Why do jet engines roar during reverse thrusting in aircrafts?

Question

Why do jet engines roar during reverse thrusting in aircrafts?

Answer 1

What they said, and the plural of aircraft is aircraft, with no s.

A thumbs down? I guess you want Jude to appear grammatically stupid. Sorry, but aircrafts bothers me ALMOST as much as people writing your, when they mean you're.

Answer 2

well durring reverse thrust the whole jet encasing opens when its shut not all the air is comppressed that air is is what they call bleed air used to cool avionics when at altutude also to cool and pressurize the cabin but during reverse thrust the incoming air moving at close to 130 MPH has to come to a dead stop then pumps its way back out against all the other air plus heres an example take a leaf blower or something that produce wind and divert it back to it will roar slightly too dont quote me  

Answer 3

Because applying reverse thrust involves opening the throttles.  Jet engines make that kind of noise, and if you are there, you will hear it.

Answer 4

its the throtles just like when they take off you are aking more from the blowing the end! Most aircraft you fly are not true Jets they are high-bypass fans and when the fan sleeve is deployed  after the gear squatch switch is engaged the air that was directed back for thrust is now ducted  in a different direction  

Answer 5

When the aircraft is going forward the thrust of the engine   is going behind you and you don't hear it. When the reverse thrust is engaged the thrust is directed  forward toward the front of the aircraft so you hear it. As simple as I can explain it.  

Answer 6

They don't.  Their exhaust streams break up in the air well away from the engines.  That is where the roar eminates from.

Answer 7

jet engines roar during reverse thrusting because when you are in front of the aircraft and the engines are at normal thrusting you hear a load roar but when it goes in reverse the rotation inside goes the opposite of normal so just imagine the engines turing 180 so the engine is going to roar because you are in front of where the engine are taking in air  

Answer 8

see those flap like things from the back on the engine?

http://upload.wikimedia.org/wikipedia/co...

These are on every plane. When the pilot engages reverse thrust these deploy and makes the engine exhaust  go forward at a high rate of speed disrupting and causing "rough" or "turbulent" airflow, which as mike said, produces more noise energy

Answer 9

During reverse operation a jet engine is more unstable and subject to engine surge (compressor stall) due to the exhaust area rematch created by the reversers being deployed.  To stabilize the engine, air bleeds in the compressor are open and dump air overboard to unload the compressors.  This high pressure high velocity air creates an additional loud hissing sound (adding to the other engine noise) which can be heard during high power reverse operation.

I have to admit I found some of the other answers amusing.

Answer 10

In simplified terms, the reason the engines "roar" during reverse thrust is because the action of the thrust reversers is to block and redirect the engine exhaust forwards. This creates very turbulent airflow which produces more noise energy than it would if it were smoothly flowing in its normal direction.

Also through the touchdown phase the engines are at idle thrust, but increase power when reverse thrust is selected, adding significantly to this noise.

Answer 11

The noise during thrust reversing is higher than when going forward due to the noise being reflected back from the runway, from the flaps deployed down from the wing, and the wing itself. The aircraft is slowing, so the doppler effect lowers the pitch of the noise, and because the wind is now going toward the aircraft instead of behind it. All of this adds up to more noise inside the aircraft.

Regards,

Dan

Answer 12

it has something to do with the air going in a totally different direction but it isn't the prime reason.

JET ENGINES ROAR. face it. When the throttles are advanced they will ROOOAAAARRRR.

now depending where you are on the aircraft or where you on are the ground, reverse thrust or not, as soon as the throttles are advanced you will hear the roar!

reverse thrust involves redirecting some of the air coming out of the engine forwards (not completely forward, but at an angle) however, the engines are also throttled up for this to be really effective.

this creates most of the noise. other noise producing factors during reverse thrust is obviously turbulent air, and depending on reverser type, noise levels will be higher because the engine cowling is "opened" which negates somewhat the sound dampening equipment inside. It's like having a wall removed from between you and the engine.