Afterburner and smokies!

[chunder27]

Couple of things

Was watching some footage the other day of a few Russian planes and noticed their afterburner glow is blue rather than the fiery colour of most other planes. Any idea why? Fuel?

Also, why do planes like the Mig29 smoke so much! The J79 engine in lots of cold war stuff smokes like hell without reheat, why does it do so and why dont other engines smoke?

It seems a characteristic of the 29 too on normal flight

[Mave]

It would be interesting to know which ones are blue - I suspect it's due to the flame temperature - not all reheat temperatures are the same. Similar reason why some engines are smoky and some aren't. There are lots of trades designing a combustor to operate around the flight envelope (and a reheat / afterburner is just a lower pressure combustor). Most smokey engines will be down to either fuel mixing / vaporisation performance , or small combustor volume considering how much heat release you are trying to achieve. Poor quality fuel won't help either.

[chunder27]

I was looking at a behind shot of a Tupolev Backfire taking off, their reheat is blue, looks amazing, am sure too that early Flankers had a similar hue.

I have since read the smoke is due to a few things. early J79's was something to do with the way the fuel was introduced and was since helped a bit.

and Mig29's it was fixed for later models but if someone bought early ones they still smoke a lot.

Not sure it is anything to do with poor maintenance or fuel quality.

[Krikkit]

The colour is all about the design changing the flame temperature.

Superficially I'd guess a higher temp produces higher total thrust, but reduces material life in the components?

[mcdjl]

The flame colour can also sometimes be an effect of the viewing angle and sky colour. Look at the jet from behind and the red/orange will dominate, from the side on a blue sky and the same is true. On a grey day from the side or front the blue will become more visible (though the orange will still be there)

[drdino]

chunder27 said:

I was looking at a behind shot of a Tupolev Backfire taking off, their reheat is blue, looks amazing, am sure too that early Flankers had a similar hue.

[IanUAE]

That's not reheat, the warp engines have been engaged.

[Eric Mc]

I remember watching a Mirage 4000 performing at Farnborough (1988) and it had very pink afterburner glow.

[chunder27]

Awesome shot Dino, that's exactly what I meant, that is not a mis colour, that is very blue

They came to visit in the early 00's and I missed them back then. Dammit.

[RichGault]

I was stood on the end of the runway at Cottesmore 2000 as the Backfire launched......loud isn't the word....

[Eric Mc]

Backfire fans might like this video I took back in 1992 -


https://www.youtube.com/watch?v=6BgjvqyESqk&t=...

[Simpo Two]

If the science is anything like a Bunsen burner, blue is more efficient (hotter) than yellow. More complete combustion. And as for smoke, well, Russia doesn't have to obey EU emission regulations...