Friday 2010-12-10 Dev. video update and Discussion

[proton45]

Originally Posted by Wutz

Ha ha well even with mid forties I then hope I will never become an "adult" as you put it.
Going by some posts one could drop all input, at the most only writen signs of awe are acceptable......Thank god your type is not an admin, or forums would be a dead place.

I dont think your really getting my point...lol

[T}{OR]

Originally Posted by W32Blaster

well not as simple as that.

The ideal mixture is about 14:1, also called lambda=1.

Almost correct. The ideal stoichiometric mixture ratio is 14,7:1 => or 15:1. When we're talking in mass, not volume.

There are two different lambdas in petrol (Otto) engines: lambda(air) & lambda(charge)*.

*not sure if this is the correct technical term in English.

In a petrol engine lambda 1 should always be constant (=1), whereas lambda(charge) can go up to 7 (with supercharged and turbocharged engines), otherwise it also equals 1.

Lambda of 1.0 is at stoichiometry, rich mixtures are less than 1.0, and lean mixtures are greater than 1.0.


Like Azimech, I am also curious of what carburetors are you talking about. The advantages of direct fuel injection over carburetors are numerous. If not, car engines would be using them even today.

Originally Posted by Sternjaeger

erm... no, in a nutshell: mixture has different ratios, which need to be varied according to your altitude (leaner/richer mixture), besides a 50/50 mixture ratio would probably send your valves into orbit (Disclaimer: just wanted to make a joke here, please don't take it literally and start posting copy/paste engineering blabber..)
What Richie said just doesn't make sense: engines won't produce different flames if they're direct injected or carburator injected. Or maybe I got it wrong in the first place.

Fair enough. I forgot to write one thing - at ground level. Or even better: at 20° C & 1,013 bar (Standard atmospheric pressure: the conditions at which every engine is constructed and tested).

As for the rest (at least to my understanding, I am more into car engines), there is no such thing as 50/50 mixture. Maybe that is a phrase used by pilots and maintenance crews - they usually don't follow correct technical terms anyway. What I am trying to say (and to comment on your reply), there is an ideal ratio needed for the fuel inside the cylinder to burn most efficiently / completely (as previously mentioned). As you go higher air density is decreasing. Thus (in non supercharged engines) you need to lower the amount of fuel inside the cylinder to achieve the desired ratio or else you risk engine damage and various other things I do not want to get into now. The added downside of that is that engine power drops as well. To compensate for that - superchargers were invented. They compress air so that you can have the very same atmospheric pressure inside your cylinder as if you were flying on sea level. They can also be used to increase engine power (this is the easiest way to do it) - compress the air enough and more fuel can be put in the cylinder.

I could go on, posting diagrams, formulas etc. - but even 100 posts would be enough...

Anyway, what Richie meat was something else. With carburetors you can't get this ideal stoichiometric mixture ratio of 15:1 throughout whole RPM range because most carburetors are tuned for a certain RPM. This results in imperfect chemical reaction when fuel is burning inside the cylinder - hence probably more variable flames coming out of the exhaust, especially when changing RPM.

Originally Posted by Spinnetti

ideal mixture is still basically the same at any altitude. The difference is that the air density decreases as you go up, requiring mixture adjustments to maintain the same air/fuel ratio. Some planes had auto compensation, but most did not, so mechanical tune and operator capability also come into play here.

Absolutely true. What I posted above. ^^

Originally Posted by Letum

I have a sneaky suspicion that Thor might know what he is talking about when it comes to engines...

I sure hope so...

[W32Blaster]

My Statemant was you can´t say it that Easy: 'Fuel Injection is working better than a carburator in terms of providing the RIGHT mixture for all operating conditions. '
Not which Technologie is best used to gain the goal of ideal mixture under all operating conditions!

Originally Posted by T}{OR

Like Azimech, I am also curious of what carburetors are you talking about. The advantages of direct fuel injection over carburetors are numerous. If not, car engines would be using them even today.

Let´s say youll have a Pierburg 4A1 Carburator with ECU for fully closed loop control of a 3-Way Katalyst System and you compare it with a early k-Jet-Tronic, guess which one is more sophisticated in terms of providing right mixture for all operational state.

Originally Posted by Azimech

The main problem with a carburetor: it's very hard to distribute the mixture to all cylinders equally. Plus fuel injected engine are less prone to icing, they have a faster throttle response and are easier to start when cold.

Now youre talking about a difference between mixture is built internal Cylinder vs external like in Intake Manifold or Carburator.
As long as you are not building mixture via direct injektion you always will put extra parameters to be recognized.

[T}{OR]

Originally Posted by Sternjaeger

Thor, I used the 50/50 expression cos you mentioned "half and half", sorry, nothing really technical there

I have a fair experience with aviation piston engines (I was lucky enough to fiddle with 2 strokes and 4 strokes Rotax, Gypsy Major, Continental, Lycoming, P&W Wasp and lately I started to get acquainted with the RR Packard Merlin), but I am no engineer or techie, I am just a flier who's interested in knowing what's happening under the bonnet in front of his nose..

I am not entering in the merits of lambdas or mixture ratios because they're peculiar to the engines and aeroplanes (and as you said 100 posts wouldn't be enough), all I can tell you though is that yes, in theory a direct injected engine like the DB could be more "mixture efficient", although carb engines are handled according to strict parameters, so you would hardly notice any difference in the flames colouring.. if Oleg managed to implement a flame colour changing according to mixture values then this would be a boomer, cos we'd be able to adjust our mixtures by looking at the exhausts and might also be able do diagnose engine problems (i.e. red exhaust flames and sparks coming out would mean a bad, bad day.. or in case of radial engines, where the exhausts are normally connected via a ring exhaust, an intermittent flame from the main exhaust would mean misfiring cylinders etc..).

First I would like to say how much I envy you for the described experience. I am much more into theory, calculations and various physic laws related to engines. Unfortunately I have very little time with real engines. I did say 'probably' more variable, so this means that someone who is also an engineer and has the experience should have to come here and verify this in practice.

I am though, more inclined to believe that this difference in flames is almost invisible or not noticeable when comparing them with fuel injected engines of the same era.

Originally Posted by Sternjaeger

Come on Oleg, this is quality material we're delivering you here!

Agreed. I see that Oleg has posted while I was writing my reply. Very nice.

Originally Posted by W32Blaster

My Statemant was you can´t say it that Easy: 'Fuel Injection is working better than a carburator in terms of providing the RIGHT mixture for all operating conditions. '
Not which Technologie is best used to gain the goal of ideal mixture under all operating conditions!

Alright. It may not be that easy to claim that (especially when comparing mechanical fuel injection with carburetors), there are advantages and disadvantages of both - but from technical perspective and engine development advancements (especially in todays road vehicles) direct fuel injection is light years ahead.

Originally Posted by W32Blaster

Let´s say youll have a Pierburg 4A1 Carburator with ECU for fully closed loop control of a 3-Way Katalyst System and you compare it with a early k-Jet-Tronic, guess which one is more sophisticated in terms of providing right mixture for all operational state.

The K-Jetronic lacks proper feedback to adjust the mixture because it doesn't have a lambda loop or lambda control. The biggest advantage of 3-Way Catalyst System (lambda control) is that engine can adjust to different types of fuel more or less automatically. It does not fix the main flaw of carburetors - inability to provide ideal mixture on all operational states.

However, mechanical injection could do only so much. Before ECU & lambda control were implemented.

Direct fuel injection coupled with specialized piston and cylinder head shapes to further improve fuel oxidation (burning) by creating swirls and tumbles (idling at low RPM even with high lambda values, up to 3.0) - is a light years ahead from any carburetor...

Originally Posted by T}{OR

First I would like to say how much I envy you for the described experience. I am much more into theory, calculations and various physic laws related to engines. Unfortunately I have very little time with real engines. I did say 'probably' more variable, so this means that someone who is also an engineer and has the experience should have to come here and verify this in practice.

I am though, more inclined to believe that this difference in flames is almost invisible or not noticeable when comparing them with fuel injected engines of the same era (see my reply to W32Blaster below).

it's a dirty business, hands always covered in grease, oil and cuts, but when you feel 1650HP growling in your guts, swinging that big propeller 10ft in front of you, 12 cylinders furiously roaring in all their power.. well it's well worth the dirty hands

..The truth is that I like physics but I've always been rubbish in maths (I always lose a + or a - somewhere..).. LOL

[wildone_106]

Looks guys we want them to ship the game this decade..with all these inane requests it will never get done. You just gotta realize in the end its a simulation game..not real life. Once you come to terms with that your mind will rest...

[pencon]

I agree with Wildone,next we will be debating on what colour shoelaces the pilots wore.It's been a long enough wait for this sim and if everybody keeps going all Frazier crane on every little detail,Maddox will go broke trying to please all the anal retentives.

[T}{OR]

Originally Posted by Sternjaeger

it's a dirty business, hands always covered in grease, oil and cuts, but when you feel 1650HP growling in your guts, swinging that big propeller 10ft in front of you, 12 cylinders furiously roaring in all their power.. well it's well worth the dirty hands

..The truth is that I like physics but I've always been rubbish in maths (I always lose a + or a - somewhere..).. LOL

Now you're just talking dirty...

For me it is the other way around - I was always better in maths than in physics, but loosing a '+' or '-' is not strange to me either.



@ wildone & pencon: What we have been discussing here on last two pages are basics (of basics) of how internal combustion engines work. The mere fact that Oleg is considering to implement something like variable exhaust flames dependent on the mixture ratio is mind boggling. Let alone the individual cylinder modeling that has already been confirmed. Simply phenomenal work Oleg & co.


Before this gets more OT I will get back to the subject...

I wonder if the proper firing order has been simulated as well? Judging by the amount of details already shown, I would be surprised if it wasn't.

[Abbeville-Boy]

Originally Posted by T}{OR

Before this gets more OT I will get back to the subject...

I wonder if the proper firing order has been simulated as well? Judging by the amount of details already shown, I would be surprised if it wasn't.

rumor is that game ships with a timing light and cloth map

[ElAurens]

Originally Posted by Sternjaeger

it's a dirty business, hands always covered in grease, oil and cuts, but when you feel 1650HP growling in your guts, swinging that big propeller 10ft in front of you, 12 cylinders furiously roaring in all their power.. well it's well worth the dirty hands

..The truth is that I like physics but I've always been rubbish in maths (I always lose a + or a - somewhere..).. LOL

Never been into an aero engine, but I work on lots of old stuff. Everything from a Model T Ford to E-type Jaguars and a Lotus 11 LeMans.

Actually, driving the very early cars has much in common with early aircraft. The carbs are very rudimentary, as are all the other systems. They require constant input from the operator to be at their peak. Every gross change in throttle setting demands a change in mixture and spark advance, and it all changes as the engine warms. The settings you left the shop with will not be the settings you come back with.

It's a type of driving I really enjoy as it requires actual thought and input.