Unexpected Mixture Behavior at High Altitude (Grand Duke)
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I was cruising at FL260 yesterday and had some unexpected behavior with the mixture controls in the Grand Duke. Maybe this is just something I don't understand about how it is supposed to work. I had previously leaned the engines out and was trying to increase the mixture, but moving the mixture lever forwards caused a significant reduction in fuel flow and a reduction in RPM. Decreasing back down to approximately halfway achieved the greatest fuel flow, and then reducing it below halfway caused fuel flow to start dropping again (as expected). I would have expected that the highest fuel flow is achieved with the mixture lever full forward, as opposed to the highest fuel flow being somewhere in the middle. Am I misunderstanding something or is this a bug? This was in MSFS 2020.
I took a video of this behavior but not able to upload it here.
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A combustion engine is most efficient at a specific air/fuel ratio. The throttle setting that gives best power at sea level will not be optimal with the less dense air at a higher altitude.
Eventually the fuel flow will drop as engine rpm decreases with the too rich mixture.
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Got it. I see the section in the manual. Thanks.