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

[AdMan]

Originally Posted by winny

Flame colour has nothing to do with the angle you view it from or the length of the exhaust pipe, it is nothing to do with temperature either. It simply shows how efficiently the fuel is burning.

If the combustion is burning all the carbon you get blue flames and no smoke. If there's carbon coming out in the exhaust gases then you'll get yellow-er/smoky-er flame.

This is chemistry not opinion.

Originally Posted by changai

Actually, Winny is right, it doesn't depend on those factors.
Color is related to the temperature of gases produced during combustion: the hotter, the whiter; the colder, the redder. Blue indicates a very high temperature. Near-perfect combustion of hydrocarbons is always blue.

Yellow indicates an imperfect combustion, i.e. lack of combustive agent (usually air) which causes production of soot, i.e. smoke. However, even a very rich mixture as used on a cold engine would not produce yellow flames, but add a yellowish hue at the end of blue flames.

Red indicates a very bad combustion. A damaged engine burning oil would probably produce reddish flames.

Hope this helps

these people seem to make sense

[Rodolphe]

Originally Posted by changai

Actually, Winny is right, it doesn't depend on those factors.
Color is related to the temperature of gases produced during combustion: the hotter, the whiter; the colder, the redder. Blue indicates a very high temperature. Near-perfect combustion of hydrocarbons is always blue.

Yellow indicates an imperfect combustion, i.e. lack of combustive agent (usually air) which causes production of soot, i.e. smoke. However, even a very rich mixture as used on a cold engine would not produce yellow flames, but add a yellowish hue at the end of blue flames.

Red indicates a very bad combustion. A damaged engine burning oil would probably produce reddish flames.

Hope this helps

Welcome Changai.

Thanks for your first post here, and I can say that you are Spot On !

Following the A.P. 1565 A (Spitfire I, Merlin II or III engine) 'STARTING THE ENGINE AND WARMING' procedure, the mixture should be in Full Rich with a 1/2 inch open Throttle , not quite a blue near-perfect combustion situation.

On this 'September Fury' dusk video, the blue flames panache appears only at a continuous high power regime.
Note the absence of blue light reflection on the 'Fury' fuselage.


and by the way, thanks for the Update. ; )


...

[ATAG_Dutch]

Originally Posted by AdMan

these people seem to make sense

Yes, it's the 'Ki gas' primer I don't know about.

[Blackdog_kt]

Originally Posted by Oleg Maddox

Please read with atention: The color of exhaust from the direct pipe and from the extended are different. The temperatue of the flame decreasing with the longer leght of pipe. More lower temperature - more red flame. The most hight is right from the hole without pipe.

As I told above a lot of factors is present in forming of color.

Exactly. In general, hot=blue, cool=red/yellow, plus a flame that's seen directly exiting the piston will be hotter than a flame seen after travelling the entire length of the exhaust pipe.

So, since the colour is a function of exhaust gas temperature, i guess that running on higher power will produce bluer flames. Also, leaning the mixture at night could be done by watching the flames, you just have to lean until the highest exhaust gas temp which means the bluest flame you can get, then enrich it again just a tad from that point.

I might know how the stuff generally works but it don't know what the correct colour for each circumstance is. However, i'm really excited about these features because they give the impression of a real, working machine under the hood. Excellent update!

Originally Posted by winny

Flame colour has nothing to do with the angle you view it from or the length of the exhaust pipe, it is nothing to do with temperature either. It simply shows how efficiently the fuel is burning.

If the combustion is burning all the carbon you get blue flames and no smoke. If there's carbon coming out in the exhaust gases then you'll get yellow-er/smoky-er flame.

This is chemistry not opinion.

...and the way pilots of prop driven aircraft adjust their mixture today is by, guess what, a temperature gauge that monitors how hot the exhaust gas is. So you're correct generally, except the part where you say it has nothing to do with temperature. This is also not opinion but physics, whatever burns hotter is to the blue/white side of the spectrum and stuff that burns cooler is to the red/yellow side. It's the reason even the stars are not all the same colour. Cheers


Edit: I just saw you corrected it yourself

[winny]

So, now I've thought about it.. anytime the engine is running efficiently we should see blue-er flames in SoW.

The less efficiently the engine runs the yellow-er the flame.

That would beg the question, what effects an Aero engines effectivness at burning fuel?

Rubbish fuel?
Altitude?
Damage?
Mixture?

I put question marks because when it comes to engines I find them exactly like women.. I love them, but I dont understand how they work...

[Sutts]

Originally Posted by Trumper

Do these help

7 mins in

3 mins in for night time CREDIT TO THE AUTHORS OF THE VIDEOS

Great videos Trumper. I've put together a few stills from the Just Jane night runup you posted.

When running fast the flames were short and a dull red in colour.
When reduced to an idle the flames were longer and blue in colour.

The red flames flickered but were visible at all times from all exhausts.
The blue flames were intermittent - just ejected every now and then.

None of the flames were bright enough to illuminate the cowlings of the aircraft. This is my experience from a couple of merlin night runs I've witnessed. The only time the aircraft is lit up is when the engine has been overprimed and the full fuel flames are seen pouring out for a few seconds on initial start.

This makes sense since an aircraft lit up to the extent we see in the SoW video would have made a perfect target at night. I know the brightness of the exhausts was a problem at night for pilot vision - in First Light I remember reading that Geoff Wellum couldn't see the runway lights below him at night because strips of metal were attached to the fuselage of his Spit to hide the exhaust outlets from the pilot, partially obscuring his downward vision - he hadn't realised that and thought the runway lights were being switched off every time he flew approach!

[Sutts]

Originally Posted by Blackdog_kt

Exactly. In general, hot=blue, cool=red/yellow, plus a flame that's seen directly exiting the piston will be hotter than a flame seen after travelling the entire length of the exhaust pipe.

So, since the colour is a function of exhaust gas temperature, i guess that running on higher power will produce bluer flames. Also, leaning the mixture at night could be done by watching the flames, you just have to lean until the highest exhaust gas temp which means the bluest flame you can get, then enrich it again just a tad from that point.

I might know how the stuff generally works but it don't know what the correct colour for each circumstance is. However, i'm really excited about these features because they give the impression of a real, working machine under the hood. Excellent update!






...and the way pilots of prop driven aircraft adjust their mixture today is by, guess what, a temperature gauge that monitors how hot the exhaust gas is. So you're correct generally, except the part where you say it has nothing to do with temperature. This is also not opinion but physics, whatever burns hotter is to the blue/white side of the spectrum and stuff that burns cooler is to the red/yellow side. It's the reason even the stars are not all the same colour. Cheers


Edit: I just saw you corrected it yourself

Unfortunately, the stills I've captured from the Just Jane Lancaster nighttime runup show exactly the opposite Blackdog......when RPM is high we see short red flames. When idling the long blue flames are ejected intermittently. Could be that this old Lanc just isn't tuned up properly like a flyer would be.

Dunno!

EDIT: Sorry, it was someone else who related colour to engine speed. I agree it is temperature based like you say and the temperature at any RPM will be dependent on the efficiency of the burn...mixture, cold/warm engine, degree of wear in the barrels etc.

[LukeFF]

Originally Posted by Flanker

The sound of the plane is the same as in il-2. Is it just temporary or final?

Did you read Oleg's first post?

[TeeJay82]

Engine runs with an external program... to me it sounds like your utilizing the a2a`s accusim

is this the case?

[klem]

Originally Posted by Oleg Maddox

I need immediatly to run from office.

Please if you find any materials that to show, read, and you own suggestion - write it here.
I and my guys will read it.

I will be back soon. Hope on Sunday.

Try this Oleg

http://www.rogerdarlington.co.uk/Hurricane.html

"Even with the flame shields over the exhaust, I found the flickering blue flames strangely comforting over the water but, once over the French coast, one felt very conspicuous in the night sky". His squadron colleague Morrie Smith makes the same point: "I felt that everyone for miles around could see the exhaust stubs glowing in the night, but the anti-glare cowlings protected the pilot's night vision from this glow".

"As I descended deeper into the cloud, I experienced a frightening phenomenon: the whole inside of the cockpit was lit up by a red glow. My immediate reaction was: 'Fire!' But there was no heat and all my instruments showed everything to be in order, so I ventured to look outside. My two exhaust manifolds were belching out the usual flame, made perhaps a trifle more red and less blue from being throttled back, and this source had illuminated the surrounding very dense cloud. It was an eerie sensation but, once I knew what it was all about, it ceased to trouble me".

Don't forget the glowing stubs