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

[flyingblind]

I don't think an exact colour match could ever be achieved as every monitor shows a slightly different colour anyway. The only comment I would make about the first video compared with the real life videos people have posted is that in real life the yellow flames are produced by a cloud of unignited fuel/air mixture being expelled from the engine and subsequently being lite by the burning exhaust gas once the engine has fired. As such no pressure is involved and the flames are quite 'lazy' in appearance. In Olegs game video the yellow flames are being expelled with considerable force. In the second video it looks like the engine is idling before takeoff rather than running under power so exhaust gases could well look more yellow than blue.

[T}{OR]

Originally Posted by flyingblind

I don't think an exact colour match could ever be achieved as every monitor shows a slightly different colour anyway. The only comment I would make about the first video compared with the real life videos people have posted is that in real life the yellow flames are produced by a cloud of unignited fuel/air mixture being expelled from the engine and subsequently being lite by the burning exhaust gas once the engine has fired. As such no pressure is involved and the flames are quite 'lazy' in appearance. In Olegs game video the yellow flames are being expelled with considerable force. In the second video it looks like the engine is idling before takeoff rather than running under power so exhaust gases could well look more yellow than blue.

+1000

And it also depends on the mixture / priming of the engine in the first place. The biggest remark is just that - on low RPM when starting an engine the flames should be 'lazy', because un-ignited fuel is coming out of the engine cylinders and thud burns outside it - vertically. Only when the engine actually starts the flames get expelled horizontally (axially with the each cylinder exhaust pipe) as in many videos posted here accompanied with a transparent blue flames. Not to mention the vast amount of smoke as well (but this effect is done nicely).

[smink1701]

Oleg,

Flame looks fine...only lasts a few seconds anyway. The visuals we've seen are amazing. I hope you put equal effort in getting the sounds right. IMHO

[FG28_Kodiak]

Have found this table for the Allison V-1710 Models 'E' and 'F' (from Allison Service School Handbook ALD-SSH-5) I know its not a Merlin

[Blackdog_kt]

Originally Posted by FG28_Kodiak

Have found this table for the Allison V-1710 Models 'E' and 'F' (from Allison Service School Handbook ALD-SSH-5) I know its not a Merlin

That's very useful. It also confirms what most people have been saying, that the temperature of the exhaust gas and the subsequent colour is a consequence of a variety of factors that can affect fuel burn. High or low power, mixture settings, etc, all seem to play a role.

The most interesting part in the picture you posted is the possibility to diagnose problems or verify the correct operation of the engine.

For example, leaning the mixture. In today's general aviation piston engined aircraft, leaning is usually done by moving the mixture lever back until you see the EGT (exhaust gas temperature) gauge reach a peak, if you lean any further it will start dropping again. So, for example let's say the peak EGT occurs with the mixture lever at the 75% forward position. If you move it forward/backward from that position the EGT will drop. What the pilots do is start leaning and watch for the reversal in the needle (watching it rise, then drop again from over-leaning), at which point they enrich it a bit to get it back to peak EGT.
Then, they enrich a bit further until the EGT drops a set number of degrees, which is usually specified in the aircraft manual. This is usually stated like this: "lean mixture as follows: for best cruise enrich to 50 degrees below peak EGT, for best economy enrich to 30 degrees below peak EGT". Peak EGT is not a constant but that doesn't bother us. For example, if running 75% power the EGT on the whole (which includes the peak value) will be higher than what we would get if running at 60% power, but all we care about is "catching" the highest temp on the gauge and enriching a set number of degrees from that, not what the highest temp actually is.

So, why do we care? Because i think most aircraft in WWII didn't have an EGT gauge, but the picture you posted showed the same method being possible to use by watching the exhaust stacks.
Lean mixture on the allison gives a blue flame, rich mixture gives a red flame near the stack and a blue flame further away but it says the blue flame moves closer to the stack as the mixture is corrected. Finally, the correct mixture has the blue flame near the stack and the red flame behind the blue one.
So, one could theoretically lean the mixture until he sees too much of a blue flame that signifies the peak EGT (the higher temperature of exhaust gas, which gives off the blue glow). Then, they would have to enrich it a bit as described before, judging when to stop by the appearance of red flame behind the blue one, but not going as far as having the flames reversed (blue after red) because that would signify an overly rich mixture.

Excellent stuff!

[Ltbear]

Many engine heads know the exhaust smoke is a good indicator about how the state of an engine is...

If you test run engines in a test bench without the exhaust pipes on the colour of the flames are also a decent way to identify any problems...

My observations of engines i have worked on

idle should be yelow with a blue base

i work with RPM`s not power settings..

at 2800 RPM`s with no load on the engine it should be yelow with a small red base

at 2800 RPM`s with load its a 50/50 yelow and red

at max settings and full work load it should be blue base with red and yelow..

This is what i know from carburator engines...

When a engine works the tempeture will change etc....

Overprimed engines will make a yelow flame, normaly with werry dark grey or black smoke puffs....

But there is more to it.....how well do the oilring scrape the cylinder wall etc....a small ammount of black smoke doing start up can indicate a small ammount of oil left in the cylinder.....thats actualy ok as long it stops when the engine gets to operating tempeture...

Whitesmoke is also ok...again if it stops at operating tempeture

White and blue`ish smoke on startop is a no go....that is both water and oil and thats bad no matter if it stops or not, that is a mixture of oil and water...and that should not happen.....

I personaly dont care about colours, the awsome part for me was the working of each seperate cylinder....that is cool, and that realy give my hope up for the shot up cylinders...German and british plane dont like that, but later on the yanks radials aircooled will love that...we might get the **holy crap i landed on 4 cylinders**

Spits and 109`s wount like loosing cylinders....the 190 will fare abit better on it....man just the ideas about the different things that can go wrong with engine hits....

woooooot!!!

LTbear

[Jumo211]

Please , click the YouTube link to directly watch this video in bigger screen and HD
in order to see all details

http://www.youtube.com/watch?v=EsAXDB-sV8w

[major_setback]

Originally Posted by FG28_Kodiak

Have found this table for the Allison V-1710 Models 'E' and 'F' (from Allison Service School Handbook ALD-SSH-5) I know its not a Merlin

Excellent information find!
It shows that all types of fires can be seen depending on what is happening in the engine.

Unfortunately I doubt that the game engine has been programmed with allowance for these variations if Oleg is only just now asking for information on stack-fire types.

Oleg: I hope I am wrong. Am I?

[SlipBall]

Originally Posted by FG28_Kodiak

Have found this table for the Allison V-1710 Models 'E' and 'F' (from Allison Service School Handbook ALD-SSH-5) I know its not a Merlin

Excellent find FG28_Kodiak

[Tbag]

Oleg&Team, thanks for the update. Completely OT but a very interesting document for the future:

http://www.cockpitinstrumente.de/arc...0Air%20War.pdf