Usually at daylight or even in the evening there usually is very certain red-light component in the exhaust.

But I went to jabog32's site and downloaded the video where they show how a brand new Su30 is put together and then makes, what I assume is it's maden flight.

In that video while it is taking off the exhaust is all blue in broad daylight !!!!! Ha!!

Is my guess as good as yours? First I was thinking new engines burn fuel more efficiently and olde ones have a lot of carbon in there.

Next guess is maybe the blue shine comes from the engine burning off a lot of substances it got covered with during manufacturing, it could be anything just pictuere the entire assembly line ....

Or is it just that new engines ignite and burn fuel more efficiently causing higher temperatures?

Or is this a picture af a newer model Su with newer engines that have another signature back there?

Or does the factory fuel the Sue with an extra good 'dragster-fuel'

What you think? The podium is yours ....

It also could be the air humidity...

That video is funny when stoned

hi or low humidity? i would guess high humidity then or ?

yes I think you are right. Browsing through my video archive I now find more evidence that the Sue does that, how about takeoff at sea in the polar region ..... blue exhaust , dang I think u r right .....

And your answer is ofcourse: "told you so (shrug)"

it depends on a lot of things.... mostly on the engine model I think. also I think a lot has to do with the age and time since last overhaul of the engine. the t-38's have a nice blue flame if you are looking up the tailpipe and the tornados here have a orange flame looking up the tailpipe. but I swear that at night I saw a tornado with a blue flame lol.... go figure!

Here is a Tu-22M3 (UkAF) in UK taking off in (presumably) high humudity conditions.



link to page

Some time back, I saw 8 Su-30MKI take off at night on full reheat, all with long blue flames. Also, I have seen the same a/c early morning with yellow flames.

Probably, a lot of the color of the flame is related to fuel-air mixture in the combustion within the burner. Have any of you guys done any Oxygen/Acetylene brazing? The flame on the torch starts off orange, with lots of black smoke coming off of it. Then, you slowly increase the level of Oxygen until you get a nice, blue, pencil-point of a flame. The blue flame indicates a more efficient burn of the fuel.

Like the reference to the acetylene torch, the blue flame in afterburner is a result of precisely measured ratios of afterburner fuel to incoming air on a bypass engine. As you know a bypass engine gets a substantial amount of its thrust from the air flow created by the large fan in the engine intake, some of this "bypass" air is rounted into the exhaust along with the required afterburner fuel, the air to fuel ratio is such that a blue afterburner exhaust flame is created.