Why is it so loud when a commercial jet lands?

Question

Why is it so loud when a commercial jet lands? I notice when I am sitting next to the jet engine, I see the inside part of the jet engine slide backwards, is the air of the jet engine being diverted to the side?

Answer 1

the engines would almost be at idle (I'm not exactly sure, i don't fly airliners) and when the wheels make contact with the runway the pilots slams on the reverse thrust. When this is enabled the movement at the back of the engine are levers redirecting the air so the force is opposite to the direction of the aeroplane thus slowing it down faster. The thrust (engine power) also needs to be increased for this to work, and this power in the engines makes it louder.

Answer 2

That's a thrust reverser. The sides open and the back closes up to force the engine's power forward, helping slow the aircraft. This is done with the engines at high power, which is why it's so loud. This process allows an airplane to stop in much less distance than with wheel brakes alone.

Answer 3

both answers are correct it is the thhrust reversers, during its deployment the throttle levers must be at idle otherwise you can't pull the thrust levers uo to deploy, however even though at idle (throttle levers) as the T/R lever is pulled a mechanical cable will enable the solenoid of the Main Engine Control to a high power setting making the sound a full thrust yet the effect is reverse.

Answer 4

"There's a series of sounds that occur at landing that increase the general loudness of the aircraft.

1. The wheels and the vibrations coming up through the ground causes a lot of shakiness, vibrations, and general noise.

2. The spoilers come up, these might not be so audible since the aircraft is at a fairly low speed at landing, but they will still add to the generic loudness of the landing.

3. As most are pointing out, yes the reversers. Since the panels in the engine open up, the sound absorbant material isn't quite as effective, making the engines sound louder even if they aren't fully powered up. Additionally, in turbofan engines (found on all airliners) the cold airstream (air that does not pass through the combustion chamber) produces 70-90% of the thrust, and surrounds the faster moving hot airflow (which does pass through the combustion chamber) at the engine nozzle. The cold air surrounding the hot air reduces the effects of 'shearing' noise. Once the thrust reversers are activated, the cold air no longer surrounds the hot airflow, increasing the noise level of the engine nearly to that found on turbojet engines (found in fighter jets)." -my answer to a similar question.

Sometimes what people don't understand, is that jet engines are spinning WWAAYY too fast to "reverse" in the sense that they spin the other way. All thats happening is panels divert most (not all) of the air out the sides of the engines, in the opposite direction.

Similar question:

http://ca.answers.yahoo.com/question/ind...

Hope it helps!

Answer 5

Thrust reversers . Some have air brakes such as Avro-RJ-85 (Northwest Airlink Regional Jet ) Carried 42 PAX . Recently retired out of the fleet.