LaGG; 7.5k; Mixture - need confirmation

[Yakdriver]

'Sup, good evening everyone.

In the OLD days...1946... i had to adjust my supercharger settings and my mixture settings myself.
Having flown a scarily beautiful, cold and almost lonely flight up to 7.5k, trying to hunt some Heinkel,

Campign, hard settings. Intercepted 3, and hurt 1 of them, and then i followed orders to stay in the area, and did so for another 20 minutes.

 

 

I have not experienced any need to manually adjust the mixture of the Klimov engine.

which at some point surprised me, as in the past i would get audible and visual clues such as shafty power output, RPM loss and incomplete fuel burn streaks.

 

Revs were choppy at that altitude, bouncing 50 up, 50 down and i was able to pull the mixture down to 8% before i noticed a significant drop.
Power output and speed seemed normal, but overall, the impression was that the engine drank as much fuel as at say 2k.

 

Can any of you "high altitude jockeys" confirm this?
If others have similar impressions about the subject, can this be submitted to the coders in charge of the subject?

I would be quite thankful for further input.

Bob

 

 

 

 

- i pulled a loop to 8k, and chopped the power, and somehow, with the temps already quite low , when nosing over i put the juice back on, somehow i killed the klimov because - i think- when i pulled the power the oil temps dropped below a critical point, and when i put it back on, lubrication was insufficient. Prop stopped. engine seized solid. FUUUUUU.
that was quite a thing... Temps seem to work really well there.
 

Edited November 3, 2014 by Hawker_Typhoon

[Descolada]

the klimov likes lots and lots of gas

 

you can pretty much leave it full rich until 7kish and be totally fine, and even there you dont have to lean it much

 

you can get more HP by leaning it before that, but you gain just as much by cooling it with the richer mixture and closing your radiators more

[Yakdriver]

Hmm... okay, i will need to try that.
Is there some sort of information, on when to start leaning out and how fast at different altitudes?
I am in flight again, and completely lost on how to properly treat this engine.

the supercharger thing has its own gauge, so i am not lost there, but for mixture... 

There is no clue on how to act at all.

 

wish i could have a manual from those who wrote this... :-/

[WhoCares]

I guess as long as the supercharger maintains a constant pressure at the air intake, the engine can burn the same amount of fuel, disregarding altitude (assuming same temperature). Once the manifold pressure drops with altitude, you have to lean the mixture to adjust; that's at least how I explain it to myself

[Yakdriver]

It's intriguing and much simpler compared to the "OLD" game where at 7k, i would probably be at 70 or even 60%Mixture.

 

I will try your suggestion... taking full pressure as 100%, and as it leans out, reduce mixture in parallel: 10% pressure drop=90%, 20%pressure drop=80%
But it amazes me on how high i can get without any critical "need" for action on my part.

It seems i got away with treating this engine in a very simplified way, and i did not break it - only potentially reducing my flight time.

 

 

 

 

 

love my Mule.

[chris455]

What was critical altitude for thr Klimov?

[Yakdriver]

well, wiki says 2000 meters for the first stage and 4000 meters for the second stage.
so... from then on i should lean out because the pressure drops, but how much, how fast? to what point?
How to properly treat this DOG of a plane?

[VBF-12_Snake9]

I did a test about 2 months ago with mixture and Russian fighters.  What I found.  There is no real performance increase no matter what the mixture is.  In fact, back then the exhaust flames always changed colors at exactly 87 % mixture.  Didn't matter if I was 2k or up to 6k.  Always changed color (red to blue) at exactly 87 %.  This was two months ago, so I would be interested in knowing if mixture is meaningful now.  It was clearly a place holder back then. 

[chris455]

Bob,

Ive got a book at home entitled "Allied Aircraft Piston Engines of WWII". Ill take a look at it and see if I can scare up the figures for critical altitude on the Klimov.

[chris455]

In the meantime, you,ll lean enough to maintain you power setting for whatever (cruise, climb or combat) you want the airplane to do. Above critical altitude, the supercharger will no longer be able to provide sea- level MAP, and your performance will decrease as altitude increases. Provided they have modelled all this.

[Yakdriver]

Those are the basics... i would VERY MUCH EXPECT them to.

I mean... O.o

meanwhile i found a bit of info on the 105 concerning how much Oomph i can expect at different altitudes.

http://chart-speed-aircraft.comxa.com/
and in particular the engine itself

http://chart-speed-aircraft.comxa.com/Aircraft_engines_USSR_1941-1945.html

 

just bagged a 111 an another damaged, but the intercept was at 4k, so i had less trouble with temps and mixtures...

 

 

[chris455]

You..................understand Russian? 

The chart looks like we're looking at 4 different engine configurations showing HP (horizontal) at Altitude in Kilometers (vertical)?

Am I reading this corrrectly? If so it appears the M-105IIA engine (yellow) had three supercharger speeds or stages?

Edited November 4, 2014 by chris455

[Yakdriver]

nah.

but the base engine is the 105, and that is the green line.
at 7k you get "nothing at all" out of all the variants :D

[VBF-12_Snake9]

Did some simple test for the lagg tonight. (since it seems the campaign xp is not working)  I tested the mixture effects at five different altitudes.  It seems they have adjusted things a little from last time. 

 

2000m flames always blue

3000m  flames changed red to blue at 96% mixture

4000m flames changed red to blue at 98% mixture

5000m flames changed red to blue at 78% mixture

6000m flames changed red to blue at 60% mixture

 

It is interesting to note that while the color of the flames changed at different altitudes, there was still no improvement in RPMs, Manifold pressure, or top speed.  So from a performance stand point there is no need to adjust the mixture from full rich.  Again this was the lagg I tested.  So unless you just like seeing the pretty colors of the flames, leave it at full mix.  I do not know if this effect was accurate in real life, but it is the way it is modeled currently in this game. 

[Yakdriver]

Salute snake!

I am intrigued - why do you think that the change of color matters?
I have not found bits of info around the flame colors.
What do they mean?

 

I understand that yellow/red flames are "full richness" or even "more than full richness" Mixture settings.
am i right?

and the blue flames appear when we start leaning out, and combustion is complete.

There are no unburnt fuel remains that come out of the engines, so no fuel is wasted when the flames are blue.

 

so much for the "red vs blue" colors?

lets start at the other extreme...
lemme take off at low mixture, see if i get that thing off the ground before rolling all the way to berlin in my takeoff attempt :D

[VBF-12_Snake9]

Well I'm not a technical person, but I know how to "game the game" I guess you say.     It's been a long assumption that to get the best performance up high out of a WWII plane was too find that point at which the flames change from red to blue.  That is your sweet spot, and you get the most out of the engine in that sweet spot.  In other games you could actually see a difference in RPMs and speed up high, (ROF being one) when you found that sweet spot.  You controlled your engine mixture better up high than your enemy and the fight was yours.  So it was a important tool in other WWII sims.  This one it seems not so much.   

 

Just tested the La5.  It's seems nothing has been done to this plane mixture wise.  It always changes at 88%. 

 

2000m flames changed red to blue at 88% mixture

3000m  flames changed red to blue at 88% mixture

4000m flames changed red to blue at 88% mixture

5000m flames changed red to blue at 88% mixture

6000m flames changed red to blue at 88% mixture

 

Again no performance increase by leaning mixture. 

Edited November 4, 2014 by VBF-12Snake9

[LukeFF]

I am intrigued - why do you think that the change of color matters? I have not found bits of info around the flame colors. What do they mean?

 

This is what the colors translate to: http://forum.il2sturmovik.com/topic/11436-those-exhaust-flashes/?do=findComment&comment=175586

 

So, bluish-purple is what you want to be seeing.

Edited November 4, 2014 by LukeFF

[[BTEAM]_Shifty_]

La5 doesn't need leaning. Apart from cruising fuel saving mode 

 

I've seen tests done ingame that show a better performance at optimal mixture as opposed to full rich. At 5km there is a difference on Lagg. Additionally optimal mixture is just BEFORE blue flames appear. Rule of thumb is you dont touch mixture setting until 4km.

[71st_AH_Cujo]

I believe you can't lean mixture to archive max rpm with constant speed propeller. You lean it to archive max speed. Orange/blue flame will give you best power while blue flame will give you best economy.

[WhoCares]

@snake: I think that's related to the different types of engines: in RoF we have engines with carburator, in BoS (most/all?) engines have an injection system.

With the carburator, going over-rich means you will have less oxygen in the combustion chamber. With less oxygen you will have a reduced power output.

With a (direct) injection engine you have a defined amount of oxygen in the chamber, but you vary the amount of injected fuel. With the defined amount of oxygen you burn the same amount of fuel, getting the same power output, disregarding whether you are over-rich or have the ideal (stoichiometric) mixture.

[Yakdriver]

This gets complicated... i am not a mechanic for engines.

 

 

 

With the carburator, going over-rich means you will have less oxygen in the combustion chamber. With less oxygen you will have a reduced power output.

less oxygen compared to fuel?
can i change that and say:
too much fuel for the available oxygen?

=bad mix; =red flames.

 

 

 

With a (direct) injection engine you have a defined amount of oxygen in the chamber, but you vary the amount of injected fuel. With the defined amount of oxygen you burn the same amount of fuel, getting the same power output,

 

i do not understand how you can get the same power output.
for low altitudes where the air is compressed to have the standard oxygen this is not a problem, i just let the compressor or turbo or supercharger do its job.

but i do not understand it at high altitudes, where the supercharger can not keep up.

 

less thin air+ insufficient compression = less air density.
=less oxygen to burn in the chamber.

when the defined amount of oxygen is less, how can the same amount of fuel be injected to get standard power output?

 

I understand some basics that say:
less air density, less oxygen

less oxygen, need to inject less fuel to have a mix that burns well/effectively.

 

How can that bring the same Power output?

I understand that an effective mixture brings the best possible power output for the altitude that the engine is at, but not necessarily the best power output at sea level?

 

 

I apologize for my lack of expertise.
Ah and by the way... this discussion can also contribute to Yak pilots...
It was a very similar engine
 

[Brano]

You..................understand Russian? 

The chart looks like we're looking at 4 different engine configurations showing HP (horizontal) at Altitude in Kilometers (vertical)?

Am I reading this corrrectly? If so it appears the M-105IIA engine (yellow) had three supercharger speeds or stages?

 

I will correct you.It is M105PA engine and it was specially built and tuned for bombers (Pe2,Pe8...) and had better high altitude performance then 105PF we have in LaGG3/Yak3/Pe2. They stopped to produce PA version simply because of reducing variants and focus mass production for low altitude PF engines.As airwar was seldomly fought over 3-4km. 

When climbing with M105PF over 4km,you will only lose power.By leaning mixture you will not gain power,you will only economise your cruise and help not to overcool engine with rich mixture.

[Yakdriver]

oh yes, good point...
temperature...

efficient mixture= high temperature.
inefficient mixture= low temperature [only minor difference maybe, but an important factor for properly manipulating the engine]

Thank you!

[Brano]

One more point: M105 engines had Altitude corrector device installed (You can find such lever at least on Yak with description высотны корректор) This device was supposed to be switched on at altitudes above 4km,where supercharger stage 2 was at its max output.Altitude corrector was responsible to keep mixture in ideal ratio.For now it looks like it is automaticly switched on by game itself.In real life it had to be manualy switched by pilot himself.But that must be confirmed by devs.

[Yakdriver]

and this is how you learn russian.
i found the same thing on the top of the label of the LaGG trim tab.

The top part of the label is usually the name or title. below that come the instructions on how to use.

высотны means something like "control" [actuator, button, lever, wheel...]

 

BoS is good for your education

but i did not find something with the exact same name to regulate mixture above 4000m

Edited November 4, 2014 by Hawker_Typhoon

[=LD=Penshoon]

Remember that best mixture settings vary with throttle position.

For the Yak; 100% mixture is fine at 100% throttle under ~3000m altitude.

 

If you lower the throttle to say 30% you also have to lower mixture to keep the flame the same colour.

 

Sit on the runway with engine idle, set mixture to best power so the flames turn blue-orange and then start opening the throttle  You will see the flames again turn bright orange as you now running enriched setting instead. 

 

It's fun to play with but the actual performance gain I have no idea about. I just like the look of the blue-orange flames more 

[chris455]

Thank you for the clarification, Brano!

[Yakdriver]

 

It's fun to play with but the actual performance gain I have no idea about. I just like the look of the blue-orange flames more 

 

i see it more from a Pilot's PoV trying to use the engine "right" in order to extend flying time and increase engine life as a secondary element.

eventually, some day i will need to use this engine in a yak to escort an IL-4, or fly one myself for several hundred kilometers, and at more than 4k too.

 

and then, properly leaning out the mixture could be important, hence it is worth checking if these things work properly, right from the start.

 

so far i retain:

- get some info on the engine itself by googling.

- mixture is optimal at the stage where red and blue flames change, as snake helped to point out. No internal indicator exists, need to stick the head out the window.

- over-rich mixture, especially at high altitudes is a bad idea, as temperatures come into play. need to watch the temps and adjust the radiator flaps.

 

The only element i am not happy with is that there is no  real clue inside the cockpit that tells you to go and change mixture.

At 6/7k it is awfully cold outside.

 

But okay, this works, mystery solved!

thank you all for playing along and learning as we go!

Edited November 4, 2014 by Hawker_Typhoon

[Brano]

I have to correct myself a bit,as my statement about 105PA engine was not very clear.Those special versions were called 105R and 105RA and were bomber versions of their respective 105P and 105PA counterparts with specially reduced gear ratio for propeller.And Pe8 had A.Mikulin engine.

That is what happens when you write on forum during meeting at work

Difference between PA and PF version was manifold pressure increase from 910 to 1050 mmHg (1.2 to 1.38 ata)

 

@Hawker,on your ingame screen it is trim for elevator up/down (rul vysoti vverch/vniz)) and of rudder right/left (rul povorota vpravo/vlevo)

[Yakdriver]

i have a lot to  learn i see! :D

[chris455]

Bob, engine RPM is your indication.

Wheen engine speed falls with altitude, lean. I hear you on the exhaust color, but Ill bet if you continuouslu lean to strive for max RPM (for yout throttle setting) your exhaust will be an additional confirmation that your mixture setting is optimal. Your primary imdicator remains your tachometer.

[Brano]

Well,in fact it is simple.For LaGG3 or Yak1 you should not touch mixture lever up to 4000m.This is height to which supercharger (at 2nd stage) can keep enough air coming into engine with best fuel to air ratio.This is what your mechanics would setup for you on the ground (each engine can bit a bit different)

You only start playing with mixture (or vysotni korrektor) from 4000m and up.As in this altitude even supercharger at 2nd stage is not able to sustain enough air intake and you must adapt amount of fuel accordingly.

 

With La5 supercharger should work up to 5000m.From there up you start playing with mixture.

 

If it is implemented like this,only devs know.

[Yakdriver]

getting there... i think.

tacho below 2.7: over rich(red flames). need to lean out to get max RPM

tacho at 2.7: rich (yellow flames) max RPM - but ineffective combustion

tacho at 2.7(blue flames zone): effective combustion, best use of injected fuel

 

 

here at around 35% mixture, full PP, full manifold

 

what is also interesting, is that the flames change color from removing power - temporarily, for a few seconds - but then adjust to going back to blue.

Damn... i barely understand the basics, that i find phenomena i do not understand.

 

No - no confusion.

hold on.(major mental effort :D )

Pulling back on the power= manifold pressure drop= RPM drop = less dense air at same injection.
Result= higher richness= yellow flames

 

...till the RPM's adjust to 2700 again(dictated by prop pitch lever), and the process reverses.

 

 

Till the russkis get their Stuff together and sort out the XP trouble, this is a way to learn the plane.

Edited November 4, 2014 by Hawker_Typhoon

[Yakdriver]

Some might be laughing, but in the old day on the finland(leningrad) map, i took part in a navigation challenge flying a P-39N from Leningrad all the way West to some god-forsaken airfield in Finland.

 

 

That took well over the 1h20 endurance, and had i not flown at high altitude  and played the mixture game, i would not have been the winner.

Edited November 4, 2014 by Hawker_Typhoon

[Nonolem]

and this is how you learn russian.

i found the same thing on the top of the label of the LaGG trim tab.

The top part of the label is usually the name or title. below that come the instructions on how to use.

высотны means something like "control" [actuator, button, lever, wheel...]

 

BoS is good for your education

 

but i did not find something with the exact same name to regulate mixture above 4000m

 

 

It's not "высотны" (vissotny), it's "высоты" (vissoty), which I understand as "altitude", but my russian is very poor...

[Yakdriver]

altitude or attitude?
trim=attitude adjustment?

[Nonolem]

Altitude, or height. Maybe to be understood as "height adjustment", or "elevation adjustment", because this is the elevator trim.

[chris455]

Bob, question: Are the Russian superchargers automatic or manual? If automatic, are they engaing properly? Curious.

[Yakdriver]

'sup, Chris!

manual, and working as expected at the altitudes indicated on wikipedia.
*thumbs up*

[chris455]

That is good news.

I don't fly Russian rides.................but someday I just might!