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CCA
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747-8 Flap Pic.

Sat Dec 19, 2009 10:35 am

Found a pic of the 747-8F flaps as advertised single O/B double slotted I/B.



http://i.bnet.com/blogs/747-8.jpg?tag=col1;attachment_2518


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Photo © Martin Robson



[Edited 2009-12-19 03:28:24]
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N243NW
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RE: 747-8 Flap Pic.

Sat Dec 19, 2009 8:57 pm

Those still are enormous flaps, although I will miss the triple-slotted flaps of the classic 747s. Thanks for the image.
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MSPNWA
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 12:45 am

Still big, but I'll miss the triples. These look very plain in a such a large size.

Thanks for the pic.
 
soon7x7
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 1:18 am

Is the entire wing re designed on this NG version?
 
tdscanuck
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 1:42 am



Quoting Soon7x7 (Reply 3):
Is the entire wing re designed on this NG version?

New loft, new control surfaces, mostly the same structure.

Tom.
 
JoeCanuck
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 2:15 am

I can't tell from that photo if the 748 has drooped ailerons...does it?
What the...?
 
UAL747
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 3:12 am

Yes, it has drooped ailerons, or flaperons.


This wing is super critical whereas the others were not. Don't ask me to define it, because I don't really know what it means other than the underside is scooped out near the rear? I'd love a definition of super-critical.

UAL

[Edited 2009-12-19 19:13:40]
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 3:24 am

What the...?
 
vikkyvik
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 5:30 am



Quoting UAL747 (Reply 6):
This wing is super critical whereas the others were not. Don't ask me to define it, because I don't really know what it means other than the underside is scooped out near the rear? I'd love a definition of super-critical.

While I don't know the technical reason they're called super-critical, what it basically does is push the shockwave farther back on the wing. At that point, you get a weaker shock, and reduced drag.
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tdscanuck
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 7:30 am



Quoting UAL747 (Reply 6):
This wing is super critical whereas the others were not. Don't ask me to define it, because I don't really know what it means other than the underside is scooped out near the rear?

The scoop at the back is called a reflexed trailing edge...it's not essential to a supercritical airfoil, but most of them have it to improve the pressure recovery at the back and make the moment curve a little nicer.

Quoting UAL747 (Reply 6):
I'd love a definition of super-critical.

It's like a Supreme Court justice once said "I know it when I see it." A hard technical definition is quite difficult, but anybody with solid aerodynamics knowledge can recognize a super-critical airfoil when they see one. The giveaway is usually a fairly flat upper surface and an evenly thick middle. Put another way, a supercritical airfoil usually looks like a thick plate with a leading and trailing edge stuck on. A conventional airfoil usually doesn't have a near-constant thickness section in the middle.

Quoting Vikkyvik (Reply 8):
While I don't know the technical reason they're called super-critical, what it basically does is push the shockwave farther back on the wing. At that point, you get a weaker shock, and reduced drag.

Critical Mach number (Mcr) is the Mach number when some portion of the airflow somewhere on the airfoil first hits Mach 1. In conventional airfoils, this usually happens right around the thickest part, is a relatively strong shock, and causes a fairly abrupt drag rise if you go much beyond Mcr. As a result, conventional airfoils rarely operate very far above Mcr.

A supercritical airfoil is designed to have more gradual velocity gradients over the top surface (they spread out the low pressure area) so that the supersonic point is farther back and the shock is weaker. This lets them get farther past Mcr before the drag gets too unpleasant, so they can perform better above their critical Mach number...they work OK when super-critical.

Tom.
 
vikkyvik
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 7:34 am



Quoting Tdscanuck (Reply 9):
Critical Mach number (Mcr) is the Mach number when some portion of the airflow somewhere on the airfoil first hits Mach 1. In conventional airfoils, this usually happens right around the thickest part, is a relatively strong shock, and causes a fairly abrupt drag rise if you go much beyond Mcr. As a result, conventional airfoils rarely operate very far above Mcr.

A supercritical airfoil is designed to have more gradual velocity gradients over the top surface (they spread out the low pressure area) so that the supersonic point is farther back and the shock is weaker. This lets them get farther past Mcr before the drag gets too unpleasant, so they can perform better above their critical Mach number...they work OK when super-critical.

Wow, I can't believe that never crossed my mind as the meaning of "supercritical"!

Thanks Tom.
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jetmech
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 9:46 pm



Quoting Tdscanuck (Reply 9):
drag gets too unpleasant,

Would you know what is the main component of drag experienced by airfoils operating near their critical Mach numbers? Is it the shock wave itself or the shock induced separation?

Regards, JetMech
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prebennorholm
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RE: 747-8 Flap Pic.

Sun Dec 20, 2009 11:29 pm



Quoting UAL747 (Reply 6):
This wing is super critical whereas the others were not. Don't ask me to define it, because I don't really know what it means other than the underside is scooped out near the rear? I'd love a definition of super-critical.

Have a look at this... http://www.nasa.gov/centers/dryden/a...hnology/Facts/TF-2004-13-DFRC.html You can google a lot more.

Supercritical wings are the industry standard on airliners and have been so for quite a few decades. I am pretty sure that the 744 was the very last airliner to be produced with non-supercritical wings.

"Supercritical" was a buzzword in the 70'es, but since it became the industry standard in the 80'es, it mostly went out of use.

It is much like my grandfather's Ford model T which he in the mid 20'es had modified with automatic windscreen wipers. In this case "automatic" means that the wipers were driven by an electric motor, and not by a handle.
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tdscanuck
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 2:22 am



Quoting JetMech (Reply 11):
Would you know what is the main component of drag experienced by airfoils operating near their critical Mach numbers? Is it the shock wave itself or the shock induced separation?

I suspect it's the shock wave itself, but that's just a gut feeling...I'd be curious to see some wind tunnel data or Schlieren photos of a wing right at Mcr.

Tom.
 
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Faro
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 10:04 am

Are the flap track fairings unchanged? The ones on the 744 are big, hefty contraptions, maybe Boeing took the opportunity to streamline them a bit with the 748?

Faro
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tdscanuck
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 4:49 pm



Quoting Faro (Reply 14):
Are the flap track fairings unchanged?

Given that it's a relofted wing, I think they'd have had to change them.

Tom.
 
FWI747
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 6:50 pm

they did

Last 744F
http://farm4.static.flickr.com/3581/3306313817_9dbc376263_o.jpg

1st 748F


They look more like those of the 777 now :
http://microvoltradio.com/images/kpae3691.jpg
 
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Faro
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 7:04 pm



Quoting FWI747 (Reply 16):
they did

Maybe it' just a question of detail that a closer-up image might clarify, but I have the impression that those fairings on the 748 are in fact the same as the 744's...

Faro
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FWI747
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 7:13 pm

I think the most inboard flap fairing has its max thickness a little more fore on the -8 than on the 744... and it seems to me that the outboard ones are a little thinner toward the end but, I agree one need sharp eyes

rgds

[Edited 2009-12-21 11:14:34]
 
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DocLightning
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RE: 747-8 Flap Pic.

Mon Dec 21, 2009 8:52 pm



Quoting Tdscanuck (Reply 4):

New loft, new control surfaces, mostly the same structure.

New airfoil, new bending moment, new materials... a very different wing from the original. AFAIK, the 744 wing, was essentially identical to the 741 wing except for the winglet/extension and an improved wing root fairing.

Quoting Faro (Reply 17):

Maybe it' just a question of detail that a closer-up image might clarify, but I have the impression that those fairings on the 748 are in fact the same as the 744's...

The fairings are not just covers for the flap apparatus. They also serve as anti-shock bodies. They soften the sudden decrease in aircraft cross-section at the trailing edge of the wing. The nacelles, mounted way out in front of the wings, also serve the same role ahead of the wing.
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dynamicsguy
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RE: 747-8 Flap Pic.

Tue Dec 22, 2009 10:13 am



Quoting DocLightning (Reply 19):
New airfoil, new bending moment, new materials... a very different wing from the original.

Still mostly the same structure though - same architecture, regauged for the changes in loads. The loft changes the shape a little, but it's still the same layout. Are the materials different for the structure?
 
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Starlionblue
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RE: 747-8 Flap Pic.

Wed Dec 23, 2009 6:10 am

Question: What does "relofting" mean?
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jetmech
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RE: 747-8 Flap Pic.

Wed Dec 23, 2009 6:56 am



Quoting Starlionblue (Reply 21):

I'd say it means that Boeing adjusted the shape of the airfoil sections used in the wing. This could be done by adjusting the camber line and / or thickness distribution as well as other parameters.

Regards, JetMech
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tdscanuck
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RE: 747-8 Flap Pic.

Wed Dec 23, 2009 4:40 pm



Quoting Starlionblue (Reply 21):
Question: What does "relofting" mean?

The loft is the shape of the wing. The term is a throwback to aviation's naval roots:
"Lofting is a time honored tradition amongst boat builders. It refers to the tradition of building full scale templates for the boat's hull in the loft of a boat building building(?), then dropping lines down through the loft to the building area that periodically delineate the curve."
http://www.recumbents.com/wisil/Plans/lofting.htm

Quoting Jetmech (Reply 22):
I'd say it means that Boeing adjusted the shape of the airfoil sections used in the wing.

Changing airfoils is definitely relofting, but it could also include changes to the twist, sweep, di/anhedral.

Tom.
 
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Starlionblue
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RE: 747-8 Flap Pic.

Wed Dec 23, 2009 7:23 pm

Ok so if there is relofting does that mean there is a new wing? I mean when does a redesign of an existing wing become an "all new" wing?  Wink
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soon7x7
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RE: 747-8 Flap Pic.

Wed Dec 23, 2009 10:57 pm



Quoting Tdscanuck (Reply 23):

The 747 has proved the success of the flexible variable leading edge flap...why other models and or manufacturers not utilizing this concept?  Confused
 
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 1:22 am



Quoting Starlionblue (Reply 24):
Ok so if there is relofting does that mean there is a new wing? I mean when does a redesign of an existing wing become an "all new" wing?

As I understand it, the primary structure of the wing (spars, ribs, etc) is pretty much the same as on prior versions of the 747, with two obvious exceptions:

1) when needed, shapes of pieces (ribs most likely) are modified slightly to conform to the new airfoil shape

2) additional strengthening and/or new materials are used to support the higher gross weight

In short, this cuts the structural engineering costs on the wing to a fraction of what they would be, as well as enabling tooling and jigs from the 744 to be reused for many parts. Of course, it also constrains how much of an aerodynamic change can be made.

In many ways its like building multiple cars on the same platform. There is a LOT of variation that is possible, but keeping core parts the same reduces development costs on new models.

an all new wing would be a clean-sheet design with everything done from scratch, at least in my opinion.
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 2:05 am



Quoting Soon7x7 (Reply 25):

The 747 has proved the success of the flexible variable leading edge flap...why other models and or manufacturers not utilizing this concept? Confused

I've always wondered this myself. The 747 was the only model with this curious design. I never understood why. I would imagine that during extension/retraction the leading-edge devices would seriously disrupt the airflow under the wing. It amazes me that the aircraft doesn't drop during leading edge slat retraction/extension. Why does Boeing use this instead of the drooping leading edge used in every other model?
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tdscanuck
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 5:45 am



Quoting Starlionblue (Reply 24):
Ok so if there is relofting does that mean there is a new wing?

In my book, yes, since the biggest design factor in the wing is the aerodynamics.

Quoting Starlionblue (Reply 24):
I mean when does a redesign of an existing wing become an "all new" wing?

I don't think there's any clear-cut definition, but Dw747400's sounds good to me.

Quoting Soon7x7 (Reply 25):
The 747 has proved the success of the flexible variable leading edge flap...why other models and or manufacturers not utilizing this concept?

I suspect it doesn't scale down well...although effective, it's got a bazillion more parts than any other comparable design. I can't think of a more complex leading edge mechanism in large jets, and if you can get good results with something as simple as a moveable slat, I'd certainly go for that.

Quoting DocLightning (Reply 27):
I would imagine that during extension/retraction the leading-edge devices would seriously disrupt the airflow under the wing.

I suspect they do, but the flow on the underside of the wing is pressurized and working with a favorable pressure gradient...it's really hard to separate that flow. The variable camber Kruegers on the 747 are probably no worse, and maybe better, than the straight Kruegers used on the inboard section of the 737 and other Boeing's.

Quoting DocLightning (Reply 27):
It amazes me that the aircraft doesn't drop during leading edge slat retraction/extension.

Why would it? If you do cause a giant separation underneath the wing, that's not going to change the pressure distribution much (drag would go way up though).

Tom.
 
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Starlionblue
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 6:53 am



Quoting Soon7x7 (Reply 25):

The 747 has proved the success of the flexible variable leading edge flap...why other models and or manufacturers not utilizing this concept?

As I recall, the reason for the design was that the 747 leading edge was quite thin in order to achieve the speeds required by Pan Am. But I could be remembering that wrong.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Western727
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 4:06 pm



Quoting Starlionblue (Reply 29):
As I recall, the reason for the design was that the 747 leading edge was quite thin in order to achieve the speeds required by Pan Am. But I could be remembering that wrong.

This is also how I understand it; the "thinness" of the 741/4's wing leading edge meant that installing slats (and the associated hardware) was not possible. The PanAm bit is new to me, though.
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Starlionblue
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RE: 747-8 Flap Pic.

Thu Dec 24, 2009 5:17 pm



Quoting Western727 (Reply 30):
The PanAm bit is new to me, though.

The legendary Juan Trippe, then CEO of Pan Am, was one of the strongest forces behind the 747. With a handshake between him and Bill Allen at Boeing, the project got started. The deal was basically "if you build it, we will buy it" and Boeing said "if you buy it, we will build it". Very much a gentleman's agreement in the beginning.

Trippe wanted a high cruise speed, thus the rather radical sweep of the wing. Actually Pan Am wanted even more sweep, all of 40 degrees. The final angle of 37.5 degrees split the difference between what Boeing wanted (35) and what Pan Am wanted (40).
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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DocLightning
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RE: 747-8 Flap Pic.

Fri Dec 25, 2009 11:52 pm



Quoting Starlionblue (Reply 31):

Trippe wanted a high cruise speed, thus the rather radical sweep of the wing. Actually Pan Am wanted even more sweep, all of 40 degrees. The final angle of 37.5 degrees split the difference between what Boeing wanted (35) and what Pan Am wanted (40).

I read that the plane was originally designed to cruise above above M 0.9, but it was found to be uneconomical. Still, the shape of the nose is designed around that goal, and that is why the forward section of the 747 is so amazingly quiet in flight. If you look at the planform of a 747, you will see that the nose is a perfect parabola almost to the wing root.
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747classic
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RE: 747-8 Flap Pic.

Sun Jan 10, 2010 10:52 am

Quoting DocLightning (Reply 19):
New airfoil, new bending moment, new materials... a very different wing from the original. AFAIK, the 744 wing, was essentially identical to the 741 wing except for the winglet/extension and an improved wing root fairing.

The improved wing root fairing as seen on all 747-400's is a product improvement developed to decrease the fuel consumption with approx. 0.5%. It's also installed on several late production 747-200 and -300 aircraft, see pictures below.
It was also offered as a retrofit, but it was relative expensive, because of additional rerouting of some ducting and the replacement of the slides of doors 21 and 22 by an adapted type of slide. As far as i know no retrofit kits were ordered.


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Photo © Kas van Zonneveld
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Photo © Yash Rajgor



[Edited 2010-01-10 03:34:37]
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