Aircraft exhaust?

Question

Normally we can see exhaust fumes coming out of engines fitted to wings of aircraft. At the tail portion of the aircraft also, we can note exhaust fumes coming out. Why it is coming even thou there is no engine at that part.

Answer 1

If the aircraft has an engine a the rear of the fuselage it has an S duct which feeds air into the engine. This S duct is located at the forward section of the vertical stabilizer and the engine expels exhausts fumes as normal. Another area where you may see fumes at the rear of the fuselage comes from the auxiliary power unit which maintains power while the aircraft is idle. The APU has an exhaust which which expels fumes to the rear right hand section of the fuselage. An example of an aircraft with an S duct which feeds the engine at the rear of the fuselage is the boeing 727

Answer 2

First of all it isn't exhaust (meaning unburned fuel) fumes!! It is called a "con-trail" (condensation trail). The aircraft moving through the atmosphere at high speed makes tremendous pressure presure changes as it moves along, - the pressure literally "squeezes" the mioisture out of the air into droplets - which makes a string of "cloud" behind the ariplane! "Cloud" is just what it is too, as it is made of the same thing!! This pressure makes turbulence - which makes a trail , which makes the trail pretty much stay in a direct path behind the plane! If it curves one way or the other, you are actually seeing the air currents (wind) in action! After a considerable time it finally vaporizes and goes back ito the air making it invisible again! There is a minor component that heat from the engines plays too, but it is a small part!

If you go to a "small plane" airport early in the monrning - Preferably around 40-50 detgrees temperateure and high humidity day, -- watch the airplanes "run up' their engines when they check out to make sure they have full power before take off!
If you are close enough, you will see water flying off the tips of the propeller. If you are lucky to be at the right angle to the sun, you will see a rainbow there! This is because the propeller makes so much pressure, - and the tips of the prop are traveling at almost the speed of sound!

Answer 3

All good answers.

Modern jet aircraft have a component (actually, they usually have two) called an pressurization pack. The packs take compressed air from the engines and use it to pressurize the cabin and regulate the temperature. The packs dissipate heat, which can appear as "exhaust" at the rear of the aircraft.

Answer 4

You are seeing the exhaust of the APU (Auxiliary Power Unit) The APU is a small gas turbine engine that runs off the main fuel supply of the aircraft and is used, as the name suggests, to provide supplemental power on the ground. and sometimes during flight.

Answer 5

Transport airplanes like the Boeing 747 do have engine in the tail section which is called the Auxillary Power Unit (APU). . It is there for two reasons:
1) to run an additional electrical generator.
2) to provide compressed air (pneumatics) for main engine starting, air-conditioning and pressurization.

This APU is not used for propulsion.

Answer 6

There are other mechanics on the aircraft that generate heat. Particularly when on the ground. The other power sources have to have a way to expel their heat and thus it is piped up through the tail section you are referencing.

Answer 7

Because most planes have an exhaust port there as well. I'm not sure why but I noticed it while getting ready for take-off one day.

Answer 8

Exhaust plume from the auxiliary power units.

Answer 9

Maybe its giving the illusion because it is so far away.. up high... the aerodynamics may cause the exhaust to travel a certain direction.. illusion is my guess