ti think youl find that photo is off 85 sqdn

While I do agree that the initial engine startup (flames) is too fast, as for the rest - the engine flames should behave depending on how we use the engine. Different mixtures and priming should effect how the flames look (color and volume). Not to mention the overall effects that different usage will have on the engine, like shown in the videos.

These look like startup pictures to me Harti. btw it's a griffon engine but the merlins look similar on initial startup.

i like the wealth of knowledge that is displayed here sometimes. from a brief video and question on flame colour we get a huge discussion on possible engine states etc, actually learnt quite a bit. so has the question been answered with another one - will the flame colour reflect different levels of fuel/air mixture and engine condition, and if so, what are the factors at play in the video to give this particular flame?

We have videos showing it, some have seen it and most have read it in the accounts from pilots and crew that flew.

The Halifax I and II had terrible trouble with their positions being given away by blue exhaust flame from the merlins. They tried to cover it with metal guards but they glowed red instead. Only when the hercules engines were fitted in the III was the problem resolved.

I would like to hear the argument and evidence as to why it should be red and yellow rather than blue.

I have many airshow daytime films of Hurricanes, Spitfires and the Buchon (merlin-engined) 109 taxying and low passing. There are no flames visible in any of these films. They would often give yellow 'flowers' of flame on startup (see other posts) so your video seems generally correct for daytime conditions except the exhaust gases seem to have too much "thrust" on that initial startup.

It's about the startup effect and not the exhaust glow of running engines. Whether we'll see a blue glow at night, possibly even depending on engine settings as explained in some posts (probably overkill though), is a different issue. Fingers crossed :)

Anyway, nice details and I'm especially happy to see the subtle reflectivity on the plane skin again, which has been absenst in all screens since months.

You know on one of the other sim forums they're having a discussion about why an HP 0/400 might still be able to fly with no wings and only 1 engine, I guess we should count ourselves lucky all we got is what colour the exhaust flames should be

Thanks for the update Oleg!

About the flames, it seems to me there are two main effects:

1. Yellow / red flames from excess fuel exiting the exhaust sometimes during startup. This is so visible it can be seen both at day and night, as shown in pictures in this thread. This is probably so bright it will illuminate the plane at night.

2. Blue flames: at night you can see that the exhaust itself is has a blue glowing color, at least at high power settings (see the Reno video earlier in this thread). This isn't very visible in daytime. Pilots often describe seeing only the blue exhaust flames of the enemy planes at night.

Edit: So my conclusion is:
- The startup flame in your first video looks perfect (and this should illuminate the plane if seen at night)
- The yellow flames in your night video: If this is supposed to be the second effect (engine running smoothly), the flames should probably be more blue and not illuminate the plane that much. But my main reference is the Reno video earlier in this thread, maybe running at lower power settings with shorter exhaust pipes (Spitfire vs. Sea Fury) gives more yellowish flames.

Here is another example of the first kind of flame:
http://www.youtube.com/watch?v=uNXGDi79aPw

Sorry, but the motor in the dark is running, not starting up. The timing between the flashes is too even. Also, if it was starting up, we'd presumably see a similar long flame to the daytime start clip.

Skoshi does have a point in the cylinder scavenging / cam overlap being a possible source of unburnt fuel, but all the video and literary evidence screams 'blue!';)