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

[Spinnetti]

So, some may know already, but "proper" color of flame is not just what you like, but depends on many factors including Fuel type and Mixture, and mixture varies by type and amount of boost. Actual flame color is relative to combustion temperature and oxygen concentration. Generally speaking, the leaner the mixture, the "bluer" the flame, and the richer, the more yellow it is. At full boost, you tend to run richer to avoid burning a piston, and it should be more yellow. At cruise, it should be leaner, and thus bluer. For game purposes, I would probably have a couple settings - yellower for start up and full power, and bluer for all other settings - Important to note, but generally the only time you see any flame at all is on a missfire. If the engine is running in tune, there should be little missfires, and thus not much flame (although even a 2% missfire rate is still about 11 missfires/sec on a 16 cyl at 2000 rpm if I did the math right). The flame occurs when the unburned mixture hits the hot exhaust and combusts in the exhaust stack.... This is the general truth, but I'm sure experts could refine the exact details.

let's not forget that the flaming alternation of different exhausts is more visible at low revs/idle. When the engine is on cruise the blue flames are more constant from all the exhausts, as the engine is working at higer revs.

[Sutts]

Originally Posted by Spinnetti

So, some may know already, but "proper" color of flame is not just what you like, but depends on many factors including Fuel type and Mixture, and mixture varies by type and amount of boost. Actual flame color is relative to combustion temperature and oxygen concentration. Generally speaking, the leaner the mixture, the "bluer" the flame, and the richer, the more yellow it is. At full boost, you tend to run richer to avoid burning a piston, and it should be more yellow. At cruise, it should be leaner, and thus bluer. For game purposes, I would probably have a couple settings - yellower for start up and full power, and bluer for all other settings - Important to note, but generally the only time you see any flame at all is on a missfire. If the engine is running in tune, there should be little missfires, and thus not much flame (although even a 2% missfire rate is still about 11 missfires/sec on a 16 cyl at 2000 rpm if I did the math right). The flame occurs when the unburned mixture hits the hot exhaust and combusts in the exhaust stack.... This is the general truth, but I'm sure experts could refine the exact details.

That sounds all very good but please show us a video where these yellow flames are being ejected by a running engine or point to the entry in the WWII exhaust flame colour chart where yellow flames are referred to. That chart covers everything from weak to rich mixtures and a whole lot of other scenarios including engine damage. Strange how yellow flames don't even get a mention - orange on a damaged engine but everything else is red and blue. I know it's for an Allison engine but I can't believe it differs much from any other inline carburated aero engine.

The only yellow flames I've ever seen are from raw fuel burning in the stacks of a flooded engine and an initial burst of yellow/orange flame when the engine first fires up.

I'd be happy to be proved wrong as I like the pretty yellow flames but the overwhelming evidence so far is against yellow flames from a running engine.

[major_setback]

The big question is this: Will be be able to over-prime the engine in the game?

[Richie]

That's a very good question. I think because of the fuel injection of the German fighters the Allied aeroplanes will have more fun with the flames.

Originally Posted by Richie

That's a very good question. I think because of the fuel injection of the German fighters the Allied aeroplanes will have more fun with the flames.

...what do you mean exactly?

[T}{OR]

Originally Posted by Sternjaeger

...what do you mean exactly?

When burning fuel in the cylinder, if we're talking about an ideal process - you need exactly the same amount of fuel and air in your mixture. Since space in cylinder is limited, there is only so much air and fuel you can put in there (if we're not talking about turbo or supercharging). And certain amount of fuel requires exactly certain amount of air (I forgot the exact ratio but I can dig it up if you want, I have it one of my books).

The biggest downside of carburetors is that they can produce such ideal mixture only on certain RPMs, or RPM ranges. While direct fuel injection is much more flexible and can provide the engine with better mixture on all RPM ranges.

I am talking theory here, but I believe this is what Richie meant with:

That's a very good question. I think because of the fuel injection of the German fighters the Allied aeroplanes will have more fun with the flames.

[W32Blaster]

well not as simple as that.

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

But if you have certain parameters of use like
RPM
accelaration,
Airtemperature high, low
Airpressure high, low
Cold motor (less evaporating fuel in cylinder and thus richer mixture needed)

etc. etc. etc.

you get lots of changes in actual needed air to fuel ratio. Many FuelInjection Systems are a not specified to recognize all those factors, where some really complicated carburators do.

So it´s not that simple one could say:
Fuel Injection is working better than a carburator in terms of providing the RIGHT mixture for all operating conditions.

Originally Posted by T}{OR

When burning fuel in the cylinder, if we're talking about an ideal process - you need exactly the same amount of fuel and air in your mixture. Since space in cylinder is limited, there is only so much air and fuel you can put in there (if we're not talking about turbo or supercharging). And certain amount of fuel requires exactly certain amount of air (I forgot the exact ratio but I can dig it up if you want, I have it one of my books).

The biggest downside of carburetors is that they can produce such ideal mixture only on certain RPMs, or RPM ranges. While direct fuel injection is much more flexible and can provide the engine with better mixture on all RPM ranges.

I am talking theory here, but I believe this is what Richie meant with:

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.

[SlipBall]

Originally Posted by Richie

That's a very good question. I think because of the fuel injection of the German fighters the Allied aeroplanes will have more fun with the flames.

Damm, I think I flooded her!...

Now you know the real reason, why I fought so hard for realistic start up's .. Flames