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jetmatt777
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 6:41 am

jumpseat67 wrote:
simairlinenet wrote:
United seems to be leading U.S. carriers (and maybe the world?) on winglet installations:
-All the sCO 757s have Scimitar winglets (and all the sUA have blended winglets)


Sorry, incorrect. All 757s have blended winglets.


Sorry, incorrect. The 757s do indeed have scimitar winglets. What they do not have, is the split-scimitar winglet.
 
md83ftw
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 6:59 am

MIflyer12 wrote:
Anybody with a good handle on direct costs (purchase and fitment, but not lost flight hours) and payback period with oil at $60/barrel and 1500-mile stage lengths for a 757? (Or other example.)


I wouldn't say I have a good handle, but I can give it a shot!

The 757 burns approx 3000-3200kg/hr over distances on average of approx 1000nm according to previous statistics provided in this thread viewtopic.php?t=569157

The Aviation Partners Boeing site has some really interesting info about their products worth visiting here http://www.aviationpartnersboeing.com/p ... 57_200.php including a graph showing fuel burn savings of ~3.75% over 1000nm.

If our theoretical 757 flew three x 3hr sectors a day, it could save something like 370,000kgs of fuel per annum. That's 3000kg x 9hrs x 365 days.

The 757 blended winglet kit (parts only) retails for $1,120,000 USD, so if fuel continues to hover around $76 a barrel/$600 a metric tonne, an operator could save around USD$220,000 a year in this scenario and have the winglets cash positive in 4 years.

If utilisation was increased to 12hrs per day by adding another flight, vs the 9 in our scenario, and fuel increased to $100 a barrel, the savings turn to $390,000pa.

If flight time increased to take advantage of higher savings, ie two six hour sectors per day and $100 a barrel fuel, one could save $470,000pa. A cash positive investment within 3 years, quite impressive.

Very back of the napkin math here!
Last edited by md83ftw on Wed Nov 13, 2019 7:03 am, edited 1 time in total.
 
N649DL
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 7:02 am

Pinto wrote:
United1 wrote:

As someone else mentioned while winglets are not cheap UA gets a bigger bang for its buck as its stage length is quite a bit longer than AA, DL or WN. Just to be pedantic the 737-900s (non-ERs) have blended winglets vs split Scimitars. For only 12 aircraft I am sure the additional STC was prohibitively expensive.


All of United's 737 NGs have Split Scimitar winglets


Please note that CO went crazy with winglet installs as per evident as the 735 back in 2008 (one variant that crashed in DEN) and also the 733 fleet as well.

Winglets are expensive to install, but AA and CO were nuts for it about 10 years ago. It was "hip and cool" to green back then as well (anti-Trump post it's true)
 
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747classic
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 7:56 am

Spacepope wrote:
strfyr51 wrote:
Revelation wrote:
Famously (or not) the KC-46A tanker based on 767 has no winglets for similar reasons, they just did not earn their way on to the airplane.

Even though these aircraft will presumably be flying for 50+ years like KC-135, they mainly tend to fly short hops and no where near as many hours as commercial airliners so they aren't worth the expense and the weight they add to the airplane.

The KC-46 dies not have winglets but it does have the raked wing tips which are aerodynamically superior, The USAF had no need to fit yjr KC-46 into any airport Gate space so they took the Raked wingtips. Which be accounts is superior to the winglets,


It most certainly does not.


The KC-46A has the standard 767 wing tips installed,
Installing winglets would create a lot of difficulties (flutter !!, increased wingloads) , because the KC-46A has to be operated both with and without WARPS installed.
To avoid these very difficult to resolve interference problems and to decrease wing loading the standard wingtips were retained.
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Revelation
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 2:00 pm

N649DL wrote:
Pinto wrote:
United1 wrote:

As someone else mentioned while winglets are not cheap UA gets a bigger bang for its buck as its stage length is quite a bit longer than AA, DL or WN. Just to be pedantic the 737-900s (non-ERs) have blended winglets vs split Scimitars. For only 12 aircraft I am sure the additional STC was prohibitively expensive.


All of United's 737 NGs have Split Scimitar winglets


Please note that CO went crazy with winglet installs as per evident as the 735 back in 2008 (one variant that crashed in DEN) and also the 733 fleet as well.

Winglets are expensive to install, but AA and CO were nuts for it about 10 years ago. It was "hip and cool" to green back then as well (anti-Trump post it's true)

Green is just corporate-speak for saving money on fuel.

Keep in mind in 2008 we were dealing with things like the post-Bush-era GFC and the specter of $200/bbl oil.

They could make a business case for it based on the current conditions so they went forward.

It's interesting that they are now standard equipment on 737/A320 even with cheaper than expected fuel prices.

It's pretty clear that they do earn their way on to the commercial airliners of today i.e. they will pay for themselves before the plane is retired even with relatively low fuel prices.

747classic wrote:
The KC-46A has the standard 767 wing tips installed,
Installing winglets would create a lot of difficulties (flutter !!, increased wingloads) , because the KC-46A has to be operated both with and without WARPS installed.
To avoid these very difficult to resolve interference problems and to decrease wing loading the standard wingtips were retained.

Thanks for the clarification.

If anyone wants, here's a thread from eight years ago where we bashed out all the issues related to Boeing not putting winglets on KC-46: viewtopic.php?t=1024391

If you think a.net is chippy now, you should read some of the old threads! :biggrin:
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trpmb6
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 2:08 pm

It always amuses me that armchair engineers here on a.net think they're better at understanding all the intricacies of what we do when designing and producing aircraft. We didn't do X on aircraft Y so we clearly must be idiots, deceiving customers, or didn't consider it. If anything there is too much debate about every minute detail on aircraft these days. Takes forever to release a drawing at this point.
 
CRJ200flyer
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 2:33 pm

Random observation - a friend of mine has been a captain with Delta for a long time. He flew one of the first 767s at Delta with the new winglets before the flight planning computers had been updated with the new fuel burns. On a 12 hour flight he said he landed with 7,000 pounds more fuel than planned.
 
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Revelation
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 2:52 pm

trpmb6 wrote:
It always amuses me that armchair engineers here on a.net think they're better at understanding all the intricacies of what we do when designing and producing aircraft. We didn't do X on aircraft Y so we clearly must be idiots, deceiving customers, or didn't consider it. If anything there is too much debate about every minute detail on aircraft these days. Takes forever to release a drawing at this point.

Yes, the thread I linked was especially egregious. The OP was saying because an early marketing illustration had winglets on it then Boeing was cheating the taxpayer by not having winglets on the final product. A marketing illustration was in essence a contract in their mind, it was ridiculous! Boeing had a bid to a spec and won the contract based on hitting that spec. How they did it was largely up to Boeing. If USAF wanted winglets, all it would have taken was adding it to the requirements. As it turns out they add weight and cost and potential issues with flutter so they weren't used, which is the right outcome.
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txflyguy94
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 3:47 pm

jumpseat67 wrote:
simairlinenet wrote:
United seems to be leading U.S. carriers (and maybe the world?) on winglet installations:
-All the sCO 757s have Scimitar winglets (and all the sUA have blended winglets)


Sorry, incorrect. All 757s have blended winglets.


actually jumpseat67 is correct, the sCO 757's do have Scimitar winglets, just not the split Scimitar's. the sUA ones do still have the blended winglets, with no plans to add the Scimitar's.
 
DualQual
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 3:53 pm

txflyguy94 wrote:
jumpseat67 wrote:
simairlinenet wrote:
United seems to be leading U.S. carriers (and maybe the world?) on winglet installations:
-All the sCO 757s have Scimitar winglets (and all the sUA have blended winglets)


Sorry, incorrect. All 757s have blended winglets.


actually jumpseat67 is correct, the sCO 757's do have Scimitar winglets, just not the split Scimitar's. the sUA ones do still have the blended winglets, with no plans to add the Scimitar's.


To clarify, the sCO 757-200s have scimitar winglets. The sCO 757-300s have blended winglets as do the sUA 757-200s.
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maps4ltd
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 4:12 pm

jumpseat67 wrote:
simairlinenet wrote:
United seems to be leading U.S. carriers (and maybe the world?) on winglet installations:
-All the sCO 757s have Scimitar winglets (and all the sUA have blended winglets)


Sorry, incorrect. All 757s have blended winglets.


UA has scimitars on some 757s (without the below-wing part).
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nws2002
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 4:55 pm

Veigar wrote:
BWIAirport wrote:
All AS 737s minus a few ancient 739 non-ERs have split scimitars and have had them since like 2015


Are you sure about that.

At LAS I saw an AS 787 land (looked like an -800) in the older livery with no winglets at all and the cockpit eyebrows still there.

Also, Sun Country has some raw 73G (no winglets) and some 738s with no winglets at all either. Let alone splits


For SY, they have two without any winglets (713SY and 813SY) and two with split scimitar (820SY and 821SY). The remainder have the normal winglets.
 
BooDog
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 5:14 pm

joeljack wrote:
tjwgrr wrote:
trpmb6 wrote:
Winglets have costs associated with them. Have to get the most bang for the buck to make up for the small improvement per cycle on fuel economy. It's a long term investment with a high upfront cost and when fuel costs are cheap there isn't much incentive to do that.


IIRC, FedEx acquired some 752s w/ winglets and had them removed.


Why in the world would FexEx remove them? Wasted fuel and greenhouse gas emissions.


http://www.aviationpartnersboeing.com/p ... 57_300.php

The company that does the retrofits has all the data. WInglets add 1700 lbs. to the total weight of the aircraft, which is a 1700 lb. reduction in maximum FedEx packages carried on the plane. (767-300 winglets add 3000 lb. to the plane.)
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JannEejit
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 5:26 pm

Can someone explain the difference in performance terms between winglets and raked wingtips ?
 
alasizon
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 7:14 pm

maps4ltd wrote:
jumpseat67 wrote:
simairlinenet wrote:
United seems to be leading U.S. carriers (and maybe the world?) on winglet installations:
-All the sCO 757s have Scimitar winglets (and all the sUA have blended winglets)


Sorry, incorrect. All 757s have blended winglets.


UA has scimitars on some 757s (without the below-wing part).


For those who are confused, see the below picture, you can clearly see the trailing point of the scimitar winglet.
Airport (noun) - A construction site which airplanes tend to frequent
 
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Revelation
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 8:12 pm

JannEejit wrote:
Can someone explain the difference in performance terms between winglets and raked wingtips ?

Google leads me to:

Raked wing tips are more efficient in reducing drag due to lift (induced drag) than winglets.

As a rule of thumb, a winglet of height 2X will reduce induced drag as much as a raked tip of span X. To reduce induced drag, it’s better to keep the reduction device in the same plane as the wing.

A drawback of a raked tip is that it increases the span of the wing as opposed to the small span increase of a winglet. This can cause difficulties in maneuvering on the ground and restrict the airplane from using some gates.

Ref: https://www.quora.com/Are-raked-wingtip ... -winglets#

I think we see most new designs for long range airliners using raked wingtips for the reason given above, and 777x even going to folding wingtips to get the most efficient design.

Other interesting sources:
* viewtopic.php?t=744857
* https://aviation.stackexchange.com/ques ... g-787-work
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
mjoelnir
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Re: Winglets - Why aren't others following United?

Wed Nov 13, 2019 9:32 pm

Revelation wrote:
JannEejit wrote:
Can someone explain the difference in performance terms between winglets and raked wingtips ?

Google leads me to:

Raked wing tips are more efficient in reducing drag due to lift (induced drag) than winglets.

As a rule of thumb, a winglet of height 2X will reduce induced drag as much as a raked tip of span X. To reduce induced drag, it’s better to keep the reduction device in the same plane as the wing.

A drawback of a raked tip is that it increases the span of the wing as opposed to the small span increase of a winglet. This can cause difficulties in maneuvering on the ground and restrict the airplane from using some gates.

Ref: https://www.quora.com/Are-raked-wingtip ... -winglets#

I think we see most new designs for long range airliners using raked wingtips for the reason given above, and 777x even going to folding wingtips to get the most efficient design.

Other interesting sources:
* viewtopic.php?t=744857
* https://aviation.stackexchange.com/ques ... g-787-work


Rule of thump does not go very far when looking a wingtip devices. I do not disagree with raked being the most effective, when you can increase the span that much without hitting some restrictions. But on the 757 the tiny addition of the scimitar form, just a change at the very tip, brings fuel burn down by nearly one % against the normal blended winglet. Detail work is tremendous important, small changes can bring a lot. With the A350 and A330neo we see quite complex forms, turning in three dimension,keeping the span just inside the gate category. Yes raked is good, but when you have to move over to the next size gate category and have to fold, that does bring added weight. A delicate balance.

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