777 wingletless question
 

From the uninformed to the informed why is it that I have not seen one 777 with winglets.Thought that they had great advantages and most Boeing seem to have them as std or option?

I'm not sure if this has a bearing on B777 winglets, but the aircraft was designed to have optional folding wingtips in order to provide adequate clearance in tight ramp/gates. As yet no customers have ordered them.

probably because the 777 uses a completely new wing (as opposed to 74/76/73 series) that has been designed to reduce spanwise flow without the added expense/weight/drag that a winglet may induce.

This doesn't quite explain then why the A330/340/380, with wing technology of the same era as the 777, do have winglets. And some versions of the 787 will have winglets (others will have a completely new style of wingtip).

I thought the folding 777 wings were only an idea in response to one particular issue, at Chicago O'Hare, where the main domestic gates were sized for the DC-10s for American and United which the 777 wouldn't fit. As widebodies of all types have pretty much disappeared from US domestic flights in more recent times, it is no longer a requirement.

The 300ER has raked wingtips... man they look mean!

I thought the requirement was being able to fit in the 80m x 80m box?

The 300ER, 200LR and 200F all use the raked wingtips developed initially for the 767-400. Boeing are also using them on the 747-800 as they seem to think that's the way to go for them.

Depending on which artists illustration they are putting out today, the new 787 has something similar rather than an angular winglet arrangement. It apparently varies between the medium range -300 version's wing and the longer ranged -800 and -900 variants.

Raked wingtips will give a decrease in induced drag of approx 5.5 % compared to conventional wingtip devices of around 3.5-4.5 %. The goal is to essentially increase wing span without increasing the width of the aircraft, so it is able to fit into conventional airport gates. I love wikipedia.

I also understand that like a delta wing creates low pressure with a vortex over its surface and hence lift the raked wing tip on the later 777 uses this as boundary to span wise flow, similar design seen on the tip of a Lynx helo blade. This negates the need for any physical winglet boundary and any associated form drag.

According to some instructors in Tukwila, the simple answer is "Not Invented Here"..... Boeing were not going to build a new aircraft and copy Airbus.

Mutt

it's a bit like 'why doesn't a Veyron have as many spoilers as an F40?'

maybe Airbus couldn't figure out how to design/build a cool, tapered wing, so just went for old-school?

Couple of pointless replies there seeing as the 747 and 737 both have winglets, the 747-400 having traditional types just like the A330/A340.

Boeing's new swept wingtip device is nothing to do with some silly cheerleading reason. They designed it to achieve everything a conventional winglet design does and more, at a lower drag penalty. It has more in common with something that took hundreds of millions of years to design, namely the wingtips of fast-flying birds such as hawks.

Modern materials also mean the devices can be implemented at a much lower weight than would have been the case if done in metals.

That'll be why a Boeing wing still has vortex generators and the Airbus wing is perfectly smooth. :rolleyes:

Whitehatter

Do Boeing actually make the winglets for the B737?? Or are they made by another company in Renton? You might also find that this other company was formed by ex-Boeing engineers who were disappointed that Boeing wouldnt make winglets. So why do you think that Boeing wouldnt listen to its own engineers?

As for the B744, its 1980's technology, they couldnt increase the span, so it had to have winglets :)

Mutt

Boeing make it's own winglets for the NG ,and also there is another company ,called Boeing Partners ,which makes also winglets for the Ng ,a bit longer ,if I'm not wrong.They usually retrofit the Ng's or the classics without winglets.

www.aviationpartners.com

The Boeing Company adopted Blended Winglet technology for the Boeing Business Jet as well for Next Generation Boeing 737 series aircraft. Today, Aviation Partners Boeing, a joint venture between Aviation Partners Inc. and The Boeing Company, has supplied Blended Winglet Shipsets to over 600 NG Boeing 737-800/700 series aircraft worldwide. A typical Blended Winglet Equipped 737 consumes 110,000 fewer gallons of fuel per year. Currently, Aviation Partners Boeing is developing Blended Winglet Programs for Boeing 757 and 767 series aircraft.

Mutt

If the question is in relation to an upcoming interview the answer is supercriticl airfoil. :)

http://www.nasa.gov/centers/dryden/n...-044-DFRC.html

It's down in the hellhole, but dont tell anyone, it's a secret. ;)

blended wing
 

boeing are working on blended wing technology,where the actaul wing tip twists to offset spanwise flow.this will compensate for winglets and weight.also to answer a previous quote about airbus having no vortex generators,i think if you look at the 747 wing and even the old sp its a hella of a lot cleaner than any bus wing .the bus has sh&t hanging out everywhere,lots of parasitic drag

i always thought those CB's controlled the sky-hook that made the wings bend up at the tips....

See Boeing article here