How much effect on speed should mixture have?

[JG4_Sputnik]

Since in the I-16 it has almost none.

Just tested it on 6000m, and autopilot, and 8x speed.

 

It doesn't matter what your setting is, as long as it is not under about 40 or something, full rich is always ok and has no influence on speed.

 

Is that something to be concerned about?

 

[LFL-EightyPLUS]

ive always been told to adjust mixture till blue flame come out. But im very curious to, about its effect on performance and speed...

[JG4_Sputnik]

Also; opening and closing oil and water coolers affect the very same gauge...

 

 

Is that correct? 

[Finkeren]

Opening the water radiator should do nothing on the I-16 since it doesn't have one.

[JG4_Sputnik]

I beg you pardon, inlet radiator and oil radiator I meant.

They both affect the oil temperature gauge?

 

But you can't affect the cylinder head temperature gauge?

 

Do you have some wisdom on the mixture as well?

Cheers

[DD_Arthur]

 

Do you have some wisdom on the mixture as well?

Cheers

 

Correct mixture on a petrol engine isn't really about speed but is important for fuel economy and very important for engine health.  Generally speaking, in a high performance engine an overly weak mixture will have a relatively immediate and drastic effect on your engine - total failure due to neat little holes being burned through the crown of the pistons - whilst an overly rich mixture - as well as excessive fuel usage - will eventually lead to valve seating problems over a rather longer time period.

 

An indication of an excessively weak mixture on something like the I-16 should be rapidly rising cylinder head temps.

 

Essentially, engine life will be shortened needlessly.

[-=PHX=-SuperEtendard]

In the I-16 the 100% mixture setting is automatic mode, less than that is manual. So at 95% or so I guess it would be in manual mode and being too rich for high altitude. An overly rich mixture would leave fuel unburnt or incompletely combusted, which afaik results in loss of power, in the old IL-2 when having too rich mixture it left a trail of smoke from the exhausts.

[Finkeren]

In the I-16 the 100% mixture setting is automatic mode, less than that is manual. So at 95% or so I guess it would be in manual mode and being too rich for high altitude. An overly rich mixture would leave fuel unburnt or incompletely combusted, which afaik results in loss of power, in the old IL-2 when having too rich mixture it left a trail of smoke from the exhausts.

Hey! That would make a lot of sense. Gotta try it out.

[JG4_Sputnik]

Thats a lot of info. Thanks!
Now, has anyone tried yet if this is correctly simulated in BoS?

As I've said, it doesn't affect speed. 

Or what do you mean by "loss of power"? Manifold pressure? But that would affect speed eventually.

So it's not correct, I assume`?

[xThrottle_Geek]

Try not to think of performance as strictly a measure of "power". Mixture relates to performance in the sense of efficiency affecting both fuel burn and engine wear. Mixture is a ratio of fuel to air in the combustion process. Different types of fuel reach peak efficiency at specific ratios. This matters little in your car because altitude generally changes very little (affecting the air density). Airplanes have adjustable mixtures because they are constantly experiencing changes in air density because of altitude changes. This requires a corresponding change in the fuel. Hope this helped.

[Willy__]

Now, has anyone tried yet if this is correctly simulated in BoS? As I've said, it doesn't affect speed.  Or what do you mean by "loss of power"? Manifold pressure? But that would affect speed eventually.

 

 

Loss of power -> Manifold pressure

 

IIRC someone tested the effect of different combination of mixtures, guess it was Snake or Stick from 12AOE, but I cant seem to find the topic. The different settings of mixture would result in aprox 2-10kph speed difference depending of the altitude.

 

Also, not setting your mixture corretly wont damage the engine ingame, so I do not think its simulated.

Edited April 22, 2017 by JAGER_Staiger

[ZachariasX]

 

 

Loss of power -> Manifold pressure

 

Burn efficiency of the mixture does not reflect on the manifold pressure at all. If you inject water instead of an overly rich mixture at high power settings (as normally). MAP doesn't change at all, but you do get a significant increase in power on the shaft.

 

It is important to know that manifold pressure is an indicator for power output, it is not power output iteslf; it just refelcts upon the amount of air pumped through the engine. It says nothing about what happens with this air.

[Field-Ops]

I dont think it would affect your speed in a straight line, more of climb ability due to being able to sustain higher RPMs with a more rich mixture. Correct me if i'm wrong.

[=TBAS=Sshadow14]

cylinder Head temps you control with Mixture mostly.

Also past a certain point 14.7:1 Stoich mixture adding more fuel will have no effect
 

It's Pretty simple concept

[JG4_Sputnik]

So where the community agrees (as far as I understand it) is:

 

1. right mixture does save fuel

2. right mixture does prevent cylinder heads from overheating

 

BUt:

 

- FieldOps says "mixture affects RPM" as well

- ZachariasX says "mixture doesnt affect Manifold Pressure at all"

- Shadows14 says "mixture affects power" (which means it has effect on Manifold Pressure and therefore speed as well, since ultimately: Power = Speed)

 

Or no?

 

Interesting topic. Has anyone the solution to the points above?

[Yakdriver]

There is just some missing parts of the puzzle as far as i can understand

if power is speed, then we need to know how exactly?

=======================
power is how fast prop spins, or is it how fast the prop accellerates?
how fast prop spins defines how fast the Rat runs?
=======================

[Nibbio]

oh, wow, a teachable moment...

Power is not speed, power is defined as the quantity of energy provided by the engine in a unit of time.

With this energy you can climb (and so increase the potential energy of the aircraft) or accelerate (increasing kinetic energy, hence speed).

All this through spinning the prop at faster speeds and/or higher incidence of the prop blades, but this is secondary, just a means to an end

[Finkeren]

There is just some missing parts of the puzzle as far as i can understand

 

if power is speed, then we need to know how exactly?

 

=======================

power is how fast prop spins, or is it how fast the prop accellerates?

how fast prop spins defines how fast the Rat runs?

=======================

No. Ultimately the "power" that moves an aircraft is measured as thrust - that is: How much air does the aircraft thrust backwards and how fast?

 

How fast the prop is turning is largely inconsequential. If the prop is turning fairly slowly but with a very coarse pitch, it still moves a lot of air backwards just as it does with a fine pitch where it rotates faster.

 

The question is how effectively can the engine, crankshaft and propeller transform the energy from combusting gasoline vapor into air moving backwards.

[JtD]

- FieldOps says "mixture affects RPM" as well

It doesn't. Not with a constant speed prop. The constant speed prop regulates rpm by adjustment of pitch.

- ZachariasX says "mixture doesnt affect Manifold Pressure at all"

True. Manifold pressure is just the pressure of whatever is about to enter the cylinders. On German aircraft with direct fuel injection, there's absolutely zero fuel in the air at this point. Manifold pressure is mainly a function of intake air pressure (i.e. altitude) and compressor rpm (i.e. engine rpm) and is regulated by the throttle.

- Shadows14 says "mixture affects power"

True, as can be seen in his chart. Over a large range of mixture the effect however is fairly small.

(which means it has effect on Manifold Pressure

No, why on earth would it have that?

and therefore speed as well, since ultimately: Power = Speed)

Changing power certainly effects speed, however, it's not a linear relation. At high speed, it's roughly speed = power³.

[Yakdriver]

Oh jesus
this is like flipping maths n physics.

i´ll stick to kick the tires light the fire first one to get shot down is a noob.

[Monostripezebra]

Now I need someone to explain to me why the yaks run so perfectly fine on 0% mixture and 0%prob pitch at around 300kph...

[Finkeren]

Now I need someone to explain to me why the yaks run so perfectly fine on 0% mixture and 0%prob pitch at around 300kph...

Presumably because the mixture control isn't the kind where you can lower the fuel content to 0% thereby starving it completely (on some engines you can) and because the engine runs just fine at lower rpm (remember: the rpm governor does not control rpm directly) The lower rpm will mostly be felt during climbing and maneuvering (your acceleration is going to be abysmal) But for level flight, the low rpm works just fine. 300kph is still pretty bad if you're running at full throttle.

Edited April 23, 2017 by Finkeren

[216th_Jordan]

Now I need someone to explain to me why the yaks run so perfectly fine on 0% mixture and 0%prob pitch at around 300kph...

 

Probably a bit like in the Mig. (I know it uses a different system with Automatic/Sea level and high alt modes) The mixture lever does not give a linear result and 0% is not 0% fuel for 100% air but 'just' the end of the scale. Just like idle throttle does not mean the engine gets no fuel.

[JG4_Sputnik]

Hmm thanks for all the info, so here we are as of now:

 

1. correct mixture does save fuel

2. correct mixture does prevent cylinder heads from overheating (which has an own gauge to be monitored)

3. correct mixture affects "power" (= acceleration & climbing)

 

-> Now the question is; how does one know if the mixture "is correct"? Blue flame?
 

 

 

 

A question remains (although it doesn't concern mixture);

 

Is it correct, that in the Rata, the inlet radiator and oil radiator both affect the oil temperature gauge?

Edited April 23, 2017 by JG4_Sputnik

[ZachariasX]

So where the community agrees (as far as I understand it) is:

 

1. right mixture does save fuel

2. right mixture does prevent cylinder heads from overheating

 

BUt:

 

- FieldOps says "mixture affects RPM" as well

- ZachariasX says "mixture doesnt affect Manifold Pressure at all"

- Shadows14 says "mixture affects power" (which means it has effect on Manifold Pressure and therefore speed as well, since ultimately: Power = Speed)

 

Or no?

 

Interesting topic. Has anyone the solution to the points above?

 

Ok, I try to be more detailed. In order to understand manifold pressure and power output, you have to understand in detail how a combustion engine works.

 

So, what is an internal combustion engine (an Allison/Merlin/etc.)?

- It is basically an air pump. It pumps the the displacement volume of air per cycle. For the Merlin, it's about 27 litres of air. Once an engine does that, the pressure in the tube from the carburator to the engine, the "manifold" is exactly the same as outside air pressure. (Your MAP dial is basically a barometer then.)

 

How to make an engine to produce power?

- Pour in the carburator exacty the amount of gasoline that make the stochiometric fuel rate corresponding to the amount of air. Graphs posted above shows the differences in burn efficiency according to deviation from optimal mixture.

 

-> Like this, the engine will operate at maximum fuel efficiency and at the full power that in turn is dependent on the air pressure and density of the ambient athmosphere. The fraction of fuel added always hast to match this for most efficient burn.

 

Why do I need a MAP gauge then, when all is set anyway?

- You are not always in need of full power. You want it to idle down. For this, you "choke" the air entering the engine by closing a valve in the carburetor. Like putting your finger on a hose. The starving engine now sucks more air than it can get, decreasing the air pressure in the tube (the manifold) between the closing valve (carburetor) and the engine.

 

-> Closing the throttle thus makes the needle on the manifold pressure dial drop. What does that show you? It shows you how nuch the engine is starving for air, not how mch air (in numbers of molecules) is actually going through it!

The air pressure in the manifold however shows you a metric that correlates in some useful way with the air actually transported through the engine.

 

Why use something imprecise?

- You could be more precise. You could measure the airflow inside the manifold. But compared to a simple pressure sensor, this would be silghtly overengeneered. The manifold pressure gives you most of what you need already. But it doesn't give you exact power output on the shaft.

 

=> It is of note that in all of that, you use the airflow to regulate the power output of the engine, NEVER the fuel flow! Fuel is just added according to air.

 

Ok, I'm lost now. Why does almost everyone above talk about mixture and the differences in power output and fuel ratio?

-> In a real world with a real engine made from real material, with increasing the power output, you run into problems. Although internal combustion engines are extremely efficient heaters, they are not so efficient in producing shaft power. This means, the higher your power output, the more heat you generate. On one side, you can dissipate this heat by cooling the engine (radiator), but you also have more heat in the burning process itself, meaning that locally chamber temperatures go up. Steel tolerates temperatures only to about 200°C before it loses strength (it doesn't melt at that point tough).

 

This translates into you having a temperature in the burn chamber that is too high and outside of the tolerable. Also, compression and temperature have effect on burn speed of the combustion process. The faster burn is with increasing temp and pressure, the more it "explodes instead of burns" and the more wear it puts on the piston, crankshaft, etc.

 

=> The result is, this excessive heat and fast burning puts an effective ceiling on what your engine can tolerate in power output. Bottom line is with increasing power production, you have to find a way to lower the burn temperature.

 

But you want more power, what can you do?

- You cool the burn process.

 

How so?

 

> Fuel vaporizing has a chilling effect. the more fuel you vaporize, the more you cool the engine. You still burn only the amount of fuel that is stoichiometric with the air you are pumping, so you’re basically wasting fuel for the simple process of cooling the burn process. Hence the engine will start to smoke a bit.

 

> Chill the burn. Add water. Liquid water vaporizing will deduct heat from the environment in the burning chamber. It has no effect on the burn process, but it allows to remain with an optimal, more lean mixture for burning your fuel. The difference in burn efficiency is unleashed on your crankshaft as soon as you inject water instead of “too much fuel”. If you are sitting in an aircraft featuring water injection, if you are at maximum MAP for takeoff and you toggle the water injection switch, all you notcice is a shorter takeoff run and increased power. The MAP gauge will not move if you toggle watter injection.

 

> Add carburant with a low vaporizing temperature, such as methanol. In itself, it carries less energy per weight, but adding it reduces burn temperature, enabling you to up power a bit again producing similar wear on the engine parts.

 

> Add NOS. With adding nitrous oxide, coming from a compressed container, once you release it at ambient pressure it will cool down drastically, cooling your mixture. On top of that, it also has “more air per volume” than regular air in the atmosphere, enabling you to add additional fuel (~20%) to burn that extra air (made possible by the lowered burn temperature) giving you that extra power.

 

=> It is of note again, that under none of these conditions for increased shaft power output, there was any change in manifold pressure, as you didn’t touch the carburetor settings at all! Remember, manifold pressure ONLY is affected by your setting of the carburetor setting. You had to flood your engine with petrol, such that combustion is significantly impaired to make the manifold pressure get lower.

 

The only way to increase manifold pressure is to open the throttle. How far that can go is dependent on the mixture temperature. Detonation sets a limit to your compression.

[ZachariasX]

-> Now the question is; how does one know if the mixture "is correct"? Blue flame?

 

 

The higher your power output (as mentioned above) the richer your mixture should be. In fact, if you wanted to make it correct, you had a manifold temperature gauge and you would increase mixture to the point where manifold temperature is tolerable again. As you are some degree overly rich, you have most likely a more yellow "cooler" flame as well as a smoke trail.

 

If you are at cruise settings, with lower rpm and power, you can lean up the mixture, most likely making the exhaustr flames more blue as you need not to additionally cool the manifold mixture before it is compressed in the piston.

 

How the devs meant the whitish or blue flame and yellow flames to be used as a "gauge", I don't know. Flame color would also be of gradual nature, not one or the other. It would be as gradual as you can adjust the fuel mixture.

 

Personally speaking, I find it utterly weird having to use the exhaust flame color as a gauge to set mixture on such engines. If you are running an engine outside of healthy parameters, you will hear that very clearly from any real engine. And you can react upon that as well. In the sim, at least from my speakers I don't get any cue like this. Just the technochat message that it is broken/dead now.

 

So I would not want to give advise on how you should keep your mixture, beyond "automatic" where possible.

[JG4_Sputnik]

Interesting read, thanks Zacharias.

 

So what you say is that one can't know how to adjust mixture in BoS -> this would be a serious flaw in my opinion!

And it's weird that nobody noticed that yet, since here are many people who know about this stuff and find every screw that is wrongly placed within minutes.

Even more so, that this affects almost all (?) Soviet planes...

 

I just talk about this since for the first time, I began to seriously fly Soviet planes with the Rata, normally I only fly blue and there's no mixture to adjust.

How can it be that nobody knows the answer of a fundamental part of Soviet aircraft?

 

 

 

 

Besides that, the question remains:

Is it correct, that in the Rata, the inlet radiator and oil radiator both affect the oil temperature gauge?

[JtD]

Yes. Since allowing air through the inlet will cool the entirety of the engine, including the oil, while the oil radiator will effect (almost) exclusively the oil. Bottom line, they both cool the oil.

[ZachariasX]

Interesting read, thanks Zacharias.

 

So what you say is that one can't know how to adjust mixture in BoS -> this would be a serious flaw in my opinion!

...[snipp]...

 

I don't see it as a flaw. It is nice to see a reaction when setting mixture. The thing I'm not sure is if I should take that flame color as *the* gauge to set my mixture.

 

AFAIR, Russian ground crew would set appropriate mixture for their pilots before take off if no auto mixture was available.

 

But there should be recommendations for settings somewhere.

[Nocke]

 

But there should be recommendations for settings somewhere.

There are, in the planes specification text. Not seeing them now, but for some Russian planes I remember it just says what has been said here already: Mixture at 100% is auto, except for the Mig, where auto is at 50%. Reduction is only necessary if you need to save fuel, especially at altitude.

[ZachariasX]

There are, in the planes specification text. Not seeing them now, but for some Russian planes I remember it just says what has been said here already: Mixture at 100% is auto, except for the Mig, where auto is at 50%. Reduction is only necessary if you need to save fuel, especially at altitude.

Thnx for clarification!

[-=PHX=-SuperEtendard]

Is it correct, that in the Rata, the inlet radiator and oil radiator both affect the oil temperature gauge?

 

Yes. Since allowing air through the inlet will cool the entirety of the engine, including the oil, while the oil radiator will effect (almost) exclusively the oil. Bottom line, they both cool the oil.

 ^ This

 

The oil radiator control adjusts a little shutter at the exit of the radiator, it doesn't affect speed so you just set it to mantain oil temperature at will.

 

 

The oil cooler does have an intake which is open and can't be closed by the cowling inlet shutter controls

 

[JG4_Sputnik]

So great, thanks for the answers!
It is just so cool to have a forum where there's that much expertise that almost all of your technical questions can be answered...

 

Thanks again,

cheers!

[unreasonable]

There is also some quantification here for the Yak: http://www.airpages.ru/dc/doc112.shtml    Use Google translate and it is just about comprehensible.

 

Upto 4,000m optimizing the mix compared to using auto makes a small difference to speed, but as altitude increases it is increasingly significant: 70 kph at 8000m.    So for 99% of all BoS Yak sorties, we can ignore!

 

Smoking, temperature and noise/vibration seem to be the indicators to look for in RL.  Author notes that in RL this is very difficult to get right since individual aircraft vary so much - maintenance, age and so on. Not something we have to worry about.

 

BTW agree with Sputnik's comments about how educational the forum can be at it's best - Z's description of the process above pulls together various elements I had only vaguely understood in fragments - into something that I now vaguely understand as a whole!  

[mb339pan]

Correct mixture on a petrol engine is important for fuel economy and very important for engine health end engine performance

 

 

fixed

Edited April 24, 2017 by 339_pan

[Retnek]

The Pe-2 s35 had a nice pair of instruments on top of the panel, indicating the lambda (mixture), allowing to quantify the effects of rich and lean mixture. It is modelled for the Ju-88 somehow, too. Fly horizontally with climbing settings and close the radiator that much to stay at 90 degrees water temperature. Reduce power and rpm to cruise settings, don't touch the radiators and see the temperature ... rise. Has to be the effect of reduced inner cooling, right?

[HansHansen]

It is modelled for the Ju-88 somehow, too. Fly horizontally with climbing settings and close the radiator that much to stay at 90 degrees water temperature. Reduce power and rpm to cruise settings, don't touch the radiators and see the temperature ... rise. Has to be the effect of reduced inner cooling, right?

Correct, you also can see the fuel consumption gauge literally jumping when you go from climb to cruise settings and back.

[6./ZG26_Klaus_Mann]

Just my 2  Cents:

 

Running a Petrol Engine too lean is Catastophic. The internal Combustion Temperatures Climb to the Point of Burning off and melting Valve Seats, Valves, Oil and even the Piston. This can also Lead to Pre-Ignition due to Glowing hot Spark Plugs, hot enough to ignite the Mixture. 

However, running slightly Lean will also keep the Engine Clean and Running Well. This is why some Aircraft Engines are Shut off by simultaneously Reducing Mixture and Increasing Throttle to Burn the Engine free of Soot. 

 

Running an Engine too Rich on the Other Hand tends to have mostly Reversable Effects. The Ignition Temperatures are Low and the Mixture burns less clean. This tends to lead to Soot Build-Up on the Valves and Piston, but also the Sparkplug. 

The Soot Buildup can lead to incorrect Seating of the Exhaust Valves, so they don't fully close and thus Compression Suffers. This Means a further Reduction on Power. 

Buildup of Soot on the Cylinder Walls will also harm the Engine Oil and Reduce Lubrication. 

 

In Reality this Means that almost all Gasoline/Petrol Engines Run Richer than Optimal at high Throttle Settings, and Leaner than Optimal (Optimal being 14.7:1) for Cruising. 

And just as a quick Tip: If you have Engine Troubles with your Petrol Car and it not running right; Check your Sparkplugs. 

 

Thankfully I have a Diesel and don't have to worry about all that Nonsense. Petrol Engines are so Overrated. 

 

[Retnek]

... Thankfully I have a Diesel and don't have to worry about all that Nonsense ...

Red fighters will see your black diesel grime way sooner and you'll earn what you asked for! As soon as the B&V 138 is available (Kuban collectors surprise pack!) I expect you to steam along with that ship. And there has been a diesel-Ju-52, too, your tail-end-smoker.

[6./ZG26_Klaus_Mann]

Yer-2 had Two 60 Litre Turbo-Diesel V12s. Would love that in all honesty. 

Edited April 24, 2017 by 6./ZG26_Klaus_Mann