Throttle, prop pitch and mixture and getting the most climb and speed

[Uriah]

In the past I just set the mixture for good running at zero to 2K meters and leaned it out at higher altitude and controlled the manifold pressure (ATA?) by the prop pitch and throttle.  Now I am thinking I don't understand the relationship between these three and the manifold pressure.  My desire is to get the most climb ability from engine and prop and then of course most speed  on the horizontal and then getting the most out of a dive.  It is primarily the mixture in this set of throttle, prop pitch and mixture that I don't understand.  In the past I just leaned or enriched it according the the altitude but now I see I can get change it for more than just altitude situation.  But that puzzles me.  Please enlighten me.

[BlitzPig_EL]

What aircraft are you flying?

 

They are not all the same.

[Uriah]

The basics of those three items should be similar to all aircraft.  The biggest difference it seems is that mixture seems to produce a more pronounced change say in the Mig-3 than the Yaks.  And if I recall right the 109s and most German planes have automatic prop pitch and aujto mixture so not much of an issue with those planes.

[216th_Jordan]

I'm not sure I understand you completely.

 

Mixture:

Almost all planes in BoX have settings for automixture, most german planes have automix by default, most soviet planes have automixture for rich mixture at 50% (Il-2, Mig-3) or 100% setting. You get the best power output at a rich setting, but it must not be too much. As you climb the mixture regulator will 'automatically' lower your amount of fuel for air available. Above certain altitudes the regulators might fail to make proper adjustments, then you can manually put the mixture to the best settings. (In general, make short adjustments to the mixture and watch if your rpm needle drops or rises shortly)

Attention: Some engines have special regulators that allow the engine to go into a 'boosted' mode when moving the mixture lever fully forwards (Il-2, Mig-3, I-16), don't confuse that with a mixture setting.

 

RPM:

Generally speaking: higher RPM = higher power output. Depending on engine specifics and prop design there are deviations but the poweroutput is always nearer to the top rpm setting. This isnt like a "gear" in a car as all props we have in BoX are constant speed props where you will set a desired rpm and the prop will regulate its angle of attack to meet that setting.

 

Throttle:

Well, throttle is power. In your car its the accelerator.

Edited December 26, 2017 by 216th_Jordan

[Yogiflight]

 

 

This isnt like a "gear" in a car as all props we have in BoX are constant speed props where you will set a desired rpm and the prop will regulate its angle of attack to meet that setting.

In fact, it is very much like a modern automatic gearbox with seven (or even more?) gears, changing them to hold the engine in the optimum rpm, for either maximum acceleration, or minimum fuel consumption, depending on the situation.

[busdriver]

 

Attention: Some engines have special regulators that allow the engine to go into a 'boosted' mode when moving the mixture lever fully forwards (Il-2, Mig-3, I-16), don't confuse that with a mixture setting.

 

 

With genuine respect...it is in fact a mixture setting if you have to move the mixture control. It just so happens that on these engines it is a special case (not normally found in western engine technology), unique to Russian engines. Your statement is analogous to saying that a using afterburner on a modern jet is not a throttle setting.

 

Not trying to pick a fight, simply asserting that you could make your case in a less confusing manner.

[Uriah]

The issue is how much of each to use in a given situation.  The novice might think that the best thing to do to go as fast as they can on the level is to max out the throttle and have the prop pitch at max fine so the prop grabs the most air to push back and pull the plain forward.  And a novice might think that as I am at less than 1k off the ground I want full rich mixture but when I get up to 10k I want to lean the mixture.  The first thing those with a little more knowledge than the novice thinks about is not destroying the engine by either overheating it or putting so much strain and stress on various engine parts by having the max amount of RPMs and manifold pressure.  The next level of knowledge folk think beyond just destroying the engine.  They want to get the most speed out of the plane for the situation.  So they know that when speeding along on the level plain that the prop pitch needs to be a bit more course (less fine) than at take off and very course when in a dive and at high speed.  These folks also know that they can play around with the prop pitch, throttle and mixture to get the highest level of RMP out of the engine without damaging the engine.  In a steep climb they are going to give full throttle and coursest prop pitch and in a dive after they have picked up some high speed they understand that to go even faster they actually need a much courser prop pitch and even give less throttle. 

 

So what do I not understand?  Mixture!  I do know it is the amount of fuel mixed with the air and that mixture is what is fired in the pistons.  And I do understand that the thicker the air the more fuel I need to mix with the air and the thinner the air the less fuel I want to mix in.  But what stumps me is when the AI is flying about (as I watch from inside the cockpit) the AI is constantly changing all three.  I don't understand why the mixture is being changed when staying at say below 3K as most of the action in the scramble mission in Battle of Moscow is well below 3K.   And when I see the AI changing the mixture in a Mig-3 I see the ATA changing.   I don't understand what the AI is gaining by changing the mixture so much.  I'm thinking changing the throttle and prop pitch is about the only thing that needs to be done.  In fact I know that some planes and some pilots pretty much just give full throttle but just change the prop pitch to get the most speed and ease on the engine.  Why would I ever want to mess around with the mixture so much?  The Soviet planes - Lagg and LA-5 and Mig-3 all have the mixture right by the throttle so they can be used by one hand.  So there must be a good reason to be changing the mixture so much.

Edited December 26, 2017 by Uriah

[216th_Jordan]

In fact, it is very much like a modern automatic gearbox with seven (or even more?) gears, changing them to hold the engine in the optimum rpm, for either maximum acceleration, or minimum fuel consumption, depending on the situation.

 

Yeah, good example, thank you.

 

 

it is in fact a mixture setting if you have to move the mixture control.

 

Well I do not know if mixture is actually really affected by these settings (would be interesting to know if someone had more knowledge of russian engines here), but i guess you are right with the categorization.

[216th_Jordan]

But what stumps me is when the AI is flying about (as I watch from inside the cockpit) the AI is constantly changing all three.

 

The AI works in mysterious ways If it is actually gaining a higher performance by its measures? Would be interesting to know..

As I cannot tell you how the logic of the AI works the speculation about this is rather moot, it could be trying to do various things, not necessarily getting the highest power output.

[Willy__]

Generally ingame changing the mixture wont have much effect on the speed/climb with the mig3 being the exception. For climbing you want the maximum RPM you can get without destroying the engine, the same with Manifold Pressure, if you look at the Aircraft Specification tab in map screen it tells you the RPM/MP settings, keep in mind that your speed when you climb is also very important! While the 109s have the best climb speed at the range of 280-300kph, russian planes have the best climb rating at bit lower speeds.

 

Now if you want the maximum speed without climbing (i.e: level flight) it will depend on the altitude, but usually you still want the maximum MP you can get without damaging the engine, but for higher speeds you are better off lowering the RPM/prop pitch a bit, at maximum prop pitch/rpm the prop will have a higher drag than lower pitch and thats why you lower your pitch when higher speeds, but that is different for every plane ingame!

 

Hope you get the idea! And in any case, the best way is to practice, practice and practice! 

 

-edit-

 

Dont forget to close your rads when you want max speed!

Edited December 26, 2017 by 3./JG15_Staiger

[-SF-Disarray]

As an example of altitude effecting this setting, the Yak 1 runs faster at about 85% RPM at altitudes around 1 km and below. That is a little gem I picked up from the in game spec sheet for that plane. I'm not yet sure exactly how much faster it will go and if this applies to either the Yak 1b or the LaGG 3, because in so far as I know they all use the same engine, but I bet someone here might know these answers.

[Nocke]

I have the strong feeling that if you push the mixture lever in the Mig and the IL2 to 100% there is more going on than just a mixture change...

[-SF-Disarray]

Ya, there is. The engine starts working in what is called 'boost' or 'emergency' mode. It produces lots and lots of horse power for a little while and then you blow a head, or throw a rod or some other kind generally engine destroying catastrophe happens. I want to say you have 3-5 minutes of this operating time in the Mig and IL 2 but I'm not 100% sure on that.

[D3adCZE]

Hello, if you are a 109-G2 enthusiatist, I will give you info how to get ~3m/s better climb rate and ~20kph better indicated speed. Note that this is for the DB605 engine of G2, not DB601 of F4. Use manual prop pitch to keep 2800RPM and manual rads to keep your engine just below overheat temperature. It can be tough, but it saved my ass many times against reds below 3km. Please, do not forget that it is limited for only ~3 minutes and 30 seconds. 2900 RPM give even more power, but you will cook your engine after ~35 seconds. So do not forget to switch to automatic prop pitch if you do not have time to watch RPM closely since it is double edged sword.

 

On the other hand, if you want to save fuel, keep your ATA below 1.0 and you can lower your RPM by ~15% from automatic settings. You will be slow, but you will have much more flight time.

 

I hope I've helped a bit.

 

Cheers, D3ad.

[Willy__]

I'm not yet sure exactly how much faster it will go and if this applies to either the Yak 1b or the LaGG 3

 

 

If they have the same prop it should be the same as the Yak1, but I'm not sure if they share the same prop model.

Edited December 27, 2017 by 3./JG15_Staiger

[216th_Jordan]

Yak-1b has a different prop

[busdriver]

The next level of knowledge folk think beyond just destroying the engine.  They want to get the most speed out of the plane for the situation.  So they know that when speeding along on the level plain that the prop pitch needs to be a bit more course (less fine) than at take off and very course when in a dive and at high speed.  These folks also know that they can play around with the prop pitch, throttle and mixture to get the highest level of RMP out of the engine without damaging the engine.  In a steep climb they are going to give full throttle and coursest prop pitch and in a dive after they have picked up some high speed they understand that to go even faster they actually need a much courser prop pitch and even give less throttle. 

 

 

I disagree totally with the first bit I underlined, and perhaps with your overriding non specific assumptions. I think you would agree that some degree of formation integrity and cooperation would be considered essential to the survival of a 1G Comfy Chair Fighter Pilot. One would not simply attempt to fly at max speed, you must consider the RL notion of wingman consideration. So you'd set a nominal mixture, RPM and manifold pressure that allows your wingmen to stay in formation. Then as you approach an engagement increase RPM and manifold pressure to attain combat power.

 

The notion that you use full throttle (which controls manifold pressure) and your lowest RPM (the prop control determines RPM and low RPM is coarse pitch) to climb steeply is incorrect. Think that through carefully. Coarse pitch is low RPM, Fine pitch is high RPM. Throttle position controls your manifold pressure. IMO mixture is the least of your worries.  

 

When Charles Lindbergh toured the Pacific he flew missions with fighter squadrons. He was obsessive about milking the maximum mile out of each gallon of gas and treating engines kindly during the enroute portion of a mission. Saburo Sakai essentially did the same thing flying out of Rabaul. The adoption of his techniques extended the endurance and range of the Zero missions. But in the heat of combat approximate positioning of controls, as in set the RPM...leave it alone then manipulate the throttle, rather than squinting and making micro adjustments is the order of the day. Very little you do as a 1G Comfy Chair Fighter Pilot requires maximum speed. Fly solid formation (translates into gun tracking ability) and learn to shoot...solves the three keys for an air-to-air kill.. Be in gun range. Have the proper amount of lead. And be in the same plane of motion (tracking) for the best shot.

 

So why did I go off on a tangent? I think your generalizations about the different levels of knowledge would give FNGs (noobs) the wrong impression. 

Edited December 27, 2017 by busdriver

[Uriah]

I agree, low RPM is course RPM.  i think I got High and Low pitch mixed up with values of Fine and Course.

From pilot point of view:

    See more of blade=low?=fine=more RPM      |

    See less of blade=high?=course=less RPM     \

    See only edge of blade=feathered=?               _

 

I also noticed that Spitfires have the throttle and mixture side by side so as to be operated by one hand.

Regardless having the right balance of throttle and prop pitch with give you either greater speed or better fuel economy and different engine wear.

But does having a richer mixture, if even for a short moment, give you more RPM?  I think that is what is meant by a boost.  It is for sure that way on a Mig-3.  But it must have some benefit for the Spit, Lagg, LA-5, and Mig-3

I have been regulating the RPM mostly by throttle and prop pitch but now I am wondering if I should often throw in mixture too.

[Jade_Monkey]

Don't use the Mig 3 to learn these concepts or it will confuse the hell out of you.

[Herne]

I don't think i've ever adjusted the mixture in the IL2. I thought the boosted mode was done purely on RPM ? after take off, i have to remember to wind the rpm back to 2050 or a few minutes down the line the engine blows. Have I been missing out on additional power ?

[ZachariasX]

I agree, low RPM is course RPM.  i think I got High and Low pitch mixed up with values of Fine and Course.

From pilot point of view:

    See more of blade=low?=fine=more RPM      |

    See less of blade=high?=course=less RPM     \

    See only edge of blade=feathered=?               _

 

I also noticed that Spitfires have the throttle and mixture side by side so as to be operated by one hand.

Regardless having the right balance of throttle and prop pitch with give you either greater speed or better fuel economy and different engine wear.

But does having a richer mixture, if even for a short moment, give you more RPM?  I think that is what is meant by a boost.  It is for sure that way on a Mig-3.  But it must have some benefit for the Spit, Lagg, LA-5, and Mig-3

I have been regulating the RPM mostly by throttle and prop pitch but now I am wondering if I should often throw in mixture too.

Regarding the Spitfire. The mixture lever in real life has only two positions. Full back (rich) and full forward (lean). There is no point in setting it in an intermediate position. The fact that you can do it in the game is probably due to it bound to an axis. But the *automatic* mixture setting knows only two inputs: lean and rich. For most of your purposes, leave it to rich. Only shoukd you want to fly as long as possible and having the engine run in a reduced setting for cruise, you can lean the mixture to up your mileage.

 

Important to know: Rich mixture does not „give you more rpm“. The load on the crankshaft mainly determines that. What you probably meant to say is it would give you more power. Also that is not the case. On the contrary. You lose more than 10% power by further enriching the mixture. What the excess fuel does however is cool the burn in the cylinder and let you run the engine at a power setting that otherwise would damage the engine. Thus at the cost of „a lot of mileage“, you simply are allowed to increase throttle further.

 

The thing about rpm is that rpm is directly proportional to the power output of the engine. Theoretical example: if an engine produces 1200 hp at 2000 rpm, it will produce 1800 hp at 3000 rpm. It is these added 1000 hp that make you go faster, not the rpm.

 

In fact, very fast prop planes like the Tu-95 fly with a high geared prop that runs in an almost feathered position, at very low rpm and at very high torque. The higher the speed of the tip of the prop, the less margin you have from the added flight speed until the tip of the prop is going supersonic. The prop greatly loses efficiency then.

[LukeFF]

I don't think i've ever adjusted the mixture in the IL2. I thought the boosted mode was done purely on RPM ? after take off, i have to remember to wind the rpm back to 2050 or a few minutes down the line the engine blows. Have I been missing out on additional power ?

 

50% mixture in the Il2 sets the mixture to Auto Rich. Anything above that allows the engine to go into boosted mode (per the Specification tab).

[Herne]

50% mixture in the Il2 sets the mixture to Auto Rich. Anything above that allows the engine to go into boosted mode (per the Specification tab).

 

Thanks, All this time in IL2 and I'm still learning stuff

[busdriver]

I agree, low RPM is course RPM.  i think I got High and Low pitch mixed up with values of Fine and Course.

From pilot point of view:

    See more of blade=low?=fine=more RPM      |

    See less of blade=high?=course=less RPM     \

    See only edge of blade=feathered=?               _

 

I also noticed that Spitfires have the throttle and mixture side by side so as to be operated by one hand.

Regardless having the right balance of throttle and prop pitch with give you either greater speed or better fuel economy and different engine wear.

But does having a richer mixture, if even for a short moment, give you more RPM?  I think that is what is meant by a boost.  It is for sure that way on a Mig-3.  But it must have some benefit for the Spit, Lagg, LA-5, and Mig-3

I have been regulating the RPM mostly by throttle and prop pitch but now I am wondering if I should often throw in mixture too.

 

Let's stop you for a moment to clarify terminology. It's Fine and COARSE, not Course. Think sandpaper, fine grit and coarse grit. Think the of the propeller blade taking a small bite of air (Fine) at a high RPM or an increasingly bigger (coarse) bite of air at lower RPM. Feathered is a special case of the coarsest setting of blade pitch. 

 

Your pilot POV example is correct WRT to blade angle.

 

Indeed the Spitfire and many other airplanes have the throttle and prop control next to each other. While they are operated by one hand, they are not generally operated simultaneously.

 

No, increasing the mixture won't increase your RPM significantly, meaning you won't gain 5 km/h much less 50 km/h in airspeed. There are RL techniques to approximate the best mixture setting for a given cruise altitude and airspeed, where 1) the pilot slowly reduces the mixture until the engine runs roughly or 2) the cylinder head temperature increases a noticeable amount (referred to as peak temp) at which time the pilot nudges the mixture a tiny bit richer to lower the CHT. This latter technique is often referred to as leaning the mixture to "rich of peak."

 

You very last line...while you see variation in RPM while manipulating both throttle and prop control, you really need to embrace the fundamental concept that the throttle controls manifold pressure (or in the case of the Spitfire the Boost gauge) and the prop control controls RPM. It's the unseen propeller governor that is slightly varying the RPM as you move the throttle. So set your desired RPM with the prop control...set your desired MP with the throttle. Repeat that until you internalize this concept. To answer your question in the last line...No. 

[wtornado]

Now I understand thanks Busdriver.

[CIA_Yankee_]

You very last line...while you see variation in RPM while manipulating both throttle and prop control, you really need to embrace the fundamental concept that the throttle controls manifold pressure (or in the case of the Spitfire the Boost gauge) and the prop control controls RPM. It's the unseen propeller governor that is slightly varying the RPM as you move the throttle. So set your desired RPM with the prop control...set your desired MP with the throttle. Repeat that until you internalize this concept. To answer your question in the last line...No. 

 

It's also important to realize that the prop governor basically works to maintain the RPM you've set with the RPM lever. This does not necessarily coincide with a "fine" or "coarse" pitch, as the actual pitch of the prop is a function of the RPM setting, throttle, and speed.

 

For example, going full RPM will lead to a finer setting, but that's only in relation to a lower RPM setting. If the plane is moving very fast, the pitch will be considerably coarser than what it would be if it were stationary (if it weren't, you'd probably overrev the engine). In short, you're not controlling the prop pitch, but rather the RPM. The prop governor adjusts the pitch to maintain the specified RPM.

[busdriver]

It's also important to realize that the prop governor basically works to maintain the RPM you've set with the RPM lever. This does not necessarily coincide with a "fine" or "coarse" pitch, as the actual pitch of the prop is a function of the RPM setting, throttle, and speed.

 

For example, going full RPM will lead to a finer setting, but that's only in relation to a lower RPM setting. If the plane is moving very fast, the pitch will be considerably coarser than what it would be if it were stationary (if it weren't, you'd probably overrev the engine). In short, you're not controlling the prop pitch, but rather the RPM. The prop governor adjusts the pitch to maintain the specified RPM.

 

To clarify possible reader confusion. Yankee's reference to the RPM lever is the same thing as my reference to the prop control . If you check the Pilot's Notes for various WWII airplanes you will find this lever called the Propellor Control lever in the Hurricane, the RPM Control lever in the Mosquito, the Airscrew Control lever in the Spitfire. American manuals used Prop lever. My use of prop control is the modern American nomenclature. 

[Uriah]

I went back and look at a lot of the pictures I have of cockpits where others have kindly labeled the items.  On the German planes the throttle and prop pitch can be or nearly be controlled with the hand on the throttle.  The mixture is absent.  On the Soviet, British and American P40 it is the throttle and mixture that can be controlled by one hand on the throttle but with the prop pitch close by.    Based on that I do believe there is likely a very helpful reason the mixture is so 'at hand'.   The best I've heard is what ZachariasX wrtote about using richer mixture to cool the burn in the cylinders.   I'm going to be dreaming prop pitches and mixtures and throttles and RPMs and manifold pressures all night.

[busdriver]

I went back and look at a lot of the pictures I have of cockpits where others have kindly labeled the items.  On the German planes the throttle and prop pitch can be or nearly be controlled with the hand on the throttle.  The mixture is absent.  On the Soviet, British and American P40 it is the throttle and mixture that can be controlled by one hand on the throttle but with the prop pitch close by.    Based on that I do believe there is likely a very helpful reason the mixture is so 'at hand'.   The best I've heard is what ZachariasX wrtote about using richer mixture to cool the burn in the cylinders.   I'm going to be dreaming prop pitches and mixtures and throttles and RPMs and manifold pressures all night.

 

Enriching the mixture does indeed cool the cylinders...and you need a Cylinder Head Temperature gauge to make that adjustment, otherwise you're simply guessing.  Good luck.

Edited December 29, 2017 by busdriver

[Dakpilot]

Having the mixture close to hand is also quite important when you need to shut down an engine (cut the fuel flow) in 'good time'  

 

this is often theoretically more important in RL than in a sim 

 

there are other methods available in different applications such as firewall shutoff valves which can also cut the oil to reduce/slow fire hazard

 

but generally the first thing you will want to do in an emergency will be to put mixture control lever to idle/cut off

 

Cheers, Dakpilot

[Guest deleted@50488]

Having the mixture close to hand is also quite important when you need to shut down an engine (cut the fuel flow) in 'good time'  

 

this is often theoretically more important in RL than in a sim 

 

there are other methods available in different applications such as firewall shutoff valves which can also cut the oil to reduce/slow fire hazard

 

but generally the first thing you will want to do in an emergency will be to put mixture control lever to idle/cut off

 

Cheers, Dakpilot

 

I feel so relaxed for only flying gliders ( as a pilot ) IRL :-)

[Uriah]

I let the AI fly the Lagg and La-5 and in those planes the mixture was pretty much left alone.  I will hazard a guess that it is only in the Mig-3 that is played around with so much and that is likely due to the use of  boost factor for that plane.