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787 Keel Beam  
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2131 posts, RR: 56
Posted (6 years 9 months 5 days 6 hours ago) and read 12529 times:

I read in this week's Aviation Week issue that the 787 sports an external (!) keel beam that, for aerodynamic reasons, protrudes out of the belly fairing under the center wing box. Does anyone have a close-up photograph of said appendage, from the roll-out ceremony?

13 replies: All unread, jump to last
 
User currently offlineFlashFlyGuy From Australia, joined Jan 2007, 439 posts, RR: 0
Reply 1, posted (6 years 9 months 5 days 6 hours ago) and read 12402 times:

You might like to have a look at flickr.com - heaps of B787 rollout photos (from all angles) have been uploaded there. Just search for 787.

User currently offlineJogales From United States of America, joined Aug 2005, 437 posts, RR: 0
Reply 2, posted (6 years 9 months 5 days 5 hours ago) and read 12307 times:

I believe this is what they're referring to:

http://www.flickr.com/photos/rverginia/770894458/

Click on "all sizes" for a much bigger view

Josh



-
User currently offlineDeltaDAWG From United States of America, joined May 2006, 742 posts, RR: 1
Reply 3, posted (6 years 9 months 4 days 22 hours ago) and read 11817 times:

Quoting WingedMigrator (Thread starter):
I read in this week's Aviation Week issue that the 787 sports an external (!) keel beam that, for aerodynamic reasons,

What is the reasoning? Can anyone explain the details of why it is like that?



GO Dawgs, Sic' em, woof woof woof
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 25
Reply 4, posted (6 years 9 months 4 days 22 hours ago) and read 11774 times:

I wonder if IAD787 can provide us with some insight? Im also curious to know this too!


A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineOldeuropean From Germany, joined May 2005, 2026 posts, RR: 4
Reply 5, posted (6 years 9 months 4 days 21 hours ago) and read 11693 times:

This is definitely not the misteriously disapeared shark fin.  rotfl 

Axel



Wer wenig weiss muss vieles glauben
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2131 posts, RR: 56
Reply 6, posted (6 years 9 months 4 days 17 hours ago) and read 11247 times:

Quoting Jogales (Reply 2):
Click on "all sizes" for a much bigger view

Thanks, that's exactly what I was looking for. Flickr is a gold mine of 787 photos, much more abundant than a.net or even Flightblogger! For example, I saw lots of shots of airplane #2.

Quoting DeltaDAWG (Reply 3):
What is the reasoning? Can anyone explain the details of why it is like that?

Here is the direct, fair-use quote from the article in AWST:

Quote:
The externally visible keel beam was perhaps the most surprising feature, thought to represent a first for any Boeing commercial jetliner to date. Measuring 340 in., it begins toward the aft end of the Kawasaki-made Section 43 forward fuselage and ends just aft of the front end of the Alenia Section 46 center-rear fuselage. It runs under, not through, the Kawasaki Section 11 center wing box.

In all previous models the keel beam, a strengthening structural member running forward and aft through the bottom of the fuselage, has been hidden within the contours of the fuselage itself. Although clearly visible on the 787, the structure is contained within a fairing only a few inches deep. Boeing says the beam is not a bolted add-on.

The keel beam “is a very deep structure, not externally mounted,” says 787 Chief Project Engineer Tom Cogan. “It happens to protrude by choice. We could have made the fairing bigger for appearance, but by choice we wanted the fairing to be as small as possible and that’s why you see more contouring on the bottom than people are used to.”

Viewed from either end, the beam also displays slight area ruling to reduce transonic drag rise in the belly area flow field between the large engine nacelles. “A lot of study and aerodynamic work went into this aspect of the design and this was the best solution,” adds Cogan.

There's also information about another unusual 787 design detail: those funky ram air scoops for the air packs. Looks like the extra drag from those protruding scoops will have to be weighed in the balance of the cost/benefit of using a 'bleedless' architecture.


User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1021 posts, RR: 3
Reply 7, posted (6 years 9 months 4 days 16 hours ago) and read 11084 times:

I don't know the reason why,but the Convair 880/990's also had a external longeron running down the center line of the aircraft from just ahead of the center section and ended just forward of the aft outflow valve (not to be confused with the speed fairing on the upper crown of the airframe), They also had a smaller one around the tail bumper area.

Just a bit of useless information

David



Never under-estimate the predictably of stupidty
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 25
Reply 8, posted (6 years 9 months 4 days 14 hours ago) and read 10157 times:

Quoting Oldeuropean (Reply 5):
This is definitely not the misteriously disapeared shark fin.

I fail to see your humor. We are talking about the 787's keel beam, which is on the BOTTOM of the aircraft. The tail has nothing to do with it.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineRwessel From United States of America, joined Jan 2007, 2238 posts, RR: 2
Reply 9, posted (6 years 9 months 4 days 13 hours ago) and read 9705 times:
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Some bizjets have a strip similar to that running down the "keel" to protect center body fuel tanks and the rest of the hull in case of a wheels up landing.

Although that's usually a removable/replaceable piece, unlike what's Boeing has said here.


User currently offlineRverginia From United States of America, joined Dec 2006, 19 posts, RR: 0
Reply 10, posted (6 years 9 months 4 days 12 hours ago) and read 9333 times:

Hi all.
I am glad you are enjoying my photo of the keel beam on Flickr.


User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2131 posts, RR: 56
Reply 11, posted (6 years 9 months 4 days 11 hours ago) and read 8345 times:

Quoting Rverginia (Reply 10):
I am glad you are enjoying my photo of the keel beam on Flickr.

Lucky dog, you were there!  bouncy 


User currently offlineOldeuropean From Germany, joined May 2005, 2026 posts, RR: 4
Reply 12, posted (6 years 9 months 4 days 5 hours ago) and read 6524 times:

Quoting AirframeAS (Reply 8):
I fail to see your humor. We are talking about the 787's keel beam, which is on the BOTTOM of the aircraft. The tail has nothing to do with it.

I know where the keel is. Sorry that I've affronted you by making a joke about your beloved 787. That aircraft must be some kind of a fetish for some folks here.

Axel

[Edited 2007-07-18 09:16:17]


Wer wenig weiss muss vieles glauben
User currently offlineBill142 From Australia, joined Aug 2004, 8434 posts, RR: 9
Reply 13, posted (6 years 9 months 4 days ago) and read 6390 times:

Quoting DeltaDAWG (Reply 3):
What is the reasoning? Can anyone explain the details of why it is like that?

It's a skid rail for when it has to do gear up landings.  wink 


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