Different air to fuel ratio indications in Pe-2 serie 35

[303_Bies]

In Pe-2 s.35 you set the mix according to air to fuel ratio indicators when 0.9 is optimal, rich <0.9, lean >0.9

I have noticed this values for 2 engines are different,

here i set both engines mix to 63% (techno chat),

left clock indicates 0.9

right clock indicates 0.86

 

I have noticed in the Pe-2 familiarisation video there is alco a difference (i.e. 5:45  )

 

In utmost positions (100% mixture techno chat) left engine have 7.2 when right 0.7.

It looks like there is something like auto compensations for torque? or something else?

Or i should set this ratio separately for two engines to achieve 0.9 ratio?

 

cheers

Edited July 20, 2018 by bies

[JimTM]

I ran the s35 on a quick mission summer map. At 100% mixture on both sides, I saw 0.84 (left) and 0.87 (right). I needed different mixture settings to get 0.90 on both engines.

 

I wonder if they are just modeling slight differences in response between individual engines.

Edited July 8, 2018 by JimTM

[LukeFF]

1 hour ago, JimTM said:

I wonder if they are just modeling slight differences in response between individual engines.

 

That would be my guess.

[Inkophile]

12 hours ago, bies said:

Or i should set this ratio separately for two engines to achieve 0.9 ratio?

 

You need to set it separately. Note thaet you can often gain a bit higher speed by running a tad rich (0.8 - 0.85). 0.9 tends to have the engines run quite hot in summer temps, even necessitating cutting RPM and throttle not to overheat.

 

I can only guess why specifically the series 35 is modeled like this, but I don't know enough about it or other multi-engine planes to say if it's warranted.

Edited July 9, 2018 by Inkoslav

[=TBAS=Sshadow14]

Most multi egine planes 1 engine runs harder than the other..

111, 88 also use upto 35l/h more on left engine.

This might help from my post in discord.

You can clearly see the ideal mixtures when flying planes like Pe2 35 Equipped with an A/F ration Gauge (Lamda) Using this i now often run
**Pe2 35 @ 80-85% mixture on deck at 20*C**
This gives me 0.85 - 0.90 Lamda @ 2700rpm (92mm Mani Press)
 

For the pe2 87 without Lamda Gauge i use what i have learned from the Pe2 35 and Add 5-10% Mixture for the increased power output. 92 versus 108 mani press)
**PE2 87 @ 90-95% Mixture on Deck at 20*c**
SHOULD be giving me 0.85 - 0.90 Lamda @ 2700rpm @ 108mm Mani press)**

Oh Also 111/88 Left engine runs richer.


Happy Flying.

Edited July 9, 2018 by =TBAS=Sshadow14

[303_Bies]

6 minutes ago, =TBAS=Sshadow14 said:

Most multi egine planes 1 engine runs harder than the other..

 

Yes, i was thinking about something like that, some explanation of different outputs.

It's fantastic developers care about such details.

Thanks for all answers.

[GridiroN]

Dual engine planes that do not have opposingly torqued engines like the P38  and Hs129 have the left engine as the critical engine meaning the right engine has less load as it is assisted by the torque of the engine to its left. 

 

I am impressed that is modelled though...

Edited July 18, 2018 by GridiroN

[FTC_Frederf]

Sometimes I see Pe-2-35 engines require different mixture for same alpha on instrument and sometimes the same. It seems oddly randomized. I think I only get engine differences for starts from stopped engines. When mission begins with engine turning they are always identical.

[=TBAS=Sshadow14]

They are not always the same for me..
Unless there is a bug (which im not claiming)

Then its probably just a case of wind and other factors acting on the engine.
If you are parked facing north and have a strong wind coming from the East then Right engine (in the wind) will run differently from the left engine (in the planes wind shadow)
Also if modeled some planes have extra things running off one of the engines. (like a 3rd charging circuit or a heater unit)