leaning in climb

Thomas Borchert wrote:

1. We're talking density altitude here. So you might well be leaned during the
roll down the runway at 100 ft MSL elevation, if the temperature is high
enough. Not rare at all.

Density altitude cuts the other way as well. If you're flying in cold
weather on a clear day, 3,000 feet indicated altitude might not be that
far above sea level density altitude.

Some day, I'd like to get more information about how density altitude
and my engine interact. By the time the air hits my carb, it's likely
already been warmed up a fair bit, so air density at the carb is not
likely the same as the air density outside the plane.

2. It might make sense to lean even earlier when you want to maintain max
power. One advice given is: Keep the EGT where it was when it stabilized after
took off at full power. If you don't lean, EGT will decrease slowly with
altitude.

That's John Deakin's advice as well, and it seems to work. The only
extra consideration is that you want to keep EGT where it would be at a
sea level (DA) takeoff, not necessarily where it was at *this* takeoff.
It might be worth finding a low airport on a day with close-to-ISA
conditions, and actually marking the glass with a blue marker to show
where the needle ends up, though I haven't gone that far yet.

Again, the winter can be a problem, since a sea-level takeoff on a cold
day can put you far below sea level density altitude, and your starting
EGT may be on the high side.


All the best,


David

Matt wrote:
: Yes, I have been reading many great articles on avweb. Unfortunately, my
: 152 does not have EGT or CHT monitors, so I have to use the "listen, learn,
: and pray" method of leaning. I find it mentally difficult to reach over and
: start easing the mixture back with the throttle full forward.

Yeah, I would be too. One thing you might be able to do to "calibrate your
discomfort" would be to climb to an altitude where you cannot get more than 75%...
like 8000' or so. Verify your power at 75% cruise and lean to best power. Note the
mixture position. Linearly interpolate the mixture/altitude from that...

If it's your plane, I'd consider adding a cheapie CHT and EGT from Westach.
They're not that expense and it lets you have more real information on engine health.
Not really useful for cruise leaning, but good for a climb leaning and to verify
non-roasted engine CHTs.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

They probably assume that you have transitioned from Vx or Vy climb to
cruise climb by the time you reach 3000 ft. I do this transition as soon as
I hit pattern altitude.

"Matt" wrote in message
.. .
Hi everyone. I have a leaning question. The POH for my 152 says that the
mixture should be leaned to best power after passing 3000 feet in the
climb. However in other places in the POH (and the Lycoming site) they say
not to lean when at 75% power or higher in cruise. My question: Is the
engine developing less than 75% power during the climb; and is this why
leaning in the climb is OK? Does this guidance in the POH seem
contradictory to anyone except me?

Thanks for all your help.

Matt

Maybe a cht would help. I think the egt on a carburetor engine isn't much
help. I had a Westach 4 probe EGT on my C150 and found that it didn't help
any except to verify that standard look and listen method was working just
as well. I removed it to put a clock back in the hole. For sale if you
want to try it. BTW I did the Holly Run one year to Tangier Island and many
of the small planes with carburetors had to make the flight with carb heat.
I leaned the engine while using full heat. The engine went to TBO without
any burned valves.

Roger C-150E @ MD43


wrote in message
...
Matt wrote:
: Yes, I have been reading many great articles on avweb. Unfortunately,
my
: 152 does not have EGT or CHT monitors, so I have to use the "listen,
learn,
: and pray" method of leaning. I find it mentally difficult to reach over
and
: start easing the mixture back with the throttle full forward.

Yeah, I would be too. One thing you might be able to do to "calibrate
your
discomfort" would be to climb to an altitude where you cannot get more
than 75%...
like 8000' or so. Verify your power at 75% cruise and lean to best power.
Note the
mixture position. Linearly interpolate the mixture/altitude from that...


If it's your plane, I'd consider adding a cheapie CHT and EGT from
Westach.
They're not that expense and it lets you have more real information on
engine health.
Not really useful for cruise leaning, but good for a climb leaning and to
verify
non-roasted engine CHTs.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

I don't understand all this talk about leaning in the climb. Watch the
ball, use right rudder, and you get rid of all the lean. Problem solved.

Thomas Borchert wrote:


1. We're talking density altitude here. So you might well be leaned during the
roll down the runway at 100 ft MSL elevation, if the temperature is high
enough. Not rare at all.

You don't mean leaned here, you mean power-restricted.

For those of us who flew from 6000' airports, we leaned at engine
start and then set best power during the run up. We needed every
ounce of performance we could get to get 152's off the ground at
gross at 8000+ density altitudes.

OtisWinslow wrote:
My practice has always been to lean for highest rpm when I start the take
off roll. Then richen it up a couple hundred feet up when clearing something
is no longer a factor.


Actually, on most of the lycomings it's not necessary to screw with this
at all. Set the best power during your run up (at your magcheck rpm).
Climb at Wide Open Throttle. WOT lready adds extra fuel to maintain
engine cooling.

Roger wrote:
: Maybe a cht would help. I think the egt on a carburetor engine isn't much
: help. I had a Westach 4 probe EGT on my C150 and found that it didn't help
: any except to verify that standard look and listen method was working just
: as well. I removed it to put a clock back in the hole. For sale if you
: want to try it. BTW I did the Holly Run one year to Tangier Island and many
: of the small planes with carburetors had to make the flight with carb heat.
: I leaned the engine while using full heat. The engine went to TBO without
: any burned valves.

For cruise leaning, I'll pretty much agree. I put a 4-probe EGT on my PA-28,
but like you say, it generally just will verify that the lean&listen approach works
(or doesn't). One way you may may make it more useful is to play with the carb heat
trick of getting a more even air/fuel distribution. With my analog gauges that's not
really possible, but for a digital readout it may be more useful.

For the lean in a climb, I still think it's *quite* useful... even on carb'd
engines.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Roy Smith wrote:
: I don't understand all this talk about leaning in the climb. Watch the
: ball, use right rudder, and you get rid of all the lean. Problem solved.

Don't *DO* that... I about sprayed coffee all over my computer...

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

For the lean in a climb, I still think it's *quite* useful... even on carb'd
engines.


And priceless for troubleshooting.

--
Thomas Borchert (EDDH)