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Faro
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The Wedge

Sun Aug 26, 2007 9:23 am

Anyone have a pic of the elusive wing wedge used on the MD11 as well as an explanation of what it is/does exactly? How much more efficient does it make a typical airliner wing and what other types use it?

Thanx

Faro
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Faro
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RE: The Wedge

Sun Aug 26, 2007 8:26 pm

This is the only meaningful reference I could find on the net on the wedge, in a 2002 article on the 747 at:

http://seattlepi.nwsource.com/business/59777_boeing26.shtml:

"Wing improvements include raked wing tips and what's known as a "trailing edge wedge," which was developed by McDonnell Douglas to improve the efficiency of the MD-11. Tests found it would significantly help the 747."

Hope this helps...
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Faro
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RE: The Wedge

Fri Sep 07, 2007 2:35 am

Last try to revive a moribund post  sorry ; I'm really curious as to what this trailing edge wedge does/looks like.

Thanx
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OceansWorld
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RE: The Wedge

Fri Sep 07, 2007 3:00 am

Quoting Faro (Reply 1):

The link you provided doesn't work, so here's it again.

http://seattlepi.nwsource.com/business/59777_boeing26.shtml

I've never heard of the trailing wedge, but will try to find something in my books. Have you tried Google ?
 
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Faro
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RE: The Wedge

Fri Sep 07, 2007 3:13 am

Quoting OceansWorld (Reply 3):


The link you provided doesn't work, so here's it again.

http://seattlepi.nwsource.com/business/59777_boeing26.shtml

I've never heard of the trailing wedge, but will try to find something in my books. Have you tried Google ?

Many thanx Oceans. I tried the link from my end and it works alright, here is a fuller excerpt of the article from that site, dated February 26, 2002. It was about the then-projected 747-400XQLR which I guess has since become the -8.

""Several aerodynamic changes in the jet will also help make the 747 quieter.

Lighter-weight wing flaps will lower the 747's stall speed. This will result in less noise during landing, since the jet can fly at slower speeds without losing lift.

Wing improvements include raked wing tips and what's known as a "trailing edge wedge," which was developed by McDonnell Douglas to improve the efficiency of the MD-11. Tests found it would significantly help the 747.

Raked wing tips were first designed for the 767-400 and will also be used on the longer-range 777 now in development. They will increase the total wing span of the quieter 747 to 225 feet 3 inches, or about 14 feet more than the current model.""
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aeroweanie
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RE: The Wedge

Fri Sep 07, 2007 3:23 am

Look for "divergent trailing edge". This is a concept pioneered by Preston Henne and Rob Gregg at Douglas (Pres Henne is now an exec at Gulfstream). A similar concept the "microflap" was developed at Lockheed by Barnaby Wainfan. Drooped flap STCs by Quietwing for the 727 and 737 and by AvAero for the 737 use the same concept.

The idea is to induce trailing edge loading, which offloads the front part of the airfoil and decreases shock strength. The concept is used on the MD11 trailing edge and has been tested on a 747.

You can clearly see it on the aileron in this shot:

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Photo © Tommy Simms



You can kinda see it on the flap in these:

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Photo © Kurt Ams
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Photo © Willem Honders



BTW: Fedex has de-modded many of their MD11's ailerons.
 
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Faro
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RE: The Wedge

Fri Sep 07, 2007 3:27 am

Quoting AeroWeanie (Reply 5):

The idea is to induce trailing edge loading, which offloads the front part of the airfoil and decreases shock strength. The concept is used on the MD11 trailing edge and has been tested on a 747.

Many thanx Weanie; it seems to be an important advance in wing efficiency, I imagine it will become standard on the 787 and all other new airliner models, or is it a proprietary Boeing thing?

Faro
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OldAeroGuy
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RE: The Wedge

Fri Sep 07, 2007 11:53 pm

Quoting Faro (Reply 6):
I imagine it will become standard on the 787 and all other new airliner models, or is it a proprietary Boeing thing?

It won't be standard on the 787. The aft loading associated with supercritical airfoils is designed into the basic airfoil section. The wedge is handy for modifying existing wings.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis

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