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763: Blended Winglets Vs. Raked Wingtips  
User currently onlineTWA772LR From United States of America, joined Nov 2011, 2185 posts, RR: 1
Posted (2 years 3 months 3 weeks 5 days 13 hours ago) and read 9934 times:

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.


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10 replies: All unread, jump to last
 
User currently offline817Dreamliiner From Montserrat, joined Jul 2008, 2473 posts, RR: 2
Reply 1, posted (2 years 3 months 3 weeks 5 days 13 hours ago) and read 9927 times:

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.



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User currently onlineTWA772LR From United States of America, joined Nov 2011, 2185 posts, RR: 1
Reply 2, posted (2 years 3 months 3 weeks 5 days 13 hours ago) and read 9925 times:

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!  



Go coogs! \n//
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 3, posted (2 years 3 months 3 weeks 5 days 4 hours ago) and read 9777 times:

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 currently offlinebikerthai From United States of America, joined Apr 2010, 2155 posts, RR: 4
Reply 4, posted (2 years 3 months 3 weeks 4 days 22 hours ago) and read 9650 times:

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.
User currently offlinesweair From Sweden, joined Nov 2011, 1827 posts, RR: 0
Reply 5, posted (2 years 3 months 3 weeks 4 days 4 hours ago) and read 9493 times:

cargo planes should not be as limited for wing clearance? Will the AF tankers get the raked tips?

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (2 years 3 months 3 weeks 3 days 22 hours ago) and read 9422 times:

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.


User currently offlineflyboy80 From United States of America, joined Jul 2001, 1878 posts, RR: 3
Reply 7, posted (2 years 3 months 2 weeks 4 days 16 hours ago) and read 8934 times:

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?

User currently offlineViscount724 From Switzerland, joined Oct 2006, 25626 posts, RR: 22
Reply 8, posted (2 years 3 months 2 weeks 4 days 3 hours ago) and read 8827 times:

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.


User currently offlineSXDFC From United States of America, joined Dec 2007, 2386 posts, RR: 22
Reply 9, posted (2 years 3 months 1 week 6 days 9 hours ago) and read 8438 times:

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 currently offline817Dreamliiner From Montserrat, joined Jul 2008, 2473 posts, RR: 2
Reply 10, posted (2 years 3 months 1 week 5 days 16 hours ago) and read 8316 times:

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.



Reality be Rent. Synapse, break! Vanishment, This World!
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