Do you notice any effects when setting mixture to leaner ?....

[Pringliano]

I've really started to give good use to RoF.

 

On many occasions, and flying some of those beautifully represented ww1 warbirds, I really had to be careful with managing my engine(s) mixture(s) and it was remarkably evident.

 

In il.2 I am yet to be able to tell the difference, on aircraft that I think should be sensible to mixture adjustments like the LagG3, il-2 and Pe-2 ?

 

 

[303_Kwiatek]

Below 5 km don't see any difference in BOS in performance of russian fighters flying on rich mixture

Edited January 4, 2015 by Kwiatek

[Saurer]

Well cold air has a higher density than warm air so there is a lot more O2 in the same Volume if its cold compared to warm air.

Because of this the engines can handle a richer mixture.

[reve_etrange]

Do you notice any effects when setting mixture to leaner ?....

 

I know for sure the exhaust flame color can change from yellow to blue...but you mean performance I think.   

[GridiroN]

I've noticed the IL2 flies better with the mixture set to 90%. Otherwise, rich mixture seems to have little effect. Leaning it obviously loses power if it's too lean. 

[361fundahl]

Rich mixture (ratio less than stoichometric) is commonly used in performance combustion engine to keep cylinder temps down under high load and to a certain point increase torque. Too much under stoich ratio and you will have worse combustion and wash oil from cylinder walls. Low load scenario you can lean out without damage until you get too hot or not have proper combustion.

 

My spelling is probably wrong.

[SharpeXB]

Now that you can't lean that far out of the cockpit I can't tell what the flame colors are. Is there another indicator to look at and determine if your mixture is correct?

[FuriousMeow]

Now that you can't lean that far out of the cockpit I can't tell what the flame colors are. Is there another indicator to look at and determine if your mixture is correct?

 

Tachometer. You can lean or rich and watch the rpms on the tach. It does fluctuate based on mixture settings and altitude.

[1./KG4_Blackwolf]

Tachometer. You can lean or rich and watch the rpms on the tach. It does fluctuate based on mixture settings and altitude.

That's how we do it in ROF. Just read the tach.

[69th_chuter]

Rich mixture (ratio less than stoichometric) is commonly used in performance combustion engine to keep cylinder temps down under high load and to a certain point increase torque. Too much under stoich ratio and you will have worse combustion and wash oil from cylinder walls. Low load scenario you can lean out without damage until you get too hot or not have proper combustion.

 

My spelling is probably wrong.

 

Except on German carbless direct injection engines*, the pressure carburetors are located ahead of the superchargers and running rich increases the evaporation cooling effect during supercharger compression thus preventing detonation during overboosting.  Of course, once you're above the altitude you can overboost running rich is rather pointless, if not a serious problem due to fouling plugs.

 

*The BMW used an overboost fuel injector in the left hand supercharger intake trunk and early Jumo 213s had one in the supercharger inlet, but water injection was technically better in these applications.

[fjacobsen]

The requirement to lean the mixture as You climb holds true for normal aspirated piston engines.

As You climb the air becomes thinner i.e less dense. Therefore the mixture must be leaned.

 

The right mixture is when fuel and oxygen is mixed in a ratio where the burning of the mixture won´t leave any residual fuel or oxygen. This almost never happens.

When running rich, there is excess of fuel. Running lean all fuel is burned, but there will still be oxygen left in the exhaust.

 

Oxygen concentration is 21% at sea leve, although air contains 21% oxygen at all altitudes, low pressure at high altitude makes it feel like there is a lower percentage of oxygen.

 

Now add a supercharger and the density will remain the same until the altitude where it cannot longer keep up - called the critical altitude. Only from there leaning becomes necessary.

 

So if the critical altitude for the LA-5 is 5000m (15.000 ft) then leaning should not be necessary before reaching that altitude.

 

Normally full mixture is somewhat richer in order to make sure that the engine is properly cooled and to prevent detonation (when the air/fuel mixture ignites prematurely in the engine cycle.

Use full rich for takeoff and climb at high power settings, but reduce it (90% sounds right) for cruise altitude.

 

Since air temperature also affects the quotation, some slight adjustment of mixture settings will still be necessary at various altitudes.

The compression of the air by the supercharger, will increase the temperature of the engine inlet air. Hot air is less dense, which will require some mixture adjustment.

Either listen for engine roughness or look at the exhaust flames to get the mixture properly adjusted.

 

 

 

 

FinnJ

Edited January 5, 2015 by fjacobsen

[303_Kwiatek]

Yak-1 or LAg33 with M-105 PF engine had rated altitude at 2 gear of supercharger about  3 km then power rapidly decrases.

 

Other hand i wonder why Yak-1 in BOS still perform soo good at 5 km altitude.

 

For comparison M-105 PF at 5 km got 900 HP  against  1250 HP DB605A ( 1.3 Ata) and 1200 HP DB601E ( 1.3 Ata)   or 1300 HP ( 1.42 Ata).

[fjacobsen]

In reallife on a normal aspirated engine, leaning is not required below 5000 ft (1500m).

Adjusting the mixture below 5000 ft might still increase performance somewhat.

 

That means that if the Yak-1 /Lagg-3 would still perform well at 3000m + 1500m and as such not require alot of adjustment.

I´m not stating that the engine simulation in BOS is accurate, or that relative performance between aircrafts are correct.

 

If You come from FSX, then You should now that mixture requirement in FSX is much to exaggerated and I´m not even sure what effect supercharging has on engines there.

 

FinnJ

[SharpeXB]

Tachometer. You can lean or rich and watch the rpms on the tach. It does fluctuate based on mixture settings and altitude.

These planes have constant speed propellers. Do you see the RPMs vary with mixture? I'm familiar with the setting that way in RoF but figured this would be different.

In other sims I've used the Exuaust Temp Gauge or Fluel flow as a guide.

[Brano]

Critical altitude for m105PF is 4000m

Critical altitude for ASh 82 is 5000m

Mixture ratio of air/fuel is set by groundcrew on the ground.Up to critical altitude you do not play with mixture lever = thats the altitude to which supercharger on 2nd stage can keep set values for mixture.

Above critical altitude,you use mixture lever to lean fuel to match decreasing air density.Thats also why it is called vysotnyi korektor (height adjuster) in soviet engines.

EDIT

Does not work like that in game and I allready asked devs why in ''Question for developers'' thread with no answer.

Edited January 5, 2015 by Brano

[303_Kwiatek]

4 km was rated altitude for 105 PA engine.   For PF engine was exacly 2700m.

[Brano]

Supercharger at 2nd stage can keep compressing air max to 4000m.Above that altidude it loses its power and you start leaning fuel ratio to match decrease of air volume in mixture.

Edited January 5, 2015 by Brano

[303_Kwiatek]

PF engine start to losing power from 2700 m not from 4000m you are wrong here. Look at PF power curves comparing to older PA engine which start to losing power at 4 km. You just mix these two type of engines.  PF engine sacrifice higher alt power for more power at low alts.

[VBF-12_Snake9]

Just did some testing this afternoon.  Set up quick mission with lagg ( since that is what we fly most), and let Ai fly plane at 6500 meter indicated.  Max speed Ai reached with full mix, full prop pitch, open rads, super two, canapy closed was 403km/h.  Then I simply adjusted the mix and watched. 

 

403  mix 100%

404 mix 95%

405 mix 90%

406 mix 85%

407 mix 80%

408 mix 75%

408 mix 70%

408 mix 65%

408 mix 60%

407 mix 55%

406 mix 50%

405 mix 45%

404 mix 40%

403 mix 35%

 

So it seems since the last time I checked, a small performace boost has been introduced.  Proformance boost of 5km/h at 6500 meters.  So is it worth adjusting mixture?  That's up to you.  We lean the mixture just to save fuel.  We have noticed good fuel economy with lean mixture, so at least that's worth it. 

Edited January 5, 2015 by 12.OIAE_Snake9

[von_Greiff]

Just did some testing this afternoon.  Set up quick mission with lagg ( since that is what we fly most), and let Ai fly plane at 6500 meter indicated.  Max speed Ai reached with full mix, full prop pitch, open rads, super two, canapy closed was 403km/h.  Then I simply adjusted the mix and watched. 

 

403  mix 100%

404 mix 95%

405 mix 90%

406 mix 85%

407 mix 80%

408 mix 75%

408 mix 70%

408 mix 65%

408 mix 60%

407 mix 55%

406 mix 50%

405 mix 45%

404 mix 40%

403 mix 35%

 

So it seems since the last time I checked, a small performace boost has been introduced.  Proformance boost of 5km/h at 6500 meters.  So is it worth adjusting mixture?  That's up to you.  We lean the mixture just to save fuel.  We have noticed good fuel economy with lean mixture, so at least that's worth it. 

 

...so, "Kameraden",  and now tell me this ain't an good simulation already! Even they exhaust flame chances coulor depending on the mix...you take it all for garanted

 

yours

v.Greiff

[Brano]

PF engine start to losing power from 2700 m not from 4000m you are wrong here. Look at PF power curves comparing to older PA engine which start to losing power at 4 km. You just mix these two type of engines.  PF engine sacrifice higher alt power for more power at low alts.

I am not speaking about engine power but about supercharger.It can keep fuel/air mixture condition to that of ground level up to 4km at its 2nd stage.

[LeonMadDog]

Hi

This is my first post. I do not have BOS yet - but I can't find an active forum for older IL2 Ultimate Edition - and I find this forum very interesting. Cheers to 1C Company and the developers for making a great sim - better than CFS3 I think.

 

Snake9 has already shared what I wanted to share in this thread - but I will add my two bits anyway.

 

It is great fun and satisfying to run your own tests and make your own charts for each aircraft. Stall speeds, Mix charts, IAS/TAS ratio charts, bombing charts, finding min speeds for combat manouvers . . . and more.

 

With finding optimum Mix settings, if you have a Cylinder Head Temperature gauge, traditionally, you keep thinning until the temp reaches maximum, then you enrich slightly. But this is not practical in a combat situation. And many sim AC do not have CHT guage.

 

When performing test flights, set up scenario where the atmosphere temperature is mild - not hot or cold. Run trials at different altitudes and log your results.

 

In straight and level flight with speed settled given throttle setting - you then step the mix leaner until you notice a drop in power. If you find (by listening to the engine - and noticing the airspeed drop back a few knots) that the mix is say 60% . . . then set the official mix for that altitude to 80%. Now in cold conditions set the mix to 90% at that level. In hot conditions, set the mix to 70%, at that level.

 

This way, with a chart, you can easily and quickly set the mix to the correct setting, and take outside air temperature into account.

 

Cheers

[Brano]

La5 has CHT gauge as it has radial aircooled engine.By enriching mixture you can add to cooling effect (unburned fuel) and by leaning you can raise temperature of cylinder.Modeled in this game/sim.As for Fw,I do not know.Maybe others LW experts can tell.It had komandogeraet to do this mixture thing,so maybe it is not so important gauge in Fw.

[FuriousMeow]

These planes have constant speed propellers. Do you see the RPMs vary with mixture? I'm familiar with the setting that way in RoF but figured this would be different.

In other sims I've used the Exuaust Temp Gauge or Fluel flow as a guide.

 

Yes, I have seen RPMs vary with mix and altitude. Setting richer mix at higher alts causes RPM to drop a little - depending on plane's engine, alt and throttle settings. The props are CSP but the engines are still fed by fuel and air, so the RPMs will start to drop or rise or bounce a little depending on the fuel/air mix the same as the engine's MP.

[69th_chuter]

Just did some testing this afternoon.  Set up quick mission with lagg ( since that is what we fly most), and let Ai fly plane at 6500 meter indicated.  Max speed Ai reached with full mix, full prop pitch, open rads, super two, canapy closed was 403km/h.  Then I simply adjusted the mix and watched. 

 

403  mix 100%

404 mix 95%

405 mix 90%

406 mix 85%

407 mix 80%

408 mix 75%

408 mix 70%

408 mix 65%

408 mix 60%

407 mix 55%

406 mix 50%

405 mix 45%

404 mix 40%

403 mix 35%

 

So it seems since the last time I checked, a small performace boost has been introduced.  Proformance boost of 5km/h at 6500 meters.  So is it worth adjusting mixture?  That's up to you.  We lean the mixture just to save fuel.  We have noticed good fuel economy with lean mixture, so at least that's worth it. 

 

 

I find it very hard to believe that an aircraft would have a + or - of only 5 km/h across a mixture range of 65% at full power.  Actually, if a plane could get within 5 km/h of max speed at 100% I wouldn't expect it to run very well at all at 35%. 

Edited January 15, 2015 by chuter

[Brano]

"Temp.cilindra'' in russian.Recommended not to get over 210C

 

Edited January 15, 2015 by Brano

[indiaciki]

Is there an EGT?

[Brano]

Yes,you can notice that.But again,it all depends on your flight conditions.You fly straight,you dive,you climb, have cowl flaps inlet/outlet open/close etc.But definitely you can play with all of that to get engine conditions to where you want them.If you are clever

[indiaciki]

I noticed that effect caused by a supercarger flying

the seneca ll in x-plane.

[69th_chuter]

The requirement to lean the mixture as You climb holds true for normal aspirated piston engines.

As You climb the air becomes thinner i.e less dense. Therefore the mixture must be leaned.

 

The right mixture is when fuel and oxygen is mixed in a ratio where the burning of the mixture won´t leave any residual fuel or oxygen. This almost never happens.

When running rich, there is excess of fuel. Running lean all fuel is burned, but there will still be oxygen left in the exhaust.

 

Oxygen concentration is 21% at sea leve, although air contains 21% oxygen at all altitudes, low pressure at high altitude makes it feel like there is a lower percentage of oxygen.

 

Now add a supercharger and the density will remain the same until the altitude where it cannot longer keep up - called the critical altitude. Only from there leaning becomes necessary.

 

So if the critical altitude for the LA-5 is 5000m (15.000 ft) then leaning should not be necessary before reaching that altitude.

 

Normally full mixture is somewhat richer in order to make sure that the engine is properly cooled and to prevent detonation (when the air/fuel mixture ignites prematurely in the engine cycle.

Use full rich for takeoff and climb at high power settings, but reduce it (90% sounds right) for cruise altitude.

 

Since air temperature also affects the quotation, some slight adjustment of mixture settings will still be necessary at various altitudes.

The compression of the air by the supercharger, will increase the temperature of the engine inlet air. Hot air is less dense, which will require some mixture adjustment.

Either listen for engine roughness or look at the exhaust flames to get the mixture properly adjusted.

 

 

 

 

FinnJ

 

 

Actually, there's one more thing, throttle position.  As the throttle opens, largely regardless of ambient pressure, the atmospheric volume of flow through the venturi is going to draw more fuel.  So at various altitudes with different throttle settings* to maintain a specific manifold pressure** you're going to see various fuel flows.  This is essentially meaningless with American pressure carbs*** as they are self adjusting.  The pressure carb is brought up because the Brits adopted it rather quickly and I would assume the Russians were at least looking at it by 1943 as they were using and maintaining some in lend lease aircraft.

 

 

* I believe the DB variable supercharger drive is the only setup that will give you a consistent mixture setting during a good portion of climb due to fixed throttle position and stable manifold pressure.

** More of an issue with turbos but to some degree also effecting superchargers.

*** Basically just mechanical throttle body injectors.  Port injection was considered but simplicity and supercharger cooling effects won out. 

 

sideways --  Imagine a BMW without direct fuel injection and separate emergency power fuel injector upstream of the supercharger in the left intake trunk but, instead, a pressure carb feeding ALL the engines fuel into the supercharger.  It would ALWAYS be WEP - LOL.  That's the allied setup, minus the it-can't-be-too-much late-war water injection.