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Airbus and Boeing a story of noise

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posted on Aug, 29 2007 @ 07:07 AM
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Sorry for those who wish this to be a flame thread, it isn't. I have a real question requiring answers and perhaps debate from the experts on this forum... Yes Waynos I mean you (other experts are of course available).

I fly a lot (ask my children) and I have noticed that when I fly in an A319/320 etc the internal noise level seems (sorry subjective, but hey, I have ears) lower than the noise I percieve when I fly in a 737 100/200/300 etc wherever I sit in the plane. The question is why should this be the case. The technology of active noise generators being used to cancel noise is not new and is used in both planes, so why do I hear a difference (a significant one)

Anyway experts please fill me in on the details I can't wait to read the results.




posted on Aug, 29 2007 @ 07:24 AM
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There are a lot of factors, but the biggest according to your post is that you fly a lot in 737-100 and -200, which have low bypass turbofans which by their very nature are louder than high bypass turbofans.

The A320 design is also newer than the 737, meaning slightly better aerodynamics than the 737, which again contributes - most of the noise you hear in the cabin during cruise is infact the wind outside the cabin and not the engines.

Other than that, its just how the manufacturers make them - many people swear that the A340 is quieter internally than the 777 as well, and many comments have been made about how quiet the A380 is in the cabin, but I personally haven't heard many cases where a Boeing is quieter internally - maybe its just that I haven't heard any, or maybe its just an indication that the two different manufacturers concentrate on different things.

A white or pink noise generator would incur a weight penalty on each trip, so theres little reason to carry one since it doesn't have a huge effect. Even a couple of kilograms add up across the lifetime of the airframe.



posted on Aug, 29 2007 @ 07:49 AM
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I don't know of any Boeing/Airbus having active noise surpression/cancellation. The Bombardier Dash 8 turboprop does (and that is a major contributor to its success).


As Richard says, the 320 is a newer design than the 737 and it has larger BPR engines.


There will be different noise levels in different locations on the plane, and the composition of the overall sound pressure level will be different at each position as well. This is mainly related to your position relative to the engines.

There is also extensive acoustic treatments within the engine nacelle itself, and the efficiency of these will help determine the level of noise you will hear in the cabin.

Again, 320 being newer will have better - but the 737-6/7/8/9 shouldn't be too far away as its a pretty straightforward part of a redesign/update.



edit: [little known fact] The engines of the A380 are sized for take-off/landing at Heathrow (and fitting into a 747 cargo hold), not for maximum efficiency in cruise



[edit on 29/8/07 by kilcoo316]



posted on Aug, 29 2007 @ 07:58 AM
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Thanks Richard

I appreciate your quick response. I fly a great deal and I only used the 1,2,300 as examples. These are usually the connecting flights to some longer piece I am usually tired, and my noise cancelling headphones have begun to bore me. I am wide awake at three am going to some god forsaken place and all I can hear is the windnoise and the engines.

In the Airbuses it is definitely less than in any 737. I just wondered why with equal access to noise reduction and cancellation technology Airbus, according to my ears, do it better.

To put this in context I fly roughly 40-50 % of the days of my working year.

777 is great for noise, 747 is rubbish (even the 400) the 340 is good and the 330 is good as well. 767 is yuch too.

Basically as I sit "up the front" with my cool beverage the wind noise is more noticeable than the engines most of the time.

In my opinion Trents rule in the cabin.

I hope someone can tell me what Airbus do differently than Boeing.



posted on Aug, 29 2007 @ 08:06 AM
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Thanks Guys

I had assumed the 777 did have actice cancellation as it is so good but I am happy to be wrong on that one thanks for the information. I used to fly into Karlskoga in Sweden in an old turboprop, get out and not hear anything very well for at least ten minutes. It usually took that long for my stomach to settle down too.

thanks again..



posted on Aug, 29 2007 @ 08:07 AM
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Originally posted by kilcoo316

edit: [little known fact] The engines of the A380 are sized for take-off/landing at Heathrow (and fitting into a 747 cargo hold), not for maximum efficiency in cruise



Actually only the Trent 900 will fit on a 747F fully assembled, the GP7200 needs to be partially disassembled for shipping, or it needs to be shipped on an An-124. This means usually a GP7200 equipped A380 cannot have an engine replaced in the field.

Neither will fit in a standard 747 belly cargo hold.

The efficiency between the two engines is marginal, the GP7200 needs a larger fan to equal the efficiency that the Trent 900 gets with its triple spool design.



posted on Aug, 29 2007 @ 08:12 AM
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Originally posted by RichardPrice
Actually only the Trent 900 will fit on a 747F fully assembled, the GP7200 needs to be partially disassembled for shipping, or it needs to be shipped on an An-124. This means usually a GP7200 equipped A380 cannot have an engine replaced in the field.



Ahh - I had been told it was a design requirement



Unless, that was something Airbus let the engine manuf and customers work out between them. Then they come to Airbus and tell them which engine they want.



posted on Aug, 29 2007 @ 09:05 AM
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Originally posted by kilcoo316

Ahh - I had been told it was a design requirement



Unless, that was something Airbus let the engine manuf and customers work out between them. Then they come to Airbus and tell them which engine they want.


The noise limit for Heathrow was a requirement, but I have never heard of an engine size limit imposed by either Airbus nor Boeing other than what will physically fit on a wing.



posted on Aug, 29 2007 @ 11:07 AM
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Originally posted by RichardPrice
The noise limit for Heathrow was a requirement, but I have never heard of an engine size limit imposed by either Airbus nor Boeing other than what will physically fit on a wing.


It wasn't a size requirement for the the aircraft - it was (as I had been led to believe) to do with getting a spare engine out to a 380 stranded on an airport with a dud engine.


Hence, my point about perhaps that was an issue between the airlines and the engine makers, and not really much to do with Airbus.


*shrugs*



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