Typical power settings during cruise and other phases of flight

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?

--
Transpose mxsmanic and gmail to reach me by e-mail.

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?

--
Transpose mxsmanic and gmail to reach me by e-mail.

Huck,

As others have pointed out, our little inquisitive friend is not
referring to real flight.

He's dealing with MSFS issues under the guise of being a pilot.

Don't waste the 1s and 0s ...

Jay Beckman
PP-ASEL
Chandler, AZ

you can set them anywhere you want, when you are sitting on a coach.

KC


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?

Mxsmanic wrote in
:

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?


At altitude in a normally aspirated engine, full throttle may not present
maximum engine power. As a sim guy, you probably don't need all the
details, and I'm not fully versed in the mechanics of it anyway. But
basically, as you climb, the air becomes less dense, and the amount of air
let into the system by the throttle is effectively reduced. The effective
result is that while the throttle is fully open, the amount of air getting
in is going down, as if you were very slowly closing the throttle.

From my experience with the planes that I fly, once you get up to 6500' or
so, the engine at full throttle will produce 75% power or less (less as
you go higher). Variance in temperature and pressure may have impact, but
that seems to be the "standard".

I have read that engine manufacturers actually do this on purpose because
they cannot precisely control how the air is restricted when the throttle
is partially closed, so it's best to run the engine with the throttle wide
open if possible (ie: if it will produce 75% power or less).

From what I have been taught, cruising at 75% power for an extended
period of time would be worse than partially restricting the airway with a
partiallly closed throttle, so if you're cruising at 2000', you probably
don't want the throttle wide open...

As a rule of thumb, that probably developed from just where I see the
majority of pilots fly is to run about 2400 RPM and about 23 to 24
inches of Manifold pressure for Cruise. Every pilot develops there
prefered Power Settings for each airplane as they fly them more, But as
a Rule of them this is a good starting spot for Non-Turbocharged
engines with Constant Speed Propellers.

Also note that the Manifold pressure will decrease with altitude, so
you will have to increase throttle as you climb to maintian the 23-24
inches.

Most Engines are Rated for 100% power for up to 5 minutes. So you
should make these settings within 5 minutes of applying full power.
Most pilots do it either immediatly after lift off with runway
remaining to land on, or after climbing out to a point where they
could glide back to the runway if the engine quit.

Don't know for sure if it is valid or not but it has been said that it
is more likely to have a power failure while changing engine settings.
Makes some since if you figure that some engine failures are caused by
Mechanical failures of the controls or by misuse of the controls by the
pilot.

Also some pilots will either reduce the RPM setting either before take
off or immedialty after lift off when the engine has a particalary high
RPM setting and large prop. They do this to reduce the amount of noise
made during the take-off if they really don't need 100% power.

Yes I understand you are flying a simulator, But Learning is Learning.

Brian
CFIIG/ASEL

Brian wrote
Most Engines are Rated for 100% power for up to 5 minutes.

Most non-turbocharged GA engines are rated for 100% rated
power continuously.

Bob Moore

Jay B wrote:
Huck,

As others have pointed out, our little inquisitive friend is not
referring to real flight.

He's dealing with MSFS issues under the guise of being a pilot.

Don't waste the 1s and 0s ...

Jay Beckman
PP-ASEL
Chandler, AZ


Why are you being such a snob? The question he posed is legitimate
whether it is for a simulator or a real airplane. And many simmers
eventually go on to become pilots so it is in our best interest to be
receptive.

Mxsmanic wrote:


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


It depends on what the POH says. Many engines restrict full power to a
few minutes, such as after takeoff or go-around. 75% power is the
typically used power setting for continuous operations. However,
rental aircraft are probably flown at full power all the time.

i have a thought or two about people who come here with questions after
playing with computer flying toys:

welcome!!

even if they pretend they're flying real planes i don't care. should we
really think the future of g.a. is riding his bicycle up to the fence
at the airfield whispering "golly" and "gee whiz" to skippy the frog in
his pocket????

also, when one of these guys asks a really dumb question some of us are
waiting for the answer with him 'cause we didn't want to look stupid
asking the same thing.

dan


Jay B wrote:
Huck,

As others have pointed out, our little inquisitive friend is not
referring to real flight.

He's dealing with MSFS issues under the guise of being a pilot.

Don't waste the 1s and 0s ...

Jay Beckman
PP-ASEL
Chandler, AZ