G36 Engine Leaning

I don’t really hear the engines ping when I lean them so should I just lean until the fuel flow starts backing off?

The mixture modelling is not done correctly on any of the stock aircraft. You don’t see a fuel flow variation nor a cylinder head temperature and exhaust temperature change. So don’t worry. It just doesn’t work. Period.


I do see that if I back it off far enough then the fuel flow does start to decrease. Then I move it back up so that I’m just lean of peak. Is that just bogus?

I back it off until the fuel flow starts to drop, then slowly back watching the airspeed - yes that’s right, the airspeed. When that starts dropping I richen it slightly. Crazy behaviour although if you continue to lean the power starts to drop off, which is the normal point to stop and go back a bit. But then the speed has dropped back too.
At 2500/3500 feet fuel flow is around 9gph with this setting.

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In real life you look for exhaust and cylinder head temperature changes in the bonanza. In simple aircraft like the cessna 152 you reduce gradually until you see a slight rpm decrease then increase the mixture to recover the optimal rpm. None of this is simulated even in the slightest. I am more than happy to explain further if you want. Its super interesting my friend!!!


The reason why you monitor the cylinder head temperature and exhaust temperature is due to the increase in the burn temperature as you increase the air to fuel mixture. The leaner it is the hotter it will be. The pilot operating handbook POH will detailed the procedures for normal engine parameters. You monitor these parameters throughout flight especially when climbing and descending.

Sorry, I’ve had a few beers but I love aviation and I love flying. I’m actually doing a type rating in the socata tb20. All these aspects are incredibly important. I just wish they were simulated correctly. I recommend the justflight piper arrow. All these elements are quite well simulated. Bit of a cost but it’s excellent.


Yea that’s why I liked this stuff. I love those technical details. I wish they would model the physics better then we could really call this a simulator.

If I climb high enough in either of the Beechcraft planes the power goes way down. I have to pull the mixture to peak the fuel flow, that is how this was designed. Keep in mind, they had to make the sim easy enough for a child to play.

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Yeah, there is now a sufficient amount of payware GA piston aircraft that simulates leaning well enough not to fly any default stuff for me.

What’s your favourite? I’d like to buy a nice GA plane. The Justflight ones? Are they updated for SU5?

What I have resorted to in the default G36 is lean to set fuel flow to match flight planning tables… Not at all a realistic procedure (except maybe in climb) but at least the end result is reasonably realistic performance.

I would make sure your assist settings didn’t get changed during an update, because all of those changes do happen in the simulated G36. The only odd thing that happens when leaning is the inital increase in fuel flow.

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Yeah, the JustFlight ones are fully updated and are the best GA flying… Along with them, the FlySimWare’s Grumman Widgeon seaplane is one of the best. BlackBox Bird Dog is nice too, so is the Islander. A1R’s Ryan is also one of the most fun ones. DC Designs Stearman is fun as well!

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Leaning the JF Arrows isn’t realistic either.
I need to go down to less than 20% mixture in cruise altitude to get the fuel flow to match the numbers from thr POH.
You shouldn’t have to go that low - that’s where the mixture lock (which is at 40%) stops you from going lower.

As for the G36, if anyone has more insight to modify the behavior, contact the G36 mod people in the according thread. Input is welcome.
With the mod you should use the engine lean page to lean based on the EGT instead of the Fuel Flow.
But the engine pages only work with the G1000 legacy mod (0.4.1) so far.

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Thank you.

I have no assists on and maximum realism.

In the real world, leaning is a necessity. A single engine Cessna’s mixture knob has fine threads in order to get accurate control when leaning out the mixture. You bring back the red knob by 1st depressing the button in the centre of that red knob then pull it back bit by bit until RPM risess and cylinder head temperature (oil temp too) comes up and peaks. If you keep pulling back, the RPM gets lower, engine starts to run rough and cylinder head and oil temp comes up towards red line. At that point, push the mixture knob in about a quarter to half an inch and watch the RPM come back up, cylinder head/oil temp come down and engine runs smoothly. Then you turn the mixture knob counter clockwise (just like a screw), which brings the knob out very slowly. Watch the RPM, Cyl head and oil temp rise. As soon as the engine starts to run roughly, turn the mixture knob clockwise (it goes inward slowly) until the engine runs smoothly. Then turn the mixture knob clockwise slowly by a tiny amount until the cylinder head and oil temps are at the “cool edge” of hot. Your fuel flow will be optimised (fuel burn rate much slower than full rich). It takes practice and fine adjustments. The sim doesn’t portray this realistically, if at all, but it’s good practise.

EDIT: Don’t forget to push the mixture back in full rich when descending into an airport! Neglecting to do so will have dire consequences :hushed:


Exactly. This is not simulated correctly in the Sim.

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At what altitude was that? Using the latest JF Arrow III version (0.9.0) I had the following results at 7000 ft altitude:

  • 65% power at best economy (i.e. EGT at peak) => mixture lever at 42%
  • 2500 RPM
  • 22.8 inHg manifold pressure
  • fuel flow: somewhere between 10 -11 GPH (hard to read-out if you ask me)

The POH (I’m using the JF supplied data handbook) states 10.3 GPH, so it checks out.

The TAS does not check out though. At 7000 ft in standard atmosphere the air temperature is about 1 oC, this is in correspondence with the OAT gauge. According to the POH the TAS should be 131 kts, but I get 139 KTAS and 125 KIAS. The KTAS and KIAS are consistent, but the 139 kts itself is 8 kts too high.

I tried leaning until the airspeed started to drop, but by the time I got at 131 KTAS I had almost stopped the engine. The fuel flow was also very low. So something is off, but the leaning seems to work ok?

In what altitude and environmental conditions did you experience the mismatch in fuel flow?