Leaning for density altitude

[Ragsf15e]

1 hour ago, midlifeflyer said:

I didn't say "climb." I said I wanted manual confirmation that have best power for "takeoff." I should have been clearer. You are right about extended climb. The altitude and hence the requirements are changing and maintains target EGT is a bit better than guestmating.

But I am not willing to bet on the numbers for takeoff at Key West automatically applying for takeoff at Leadville. I want to see it and feel it. I can be a Luddite about some things.

Fair enough.  Nothing wrong with a full power runup.  Just be careful that it’s rich enough.  It’s pretty easy to get the “maximum power” part close, but you actually need to be richer than that.  At least enough to keep chts under control.

 The target egt works surprisingly well for a large range of density altitude although I haven’t tried Leadville.

[mike_elliott]

3 minutes ago, Ragsf15e said:

Fair enough.  Nothing wrong with a full power runup.  Just be careful that it’s rich enough.  It’s pretty easy to get the “maximum power” part close, but you actually need to be richer than that.  At least enough to keep chts under control.

 The target egt works surprisingly well for a large range of density altitude although I haven’t tried Leadville.

The higher DA of Leadville typically will be compensated by the target EGT reduction of fuel to keep the Air/fuel the same as best power Air/fuel as at sea level. This doesnt mean it is the same power, however, just same A/F ratio. Mark pointed to Walter Atkinsons' (RIP) advanced pilot seminar brief on this very point. The wing is a different matter.

[Rusty Pilot]

1 hour ago, Missile=Awesome said:

Hey Rusty,

You really should invest (I just sold an edm700 for $500) in a multi probe engine monitor.  The cylinder temps and egt’s And lean features are worth the price of admission.  Once probes are installed you can likely reuse for a “latest and greatest” at a later date.  You will NOT like flying without one once you have one.  I consider them “basic” for today’s flying.  I paid like $200 for a Gem 602 in my first plane.  NOT a big hit for a nice chunk of info.  GET ONE  

An JPI EDM is on the top of my improvement list and I plan to get one soon.  Still deciding which one to get whether I should step up to primary or not.

[midlifeflyer]

3 hours ago, Ragsf15e said:

Fair enough.  Nothing wrong with a full power runup.  Just be careful that it’s rich enough.  It’s pretty easy to get the “maximum power” part close, but you actually need to be richer than that.  At least enough to keep chts under control.

I'm pretty sure I said that in my earlier post on the method I used in Colorado for 20 years.

[EricJ]

17 hours ago, Ragsf15e said:

1. True.  However it only takes 1 takeoff at sea level, full rich.  Look at the egts.  IO-360 should be low 1200s if mixture is set up right.  I don’t know where a carb version falls.

2.  With respect, I think you’ve got it backwards.  Target egt is real good to keep max power balanced with CHTs as you climb.  You will have to lean slowly every 1,000’ or so as you climb to keep egt at your target.  Doesn’t have to be exact, just within about 20-50 and you’ll see consistent power and CHTs.  If you leave a target egt set in cruise, you’ll be overly rich.  Maybe 150-200 ROP as a guess.

My home field elevation is only 1500', and my typical full rich TO EGTs are in the 1230F range, so for a high DA takeoff (which one does pretty frequently in AZ), at the end of the runway I give it full throttle, adjust to about 1230F EGT and then release brakes.    Also as you say, climbing out I do the gradual pull back to keep it in about that EGT region.

Once in a while doing a run-up in high DA it won't even pass mag check at full rich.   That's a good reminder to pay attention to takeoff leaning.  This is also why I favor doing a run-up before every takeoff.
 

Edited September 10, 2020 by EricJ

[Ragsf15e]

6 hours ago, midlifeflyer said:

I'm pretty sure I said that in my earlier post on the method I used in Colorado for 20 years.

Ok, glad you got it under control!

[flyer338]

How about using fuel flow to set the mixture for a higher density altitude take-off? Then refining by the egt during climb. I generally cruise at altitudes where the max manifold pressure is 17-20 inches at 2400-2500 rpm. I do this because my electronic ignition (EIS 41000) provides maximum spark advance, and therefore potentially best effiency at 18 inches manifold pressure.

A recent example was a flight a week ago from KFOT to KVGT. Cruising altitude was 13,500 feet, DA was 16,400. We were at gross weight for take-off, TAS was 143 knots, and the fuel burn was 7.22 gph during cruise. The works out to 19.8 kmpg. It was actually better because I had a little bit of push from the wind.

[carusoam]

If I did the math correctly...

Brian got 22.8 mpg on his 143nm/hr flight.... (statute miles to compare with automobiles)

If I didn't get the math right...  I’m Only a PP, not a mathematician... 

Best regards,

-a-