't help the motor
all that much and proper leaning techniques are much more important.
Good luck to you.
Matt tiberii
Comm ASEL ASES AMEL
CFI CFII
Mxsmanic wrote:
Is it normal to have throttles set to the maximum during cruise, in
small aircraft? I always set them all the way forward because that
seems to get the best speed, and the engine parameters still stay in
the green areas, but I don't know if this is actually a good idea.
Obviously it would be a bad idea in a car, but perhaps aircraft
engines are specifically designed (?) to operate mainly at full
throttle during cruise.

In other phases of flight I use other settings: always full throttle
for take-off (the manual said so), and low settings or idle to
descend. Also if I'm not in a rush I use lower throttle settings at
cruise, as long as I (or the autopilot) don't have to keep the nose
too high to maintain altitude.

So what is the deal? Is it okay to run for several hours at full
throttle?

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