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Topic: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Keesje
Posted 2009-02-04 04:34:43 and read 15545 times.

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While the first flight and service entry of the Boeing 787 with ANA gets closer and closer we already know it will be comfortable. It will provide passengers more room (although airlines are in charge here), it provides a lower cabin attitude (reducing fatigue) and offers higher cabin humidity. Then there is the larger windows and nice cabin design, including larger bins and lavatories.


Photo: http://www.daylife.com/photo/03ih6roeQL9xK

Now what about cabin noise? I did a little googling and it strikes my this specific topic seems to be absent everywhere from the start. http://www.boeing.com/news/feature/aa2006/787_cabin.pdf

I suppose from an engine perspective Rolls Royce / GE / Boeing should be able to achieve the same low external noise levels as e.g. the A380.

Maybe the innovative CRFP fuselage has a different noise propagation then a conventional metal fuselage. Thinner, lighter and stiffer materials do not immediately make me feel as better for noise insulation.


Photo: http://www.flightglobal.com/blogs/flightblogger/

In June 08 (well after the Dreamliners design freeze) a Memorandum by the Boeing Company said:

Boeing has set aggressive cabin noise level targets for the 787. Targeted noise levels are less than existing in-service aircraft.

http://www.publications.parliament.u...0708/ldselect/ldsctech/7/7we07.htm

 arrow  I wonder if that means a little better then 747/757/767 or e.g. on par with the A380.

Any newer / better info available on this?

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: AA737-823
Posted 2009-02-04 04:50:13 and read 15524 times.

Keesje, I'm surprised. Do a search- we discussed it about a year ago.

It was SUPPOSED to be targeted to be quieter than anything else, and then through a weight reduction program, that all changed. Boeing did some weird research showing that passengers actually prefer a loud cabin, so that they can't hear babies crying.
Randy wrote about it on his blog.
I called foul, and wrote a very long reply that I was disappointed that Boeing was being cheap and telling us it's what we, as passengers, prefer.
Randy respected my views.

There was a thread here about the whole thing.


Anyhow, so, it's going to be noisy, I suspect Airbus will MAINTAIN their quieter cabin lead.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Keesje
Posted 2009-02-04 05:05:54 and read 15467 times.



Quoting AA737-823 (Reply 1):
Do a search- we discussed it about a year ago.

AA737-823 thnx I don't remember / can't find. Do you mean this one? (short & not specific)
http://www.airliners.net/aviation-fo...general_aviation/read.main/3823113

The Discussion you mention was on a different topic I guess. It was about the A380 noise levels and EK crew perception I think. Tinset / Leahy reacting etc etc..

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: BlueSky1976
Posted 2009-02-04 05:47:20 and read 15309 times.

I expect the "definition of quietness" to look like this:
A380 < 787 < 747-8i < A340 < 777 etc...

where "<" means "quieter than" in this instance

Generally, A380 will take the crown as being "the quietest", followed by 787. I don't believe Airbus released any data regarding A350XWB in this matter, therefore I left it out.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Khobar
Posted 2009-02-04 06:08:07 and read 15236 times.



Quoting AA737-823 (Reply 1):
It was SUPPOSED to be targeted to be quieter than anything else, and then through a weight reduction program, that all changed. Boeing did some weird research showing that passengers actually prefer a loud cabin, so that they can't hear babies crying.
Randy wrote about it on his blog.

Randy's blog had to do with the A380 being too quiet, with the usual crowd here howling at the thought. And then A380 crews complained the A380 was, in fact, too quiet - they couldn't sleep because - lo and behold - they were disturbed by babies crying.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Gorgos
Posted 2009-02-04 06:17:54 and read 15186 times.

Its not only about insulation material, but also the position of the engines I suppose. The inboard engines of the A380 are removed relatively far away when compared to other aircraft. The outboard engines, well you need binoculars to see them!

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Stitch
Posted 2009-02-04 06:21:55 and read 15168 times.

I'll be very impressed if it's as quiet as an A380, but since I don't generally sleep on planes, noise isn't much of an issue for me thanks to noise-canceling headsets.

I expect it will be quiet even with thin walls thanks to advances in insulation and noise-modeling.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Pnwtraveler
Posted 2009-02-04 07:16:58 and read 14902 times.

CFRP in boats (and fiberglass for that matter) is quieter than metal. I have been told the way the layers lay down it stifles noise. But some of that depends on thickness. Aluminum is the noisiest and steel is slightly better. CFRP also apparently insulates temperature wise better than metals. So if that is the case the 787 should be a quiet plane depending of course on insulation and mechanical noise.

I am one that white noise (although fatiguing over a long period of time) is less stressful than hearing loud conversations and children crying. As I said on the original A380/Randy brewhaha, having worked in an office that was open concept and employed white noise, no noise was perfect at night when the office was nearly empty and shutting off the white noise was a major relief. However, during the day with the office buzzing, if the white noise was off, everyone was in an uproar and stressed out.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Swallow
Posted 2009-02-04 07:41:03 and read 14790 times.



Quoting Khobar (Reply 4):
And then A380 crews complained the A380 was, in fact, too quiet - they couldn't sleep because - lo and behold - they were disturbed by babies crying

Because EK placed the crew rest at the back of Y, where lavs flushing and other background noise is more prevalent.

SQ has its crew rest behind the cockpit and we have not heard complaints from that carrier's crew.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Nomadd22
Posted 2009-02-04 09:56:40 and read 14761 times.



Quoting AA737-823 (Reply 1):

It was SUPPOSED to be targeted to be quieter than anything else, and then through a weight reduction program, that all changed. Boeing did some weird research showing that passengers actually prefer a loud cabin, so that they can't hear babies crying.
Randy wrote about it on his blog.
I called foul, and wrote a very long reply that I was disappointed that Boeing was being cheap and telling us it's what we, as passengers, prefer.
Randy respected my views.

People have known that a bit of white noise makes for a more relaxing trip than a dead quiet cabin for years. It's not exactly cutting edge science.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: TristarSteve
Posted 2009-02-04 11:27:34 and read 14716 times.

Funny, I was thinking about noise last week.
I was flying in an A320 in Row3. There was no noise from the engines at all, it was all masked by the hiss of the air conditioning outlets in the ceiling. I was sitting there thinking that there must be a way to make that quieter. Why is air conditioning hiss so loud on a plane, but not in other places (car, office etc.) I know the aircraft has less cubic footage than other placed per person, so needs more mass flow, but why is it so noisy. Perhaps the reason the A380 is so quiet is that there is more cabin volume per person, so less flow?

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: 2H4
Posted 2009-02-04 12:24:13 and read 14672 times.

I assume the 787 will have no exposed rivet heads or similar fasteners protruding out from the skin. How much of a difference will this make in terms of cabin noise?

2H4

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Tdscanuck
Posted 2009-02-04 13:03:16 and read 14652 times.



Quoting TristarSteve (Reply 10):
Why is air conditioning hiss so loud on a plane, but not in other places (car, office etc.)

Two major reasons...the airflow is *way* higher, and the vents are way smaller. Typical office/car vents are very large, very low velocity, which is quiet.

Quoting 2H4 (Reply 11):
I assume the 787 will have no exposed rivet heads or similar fasteners protruding out from the skin. How much of a difference will this make in terms of cabin noise?

It's got flush fastener heads (no rivets, as far as I know) on the skin, but from the photos it doesn't look like any of them stick out. Assuming their aerodynamically faired, it should help some, but I have no idea how much.

Tom.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Rheinbote
Posted 2009-03-13 12:47:32 and read 13707 times.



Quoting Keesje (Thread starter):
Now what about cabin noise? I did a little googling and it strikes my this specific topic seems to be absent everywhere from the start.

Well, how about this one then?
http://www.aiaa.org/events/aners/Presentations/ANERS-Hawk.pdf

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: JoeCanuck
Posted 2009-03-13 15:02:24 and read 13651 times.

At the moment, it's so quiet you can't even hear the engines.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: 474218
Posted 2009-03-13 15:44:09 and read 13633 times.



Quoting 2H4 (Reply 11):
I assume the 787 will have no exposed rivet heads or similar fasteners protruding out from the skin. How much of a difference will this make in terms of cabin noise?

I can't think of any airliner that has used protruding head rivets since the DC-3. I did see a RAF Comet with protruding head fasteners on the fuselage and Boeing used them on the 737 and 747 lap in the lap joint mod.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Boeing767mech
Posted 2009-03-13 15:51:10 and read 13630 times.



Quoting 474218 (Reply 15):
I can't think of any airliner that has used protruding head rivets since the DC-3. I did see a RAF Comet with protruding head fasteners on the fuselage and Boeing used them on the 737 and 747 lap in the lap joint mod.

757, 767 and 777 use them around the APU compartment area, but that far back your not going to hear anything off the rivet heads.

David

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: 474218
Posted 2009-03-13 18:22:46 and read 13565 times.



Quoting Boeing767mech (Reply 16):
757, 767 and 777 use them around the APU compartment area, but that far back your not going to hear anything off the rivet heads.

Does anyone really think the reason that countersunk (flush) fasteners are used is because of the noise they cause?

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Tdscanuck
Posted 2009-03-13 19:54:11 and read 13527 times.



Quoting 474218 (Reply 15):
I can't think of any airliner that has used protruding head rivets since the DC-3.

All current production Boeing's (not counting 787) have them somewhere near the back. Once the boundary layer gets appreciably thicker than the rivet head, there's not much benefit to going flush.

Tom.

Topic: RE: Boeing 787 Dreamliner Cabin, How Silent / Noisy?
Username: Baroque
Posted 2009-03-14 05:07:02 and read 13429 times.



Quoting Stitch (Reply 6):
I'll be very impressed if it's as quiet as an A380, but since I don't generally sleep on planes, noise isn't much of an issue for me thanks to noise-canceling headsets.

Same here. Maybe we need a technical thread on" why is this so?" to quote the late Julius Sumner Miller. I remember once having a super flight from the US to LHR on a Tristar and not sleeping a wink. I was picked up at LHR and taken to visit a factory up to M11 N of London and they were driving me there in a horrible small Ford, and I fell fast asleep quick as a flash on the North Circular road complete with noisy everything and stopping for traffic lights every half a mile.

Noise to suppress that from babies did strike me at the time as the best cop out of last year, well aside from ones about toxic debt.


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