rzbill

rzbill

Well Known Member
While I get mountain wind flying experience, my base at Asheville is not high enough to demand leaning on takeoff.

I have searched with a couple of different terms for high field takeoff leaning but I only found instructions to "lean to best RPM" which does nothing for me with a CS prop. Sorry if this is a rehash from missing a previous discussion on this.

Planning to go to ABQ for the balloon thing this year (plus other places), so I want to know how you CS guys lean for takeoff. Is it done during a runup procedure or during the roll as matter of acceleration "feel" and an eye on CHT after liftoff?
 
No difference with CS prop.

If the prop control is full forward (which it should be), it will remain at min pitch, making it essentially a fixed pitch prop. Run up to full power (which will be in the 75% power range at that altitude), and lean to best RPM. Some add a turn or 2 toward rich after that, but that is optional at those power settings.

My son built his RV7A when he lived in ABQ. He lived about 2 miles east of where the balloon fest is held. We could watch from his second floor porch.
Plan to get up at 4:30 am at least one morning to see the Dawn Patrol launch. Wear warm clothes :rolleyes:
 
Standard procedure works with C/S.

With the prop adjusted to "fine" pitch, during run-up, you will not have enough rpm to cause the prop to increase pitch. So you can still adjust the mixture for max rpm.

OOPS, looks like Dennis types faster than I do.
 
OK then. Done during runup procedure. Thanks for the tip. High altitude ramps must be clean (from the procedure) and every EAB hangar must have files in their tool boxes. :D
 
Additional note

Others have told you how to get close. All I have been able to do is get close. When you start your takeoff roll at full power, you can adjust the mixture as needed. I say as needed as I have at least once went to full power and did not get full RPM. (~2,500) I was too lean. Rotating the mixture in (richer) as RPM went up I accelerated better and reached full RPM. I rotated the mixture richer about a 1/2 to 1 turn more and continued to climb. Yes my carb equipped engine can run smooth lean of peak.

One time (actually more than once), I was too rich on my takeoff roll and had a slight miss. Rotating the mixture out or leaner, the engine smoothed out with a normal takeoff.

Summary: Be ready to adjust the mixture a little on your takeoff roll after attempting to set it as best you can in the run-up. If you flew your Phase I in the summer, you should have a good idea where the best mixture is for takeoff. I did my Phase I in Southern California during the hottest month of the year. I had to lean for taxi and ground operation during my Phase I.

IF you have concerns about making a small mixture adjustment on your takeoff roll, get an experienced RV pilot or CFI to ride along on a hot day.
 
I run up to about 1,800 rpm (no need for more) and adjust the mixture. With the prop set for max rpm, I lean past peak rpm. The tach starts to drop. Then I enrichen the mixture till the rpm peaks and then slightly drops after peaking.

After that, check the mags, check the carb heat, good to go.

Dave
 
Find out during climb.

Bill, you should lean your engine continuously during any climb. Note your EGT as soon as you lift off (mine's around 1325 F, 23 Gal/hr) and it'll go down as you climb..then lean it back to the same temp as at liftoff, and continue to maintain that EGT all the way to your cruise altitude, then lean for cruise. In the case of ABQ, look up it's altitude and on the way over, read your fuel flow as you pass ABQ's altitude as you climb to cruise altitude.

Now that you know what the fuel flow was on your GRT, set it there when you leave ABQ.

Best,
 
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Agree with Pierre...

figure out your target EGT for climb, then maintain that value for every takeoff you ever make from then on out.

This process needs to replace the "...push red knob in below 5,000 feet..." most of us learned as students
 
Small correction to Pierre's post:
If you are going to lean to a fuel flow, use Albuquerque's DENSITY altitude as a reference, not its true altitude. It can be pretty hot there. In hot/high situations I find I have to run rich of best power, to help keep CHTs down.
 
DGlaeser said:
If the prop control is full forward (which it should be), it will remain at min pitch, making it essentially a fixed pitch prop. Run up to full power (which will be in the 75% power range at that altitude), and lean to best RPM. Some add a turn or 2 toward rich after that, but that is optional at those power settings.

My son built his RV7A when he lived in ABQ. He lived about 2 miles east of where the balloon fest is held. We could watch from his second floor porch.
Plan to get up at 4:30 am at least one morning to see the Dawn Patrol launch. Wear warm clothes :rolleyes:
Click to expand...

This, of course assumes that the prop has the fine pitch stop set correctly, which may not always be the case.

Skylor
 
target EGT?

so is this target EGT right after wheels up or is it the max EGT seen on climb out before it starts dropping? I've been curious about that for a while ?
 
Lets get one thing straight. I am one of the LOP crazed zealots and I'm no chicken when it comes to the red knob.
Been running LOP and leaning on climb and I know what my T.O. EGTs and fuel flows are for my home base. I leave the red knob alone (already LOP) on decent and reduce power with the blue one. Have not experimented with the BMP on climb yet, but I have played with the BMP for finding peak from the lean side. Interestingly enough, I have not found a big difference searching from LOP or ROP on my chariot.

The experienced folks talking about the high altitude mixture setting runup technique, while bone simple, was educational to me. Fine tuning on the roll if needed seems to be a natural too.

Gary,
Yes, in phase 1 I had to do ground leaning really aggressively to keep the plugs clean. The need declined as I passed about 50 hrs although I still do it frequently as a matter of habit.

Pierre,
I was thinking about that. I'll pay closer attention to my common top of climb FF since it is frequently 5500 ft to get over the low ridge towards the hamburgers. Memory says its around 13 to 14 gph



SO..Carry ON! Drift at will. :D I like talking about this stuff.
 
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