noelg
Posts: 2313
Joined: Fri Apr 26, 2002 11:39 pm

Would Winglets Improve The 777s Performance?

Mon Jul 28, 2003 11:31 pm

Is there a reason why the 777 does not have winglets fitted?

I would have thought that for such a modern aircraft winglets would improve the performance, and make it more efficient?

Or did Boeing not want to completely rip off the A330 design for fear of being accused of plagiarism?  Smile/happy/getting dizzy

(Ducks underneath the table at that comment.....)

NoelG

 Big thumbs up
 
N79969
Posts: 6605
Joined: Tue Jan 29, 2002 1:43 am

RE: Would Winglets Improve The 777s Performance?

Mon Jul 28, 2003 11:38 pm

This is an interesting question. I am not an engineer so I do not understand the design considerations that go into determining whether winglets, tip-fences, or other devices are used.

I don't think Airbus innovated the use of winglets.
 
VS744
Posts: 659
Joined: Mon Aug 06, 2001 9:22 pm

RE: Would Winglets Improve The 777s Performance?

Mon Jul 28, 2003 11:44 pm

Apaprently not. There was a thread about this a while ago, i'll try and fish it out. It might be in the tech section...
 
DIA
Posts: 3053
Joined: Sun Jan 28, 2001 2:24 pm

RE: Would Winglets Improve The 777s Performance?

Mon Jul 28, 2003 11:57 pm

Good question. I was wondering why they are putting raked wingtips on the 777-200LR and 777-300ER, but not offering them on the other 777 models. You would think that if Continental flies a 777-200ER from EWR to HKG, some type of winglets wouldn't be a bad idea. . .as far as fuel consumption is concerned.

Maybe the raked wingtips are mainly for extra fuel areas more so than fuel efficiency.

Ding! You are now free to keep supporting Frontier.
 
MITaero
Posts: 485
Joined: Mon Jul 28, 2003 8:00 am

RE: Would Winglets Improve The 777s Performance?

Mon Jul 28, 2003 11:57 pm

There is probably a thread about this, but while Vs744 looks for it...

Winglets are considered "efficient" because they lower induced drag: at the wingtip, air from the high-pressure underside of the wing tries to wrap around to the top, creating a vortex. Winglets have been shown to dissipate this vortex to a point, lowering induced drag. There are probably tech threads about this which give more detail.

There are other considerations besides efficiency at work. Winglets add weight at the wingtip (structural considerations) and also take up extra room at airports, which could be troublesome for a large aircraft (space considerations). I'm probably forgetting some stuff, but it's not an easy or clear-cut decision to just pop on some winglets.
 
DIA
Posts: 3053
Joined: Sun Jan 28, 2001 2:24 pm

RE: Would Winglets Improve The 777s Performance?

Tue Jul 29, 2003 12:12 am

To answer part of my own thoughts above. . .

Maybe they are put on the higher MGTOW 772LR and 773ER for obvious reasons.
Ding! You are now free to keep supporting Frontier.
 
SInGAPORE_AIR
Posts: 11619
Joined: Mon Nov 13, 2000 4:06 am

RE: Would Winglets Improve The 777s Performance?

Tue Jul 29, 2003 12:18 am

Anyone can fly, only the best Soar.
 
SailorOrion
Posts: 1959
Joined: Tue Feb 06, 2001 5:56 pm

RE: Would Winglets Improve The 777s Performance?

Tue Jul 29, 2003 12:28 am

Winglets do nothing else but to increase the aspect ratio of the wing, but not the actual wingspan (because they point upwards). Higher aspect ratio means generally higher performance, but you trade that off with strength and stiffness problems of the wing.

Celestar
 
BR715-A1-30
Posts: 6525
Joined: Thu May 30, 2002 9:30 am

RE: Would Winglets Improve The 777s Performance?

Tue Jul 29, 2003 2:09 am

The 777 wing is New, It doesn't need winglets as the "Winglet purpose" was built into the wing. Just as the DC9/717 does not need them, because that wing was and still is the most advanced wing of its time.
Puhdiddle
 
osteogenesis
Posts: 494
Joined: Tue May 27, 2003 9:44 pm

RE: Would Winglets Improve The 777s Performance?

Fri Aug 01, 2003 3:44 am

N79969,

I don't think Airbus innovated the use of winglets.

I don’t know but their where the first to offer them on an commercial airliner.

Does somebody really know who invented them?
 
AngelAirways
Posts: 480
Joined: Wed Nov 10, 1999 3:55 am

RE: Would Winglets Improve The 777s Performance?

Fri Aug 01, 2003 3:54 am

Hmmm

makes me wonder too. remember boeing did put them on the 747-400. perhaps they thought the decrease in drag was so small that it was not worth adding them to the 777.

I've also wondered why the 777 has a lower aspect ratio. (smaller span per unit chord). Either the boeing stress engineers could not manage a wing like that on the A330, or perhaps they just decided to keep them 'short n sturdy' in line with boeing's 'sturdy and reliable' principles

 
bobrayner
Posts: 2038
Joined: Sun Apr 27, 2003 8:03 am

RE: Would Winglets Improve The 777s Performance?

Fri Aug 01, 2003 3:56 am

Does somebody really know who invented them?

NASA.
http://www.google.com/search?num=100&q=%22first+use+of+winglets%22

Cunning linguist
 
osteogenesis
Posts: 494
Joined: Tue May 27, 2003 9:44 pm

RE: Would Winglets Improve The 777s Performance?

Fri Aug 01, 2003 4:06 am

Thanks Bobrayner very interesting to read.
 
Hamlet69
Posts: 2466
Joined: Thu Mar 09, 2000 2:45 am

RE: Would Winglets Improve The 777s Performance?

Fri Aug 01, 2003 5:00 am

To make a very complex answer as simple as possible:

The 777 wing was a clean-sheet, new design. Thus, winglets were unnecessary, as the engineering advancements of the day (early 1990's) meant that the wing could be engineered as efficeintly (see MITaero's very concise write-up) without winglets as with them, without the corresponding penalty of wing-tip weight. This is still true today, as you'll notice that the raked wingtips of the 767-400ER/777LRs are not true winglets, but angled wingtip extensions which not only further reduce induced drag, but move it further off the wing.

The 747-400, A330/340, MD-11 all have winglets because they were the simplest, most cost-efficeint design solution at the time.


AngelAirways,

"I've also wondered why the 777 has a lower aspect ratio. (smaller span per unit chord). Either the boeing stress engineers could not manage a wing like that on the A330, or perhaps they just decided to keep them 'short n sturdy' in line with boeing's 'sturdy and reliable' principles"


Boeing's overriding engineering principle has always been to design their base designs with the possibility of future growth, while Airbus' used to be to design their wings to precisely match the current aircraft (this has sinced changed to match Boeing's philosophy on the A380). Thus the 777-200 had an oversized wing, while the A330-300 had a 'right-sized' wing. The 777's lower aspect ratio compared to the A330/340 allows Boeing to use the same wing on much larger versions of the aircraft (i.e. 777-200 = 777-200ER = 777-300ER). There was no way in hell Airbus could build an aircraft the size of the 777-300ER using the original wing of the A330/340. Thus the extensive modifications and triple the investment to bring out the A340NGs compared to Boeing's efforts on the 777LRs.

Regards,

Hamlet69
Honor the warriors, not the war.

Who is online

Users browsing this forum: 666wizard, AMIKI, Anansaudiajet, angelopga, babatonton, Bing [Bot], etops1, oldannyboy, Planesmart, pompos, RalXWB, Someone83, Spyhunter and 216 guests