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Still No Winglets For 777s  
User currently offlineJoeCattoli From Italy, joined Aug 2005, 569 posts, RR: 3
Posted (8 years 7 months 1 week 7 hours ago) and read 3998 times:

Hi A-netters, I checked in the past threads about the viability of winglets on the 777. There is something but not a proper answer to what I'm gonna ask.
Since I've heard that winglets are always saving-fuel especially on long-haul (and I don't wanna teach to anyone that 777s are actually long-haul airplanes) why there's not even one model that offers this improvement?
Is Boeing waiting on the next move of Airbus to propose than a winglet that keeps the T7s life longer? (or... since the T7 program has no problem in orders I should say even healthier...).
Or the reason is is simply that the winglet doesn't improve significantly the characteristics of the larger twin-jet on earth?
Thanks in advance
Ciao
Joe

14 replies: All unread, jump to last
 
User currently offlineDfwRevolution From United States of America, joined Jan 2010, 978 posts, RR: 51
Reply 1, posted (8 years 7 months 1 week 7 hours ago) and read 3983 times:

Quoting JoeCattoli (Thread starter):
Is Boeing waiting on the next move of Airbus to propose than a winglet that keeps the T7s life longer?

Aviation Partners, the manufacture of the 737NG and 757 winglets, are considering a winglet retrofit for the non-LR 777 variants. They are currently running performance and economic projections before offering the product for sale.

Boeing will not likely get involved with winglet production for the 777 series, it will be an aftermarket product.

Quoting JoeCattoli (Thread starter):
Since I've heard that winglets are always saving-fuel especially on long-haul (and I don't wanna teach to anyone that 777s are actually long-haul airplanes) why there's not even one model that offers this improvement?

Winglets are typically used as a "band-aide" to add performance to a wing, a properly optimized wing does not need winglets.

When building the 777, Boeing considered winglets. They discovered, however, that increasing span 5/4 the hight of the winglet produces the exact same aerodynamic result with less structural weight. Remember that vertical winglets requires substantial wing reinforcement while a minor span increase does not.

There are few aircraft designed with winglets in mind. If they are, it is because increasing span would yield logistic complications like hampering gate clearance: A388, 744, 783, E170/E190, etc. Nearly all other aircraft recieved winglets midway through design or on the aftermarket to boost performance: MD11, 737NG, etc. The A340 only recieved winglets when it was discovered the CFM56 would not yield the performance of the IAE Superfan.

http://airtransportbiz.free.fr/Technique/Thewinglet.html


User currently offlineN160LH From United States of America, joined Aug 2004, 280 posts, RR: 0
Reply 2, posted (8 years 7 months 1 week 6 hours ago) and read 3902 times:

I wonder why we have not seen more aircraft's getting motified with the racked wingtips like the 767-400's....?

N160LH



"I do alright up in the air, its down on the ground that I tend to mess up..."
User currently offlineKaitak744 From United States of America, joined Jul 2005, 2379 posts, RR: 3
Reply 3, posted (8 years 7 months 1 week 6 hours ago) and read 3820 times:

But, Boeing's philosophy is that for short haul flights, blended winglets. For long haul, raked wingtips. So, if anything, older 777s would be refitted with raked wingtips.

User currently offlineLehpron From United States of America, joined Jul 2001, 7028 posts, RR: 21
Reply 4, posted (8 years 7 months 1 week 6 hours ago) and read 3820 times:

Quoting N160LH (Reply 2):
wonder why we have not seen more aircraft's getting motified with the racked wingtips like the 767-400's....?

Your question was answer in the previous post:

Quoting DfwRevolution (Reply 1):
it is because increasing span would yield logistic complications like hampering gate clearance: A388, 744, 783, E170/E190, etc.

Essentially, raked wingtip devices are better at taking load off of the wing, but they increase span.



The meaning of life is curiosity; we were put on this planet to explore opportunities.
User currently offlineLevg79 From United States of America, joined Sep 2003, 994 posts, RR: 0
Reply 5, posted (8 years 7 months 1 week 6 hours ago) and read 3791 times:

I remember reading that B777's wing is efficient as it is, therefore the winglets are not required. Don't forget that winglets weight a lot so there are soome disadvantages involved, especially on short and medium haul flights. An example of this would be B744D. Remember that when Boeing designed the 777, winglets were already widely used therefore they must have been considered (I'm not a Boeing engineer, just a guess). And I've never heard anyone complain about the 777's performance, so I guess there's no need to work on its efficiency.

Leo.



A mile of runway takes you to the world. A mile of highway takes you a mile.
User currently offlineAvObserver From United States of America, joined Apr 2002, 2472 posts, RR: 9
Reply 6, posted (8 years 7 months 1 week 6 hours ago) and read 3791 times:

The raked wingtips on the -300ER and -200LR perform the same function as winglets and Boeing jusged them to be more effective the 777's aft-loaded wing. No doubt that many older 777's will eventually be retrofitted with these.

User currently offlineMudboy From United States of America, joined Jan 2006, 1167 posts, RR: 5
Reply 7, posted (8 years 7 months 1 week 5 hours ago) and read 3674 times:

What would happen if one of the winglets broke off in flight?

User currently offlineCloudyapple From Hong Kong, joined Jul 2005, 2454 posts, RR: 10
Reply 8, posted (8 years 7 months 6 days 19 hours ago) and read 3514 times:

Given you stay within a box of 65m span for a Code E aircraft it's more efficient to stick with a simple span extension. That's why the span went up from 60.9m on the B772 to 64.8 on the B772LR. That's very close the maximum you can fit on a Code E stand. Airport compatibility is a huge issue if you go any wider.

Interesting fact that the B748 is going outside the 65m span box at 68.4m. It's a "narrow" Code F aircraft which means it can park at a Code E stand with restriction on the span of neighbouring aircraft (up to 61.6m span - B772/B773 "classics", B789/A333/A343/A358) if both centrelines offset to 1 side.

[Edited 2006-02-27 12:46:20]


A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
User currently offlineJoeCattoli From Italy, joined Aug 2005, 569 posts, RR: 3
Reply 9, posted (8 years 7 months 6 days 18 hours ago) and read 3414 times:

Quoting DfwRevolution (Reply 1):

I didn't know about raked wingtips and adding wingspan to avoid the extra weight of a winglet. Thanks
It's a pity that we will almost surely never see one of those marvellous T7s with winglets... It should be quite impressive.
Ciao
Joe


User currently offlineLevg79 From United States of America, joined Sep 2003, 994 posts, RR: 0
Reply 10, posted (8 years 7 months 6 days 16 hours ago) and read 3252 times:

Quoting JoeCattoli (Reply 9):
It's a pity that we will almost surely never see one of those marvellous T7s with winglets... It should be quite impressive.

It would look something like this:

Modified Airliner Photos:
Click here for bigger photo!
Design © Joe Perez
Template © Pete Bennett




Leo.



A mile of runway takes you to the world. A mile of highway takes you a mile.
User currently offlineViv From Ireland, joined May 2005, 3142 posts, RR: 29
Reply 11, posted (8 years 7 months 6 days 16 hours ago) and read 3232 times:

Quoting JoeCattoli (Thread starter):
winglets are always saving-fuel

Not always.



Nikon D700, Nikkor 80-400, Fuji X Pro 1, Fujinon 35 f/1.4, Fujinon 18 f/2
User currently offlineSTARalliance24 From Canada, joined Jun 2005, 378 posts, RR: 2
Reply 12, posted (8 years 7 months 6 days 16 hours ago) and read 3232 times:

Quoting Levg79 (Reply 10):
It would look something like this:

SWEET! The T7 looks awesome with winglets!

Quoting Mudboy (Reply 7):
What would happen if one of the winglets broke off in flight?

All aircraft with winglets are certified to fly without one on a wing. Like the B747 and A340.


User currently offlineGlom From United Kingdom, joined Apr 2005, 2818 posts, RR: 10
Reply 13, posted (8 years 7 months 6 days 15 hours ago) and read 3167 times:

I'm not so keen. They work sometimes, like on the A340, but I think the 777 looks better with raked wingtips.

User currently offlineDfwRevolution From United States of America, joined Jan 2010, 978 posts, RR: 51
Reply 14, posted (8 years 7 months 6 days 15 hours ago) and read 3134 times:

Quoting Viv (Reply 11):
Not always.

Maybe on a positioning flight under 30 minutes, but most winglet packages break-even in under an hour of flight time.

The benefit of winglets is more dramatic as the flight goes on, but the effects of winglets are felt even on the take-off roll.


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