Lean Of Peak

[awash2002]

I'm wondering if the IO-520-BB can run Lean Of Peak EGT or will it stutter and cough I'm thinking of trying running it at 22.6"MP and 2100 RPM Leaned to 9.6 gph fuel flow

[AKar]

A2A Bonanza simulation allows you to reach somewhat lean of peak mixture settings before it starts coughing. I've not taken note how far it is on the lean side at cruise power when it starts to run poorly.

-Esa

[Jarek]

For me right now it's next to impossible.
However I will not complain as it was not uncommon. Balanced injectors are the key factor here. In early implementations difference between individual cylinders could reach 1gph and more, and this caused engine to run rough so LOP operation was not recommended.
But we can still invent a common rail system for Bonanza

[awash2002]

Thanks for the info Akar But for right now I've decided to run it at 50 degrees ROP

[Oracle427]

This makes me think of a potential improvement suggestion for A2A. The engines lean out way too smoothly.When you go too lean they just quiet down and eventually die. In real life they start to misfire and shake a bit before going quiet if you continue to lean through that warning.

The real life misfiring behaves a lot like the fouled plug simulation when running on single mag during run up. Would it be possible to implement this in the future? I think it would give a more realistic leaning experience.

[AKar]

The real life misfiring behaves a lot like the fouled plug simulation when running on single mag during run up. Would it be possible to implement this in the future? I think it would give a more realistic leaning experience.

This is precisely the behavior I get with A2A.

Rough running engine is indicative of unbalanced mixture distribution which causes the cylinders' power output to drop unevenly when they pass their peaks. Well-balanced engine does indeed simply fade away with leaning the mixture beyond what can be ignited.

-Esa

[Oracle427]

Esa,

Do you get a smooth loss of power when slowly leaning to the point of shutdown with A2A?

I never see a rough running engine while flying when I lean the engine out. It only runs rough when on the ground at lower RPM.

Dave

[AKar]

Esa,

Do you get a smooth loss of power when slowly leaning to the point of shutdown with A2A?

I never see a rough running engine while flying when I lean the engine out. It only runs rough when on the ground at lower RPM.

Dave

No, I get the very same engine roughness effect that comes with fouled plugs or trying to advance the power with leaned mixture on ground. Of course, the engine loses some power before reaching that point, but subjectively, Bonanza starts coughing sooner than earlier GAs.

-Esa

[Oracle427]

Do you get this only with the Bonanza? I don't see this with the 172 or Cherokee.

[AKar]

Certainly with all the GAs, though it has been some time since I last tried either 172 or Cherokee - can't say if something has gone funny in recent update or something like that.

-Esa

[Caldemeyn]

I see this only with the bonanza, its very smooth, then there is a very small range where the tach starts jumping but engine still goes on and then with tiny bit more leaning its dead. The egt is quite close to peak there. The plane also loses so much airspeed that im not to keen on lop in this particular plane. But others very much

[AKar]

I need to try that if anything has been changed, but for each of the A2A GAs my to-go leaning technique has been to smoothly reduce the mixture until this coughing starts and then enrich just a bit, or as desired. It has definitely worked with every one of them. I think remembering the Cessnas in particular were noticeably on the lean side of the peak EGT by that time, enough so that I questioned by myself whether this rough running should occur at all to be realistic.

-Esa

[Caldemeyn]

In other planes there is ample warning before flame out, one sees the engine hesitating quite alot before it stops and they run lop quite nicely, even pipers this one though, it seems to me, likes to be rich ......(don't we all )
I lean the same way, to hesitation.

[ClipperLuna]

I've flown the Cherokee, Comanche, and Bonanza with all the latest updates and they all more-or-less do the same thing (though to different degrees of suddenness and subtleness) when I lean them. You get to a point, usually somewhere in the neighborhood of 50 degrees ROP give or take, where if you lean past that point you start to get a noticeable reduction in power. I see this most directly in the Cherokee as the engine RPMs start dropping. If I keep leaning, eventually I get to some point where the engine starts missing and the tach starts bobbing back-and-forth; kinda like a fouled plug. It runs smoothly between this rough spot and where the power loss is first noticeable, though. I *think* the range between where the roughness starts and the engine dies completely is smaller in the Bonanza, though I haven't compared them much to see.

[Oracle427]

Interesting, I'll try again when I get home...