Engines Smoking After Takeoff

[BAe 146-100]

Hi,

I'm intrested to know why some aircraft's engines smoke after takeoff. What is this to do with? :confused:

A300 After Takeoff (http://www.airliners.net/open.file/306599/M/)

B747-400 After Takeoff (http://www.airliners.net/open.file/293879/M/)

MD-11 After Takeoff (http://www.airliners.net/open.file/278362/M/)

Regards
BAe 146-100

[PAXboy]

Since it is quiet in here on a Saturday evening, a non-expert reply!

This is unburnt fuel. In the same way that you may see a car with a slightly smoking exhaust. If you REALLY want to see smoke, watch a B52 departing and you will see why it is said that they are coal fired.

The reason, as far as I know, is that the engine is working at (or near) maximum and is unable to use all of the fuel BUT that the balance between pumping in enough 'go juice' and not quite enough is a fine balance. It is affected by the actual take off weight of the machine, temperature of air at the intake, and a number of other factors. The error is always on the side of enough fuel rather than the 'not quite enough fuel'!

Right, now let me sit back and be shot down in flames. Or would that be shot down in smoke?:p

[chiglet]

Look at a B737/200, B727, TU154 on LANDING, never mind t/o:(
I once [in the '70's] watched a "Vulcan Scramble" :ok: The runway was "IMC" for a couple of mins:rolleyes: Triffick:ok:
we aim to please, it keeps the cleaners happy

[ETOPS]

It's interesting that that two of the photo's above show North American operators. Here in Europe we use Jet A1 whereas in the USA it's Jet A. The main difference for airline operations is the respective freeze points (-47 C for A1 and -40 C for A) but a side effect is the visible smoke generated by so called "wide cut" fuels such as A. An even better example is the military equivalent used by US forces called JP5. Not only is this very smokey it is prohibited in civil use............

[VS-075]

I live in manchester and you can see the Tu 154 coming miles away smoking to land its interesting to know of the different fuels i did not know about i thought it was old technology obviously not.

[ramsrc]

They don't make 'em like this anymore :(

707 Takeoff (http://www.airliners.net/open.file/199056/M/)
Landing 707 (http://www.airliners.net/open.file/052404/M/)

[Georgeablelovehowindia]

The Convair 990 was a smokey old bird, until they modified the combustion chambers, which improved it a lot.
One of Britannia's 737-200s flew around for a long time with a very smokey engine on one side and a very clean one on the other. Weird.

[PAXboy]

ETOPS, thanks for the detail of the fuels. Do you know why the JP5 is not permitted for civilian use and what benefits does it bring the air force?

Also, as engines may produce smoke on approach, my suggestion (above) appears to be wrong. I had thought that the engines working at max might smoke on departure but not in the cruise. Is the anti-ice component the main reason for smoke?

Thanks.

[ETOPS]

JP 5 has a higher flash point than civil Jet A/A1 thus can ignite more easily. The selling point of Jet A1 is you can drop a lighted match in a pool of it without causing a blast. Don't try that with JP 5..............

[chiglet]

was it Lord Brabazon who said to his US "opposite number"
I will stand in a pool of JP1? and you stand in a pool of JP4? and we will drop lighted matches. Needless to say, it wasn't taken up
we aim to please, it keeps the cleaners happy
[I cannot remember the designations in use at the time, sorreeee

[BAe 146-100]

Hi,

Thanks for your reply's :ok:.

Regards
BAe 146-100

[Unwell_Raptor]

The engines may smoke but the passengers may not.

[mustafagander]

As I understand it, jet A and jet A1 are NOT wide cut fuels. JP4 is the wide cut fuel. Wide cut means a larger number of the fractions of oil distillation. This is what makes JP4 lethal to handle. At room temperatures in an open container, jet A is too lean to burn, avgas is too rich and JP4 is just right. I have watched the old demo - toss a cigarette butt into a can of jet A and avgas no problems, but I've never met any survivors using JP4. It certainly impresses the apprentices when someone flicks a butt into a can of fuel!!!

[PAXboy]

How interesting. Now for a silly question ...

Why to the Americans use a different fuel to Europeans? Is the freeze point the only diff?

For the military, is it due to the engines functioning in a very different manner? Is the 'tuning' (in layman terms) of the engine that much different?

Thanks.

[chiglet]

Cost:( JP4 is cheaper
we aim to please, it keeps the cleaners happy

[Golden Rivet]

More likely to be burnt oil.

[PAXboy]

Ah, interesting. So, if it is oil, why just during depart/arrive? I think it is rare to see smoking engines in the cruise?

[tom775257]

A touch off topic, but: After engine start do you leave the PACKs turned off for a while to allow any smoke to clear before turning them on – saving pumping the aircraft full of nasty fumes?? (e.g. if you have a tail-wind on start-up blowing smoke forward allowing it into the engine inlet)
cheers..

[Cornish Jack]

Maybe one or two other 'wrinklies' remember the tale of the Pan Am 707 taking off at LHR in front of a (then) BOAC Comet. The 707 departed in its usual smoke cloud and the Comet requested an IFR take-off. The Pan Am response was "Son, when you grow up, you'll be allowed to smoke, too" ;)