|
|
|
|
#1
12-12-2010, 09:13 AM
|
|||
|
|||
From Jack Torrence, 43 Squadron Hurricane II night intruder pilot.
Quote:
|
|
#2
12-13-2010, 02:36 PM
|
|||
|
|||
|
Flame color...
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.
__________________
"A witty saying proves nothing" - Voltaire |
|
#3
12-13-2010, 03:12 PM
|
|||
|
|||
|
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.
|
|
#4
12-13-2010, 10:04 PM
|
|||
|
|||
|
Quote:
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.
|
|
#5
12-14-2010, 05:33 AM
|
|||
|
|||
|
Oleg,
If you havent already recieved enough info at this point, I want you to know that the flame color coming out of the exhaust of a running engine like that would be more blue! than red or yellow. The flame is burning hot and mostly clean, so it comes out with a nice blue flame at night. In the day, you wont see it. On engine start, the only time you will get the yellow/orange flame out the exhaust is if the engine is too rich and it spits out unburnt fuel that burns exiting the exhaust stack. In that case you will get a lot of orange/yellow fire coming out for a short time. I was on the wing of a P-51 when that happened and it does get warm... Note: its easiest to over prime with the electric fuel pumps found on P-51s and the like. *edit The short stacks in most of the videos lets you see a lot of blue flame...more than if the full length stack was in place. If you leave the exhaust as is with no blue, you really will be misrepresenting the way exhaust looks coming out of the stacks at night... This video (previously posted) shows what I would expect to see coming from the exhaust at high power settings at night...see it at 0:30 video time This video shows over priming at about 5:30. His first couple of attempts to start were underprimed and he didnt keep it running with additional priming. Also, when you go from high power to low power rapidly, you will get some light popping and orange flame as the rpm comes down. Good luck with your great project! Chill31 *edit, looking back at all of the posts, it looks well covered! Last edited by Chill31; 12-14-2010 at 07:53 AM. |
|
#6
12-10-2010, 03:29 PM
|
|||
|
|||
|
Quote:
We have original table of the exhaust colors by which British crew were need to define is in good or not so good conditions the engine before the flight... |
|
#7
12-10-2010, 03:35 PM
|
|||
|
|||
|
Quote:
Ok, but even if it's dependent on those factors, and there would be set of factors that would produce yellow colors like in the video you posted, it's still too yellow. Actually, the problem is (as far as I can see in compressed video) that the spectrum is too narrow. There should be a wider range of subtle hue/value (not saturation) difference in the different flames as they appear, in some random pattern. It's however hard to tell -- who knows what the video codec does, and then it's that everyone has a different monitor. I played it however on my color calibrated Wacom Cintiq, and that is what I thought first. |
|
#8
12-10-2010, 06:44 PM
|
|||
|
|||
|
Quote:
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 
|
|
#10
12-10-2010, 07:10 PM
|
|||
|
|||
|
Is anyone familiar with the colour produced when the 'Ki gas' primer is used with full rich mixture, 100 octane fuel and a cold engine?
These are the only factors I can think of which might together produce a yellow flame, other than unburnt fuel igniting against hot exhaust stubs, which from video evidence already posted is more orange. Otherwise, I'm a little confused as to why our opinions were invited. All evidences posted point to blue flames and yet we're told we're wrong. 'Confused' of Milton Keynes |
 |
|
|
Hybrid Mode
