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lutorm / N132EA

N132EA, LLC operations documents.
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Tune Aerocarb #41

Open lutorm opened 5 years ago

lutorm commented 5 years ago

While the current tuning gives about right fuel flow at full throttle/full rich, idle requires leaning so much that it's almost at cutoff and it's very hard to get the idle mixture set right. Try other needles to see if we can get this better.

lutorm commented 5 years ago

Reading about Jeff Schultz' custom-tapered needle, I think the proper sequence to perform this is:

  1. Determine desired fuel flows at different operating points in flight by leaning and looking at EGTs. We want WOT to be about as rich as it is now, but at lower cruise powers it would be good to have the default mixture be less adsurdly rich.
  2. On the ground, see how needle needs to be adjusted to get those fuel flows at the different throttle settings. There will likely not be a single needle setting that is good for all throttles.
  3. Determine what the optimal needle taper should be from the data just obtained.
  4. Start with a less tapered needle and modify it by grinding off material at the right points.

The properly tapered needle appears to not have a linear taper but a steepening taper as you get towards full throttle.