Engine mixture guidelines

"Thomas Borchert" wrote in message
...
Newps,

No. Lean above 5000 as a general rule.


I would say 3000. But that's pretty much a matter of taste. What's
important is: we're talking density altitude!

--
Thomas Borchert (EDDH)

You are in agreement with the POHs for the C152 and Tomahawk, which are the
two that I recall at the moment. IIRC, that involved leaning to peak RPM at
full throttle--part throttle operation was another matter. One of them
specifically authorized 25 RPM lean of peak for reduced power operation,
such as transitioning at 60% power--which my rather old instructor refused
to believe even when shown!

Amusing but true. He was quite serious, and the same debate is still
raging--25 years later!!!

Peter

"Thomas Borchert" wrote in message
...
Lean the mixture until it peaks and then enrichen it
(turn it back in) until it drops 50°C.

Not necessary the best advice.

Remember FULL rich for takeoffs and landings unless your flying at
Leadville, CO or some other really high altitude airport.

That is actually VERY BAD and DANGEROUS advice! You will need to lean
for take-off at density altitudes of 3000 feet or above for max power.
Actual airport elevation is irrelevant in this discussion, density
altitude is all that matters.

--
Thomas Borchert (EDDH)

Ok confession time: I've never been PIC with a controllable prop.

3000 feet density altitude fits with 75% power in the POHs that I recall
reading for trainers with fixed pitch props.

OTOH, high power levels are available to a higher density altitude with a
controllable prop--consult the POH. If the POH is old, consult the engine
manufacturer.

(I really wish that I could say "consult an instructor or mechanic at the
local FBO" )

Peter

"Thomas Borchert" wrote in message
...
Matt,


I didn't say definitely not, just _probably_ not.


I still don't get it. Why "probably not"?

--
Thomas Borchert (EDDH)

I have put on my Great-what's-his-name turbin, inherited from the late
Johnny Carson; and I have read in the stars that one of you has a fixed
pitch prop and the other has a constant speed prop...

Peter

Peter,

OTOH, high power levels are available to a higher density altitude with a
controllable prop.


They are? How would that work? (flying a Tobago with CS prop)

--
Thomas Borchert (EDDH)

Peter Dohm wrote:



3000 feet density altitude fits with 75% power in the POHs that I recall
reading for trainers with fixed pitch props.

75% is available to about 8000 feet, depends on temp.



OTOH, high power levels are available to a higher density altitude with a
controllable prop--consult the POH.

Yes, indeed, consult the POH. The prop is irrelavant to the discussion
unless you've installed one hell of a cruise prop that just won't turn up.

Carnak

Peter Dohm wrote:

I have put on my Great-what's-his-name turbin, inherited from the late
Johnny Carson; and I have read in the stars that one of you has a fixed
pitch prop and the other has a constant speed prop...

"john smith" wrote in message
...
Carnak

Peter Dohm wrote:

I have put on my Great-what's-his-name turbin, inherited from the late
Johnny Carson; and I have read in the stars that one of you has a fixed
pitch prop and the other has a constant speed prop...



Thanks!

"Thomas Borchert" wrote in message
...
Peter,

OTOH, high power levels are available to a higher density altitude with
a
controllable prop.


They are? How would that work? (flying a Tobago with CS prop)

--
Thomas Borchert (EDDH)

Full RPM on a CS prop is usually higher than the fixed pitch prop will allow
under most conditions of flight--especially take off and climb.

Peter

Peter,

Full RPM on a CS prop is usually higher than the fixed pitch prop will allow
under most conditions of flight--especially take off and climb.


Does that mean higher engine power output or just better conversion of the
same engine output?

--
Thomas Borchert (EDDH)

"Thomas Borchert" wrote in message
...
Peter,

Full RPM on a CS prop is usually higher than the fixed pitch prop will
allow
under most conditions of flight--especially take off and climb.


Does that mean higher engine power output or just better conversion of the
same engine output?

--
Thomas Borchert (EDDH)

Higher power, presuming of course that you also have the throttle full
forward and similar induction systems, etc...

Peter