Excessive leaning does not damage the engines?
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Hello everyone,
two weeks into the most fun I have had with the simulator in years due to the excellent Professional Series aircraft, I stumbled over an issue I'm not quite sure of if it's on purpose or not:
When I lean the engine down the very minimum, audible detonations set in. As far as I understood the matter, those must be avoided at all costs in real life because of the damage they cause on the cylinders and the engine as a whole. I therefore expected to see a direct impact on the engine's health status, but it looks like I cam fly with a detonating engine for hours without any impact on the engine status.
While I'm not a motor pilot in real life: Did I get something wrong here or is this just a nitpick that's not part of the engine simulation yet?
Best regards,
Mathias -
Curious if this will
Be fixed -
Real pilot here (albeit a student). The "detonations" that you hear when leaning excessively to the point of rough running are not "detonations" as such, but are actually cylinders being starved of fuel and not firing, while others still are. Even a really well tuned fuel injector setup will have some variation between the cylinders, so right before a total engine cut, that will happen. Running an engine like this isn't harmful to it, per se, but it's certainly not going to be happy running that way. I guess I don't really know if it would be harmful if left that way for a long time, as I don't think an actual pilot would ever leave their engine like that for long lol. It's actually how some people lean their engines, leaning to the point of roughness and then adding a little mixture. Hope this answers your question!
Some additional information: detonation happens in an engine when pressures and temps are excessively high and the engine is leaned to the point where there's just the right amount of fuel in the mixture to self-ignite prior to the spark plug sparking. The conditions required for this vary, but are typically above 65% power with high CHT's. The higher the % of power, the wider the band of potentially problematic mixtures is. The general advice is to be careful between 50 degrees ROP and 25 LOP when operating greater than 65% power.
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Thank you for the clarification. I got it that "How much leaning is good for your engine" is a battlefield since the Wright Brothers, but I thought there's a threshold where you simply run the engine too "dry".
At least in the sim, you get the best range out of combustion engines with the throttle full open and the mixture pulled out until the plane holds itself barely in the air. If there wouldn't be any downside on this, everybody would handle it that way for ferry flights instead of installing ferry tanks and sorts?
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Thank you for the clarification. I got it that "How much leaning is good for your engine" is a battlefield since the Wright Brothers, but I thought there's a threshold where you simply run the engine too "dry".
At least in the sim, you get the best range out of combustion engines with the throttle full open and the mixture pulled out until the plane holds itself barely in the air. If there wouldn't be any downside on this, everybody would handle it that way for ferry flights instead of installing ferry tanks and sorts?
@bocian I honestly have no idea what a ferry pilot would do in terms of leaning, but I assume that they'd likely run quite lean of peak, in addition to using ferry tanks. There is a point of diminishing returns where, if you lose too much speed over a long distance, it will actually cost you more fuel as the time it takes is much longer. I'm gonna look into it, as I'm interested now. I'm sure there are math people out there that can calculate that all out, but I'm not one of them.
Also, if you want a great video on leaning in general, check out this one by Martin Pauly: Lean of peak engine operation
