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John_Yossarian

A20 fuel mixture 'smoke point'

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Hi,


I may be wrong on this but currently the A20 mixture needs to be under 50% to not get the smoke effect, should there actually not be smoke when it is on auto-rich (around 66% or whatever it is).

 

My understanding is that auto-rich is the normal setting for flight, it seems odd to have to stick it somewhere between auto rich and auto lean in order to not have the 'bad mixture smoke' occuring.

 

Thanks for your time.

 

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17 minutes ago, John_Yossarian said:

Hi,


I may be wrong on this but currently the A20 mixture needs to be under 50% to not get the smoke effect, should there actually not be smoke when it is on auto-rich (around 66% or whatever it is).

 

My understanding is that auto-rich is the normal setting for flight, it seems odd to have to stick it somewhere between auto rich and auto lean in order to not have the 'bad mixture smoke' occuring.

 

Thanks for your time.

 

 

I think it may have to do with whatever atmosphere calculations are made according to the weather on the map.  I don't know if humidity is factored, but cold and snowy does effect mixture differently than hot and humid.

 

All planes seem to smoke more when pushing the upper limit of max continuous power when the mix is set to auto rich / run position.  

 

If you're pushing the max continuous / combat power line, I'd suggest backing off the manifold pressure and rpm settings a bit and using the opportunity to get well-trimmed aileron, elevator and rudder settings and tighten up the radiators a bit to compensate.  Besides, running with some amount of "headroom" and a few extra % of available power can be a good thing.  

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LOL Mobile, almost everybody runs just as fast as they can to not get caught, so they are going to have the exhaust smoke.  I try to keep it just under optimal operating limits and usually get rid of the exhaust

 

                                                                               ENGINE LIMITATIONS:

                                                                  RPM                    MP Stage 1/Stage 2

MAX LEAN CONTINUOUS                             1705                               27.5” / 30”

MAX RICH CONTINUOUS                              2300                               36” / 40”

TAKEOFF POWER (5 MIN LIMIT)                 2400                               45”

Hoss

 

 

 

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I've looked at external view and see that there are actually two smoke levels.

 

My mistake was that from the pilot seat I was thinking the 'lesser' smoke level was the 'heavy' one, it is indeed easy to avoid the heavy smoke as I don't run at full settings everywhere at all; the lesser smoke then cuts off at 50%. The 'lesser' smoke is not anywhere near as much of a thing for me to worry about.

 

I still thought however that the fuel mix was distinct settings rather than a gradient, as the guidance says:

 

Quote

- Engine is equipped with an automatic fuel mixture control which maintains optimal mixture if mixture lever is set to Auto Rich (66%) position. To use automatic mixture leaning to reduce fuel consumption during flight it is necessary to set mixture lever to Auto Lean (33%) position. In the case of mulfunction of the automatic mixture control the mixture lever should be set to Full Rich (100%) position. To stop the engine mixture lever should be set to the Cut Off (0%) position.

 

So as there is no 50% setting, I don't understand why the mix (represented by smoke) would change there.

 

Unless of course it is a gradual range somehow as well as distinct settings, but that seems odd, especially when it says if the 'auto' malfunctions it should be set to 100%

 

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1 hour ago, John_Yossarian said:

I've looked at external view and see that there are actually two smoke levels.

 

My mistake was that from the pilot seat I was thinking the 'lesser' smoke level was the 'heavy' one, it is indeed easy to avoid the heavy smoke as I don't run at full settings everywhere at all; the lesser smoke then cuts off at 50%. The 'lesser' smoke is not anywhere near as much of a thing for me to worry about.

 

I still thought however that the fuel mix was distinct settings rather than a gradient, as the guidance says:

 

 

So as there is no 50% setting, I don't understand why the mix (represented by smoke) would change there.

 

Unless of course it is a gradual range somehow as well as distinct settings, but that seems odd, especially when it says if the 'auto' malfunctions it should be set to 100%

 

Probably as soon as it goes below 50 it goes to Auto Lean

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8 hours ago, RedKestrel said:

Probably as soon as it goes below 50 it goes to Auto Lean

 

Yep thats my point: the simulated fuel mix, or the graphical display (or both) should align wiht the 33% and 66% settings, and more importantly the lever positions and what is said in the guidance.

 

 

 

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8 hours ago, RedKestrel said:

Probably as soon as it goes below 50 it goes to Auto Lean

I don't think it does that. from what I see it proportionally leans out the lamda between rich and lean mixture. The lighninghas the "smoke point" at full power ar 48% mxture. I don't know if the automixture in the real aircraft could be progressively set like that instead of just the discreete settings.

 

There are mixture levers that allow both, discrete settings and gradial, manual adjustment. In prop airliners, you have the mixture lever positions rich, lean and behind lean there is a section wher you can gradually lean further, indicated by tickmarks.

 

This manual leaning is only menaingful, as those propliners do have a torque meter. You can see how far you can lean the mixture by not going as far as torque doesnt drop. Leaning has no effect on MAP and rpm. Engine temp is only very indirect. Powerloss of the engine you only see in torque.

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Thanks for the detailed analysis of the problem, the engineers refactored the automatic mix and fixed it in the next version.

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From what I see this now works as 'expected' in single player, but when online, I still see that the faint engine smoke triggers on and off at 50%, I thought this would be impossible? I've seen this on a couple of different online maps.

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