B777 Winglets or not as is really the case!!

[jetjockey737]

Hi

Can anyone explain why the 777 doesnt have winglets yet most modern widebodies do?...I know why they do I am only interested in why the 777 doesn't !

Answers on a postcard to........

Thanks in advance chaps and chappeses!!

[BerksFlyer]

Raked wings as on the 777-200LR and 777-300ER are more beneficial for long range operations than winglets, so Boeing hasn't bothered with them on the 777.

[Mr @ Spotty M]

Boeing 777 was originally designed with folding wing tips with winglets, similar to aircraft carrier based aircraft.
However no one took the option up because of the extra weight that was added .

[Rainboe]

Why didn't you do some of your own research? A search of B777 winglets brings up more hits than you can handle- try one:
http://www.pprune.org/forums/showthread.php?t=266009&highlight=B777+winglets

[Fargoo]

What a rude reply. No need for it.

[bobmij]

The performance of the 777 wing is better than most jet transport wings with winglets. You need to focus your research on supercritical wings in particular.
I have an article I can send you that should cover most of the Cathay interview stuff or you can just Google it!

[Dani]

What? I would argue the other way round: The 777 wing is so inefficient, it doesn't need any winglets :E

Face the facts: 777 is a great success, just because you compare it with a 747-100 or 200. If you could compare it with a 330-"600", it would show you the way it goes. That's why most Asian airlines use 330 *and* 777: the former for short haul, the later for longer flights.

Dani

[Rainboe]

Fargoo
What a rude reply. No need for it.

What part of
Why didn't you do some of your own research? A search of B777 winglets brings up more hits than you can handle- try one:
do you think is rude? Don't you think if someone is coming to a public forum with a query, they should at least first attempt to research the problem themselves? That was merely a suggestion to learn to look up a query before bothering people with it!

[mabrodb]

Delta and American are both looking at buying the APB blended winglets for the 777-200ER (yet to be cert).

[jetjockey737]

Trying to use my time efficiently thats all. Thanks to everyone for their info. it is much appreciated.

I really thought this section of the forum was to aide people in their quest for info....some people obviously think not! I really hope I am able to repay the favour to the guys with the positive answers someday!!

JJ

[wileydog3]

All the OEMs think they have the best answer to wing design. And every wing is a compromise. Until recently I did not realize there are three wings on any airplane.

1) there is the jig wing which is the wing that is built and not attached
2) there is the ground wing which is the jig wing attached to the airplane and thus subject to the effects of loading, environment, etc
3) and then there is the air-wing which is subject to all the previous plus the various aero-loads at different speeds. Of course, this air-wing changes as the various factors change (weight, speed, load, etc)

Winglets change the aspect ratio of the wing just like lengthening the wing does but there are tradeoffs. You are working at the weakest point of the wing and you are asking the wing tip to bear a greater load during flight. Obviously you will have to design the winglet for a specific regime to make it worthwhile. And in doing so, IF the winglet is after-market, you are essentially creating a NEW wing, not just bolting on a angular bit of metal.

Boeing intially offered the 777 with folding wingtips but it came with additional weight and complexity. No one wanted it. And now various groups are looking at aftermarket winglets for the 777.

Raked wingtips can offer many of the benefits of a winglet but they don't offer ALL the benefits.

Interesting thing is winglets were considered BEFORE Orville and Wilbur flew. Then they were called wingplates and they worked to diminish the vortex at the end of the wing.

You can still see wingplates today but they are on racecars where the aspect ratio is not a consideration but rather an effective wing that creates down-lift with reduced drag to pin the race car to the asphalt.

[Rainboe]

.....I really hope I am able to repay the favour to the guys with the positive answers someday!!
And one really hopes now you have learnt of the positive existence of the Search function you may have many happy hours looking up things yourself!

[forget]

Rainboe, You might argue that every conceivable aviation subject has been covered in the years of Prune. You could then argue that posting any question (other than on current events) is wasting peoples time. If you see a question then either answer it, or ignore it. That would save peoples time. :)

[Spooky 2]

An interesting side bar to this discussion is that the Air Force has installed winglets on their B757's albeit they had not requsted this mod but the local political hacks in Washington state aked for them as part of a budget request. The winglets are built in Washington! At any rate because the 89th is not as concerned with fuel burns as opposed to schedule requirements, they frequently fly the aircraft at .83/.84 under ideal conditions. What they have found out is the winglet equipped aircraft actually burn more fuel then a comparable non-winglet aircraft at the same higher mach numbers. Obviously the winglets serve a useful purpose when flown in the more conservative airline mode as opposed to a max cruise speed curve.

[wileydog3]

The winglets have to be designed for a given environment. No doubt, the winglets were designed for airline ops and not military ops.

On the other hand, the difference between normal cruise and high speed cruise is often negligible in time but incurs, of course, a significant fuel burn. It seems to me that scheduling is a problem if they require the airplanes to constantly deploy at high speed cruise.

In days of old when I was driving the water wagon KC-135, we cruised around at M 0.80 but when in SEA on refueling sorties, we let it eat.. set max cont thrust and take what it would give you until you hit M 0.90 and then you throttled back. But we are heading to fighters short of fuel or damaged coming off targets and needing fuel NOW.

And again, adding winglets is not just bolting on a stuff. It is redesigning the wing and that always creates problems. You are working at the weakest point of the wing, changing the loading, creating new stresses and new problems.

FWIW, the first tests Whitcomb did with the winglets for NASA were on a KC-135. They worked but the USAF opted to go for engines instead of wing mods.

NASA then bailed a DC-10 from Continental and it too worked but no one wanted to pay for the STC that would have been required.

The first real civil use of winglets was on the Lear Longhorns, the Lear 28 and 29 and they were really created as technology demonstrators but wound up with some buys. I don't think any of the 29s are still flying but as I remember some of the -28s are still on the FAA registry. And if I am not mistaken, they were the first ones to be certified to FL510... a LONG time ago.

[NWSRG]

As I understand it, the original plan for folding wings on the 777 was purely for shortening the span while at the gate...with the wings 'unfolded' the wing dimensions and shape would have been identical to non-folding 777s...

...the 300ER and 200LR added winglets presumably because over their longer ranges the efficiency of the winglets overcame the drawbacks (weight)...

[bjones4]

An article from 2005 outlining APBs plans re the 777,

http://www.flightglobal.com/articles/2005/06/15/199585/apb-eyes-spreading-market-for-blended-winglet-applications.html
As APB nears the 767 winglet launch, it is looking at wingtip treatments for the 777-200ER. The wingtip shape could either be a winglet or a "spiroid", which is a closed loop winglet. APB has a patent on this design.

"We hope to have a firm configuration by the fourth quarter and would like to be in a position to offer this modification to the market at that time," says Marino, with a launch customer signed up within a year.

If this goes to plan, APB could see the first 777 with winglets or spiroids entering service in mid-to-late 2007. If the spiroid design is chosen the company may have to develop a proof-of-concept flying demonstrator, which would most likely be on a 737 testbed.

A Spiroid Winglet (http://www.am-inc.com/images/MGAERO1.jpg)