Leaning for Acro?

Discussion in 'Aerobatics' started by Ed Haywood, Sep 9, 2021.

  1. Ed Haywood

    Ed Haywood Line Up and Wait

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    Aircraft is Super Decathlon. I used to set to 25 squared. Lately have been setting to 2550 RPM and full throttle. Usual practice altitude is 3K-4K MSL.

    I have always flown acro full rich. Also always based at sea level.

    Wondering if I might lean for the sequence to get a little extra oomph on verticals?
     
    Last edited: Sep 9, 2021
  2. Greg Bockelman

    Greg Bockelman Touchdown! Greaser!

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    I am by no means an expert but I have two thoughts on this.

    Lean for the altitude you are at. You would get best power output that way. (I think.)

    Stay with full rich. You need all the cooling you can get.

    How is that for an ambiguous answer? LOL
     
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  3. AA5Bman

    AA5Bman Line Up and Wait

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    I have always wondered about mixture and engine settings for acrobatics, but I think you just answered one of my bigger questions: you must burn a crap ton of fuel when flying acro!
     
  4. brcase

    brcase Pattern Altitude

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    I don't do much acro, but my opinion is lean about 100 rich of peak for about your max altitude. As I recall Decathlons seem to run richer than I like anyway. Better is if you have a CHT guage, if you are keeping the CHT under about 380 you are probably fine were ever you lean it to.

    Brian
     
  5. RoscoeT

    RoscoeT Pattern Altitude

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    I wouldn't bother unless you're doing acro in Colorado. Cooling the cylinders as much as possible is a good thing.
     
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  6. RyanB

    RyanB Administrator Management Council Member PoA Supporter

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    Doesn’t the POH say to go full rich? When I did acro in a Super D, we were full rich the whole time.
     
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  7. benyflyguy

    benyflyguy En-Route

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    If your running hard why not wet. Not sure you’d see that much of a performance boost with leaning at 3-4K anyway right?
     
  8. djpacro

    djpacro Pre-takeoff checklist

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    From Lycoming's Aerobatic Engines Operating Manual: "Maintain mixture control in "Full Rich" position for rated take-off, climb and maximum cruise powers (above approximately 75%). However, during take-from high elevation airport or during climb, roughness or loss of power may result from over-richness. In such a case adjust mixture control only enough to obtain smooth operation not for economy."

    You're above 75% power so it is very clear.
     
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  9. foka4

    foka4 Pre-takeoff checklist

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    High power settings at low air speeds (climbs, up lines) are tough on cylinders. Full rich makes life a little easier on them.

    m