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Why No 787-style Serrated Nacelles On A350 XWB?  
User currently offlineN328KF From United States of America, joined May 2004, 6482 posts, RR: 3
Posted (4 years 3 months 3 weeks 2 days 3 hours ago) and read 13847 times:

We have seen the 787's serrated nacelles become a point of distinction. The given reason for this is to promote noise reduction.

So why would the A350, which is a newer design, not feature this?


When they call the roll in the Senate, the Senators do not know whether to answer 'Present' or 'Not guilty.' T.Roosevelt
21 replies: All unread, jump to last
 
User currently offlineBoeingBus From United States of America, joined May 2004, 1596 posts, RR: 18
Reply 1, posted (4 years 3 months 3 weeks 2 days 3 hours ago) and read 13847 times:

perhaps due to patent issues. But I thought NASA developed the technology so it's free reign for an corp to use.. who knows.


Airbus or Boeing - it's all good to me!
User currently offlineEtoile From United States of America, joined Jun 2009, 114 posts, RR: 0
Reply 2, posted (4 years 3 months 3 weeks 2 days 3 hours ago) and read 13847 times:

See this thread: Why No Chevrons On The TrentXWB Or PW1000G? (by EA772LR Dec 14 2009 in Civil Aviation)?threadid=4638222&searchid=4638533&s=chevrons+lightsaber#ID4638533

User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3423 posts, RR: 67
Reply 3, posted (4 years 3 months 3 weeks 2 days 2 hours ago) and read 13668 times:



Quoting N328KF (Thread starter):
So why would the A350, which is a newer design, not feature this?



Quoting BoeingBus (Reply 1):
perhaps due to patent issues.

Note the patent assignee shown in the following link.

http://www.patentstorm.us/patents/7546727/description.html

This could have something to do with the lack of chevrons on the A350XWB.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineEtoile From United States of America, joined Jun 2009, 114 posts, RR: 0
Reply 4, posted (4 years 3 months 3 weeks 2 days 2 hours ago) and read 13605 times:



Quoting OldAeroGuy (Reply 3):
Note the patent assignee shown in the following link.

http://www.patentstorm.us/patents/7546727/description.html

This could have something to do with the lack of chevrons on the A350XWB.

No, it couldn't. The chevrons on the 787 engines are not movable.


User currently offlineERJ135 From Australia, joined Nov 2000, 679 posts, RR: 1
Reply 5, posted (4 years 3 months 3 weeks 2 days ago) and read 13375 times:

There are many answers that are possible. We must also remember that the E-Jet also has a similar device, just not in the same position. The E-Jet has been in service for years now so while recent it is certainly not new. It's existence is of course noise related so maybe the engines that will ultimately be fitted to the new Airbus may in fact not need them. Or perhaps it will actually be there but as the Airbus is still a way off we might have to wait and see.

No answer really But honestly having seen the flex of the 787 wing I can hardly wait the see the A350.



I remember when the DC-3 was new!
User currently offlineKappel From Suriname, joined Jul 2005, 3533 posts, RR: 17
Reply 6, posted (4 years 3 months 3 weeks 1 day 23 hours ago) and read 13254 times:



Quoting OldAeroGuy (Reply 3):
This could have something to do with the lack of chevrons on the A350XWB.

No, see the thread mentioned in the reply below:

Quoting Etoile (Reply 2):
See this thread: Why No Chevrons On The TrentXWB Or PW1000G? (by EA772LR Dec 14 2009 in Civil Aviation)?threadid=4638222&searchid=4638533&s=chevrons+lightsaber#ID4638533

The chevrons also increase fuel burn.



L1011,733,734,73G,738,743,744,752,763,772,77W,DC855,DC863,DC930,DC950,MD11,MD88,306,319,320,321,343,346,ARJ85,CR7,E195
User currently offlineOldeuropean From Germany, joined May 2005, 2026 posts, RR: 4
Reply 7, posted (4 years 3 months 3 weeks 1 day 21 hours ago) and read 13004 times:

Similar chevrons have been seen on a prototyp for an AN-124 variant.

http://www.flightglobal.com/articles...ication-generates-speculation.html

Axel



Wer wenig weiss muss vieles glauben
User currently offlineOldeuropean From Germany, joined May 2005, 2026 posts, RR: 4
Reply 8, posted (4 years 3 months 3 weeks 1 day 21 hours ago) and read 12995 times:

See also here:


View Large View Medium
Click here for bigger photo!

Photo © Bastiaan Smeets




Wer wenig weiss muss vieles glauben
User currently offlineAY-MD11 From Finland, joined Feb 2001, 472 posts, RR: 2
Reply 9, posted (4 years 3 months 3 weeks 1 day 21 hours ago) and read 12875 times:

Those are on the cfm powered A320s too.

User currently offlineEGNR From United Kingdom, joined Feb 2004, 507 posts, RR: 0
Reply 10, posted (4 years 3 months 3 weeks 1 day 18 hours ago) and read 12545 times:

Airbus developed the zero splice inlet during the A380 development. From what I understand, this gives a good reduction in noise, but with no fuel burn penalty (perhaps even an improvement in fuel burn), and will undoubtedly feature on all future Airbus products, including the A350.

"Among the innovations for which Airbus has filed patent applications is the Zero Splice inlet that is integrated into the A380 engines' nacelles. This invention, which consists of a single 360 degree composite piece, instead of several separate panels spliced together, contributes significantly to the A380s very low noise emissions. " Courtesy of Airbus

"Researchers found the gaps in nacelle linings are a significant source of the tremendous noise jet engines generate. Before the zero-splice inlet, nacelle linings consisted of two to three sections that were fitted together, which left gaps between the individual lining sections. The vibration and noise of the engine escape through these tiny gaps and create acoustic scattering, basically deflecting noise in all directions.

To address the problem, Alain Porte of Airbus pioneered a new material for nacelle linings that could cover the entire inside in just one piece. This was achieved through a perforated, heat-resistant fabric that is flexible enough to line the nacelle, but highly sound-absorbent. The innovative material is strong enough to withstand everything from pressure during flight, the weight of people on some portions to the aerodynamic and inertial forces of the entry of air into the motor housing.

Better yet, zero-splice inlet engines are not only much quieter than their conventional counterparts, but also lighter and more fuel efficient. This uniquely high level of acoustic performance has made it possible for the world's largest passenger plane to also be the world's quietest passenger plane, giving it a significant commercial advantage in an environmentally aware marketplace: The Airbus 380, armed with the zero-splice engine housing, generates 50 percent less noise than any other passenger plane in the world."
Courtesy of epo: The Story Behind: Quieter Jet Engines



7late7, A3latey, Sukhoi Superlate... what's going on?
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 11, posted (4 years 3 months 3 weeks 1 day 18 hours ago) and read 12477 times:



Quoting EGNR (Reply 10):
Airbus developed the zero splice inlet during the A380 development.

Interesting post. But equally interesting is that you can actually patent the bleeding obvious. Amazing world that of patents. No criticism of your post implied EGNR and thanks for drawing out attention to it. I do rather wonder however if Whittle had not figured that out in about 1940?!? He certainly spent a lot of time on design of casings for this impellers.


User currently offlineJAAlbert From United States of America, joined Jan 2006, 1491 posts, RR: 1
Reply 12, posted (4 years 3 months 3 weeks 1 day 14 hours ago) and read 10398 times:

So slightly off point, but -- in the recent flights of the two test 787s, did any observers note whether the engines were in fact quieter from where they stood?

User currently offlineShany From Germany, joined Jul 2008, 111 posts, RR: 0
Reply 13, posted (4 years 3 months 3 weeks 1 day 14 hours ago) and read 9911 times:

Could it just be that the drawings and models are still in an too early stage to have these kind of details? I mean, the pictures I have seen also don't show any antennas nor static dischargers. However, I guess/hope, there will be some.

Shany



ETOPS - Engines Turn Or People Swim
User currently offlineTigerotor77W From United States of America, joined Mar 2006, 156 posts, RR: 0
Reply 14, posted (4 years 3 months 3 weeks 1 day 7 hours ago) and read 6804 times:



Quoting JAAlbert (Reply 12):
So slightly off point, but -- in the recent flights of the two test 787s, did any observers note whether the engines were in fact quieter from where they stood?

I asked a friend who saw ZA001 the same thing, and his response was that it was a LOT quieter than older planes. (emphasis some his, some mine)


User currently offlineBurnsie28 From United States of America, joined Aug 2004, 7504 posts, RR: 8
Reply 15, posted (4 years 3 months 3 weeks 1 day 7 hours ago) and read 6799 times:



Quoting BoeingBus (Reply 1):
perhaps due to patent issues. But I thought NASA developed the technology so it's free reign for an corp to use.. who knows.

I believe things like that developed by NASA or the US Government are free reign for US Citizen and companies only as we are the ones that essentually pay for them.



"Some People Just Know How To Fly"- Best slogan ever, RIP NW 1926-2009
User currently offline797charter From Denmark, joined Jun 2005, 219 posts, RR: 0
Reply 16, posted (4 years 3 months 3 weeks 1 day 7 hours ago) and read 6714 times:



Quoting N328KF (Thread starter):

So why would the A350, which is a newer design, not feature this?

You give the answer in your question: Because it is a newer design - and thus not necessary for the RR engine, - and as other also mention - it gives a slightly higher fuel burn.


Regards

Steen



Keep it clear of the propellers
User currently offlineYyzbiker From Canada, joined Dec 2009, 9 posts, RR: 0
Reply 17, posted (4 years 3 months 3 weeks 1 day 5 hours ago) and read 6163 times:

You know what who cares ..... the more noise the better, bring back the B707's and the DC8s

yyzbiker


User currently offlinePGNCS From United States of America, joined Apr 2007, 2756 posts, RR: 45
Reply 18, posted (4 years 3 months 3 weeks 1 day 5 hours ago) and read 6075 times:

Bottom line: the people designing the A-350 did the design trades and elected not to use it.

User currently offlineTrex8 From United States of America, joined Nov 2002, 4493 posts, RR: 14
Reply 19, posted (4 years 3 months 3 weeks 1 day 4 hours ago) and read 5748 times:
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Quoting Burnsie28 (Reply 15):
I believe things like that developed by NASA or the US Government are free reign for US Citizen and companies only as we are the ones that essentually pay for them.

I don't think thats actually the case but if it were is Roll Royce N America or EADS N America an "American " company or not and would Chrysler not be American when it was owned by Daimler??


User currently offlineEtoile From United States of America, joined Jun 2009, 114 posts, RR: 0
Reply 20, posted (4 years 3 months 3 weeks 1 day 4 hours ago) and read 5657 times:



Quoting Burnsie28 (Reply 15):
I believe things like that developed by NASA or the US Government are free reign for US Citizen and companies only as we are the ones that essentually pay for them.

It's a little more complex and less nationalistic than that. The government generally will retain title to patents on inventions made by its employees on government time. If the government funds a grantee's invention, typically the grantee will be able to obtain title, but the government will still get a nonexclusive license.


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3423 posts, RR: 67
Reply 21, posted (4 years 3 months 3 weeks 1 day 3 hours ago) and read 5454 times:



Quoting Etoile (Reply 4):
No, it couldn't. The chevrons on the 787 engines are not movable.

Are you sure?

The link below indicates that "moveable" chevrons have been tested.

http://www.boeing.com/news/frontiers...archive/2005/december/ts_sf07.html

"The team also tested variable-geometry chevrons made with a temperature-reactive alloy. These "smart" chevrons automatically warp into the jet exhaust flow to reduce noise during takeoff and landing and revert to a streamlined position at cruise altitude."

A "moveable" (ie variable geometry) chevron of this type would have the benefit of takeoff thrust noise reduction without a cruise fuel burn penalty. It's possible that the 787 chevrons are variable geometry and would be protected by the patent referenced in Reply 3.

Quoting Kappel (Reply 6):
Quoting OldAeroGuy (Reply 3):
This could have something to do with the lack of chevrons on the A350XWB.

No, see the thread mentioned in the reply below:

Quoting Etoile (Reply 2):
See this thread: Why No Chevrons On The TrentXWB Or PW1000G? (by EA772LR Dec 14 2009 in Civil Aviation)?threadid=4638222&searchid=4638533&s=chevrons+lightsaber#ID4638533

I fail to see any reference to the patent linked in Reply 3 to the other thread. Variable geometry chevrons are not discussed in the prior thread.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
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