Why don't Boeing 777's have winglets?

Answer 1

Winglet is actually a name of a wing tip that is used by aircraft to reduce induced drag at the end tip of aircraft. The other example of wing tip is upswept, endplate aft-swept...
So why actually boeing does not apply this concept to their aircraft since it can reduce drag and also increases performance?
Boeing 777 operates at a very high speed zone that is around 0.80mach. Therefore most aircrat that operates at high speeds encounter another biggest problem that is aeroelasticity. Aeroelasticity = Aerodynamics and structural consideration . More on aeroelasticity read about langley history . When in high cruising speed the aircraft will experience a vibration effect that is flutter in the aviation term .
Therefore structural failure will occurs due to this kind of effect. Again design is a very huge area where all this effect will be taken account and best design will be used after considering cost wise, aerodynamics, performance, ...etc.
More details please refer Raymers (aircraft design ).

Answer 2

Apparently, the 777 has some pretty huge wings, if the 777 had winglets, then aprons and gates would have to be spaced further apart from each other because winglets take up rather some more space. Thereoff, the 777 has its own wingtip device called raked wingtips, which makes the end of the wing swept back much further than the rest of the wing, it acts like a winglet, yet since it is not bent up, it helps provide extra lift, and it allows a tiny bit more weight to be carried in a load, and it doesn't take up anymore space.

Answer 3

Ok so here it is, back when the 777-200A was made(first 777 type) the computer basically said "you can add winglets or if it was up to me just make the wings a little longer as this will decrease complexity and have the same effect".

The 777-200LR and 300ER have raked wingtips which is like combining winglets and longer wings but without the vertical portion. The 777-200ER and 300 don't have raked wingtips.

Answer 4

The current winglets available like the ones on the A330, 747 won't add much to the 777, so Boeing went for raked wingtips intead(you'll notice the 777's wingtips curve backwards kinds like a scythe). The raked wingtips are more effective than winglets, but Boeing will consider retrofits when the 13ft tall Aviation partners winglets like the ones been fitted on some 767's are available...

Answer 5

Oops, misread the question.

Basically market sector in the early ones and cunning wing design on the ones that do. They achieve the same effect as a vertical winglet by sweeping back the tip, which some still refer to as winglets. APB are considering offering them on the 772ER though, and they may be offered for retrofit.

777s reported as 77L and 77W do have a blended winglet/tip, but it's of a sharply swept and pointed type. See the photo linked below, or have a look at the Air Canada video of their 77L in the second link and compare it to other 777s.

The swept tip achieves the same as the more usual vertical type, it gets between the high and low pressure areas and stops air being sucked out from under the wing... depending on your perspective on lift.

Answer 6

Winglets supposedly increase fuel efficiency and decrease wake turbulence. Atleast that is what Boeing is telling the operators of all Boeing aircraft. I believe the retro-fit for winglets is FREE. I can't imagine Boeing paying to retro aircraft just to make them look cool, so there must be a useful purpose.

Answer 7

Some aircraft structures just cannot support the extra weight.
They would have to redesign the wing and the cost would not make it practical.
The paperwork alone for upgrading and designing is astronomical.

Answer 8

I was under the impression they had them?? I know they have gone back and put them on some of other boing models that have been on the market,,,,