acroairfun
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Airbus A321 Noise

Fri Aug 31, 2007 8:14 pm

I saw the aircraft noise charts and I saw that A321 introduced in 1994 is noisy like Boeing 747-300 introduced in 1980! Why?
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PADSpot
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RE: Airbus A321 Noise

Sat Sep 01, 2007 1:56 am

Are referring to outside noise emissions or the noise level inside the cabin?
 
JeffB
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RE: Airbus A321 Noise

Sat Sep 01, 2007 2:33 am

Quoting AcroAirFun (Thread starter):
I saw the aircraft noise charts and I saw that A321 introduced in 1994 is noisy like Boeing 747-300 introduced in 1980! Why?

That makes absolutely no sense to me. 2 engines on a smaller plane making more noise than a 747 w/ 4 engines and less noise dampening systems?

Can you provide a link to said charts? or maybe a description of where you saw these charts?
 
ncelhr
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RE: Airbus A321 Noise

Sat Sep 01, 2007 3:07 am

That's right, an A321 is noisier at takeoff than a B743 at idle.

This doesn't make sense. Too many parameters - gotta see the charts.
 
ca2ohHP
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RE: Airbus A321 Noise

Sat Sep 01, 2007 3:23 am

I fly the A321 alot, and I do notice that it seems much louder on takeoff (particularly in the back) on takeoff until the power reduction after being airborne 90-120 seconds.
 
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zeke
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RE: Airbus A321 Noise

Sat Sep 01, 2007 3:54 am

I think this is a clear case of someone reading some numbers an not knowing what they mean, in summary a A321-200 is much quieter than a 747-300.

A 747-300 with a TOW 377,800 kg and CF6-80C2B1 has the following noise characteristics relative to Chapter 3

Flyover - 6.9
Sideline - 4.6
Approach - -0.2
Cumulative - 11.3

An A213-200 with a TOW 93,000 kg and V2533A5 has the following noise characteristics relative to Chapter 3

Flyover - 4.6
Sideline - 2.4
Approach - 5.5
Cumulative - 12.5

Above numbers from http://www.aci.aero/aci/aci/file/ACI...ties/Environment/ACINoiseIndex.pdf

But what does relative to Chapter 3 mean ?

We need to look at ICAO Annex16, Volume I, Attachment A

Between a TOW of 35 and 400t, the sideline noise is defined as 80.87 + 8.51 log(TOW)

747-300 = 80.87 + 8.51 log (377.8) = 102.80 EPNdB
321-200 = 80.87 + 8.51 log (93.0) = 97.62 EPNdB

747-300 margin over chapter 3 is 4.6 = sideline noise generated is 102.80 - 4.6 = 98.20 EPNdB
321-200 margin over chapter 3 is 2.4 = sideline noise generated is 97.62 - 2.4 = 95.22 EPNdB

A321-200 is 2.98 EPNdB quieter

Between a TOW of 35 and 280t, the approach noise is defined as 86.03 + 7.75 log(TOW), above 280t it is a flat 105

747-300 = 105 EPNdB
321-200 = 86.03 + 7.75 log (93.0) = 101.29 EPNdB

747-300 margin over chapter 3 is -0.2 = approach noise generated is 105 + 0.2 = 105.2 EPNdB
321-200 margin over chapter 3 is 5.5= approach noise generated is 101.29 - 5.5 = 95.79 EPNdB

A321-200 is 9.41 EPNdB quieter

Between a TOW of 48.1 and 385t, the flyover noise for twin engine aircraft is defined as 66.65 + 13.29 log(TOW)
Between a TOW of 20.2 and 385t, the flyover noise for four engine aircraft is defined as 71.65 + 13.29 log(TOW)

747-300 = 71.65 + 13.29 log (377.8) = 105.90 EPNdB
321-200 = 66.65 + 13.29 log (93.0) = 92.81 EPNdB

747-300 margin over chapter 3 is 6.9 = flyover noise generated is 105.90 - 6.9 = 106.10 EPNdB
321-200 margin over chapter 3 is 4.6 = flyover noise generated is 92.81 - 4.6 = 87.31 EPNdB

A321-200 is 18.79 EPNdB quieter

In summary,

the 747-300 has a 11.3 EPNdB cumulative margin over chapter 3, the 747-300 chapter 3 cumulative limit is 313.70 EPNdB

the 321-200 has a 12.5 EPNdB cumulative margin over chapter 3, the 321-200 chapter 3 cumulative limit is 291.72
EPNdB

The A321-200 is 31.19 EPNdB cumulatively quieter than a 747-300, as expected.

[Edited 2007-08-31 21:20:40]
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PADSpot
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RE: Airbus A321 Noise

Sat Sep 01, 2007 4:12 am

Quoting Zeke (Reply 5):
747-300 margin over chapter 3 is 4.6 = sideline noise generated is 102.80 - 4.6 = 98.20 EPNdB
747-300 margin over chapter 3 is 2.4 = sideline noise generated is 97.62 - 2.4 = 95.22 EPNdB



Quoting Zeke (Reply 5):
747-300 margin over chapter 3 is -0.2 = approach noise generated is 105 + 0.2 = 105.2 EPNdB
747-300 margin over chapter 3 is 5.5= approach noise generated is 101.29 - 5.5 = 95.79 EPNdB



Quoting Zeke (Reply 5):
747-300 margin over chapter 3 is 6.9 = flyover noise generated is 105.90 - 6.9 = 106.10 EPNdB
747-300 margin over chapter 3 is 4.6 = flyover noise generated is 92.81 - 4.6 = 87.31 EPNdB

the lower line in each section shall refer to the A321 and not the B743, right? Impressive number cracking ... but how does 31.19 EPNdB feel?

[Edited 2007-08-31 21:21:57]
 
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zeke
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RE: Airbus A321 Noise

Sat Sep 01, 2007 4:22 am

Quoting PADSpot (Reply 7):

the lower line in each section shall refer to the A321 and not the B743, right?

Correct, fixed, thanks, just copied and pasted the first line and changed the numbers, and forgot to change the model.
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Claude
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RE: Airbus A321 Noise

Sat Sep 01, 2007 3:19 pm

hi, i guess you've heard an A321 with maybe a bit thrust just before landing, but surrely not more than a 743!
how many drinks did you have lol  Wink
 
ThePRGuy
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RE: Airbus A321 Noise

Sat Sep 01, 2007 6:17 pm

I've flown a lot of 321s recently, and perhaps you are referring to the whine you get with some of the 320 series engines with age?
I personally enjoy the noise very much so!
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TurkishWings
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RE: Airbus A321 Noise

Sat Sep 01, 2007 6:34 pm

I noticed that sound too.. Especially during take off...

Recently, I flew on a few A 321s of TK and noticed that the whole cabin shudderes when the plane touches down.. Is this also common with this type? It felt like the cabin of a very very young plane was falling apart...
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flanker
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RE: Airbus A321 Noise

Sat Sep 01, 2007 10:36 pm

I have not noticed anything weird like that. Must be because i like engine noise, but anyway i love how quiet the A320 family is when powe is reduced after takeoff. It almost scares you. I remember the first time i flew an a321 when power was reduced i thought we had lost the engine on the side i was sitting. Its SOOOOOOOOO quiet. lol
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