Boeing to fit 767s with winglets.

No, it is NOT. The difference is marked. The negligible bit is YOUR claim that the faster climb to Cruise Alt is the key. I argued against you, you typed like I defended your claim.
The post above also points you at Boeings website. It supports my argument, and my argument is based on feedback from ALL the Winglet operators. All those designed by APB that is.

My apologies for mis-stating your argument.

Furthermore, you are right. The wingletted airplane saves a significant amount of fuel even at the same flight level. Not satisfied with links to manufacturer websites, I have run that data on a fairly sophisticated flight planning system in use at a large airline. I was able to plug in a wingletted airplane and a non wingletted airplane. In one scenario I capped their altitudes at FL360, in the other scenario I let them climb to their most economic altitudes. The results are shown in the chart below, fuel burn in pounds for 4 hour 25 minute flight with exact same payload and winds:

Perhaps I am not stating it correctly. Try this:

If you run side by side comparison of a ship with winglets and one without with the exact same climb/cruise/descent profile, the difference is negligible. This is what I was trying to say when I said this: “The burn at any particular flight level is almost the same with or without.” The savings comes from being able to climb earlier and/or higher, as old shape argued.

There are other benefits that might be less obvious to some observers. For example, altitude changes on the North Atlantic track system are not routinely done, in fact they are rarely done. A 767-300ER might want to step climb on the the econ profile, say from FL330 to 350 to 370, but is unable to because he is generally locked into whatever FL he entered the track at. Thus he crosses the NA at the uneconomic FL330 while the 757ER equipped with winglets will climb right to 370 straight out of JFK at a very high percentage of his MTOW. There is also less traffic at the higher FL*s on the tracks because the heavies can’t get up there (generally). Thus the 757 is also less likely to get a track change.

No, it is NOT. The difference is marked. The negligible bit is YOUR claim that the faster climb to Cruise Alt is the key. I argued against you, you typed like I defended your claim.
The post above also points you at Boeings website. It supports my argument, and my argument is based on feedback from ALL the Winglet operators. All those designed by APB that is.

EDIT: Linked image too large, removed by Moderator.

PS

767-400 with raked winglets.

Perhaps I am not stating it correctly. Try this:

If you run side by side comparison of a ship with winglets and one without with the exact same climb/cruise/descent profile, the difference is negligible. This is what I was trying to say when I said this: “The burn at any particular flight level is almost the same with or without.” The savings comes from being able to climb earlier and/or higher, as old shape argued.

There are other benefits that might be less obvious to some observers. For example, altitude changes on the North Atlantic track system are not routinely done, in fact they are rarely done. A 767-300ER might want to step climb on the the econ profile, say from FL330 to 350 to 370, but is unable to because he is generally locked into whatever FL he entered the track at. Thus he crosses the NA at the uneconomic FL330 while the 757ER equipped with winglets will climb right to 370 straight out of JFK at a very high percentage of his MTOW. There is also less traffic at the higher FL*s on the tracks because the heavies can’t get up there (generally). Thus the 757 is also less likely to get a track change.

The winglets don’t save fuel per se, as in reduced burn. The burn at any particular flight level is almost the same with or without. They cause the wing to produce more lift (or to lose less), thereby allowing higher flight levels earlier in the flight, and generally (normal winds) the aircraft burns less fuel at the higher flight level.

Actually that’s exactly what they do, reduce fuel burn. Less drag = less thrust required = lower fuel burn.

http://www.boeing.com/commercial/737family/pf/pf_winglets.html

Yes, getting to cruise faster and being able to climb higher sooner helps but the fuel savings isn’t seen until mission length pushes 1000 nm (per the Boeing webpage) which indicates that the fuel savings is coming from that extended time flying at altitude rather than short hops.

Concur. And this is precisely why these airlines are doing this now as opposed to 10 years ago.

FYI, I have it on very good authority from a very large 757 operator that the 757 with winglets save about 3% on the trip burn versus a 757 without. When you are at limit (normally structural), this savings goes right back into additional payload, meaning additional weight and burn, thus confusing the comparison.

The winglets don’t save fuel per se, as in reduced burn. The burn at any particular flight level is almost the same with or without. They cause the wing to produce more lift (or to lose less), thereby allowing higher flight levels earlier in the flight, and generally (normal winds) the aircraft burns less fuel at the higher flight level.

The winglets save fuel burn. The drag reduction by not having the tip vortex is significant. The extra lift enabling cruise altitude to be reached earlier is only small, the craft my get to level cruise about 5-10 mins earlier, 5-10 mins at a more efficient burn level is no great shake – but not to be ignored.
Your operator is using the savings made by the winglet to cram an extra pax or more freight (The freight and postage that travels with most flights – not just freighters). This is a normal thing to do and this means extra revenue, and that revenue must be included in the benefit side of the analysis sheet. Feedback from all the operators of the blended winglets indicate 6-10% running cost savings. The longer the haul, the better the saving.
10 years ago, the blended winglet design had not been perfected, the Airbus one was garbage for example and they carried on with their fence. But Airbus are now designing a proper blended winglet. Remember, these winglets were fitted long before the present fuel crisis, and it was a benefit back then.
And, as I said on another related thread somewhere, the private operators of 737’s are having them fitted, they care not-a-jot about fuel saving as it is their private jet and it’s pedal to the metal wherever possible. They fit them because they look good. A 737 without winglets now looks old and outdated once you’ve seen one with them. And the 767 just looks divine with them. Of course, the 767 fleet operators are looking for money return not a Bling(let).

the most important element:

(4) The price of fuel.

With fuel prices so high every small percentage of savings adds up a lot quicker when fuel is $4+ per gallon vs. <$1 years ago.

Concur. And this is precisely why these airlines are doing this now as opposed to 10 years ago.

FYI, I have it on very good authority from a very large 757 operator that the 757 with winglets save about 3% on the trip burn versus a 757 without. When you are at limit (normally structural), this savings goes right back into additional payload, meaning additional weight and burn, thus confusing the comparison.

The winglets don’t save fuel per se, as in reduced burn. The burn at any particular flight level is almost the same with or without. They cause the wing to produce more lift (or to lose less), thereby allowing higher flight levels earlier in the flight, and generally (normal winds) the aircraft burns less fuel at the higher flight level.

It takes more than a couple of years payback.
There are 3 elements to the cost.
(1) The cost of the Winglets themselves.
(2) The cost of the mod kit for the existing wing tip (Some beefy structure goes in instead of the closing Rib). The mod kit and the fitting are more expensive than the winglet.
(3) The down-time of the fitting, which can mostly be done during the scheduled maintainance periods, but not always.

the most important element:

(4) The price of fuel.

With fuel prices so high every small percentage of savings adds up a lot quicker when fuel is $4+ per gallon vs. <$1 years ago.

They’re huge winglets!

They look mighty big. You’d think the additional drag would outweigh any possible gains in efficiency.

Hot dang that is one pretty bird!

Yes it does enhance her beautiful lines

Hot dang that is one pretty bird!

http://www.airliners.net/photo/American-Airlines/Boeing-767-323-ER/1372871/L/

Oh yes :cool:.

That piccy is better than the official ones that are now knocking around……

http://www.airliners.net/photo/American-Airlines/Boeing-767-323-ER/1372871/L/

Oh yes :cool:.

Southwest reported some time back that the winglets on their 737s made their cost back in around a year.

Surely, all things being equal that should equate to roughly the same time period on the 767, given that revenues on the 767 are by virtue of its nature, higher?

Any idea on cost?
I read that 737 winglets coast about $500,000 a set but would pay for themselves in a couple of years.

Of course the 767 payback wouold be much greater.

It takes more than a couple of years payback.
There are 3 elements to the cost.
(1) The cost of the Winglets themselves.
(2) The cost of the mod kit for the existing wing tip (Some beefy structure goes in instead of the closing Rib). The mod kit and the fitting are more expensive than the winglet.
(3) The down-time of the fitting, which can mostly be done during the scheduled maintainance periods, but not always.

Which begs the question: Why don’t they fit the 763 with 764 style raked wing tips or is this something that cannot be achieved as a ‘retro’ fit ?

It must be the payback period. The 300 and 400 are an ageing fleet now and maybe there aren’t enough years left.

Any idea on cost?
I read that 737 winglets coast about $500,000 a set but would pay for themselves in a couple of years.

Of course the 767 payback wouold be much greater.

Originally it was shown with 737 style blended winglets. The raked wingtips came later when they found out that they would be lighter, less draggy, and provide just as much fuel saving.

J

Which begs the question: Why don’t they fit the 763 with 764 style raked wing tips or is this something that cannot be achieved as a ‘retro’ fit ?

Originally it was shown with 737 style blended winglets. The raked wingtips came later when they found out that they would be lighter, less draggy, and provide just as much fuel saving.

J

This is not the case, if you read my earlier post on this subject, the raked/kinked/cranked winglets are the old style design. They are slightly cheaper to make (Fitting of either is about the same cost) than the Blended style. They can be lighter, because the torque loads and pressure loads are less on them, allowing them to be not as structurally beefed-up as the blendeds.

The blended style are considerably more fuel efficient than the kinked. Kinked – about 2-4 maybe 5% but the blendeds are are 6 – 10% fuel saving.
The blendeds are much less draggy than the kinked. The kinked designs are from the 90’s. The Airbus “Fence” is from the 80’s, and AUK are considering putting blendeds on the narrow body range, it will be their own though (The test version from a few years ago wasn’t that brilliant). I can’t see Airbus buying a product off Aviation Partners Boeing. 🙂
The artist impression of the 767 above needs scaling up a tad. The 767 winglet is 16 feet from the join to the tip – measured along the bottom skin surface….which becomes the outer when it’s 22 degrees off vertical.
The 777 blendeds (If they get off the ground) will be very small, not much bigger than the 737, due to the wing design already dealing with some of those nasty tip vortices and a few other aerodynamic reasons.
They may have considered the kinked for the 777, basing it on the ugly ones on the 747 but it didn’t get further than the designers sketch book.
The 747 designers and customers now want the blendeds, but unfortunately the kinked one is in production, it is certified etc. To design/test/certify another one to do the same job will be costly. But, for a further 4 or 5% fuel saving, the customers may want to pay for that extra non-recurring cost. It will be only new aeroplanes though, with plenty of service life left……..it’s not going to be worth putting a new expensive winglet on a machine that only has 5 or 6 years life left.

The Dreamliner and the A350 Nightmareliner have the blended winglets built into the design, and are more like a gentle curl up at the end of the wing. Not sure if they have kept the wingspan to the max. allowed (For airport terminal sizes) or they have designed the whole wing taking into account an “Ordinary” span but with curly ends. I suspect the latter.

Not originally…

Wasn’t the 777 designed with raked wing tips

Originally it was shown with 737 style blended winglets. The raked wingtips came later when they found out that they would be lighter, less draggy, and provide just as much fuel saving.

J