User avatar
TWA772LR
Topic Author
Posts: 3794
Joined: Thu Nov 17, 2011 6:12 am

763: Blended Winglets Vs. Raked Wingtips

Thu Jun 28, 2012 1:37 am

The 763 is certified for blended winglets, but not raked wingtips. I know winglets are more efficient below 10,000 feet on things such as take off and approach as they decrease wingtip vortexes. Wingtips are better at cruise altitudes, which is why the 77L, 77W, 764, and 787 have them. If a 763 flies similar missions (long haul) as the previous stated aircraft, then why dont they have raked wingtips installed instead? Can you not retrofit those? Or do more 763s operate shorter missions that would constitute blended winglets instead? I have heard on a.net that these winglets weigh in the ballpark of 400 lbs. and have caused strain on the wings and wingboxes of some 763s.
Beauty is watching a 787 bank to make a short final. Bliss is watching that 787 with a good beer. Nirvana is all of that with a beautiful woman on your side.
 
User avatar
817Dreamliiner
Posts: 3227
Joined: Sun Jul 27, 2008 4:12 pm

RE: 763: Blended Winglets Vs. Raked Wingtips

Thu Jun 28, 2012 1:59 am

Quoting TWA772LR (Thread starter):

The raked wingtips cant be retrofitted. The aircraft you mention were all designed with the raked wingtips onto the wing, including the P-8, the 763 is an older design which came before the raked wingtip design came about on the 764. The raked wingtips would require significant reinforcement of the wing due to increase in bending force from the increased span, therefore adding weight onto the wing. the strain on the wing from winglets is mitigated by these additional strengthening at the tip, but it wouldnt add as much weight.
Please let me know... If you know this is the end of the world, Let me know... If you know the truth...
 
User avatar
TWA772LR
Topic Author
Posts: 3794
Joined: Thu Nov 17, 2011 6:12 am

RE: 763: Blended Winglets Vs. Raked Wingtips

Thu Jun 28, 2012 2:03 am

Quoting 817Dreamliiner (Reply 1):
The raked wingtips cant be retrofitted

That's what I was thinking but I wasn't entirely sure. I would never have thought that raked wingtips cause the wing to bend as much as you are making it sound, but you learn something new everyday. Thanks for the info!  
Beauty is watching a 787 bank to make a short final. Bliss is watching that 787 with a good beer. Nirvana is all of that with a beautiful woman on your side.
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 763: Blended Winglets Vs. Raked Wingtips

Thu Jun 28, 2012 11:09 am

Quoting TWA772LR (Thread starter):
I know winglets are more efficient below 10,000 feet on things such as take off and approach as they decrease wingtip vortexes.

Raked tips do the same thing. They're different mechanical means of achieving the same aerodynamic end.

Quoting TWA772LR (Thread starter):
Wingtips are better at cruise altitudes, which is why the 77L, 77W, 764, and 787 have them.

Those aircraft have raked tips because they don't operated in span-restricted gates or hangers; raked wingtips are always better aerodynamically if you can fit them.

Quoting TWA772LR (Thread starter):
If a 763 flies similar missions (long haul) as the previous stated aircraft, then why dont they have raked wingtips installed instead?

Tips are much harder to retrofit.

Quoting TWA772LR (Thread starter):
Can you not retrofit those?

You can, but not without significant extra work beyond what a winglet would require.

Tom.
 
User avatar
bikerthai
Posts: 2175
Joined: Wed Apr 28, 2010 1:45 pm

RE: 763: Blended Winglets Vs. Raked Wingtips

Thu Jun 28, 2012 4:40 pm

Quoting TWA772LR (Reply 2):
I would never have thought that raked wingtips cause the wing to bend as much as you are making it sound, but you learn something new everyday.

This is because with the wing tip, the load is in the vertical direction and you have a large moment arm with the length of the wing causing large bending moments. I.E. P X L = M. Where P is small but L = large. You can push/pull up/down on the tip of the wing and get the wing to bend up and down.

With the winglet the load is sideways, so the moment at the wing root is smaller. P is small and H is small.

You can do the experiment yourself with a 2X4 and put a L bracket on one end.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
sweair
Posts: 1816
Joined: Sun Nov 20, 2011 9:59 am

RE: 763: Blended Winglets Vs. Raked Wingtips

Fri Jun 29, 2012 10:57 am

cargo planes should not be as limited for wing clearance? Will the AF tankers get the raked tips?
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: 763: Blended Winglets Vs. Raked Wingtips

Fri Jun 29, 2012 4:39 pm

Quoting sweair (Reply 5):
cargo planes should not be as limited for wing clearance?

That's generally true but it's been a looooooong time since anyone designed a large commercial cargo plane from scratch...they're almost always derivatives of passenger models.

Quoting sweair (Reply 5):
Will the AF tankers get the raked tips?

It all depends if they're getting a structurally tweaked wing or not. With the original 767-200/300 wing, I doubt it. With the -400ER wing, maybe.

Tom.
 
flyboy80
Posts: 1827
Joined: Fri Jul 13, 2001 8:10 am

RE: 763: Blended Winglets Vs. Raked Wingtips

Thu Jul 05, 2012 10:40 pm

Ive always been under the assumption the 400 shares the same wing as the 200/300 with the addition of the raked wingtips- could someone clarify please?
 
Viscount724
Posts: 19046
Joined: Thu Oct 12, 2006 7:32 pm

RE: 763: Blended Winglets Vs. Raked Wingtips

Fri Jul 06, 2012 11:27 am

Quoting flyboy80 (Reply 7):
I've always been under the assumption the 400 shares the same wing as the 200/300 with the addition of the raked wingtips- could someone clarify please?

Correct. Excerpt from Boeing document with detailed description of the -400 and changes from previous models:

Raked (swept-back) wingtips have been added to improve the overall aerodynamic efficiency of the wing. They help reduce takeoff field length, increase climb performance, and reduce fuel burn. The new tips are 7 ft 8 in (2.34 m) long and are an all-composite structure, with an aluminum leading edge for erosion protection. Dispatch with the raked tips removed will be allowed in accordance with the configuration deviation list. The raked tips require the addition of new position lights on the aft end of section 48.
 
SXDFC
Posts: 1664
Joined: Sun Dec 09, 2007 6:07 pm

RE: 763: Blended Winglets Vs. Raked Wingtips

Wed Jul 11, 2012 5:34 am

Quoting flyboy80 (Reply 7):
400 shares the same wing as the 200/300 with the addition of the raked wingtips- could someone clarify please?
Quoting Viscount724 (Reply 8):
Correct. Excerpt from Boeing document with detailed description of the -400

So could a customer order a BRAND NEW 767-300ER from the factory with raked wingtips?

Although a bit off topic, lets say WN or any other 737 customer wanted to buy a 737 with raked wingtips ( since its already on the 737-800 ( P-8 Poseidon ) airframe, could they be able to do so as well?
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
User avatar
817Dreamliiner
Posts: 3227
Joined: Sun Jul 27, 2008 4:12 pm

RE: 763: Blended Winglets Vs. Raked Wingtips

Wed Jul 11, 2012 10:36 pm

Quoting SXDFC (Reply 9):
So could a customer order a BRAND NEW 767-300ER from the factory with raked wingtips?

Nope, It would need to be certified fr the 300 series.

Quoting SXDFC (Reply 9):
Although a bit off topic, lets say WN or any other 737 customer wanted to buy a 737 with raked wingtips ( since its already on the 737-800 ( P-8 Poseidon ) airframe, could they be able to do so as well?

Nope, same as above. Boeing would need to certify a passenger version of the P-8.
Please let me know... If you know this is the end of the world, Let me know... If you know the truth...

Who is online

Users browsing this forum: No registered users and 17 guests