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

I wanted to post this before but just didnt have time:

As Oleg explained, the flame output of an exhaust is affected by factors like temperature and pressure. Flames visibility is due mainly to lighting factors (it'll be harder to see flames on a sunny day), but they're always there (bear in mind that what you see is the output of the avgas combustion straight from the combustion chamber!).
Exhaust fire shouldn't be confused with backfire though, which is an external combustion of a too rich mixture which causes flames like this


Oleg, I love the work you're doing, the attention to details as usual is surprising and comes from a man who obviously has experience with aviation, my humble suggestion is to keep the flames towards the red/blue spectrum more than yellow, since the temperatures involved are far higher than a "yellow flame" when it comes to exhaust output. Another important aspect is to keep them subtle (in terms of transparency/alpha channel) but visible from distance (thinking of the Zerstoerer night fighters spotting the engine exhausts of Lancasters at a certain distance).

[Richie]

Originally Posted by Sternjaeger

I wanted to post this before but just didnt have time:

As Oleg explained, the flame output of an exhaust is affected by factors like temperature and pressure. Flames visibility is due mainly to lighting factors (it'll be harder to see flames on a sunny day), but they're always there (bear in mind that what you see is the output of the avgas combustion straight from the combustion chamber!).
Exhaust fire shouldn't be confused with backfire though, which is an external combustion of a too rich mixture which causes flames like this


Oleg, I love the work you're doing, the attention to details as usual is surprising and comes from a man who obviously has experience with aviation, my humble suggestion is to keep the flames towards the red/blue spectrum more than yellow, since the temperatures involved are far higher than a "yellow flame" when it comes to exhaust output. Another important aspect is to keep them subtle (in terms of transparency/alpha channel) but visible from distance (thinking of the Zerstoerer night fighters spotting the engine exhausts of Lancasters at a certain distance).

This has nothing to do with the engine running normally it's just raw fuel on fire. That engine probably isn't even running yet. The wind from the prop would blow it out.

http://www.youtube.com/watch?v=EoyN29O8UoE

[WTE_Galway]

Originally Posted by Richie

This has nothing to do with the engine running normally it's just raw fuel on fire. That engine probably isn't even running yet. The wind from the prop would blow it out.

Half right ... once an engine fires the manifold vacuum and exhaust pressure extinguish any carby or stack fires.

The main, well documented, issue on WWII war-birds was the glow of the hot manifolds at night, interfering with pilot visibility (especially in high mounted manifold designs like the hurricane and spitfire) and making the aircraft a target to night fighters. A number of different design features were tried to mask this manifold glow.

[AndyJWest]

Yes, you have a point. It isn't the exhaust that is glowing, but the exhaust manifold. Inevitably this will be at a significantly lowe temperature than the exhaust itself, so where the exhaust is flame may be blue, the manifold will be yellow or red.

Originally Posted by Richie

This has nothing to do with the engine running normally it's just raw fuel on fire. That engine probably isn't even running yet. The wind from the prop would blow it out.

well first of all is mixture, not raw fuel, on fire; second, if you READ what I wrote you might well see that that's exactly was I was talking about