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UltimateDelta
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Why Winglets On Regional Jets?

Fri Dec 12, 2008 12:14 am

I know I might seem a bit slow asking this, plus it's possibly been asked before, but it occured to me: Why do regional jets have winglets? Based on what I have read, winglets provide no significant benefit over short distances like the ones these planes operate. Yet CRJs and ERJ-145XRs have them. Can someone enlighten me here? Thanks in advance.
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pilotpip
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 12:27 am

Winglets provide benefits regardless of aircraft size.

In the case of the XR, it's used for longer stage lengths where increased efficiency will help. In the case of the CRJ, it is a stretched Challenger which already incorporated it.
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 12:33 am

I think it is a combination of factors:
- On RJ terminals, space tends to be at a premium, and the installation of winglets allows a decrease in wingspan.
- Some of the RJ routes are in fact pretty long, running into several hours. The ERJ-145XR is a long range version, which would explain the addition of winglets.
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 4:25 am

I've even seen - of all things - a Navajo with Winglets!
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aviopic
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 9:09 am



Quoting UltimateDelta (Thread starter):
Why do regional jets have winglets? Based on what I have read, winglets provide no significant benefit over short distances like the ones these planes operate

Good question ad the best answer is probably "fashion", it looks modern(the exact words used by KL for example).
I am told that a 73NG needs at least a 2.5 hour cruise at a minimum altitude of 35.000ft to just play even with the extra fuel burned during take off and climb due to the weight increase.
The smaller the aircraft the bigger the weight impact will be and thus the longer it needs to fly in order to make it profitable.
But it seems that this hype is coming to an end like any other hype in the past.
The latest a/c have only tiny wing lets(a380) or a blended design(787).
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 9:23 am



Quoting Aviopic (Reply 4):
The smaller the aircraft the bigger the weight impact will be and thus the longer it needs to fly in order to make it profitable.

That depends on the size of the winglet in proportion.

Quoting Aviopic (Reply 4):
The latest a/c have only tiny wing lets(a380)

They really are not tiny. They are necessary so as not to exceed the 80 meter limit.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
aviopic
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 10:07 am



Quoting Starlionblue (Reply 5):
That depends on the size of the winglet in proportion.

True but the weight is not coming from the winglet but mainly from the wing reinforcement.

Quoting Starlionblue (Reply 5):
They really are not tiny.

Well all is relative of course.
Compared to 744 etc they are little.
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lowrider
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 5:35 pm



Quoting NZ8800 (Reply 3):
I've even seen - of all things - a Navajo with Winglets!

It is the Panther mod, it also comes with new engines, props, and some other aerodynamic clean-ups. Expensive, but I am told it really enhances the aircraft.
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2H4
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 6:10 pm



Quoting Aviopic (Reply 4):
But it seems that this hype is coming to an end like any other hype in the past.

Two points:

1) The term "hype" implies little or no benefit. As has already been mentioned, winglets provide benefits regardless of aircraft size. And the benefits are not limited to cruise.

2) How does it seem that this "hype" is coming to an end? There have never been more aircraft models available with winglets.

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typhaerion
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 9:16 pm



Quoting Aviopic (Reply 4):
I am told that a 73NG needs at least a 2.5 hour cruise at a minimum altitude of 35.000ft to just play even with the extra fuel burned during take off and climb due to the weight increase.

I dont know where you got this from but this is no where near what I heard. What's your source?

Frankly, if that were the case WN would not mount them at all. There are very few WN flights with a cruise time much over 3 hours. I can think of several, but the vast majority are shorter than that. Which means that if they were losing money each time they took off with those things, plus the initial outlay, they never would have done it. And yet they are still in the process of adding them to their fleet, if they arent already all the way there with their targets.
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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 9:31 pm

It's important to remember that there are more benefits to winglets than just fuel burn at cruise. Well-designed winglets allow for reduced takeoff thrust, which decreases fuel burn and engine wear. Higher initial cruise altitudes can be utilized. Climb gradients can be greater, and takeoff weight can be increased.

In short, you needn't operate solely long-haul flights for the benefits of winglets to justify their cost.

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RE: Why Winglets On Regional Jets?

Fri Dec 12, 2008 11:10 pm



Quoting 2H4 (Reply 10):
It's important to remember that there are more benefits to winglets than just fuel burn at cruise. Well-designed winglets allow for reduced takeoff thrust, which decreases fuel burn and engine wear. Higher initial cruise altitudes can be utilized. Climb gradients can be greater, and takeoff weight can be increased.

The can also act as noise reduction devices. The 727 winglet mod, for example, allows faster climb, meaning the noise is removed from the ground faster.
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RE: Why Winglets On Regional Jets?

Sat Dec 13, 2008 3:09 am

May just be my imagination, but ground collisions seem more frequent involving winglet-equipped aircraft. One recent example a couple of days ago at YYZ from the Transport Canada daily incident website.

Westjet flight WJA645, a Boeing 737-7CT aircraft, was being pushed back from Toronto Terminal 3 gate C25 when the left hand winglet contacted the right hand winglet of Westjet flight WJA208, a Boeing 737-7CT aircraft, being marshalled into the adjacent gate C24. At the time of the incident, each gate was manned by a four person ground crew which included a lead hand, two wing walkers and fourth person for chocking the aircraft and/or disconnecting the tow tractor. All personnel were in their assigned positions when the collision occurred. There were no injuries. The aircraft were removed from service so both winglets could be replaced.
 
pilotpip
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RE: Why Winglets On Regional Jets?

Sat Dec 13, 2008 5:53 am

More aircraft today have winglets. Therefore more collisions will involve winglets.

Another thing to consider is that many new aircraft that are equipped with winglets have designs optimized for the application in the first place so no additional support may be needed compared to a retrofitted design.
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tdscanuck
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RE: Why Winglets On Regional Jets?

Sat Dec 13, 2008 9:31 pm



Quoting UltimateDelta (Thread starter):
Based on what I have read, winglets provide no significant benefit over short distances like the ones these planes operate.

They always provide some benefit, and they always have some cost. Where those trades break even depends (strongly) on how the winglet was designed, and when it was designed compared to the airplane.

Quoting Pilotpip (Reply 13):

Another thing to consider is that many new aircraft that are equipped with winglets have designs optimized for the application in the first place so no additional support may be needed compared to a retrofitted design.

This is absolutely key. A wing designed from the outset to have a winglet (i.e. a wing with a span restriction) can fly better than a wing of the same span and loading designed without a winglet. This is quite different than retrofitting, where you're taking a wing designed to work without a winglet and grafting a winglet on to it. In that case, you shift the loading around and you pay a bigger penalty in wing re-inforcement.

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RE: Why Winglets On Regional Jets?

Sun Dec 14, 2008 1:22 pm



Quoting NZ8800 (Reply 3):
I've even seen - of all things - a Navajo with Winglets!

You mean like this?

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RE: Why Winglets On Regional Jets?

Sun Dec 14, 2008 6:36 pm



Quoting UltimateDelta (Thread starter):
ased on what I have read, winglets provide no significant benefit over short distances like the ones these planes operate.

As mentioned, they provide the same benefits to all aircraft. Not to mention that these regional jets don't only do short flights. Air Canada Jazz flies their CRJ's to Houston and other destinations abroad at times.

Quoting Aviopic (Reply 4):
Good question ad the best answer is probably "fashion", it looks modern(the exact words used by KL for example).

That is a very good point at well. The winglets just make any plane look cleaner, sharper, and faster.

Quoting Aviopic (Reply 4):
I am told that a 73NG needs at least a 2.5 hour cruise at a minimum altitude of 35.000ft to just play even with the extra fuel burned during take off and climb due to the weight increase.

Many 73NGs cruise at FL415 even if the cruise there only lasts for 5 minutes. This more than saves the fuel needed to lift the winglets off the ground. Prime example is WestJet flights from here in YQQ to YYC, which is as short as one hour and three minute flight depending on the wind. Many WN flights in the US which are very short would do the same.

Your statistic seems somewhat biased and exaggerated to me.


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RE: Why Winglets On Regional Jets?

Sun Dec 14, 2008 8:08 pm

I am told that the CRJ/Challenger's runway numbers would take a large penalty were it not for the winglets. The CRJ wing is not really designed for short field takeoffs.
 
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RE: Why Winglets On Regional Jets?

Sun Dec 14, 2008 11:25 pm



Quoting ROSWELL41 (Reply 17):
The CRJ wing is not really designed for short field takeoffs.

That's the truth! A fully laden CRJ-200 with a flex thrust take-off will use as much runway as a fully laden 747. Or so it seems.

Anyway, I have read somewhere that there is a 7% penalty on the CRJ if there are no winglets. That said, I doubt they can be removed. On some airplanes they can be, but I have never seen a CRJ without them.
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RE: Why Winglets On Regional Jets?

Mon Dec 15, 2008 11:02 am

When Bombardier launched the CRJ900 with Enhanced Performance Package (EFP), the winglets were slightly redesigned.

The new winglet has "increased outboard cant", 20% increase in span + 10 inch effective wing tip extension".

"This provides better lift/drag ratio and better airfield performance. The larger winglets also contribute to reduced drag in cruise, resulting in the lower fuel burn (1% lower fuel consumption)."

Source: Bombardier.com, Regional Update / March 2005

So... sounds like the winglets are quite important on the regional jets. They look good with them too  Smile

I know the CRJ1000 wingspan will be 1,33 metres longer, but will the winglets be larger than on the CRJ900?
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RE: Why Winglets On Regional Jets?

Mon Dec 15, 2008 12:32 pm



Quoting Saab2000 (Reply 18):
That's the truth! A fully laden CRJ-200 with a flex thrust take-off will use as much runway as a fully laden 747. Or so it seems.

No aircraft is going to perform well when it's at or near it's certified MTOW. Of course, the CRJ is exceptionally slow off the ground at or near MTOW due to its lack of slats.
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RE: Why Winglets On Regional Jets?

Mon Dec 15, 2008 1:36 pm



Quoting Goldenshield (Reply 20):
No aircraft is going to perform well when it's at or near it's certified MTOW. Of course, the CRJ is exceptionally slow off the ground at or near MTOW due to its lack of slats.

It also has high approach and landing speeds as well as high take-off speeds because of this. All the controllers think that because it's a small airplane it flies slow and uses short runways. But our approach speed at MLW is 146KIAS.
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RE: Why Winglets On Regional Jets?

Tue Dec 16, 2008 2:56 am

I have a couple of thousand hours of time in the front window seat of the CRJ. The -200 series is definetely not a short field aircraft. The wing is definetely designed to go high and fast. I recall having a B767 Captain in the jumpseat one day and he was astounded at how fast our approach speeds were. They were much higher than his 767 he said.
 
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RE: Why Winglets On Regional Jets?

Thu Dec 18, 2008 4:02 pm

Winglets are not all optimized for cruise, as some posts here imply. A winglet optimized for high lift coeficient flight phases (takeoff, climb) makes a lot of sense for a plane that flies short sectors and has a hard restriction on wingspan.
 
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RE: Why Winglets On Regional Jets?

Fri Dec 26, 2008 12:58 am



Quoting Aviopic (Reply 6):
Quoting Starlionblue (Reply 5):
They really are not tiny.

Well all is relative of course.
Compared to 744 etc they are little.

A380 wing tip fences:

7late7, A3latey, Sukhoi Superlate... what's going on?
 
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RE: Why Winglets On Regional Jets?

Fri Dec 26, 2008 4:58 am



Quoting EGNR (Reply 24):
Quoting Aviopic (Reply 6):
Quoting Starlionblue (Reply 5):
They really are not tiny.

Well all is relative of course.
Compared to 744 etc they are little.

A380 wing tip fences:

Nice pics. Seeing as the 744 ones are 6 ft IIRC these seem a tad larger.
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EssentialPowr
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RE: Why Winglets On Regional Jets?

Tue Dec 30, 2008 3:38 am



Quoting 2H4 (Reply 8):

Two points:

1) The term "hype" implies little or no benefit. As has already been mentioned, winglets provide benefits regardless of aircraft size. And the benefits are not limited to cruise.

2) How does it seem that this "hype" is coming to an end? There have never been more aircraft models available with winglets.

Poor analysis.

Winglets are not a cure all. The 787 does not have them; the pursuit of an elliptical wing is as valid today as it was when the Spitfire was built. Why the Spit and not the P51? A Spit took much longer to build, and therefore the cost was higher.

Winglets have become a marketing issue. The negatives of a winglet? They add or contribute to:

1. Weight
2. High alpha drag (meaning the benefit of a GOOD winglet is felt in cruise, not climb or descent)
3. Increase wing bending moments (wing fatigue).

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RE: Why Winglets On Regional Jets?

Tue Dec 30, 2008 3:58 am



Quoting EssentialPowr (Reply 26):
Winglets are not a cure all.

Any wing can benefit from a reduction in induced drag, whether that reduction comes from an increase in span or from a winglet. A winglet is simply a non-planar span extension.

Quoting EssentialPowr (Reply 26):
Winglets have become a marketing issue.

Are you contending that the marketing benefits outweigh the performance benefits? If so, please provide a source.

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tdscanuck
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RE: Why Winglets On Regional Jets?

Wed Dec 31, 2008 5:12 am

The original message where I posted this stuff got deleted due to quoting another post that was deleted. I'm reposting it here (minus the original quotes) in the hopes of answering some common questions about winglets.

There are a whole bunch of drag effects involved with a winglet:
-Parasite drag due to winglet wetted area
-Induced drag due to increased wing lift due to increased weight
-Reduced induced drag due to decreased downwash over most of the wing

If you do it right, the last item is larger than the top two combined...if you don't, it's a net drag penalty. This is why making winglets that work really well isn't at all trivial. Induced drag starts off at zero for zero lift and increases, approximately, with the square of the lift coefficient.

You don't usually see winglets on turboprops because they're not span restricted. A retrofit winglet only makes sense when you don't have enough span margin for a raked tip and you do have enough strength margin for an extension. A retrofit raked tip only makes sense when you have span margin and strength margin. If you don't have either, then there's no economical solution.

Some big aircraft, like a C5, don't have winglets because:
1) Maximum cruise range is not a priority design criteria for the C5
2) The C5 wing already has strength margin issues
3) The C5 isn't span restricted.

Something like a U2 doesn't have big winglets because they don't have a span restriction. A small winglet, as the U2 actually does have, has some non-aero advantages. A big blended winglet would be an absolutely ridiculous solution for an aircraft with those design criteria (zero span restriction, maximum range, maximum altitude, essentially unlimited budget).

Large winglets (APB-style) were *originally* added to airliners as a marketing issue (GE's insistance on the BBJ), at which point they discovered just how much benefit you could get from a winglet done right. Since then, their massive proliferation in retrofit (and the concurrent proliferation of raked tips in newbuilds) has been driven primarily by performance.

Something like a C172 doesn't have winglets for a bunch of reasons. One of the major requirements for the C172 is simplicity and producability, neither of which are a strong suit for a blended winglet. As 2H4 also pointed out, induced drag isn't the biggest aero problem on a C172, so a winglet isn't the "low hanging fruit" for aero modification on a C172 and similar GA aircraft.

There is a major difference between tips and winglets with regards to load on the wing. A winglet adds less bending moment than a raked tip of equal length to the winglet. A winglet is (one of) the solutions when you have some strength margin, but not enough to handle the increased moment of a tip extension, even though the induced drag benefit of the tip extension is larger.

Even though any wing can be made aerodynamically better with some kind of wingtip treatment, it may not make overall sense. Other than sailplanes, there basically isn't an airplane in existence that's designed solely around aero performance.

Tom.
 
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RE: Why Winglets On Regional Jets?

Wed Dec 31, 2008 11:10 pm



Quoting Starlionblue (Reply 2):
I think it is a combination of factors:
- On RJ terminals, space tends to be at a premium, and the installation of winglets allows a decrease in wingspan.
- Some of the RJ routes are in fact pretty long, running into several hours. The ERJ-145XR is a long range version, which would explain the addition of winglets.

On the EMB-145XR, the wingspan is actually 3'2" or just shy of 1 meter wider with the winglets than the non-XR versions without them. The winglets look cool though! The business jet version "Legacy" probably benefits more from the winglets than the airliner version. The XR is more capable than the older versions of the EMB-145 mostly because the engines are rated for more power and the airframe is upgraded so it can carry a heavier payload.
 
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RE: Why Winglets On Regional Jets?

Sun Jan 04, 2009 12:33 pm



Quoting ROSWELL41 (Reply 22):
I recall having a B767 Captain in the jumpseat one day and he was astounded at how fast our approach speeds were. They were much higher than his 767 he said.

No slats and a super-critical wing will do that.
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EssentialPowr
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RE: Why Winglets On Regional Jets?

Thu Jan 08, 2009 4:36 am

Quoting 2H4 (Reply 27):
Any wing can benefit from a reduction in induced drag, whether that reduction comes from an increase in span or from a winglet. A winglet is simply a non-planar span extension.

Friend, your explanation of a winglet as a "non planar wing extension" is grossly incorrect. So a bent wing offers the same benefits as a longer one, but takes less ramp space? Baloney. Every a/c since the An -2 would have had winglets. Search "bending moments" for further explanation. I guess the engineers at Boeing/Bus should design by your description, and then deal with wing spar failures due to ignorance??

Quoting 2H4 (Reply 27):
Are you contending that the marketing benefits outweigh the performance benefits? If so, please provide a source.

It seems to me that at 3% (or whatever?) fuel burn reduction would have been a great thing 10 years ago, when the AP Blended Winglets came out... but no airline bought them at $55 - $75/bbl oil. At $100/bbl oil, everyone bought them.... but 3% is 3%, right? So now the $ cost is greater, and it looks better to Wall Street. The efficiency gain is the same, but the $ cost more significant. That, friend, is a marketing decision.

[Edited 2009-01-07 21:02:08] Sonow the 757-300s get them too? MyPoint!

[Edited 2009-01-07 21:04:16]
 
EssentialPowr
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RE: Why Winglets On Regional Jets?

Thu Jan 08, 2009 4:46 am

Quoting Tdscanuck (Reply 28):
Something like a U2 doesn't have big winglets because they don't have a span restriction

Lot of "experts" on this topic; the bottom line is that wing span is always a better substitute, from a pure aerodynamic design standpoint, than winglets. Winglets increase bending moments, and are less efficient through varying alpha than a non winglet design.

Lower ramp space? Winglets have increasing merit, but it it rare to find a purpose built or non modified a/c that had winglets intrinsic to the initial design for the above reasons.

[Edited 2009-01-07 20:47:32]
 
EssentialPowr
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RE: Why Winglets On Regional Jets?

Thu Jan 08, 2009 4:52 am

2H4,

I also seem to recall a comment I made about the E145XR being a Newly Constructed RJ with winglets, along with a ventral tank and belly skid....and a weight increase from 48.5k to 53.0k (approx).


As well as my comment that asked you for a ref of any example of an airline that bought the "new" winglet for the A320 series as reported by AW&ST...

Why were those comments deleted??

[Edited 2009-01-07 21:11:22]
 
2H4
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RE: Why Winglets On Regional Jets?

Thu Jan 08, 2009 5:27 am



Quoting EssentialPowr (Reply 31):
Friend, your explanation of a winglet as a "non planar wing extension" is grossly incorrect.

It's not, actually.

Quoting EssentialPowr (Reply 31):
So a bent wing offers the same benefits as a longer one, but takes less ramp space?

A winglet is a non-planar span extension. And a properly designed winglet will reduce induced drag and will produce a net reduction in drag.

Quoting EssentialPowr (Reply 31):
Every a/c since the An -2 would have had winglets.

Negative. As people have attempted to tell you numerous times now, the benefit of a winglet does not always exceed the cost of design, certification, and installation of the winglet.

This is precisely why winglets aren't being developed for the BAC 1-11. The installation would reduce induced drag and save fuel, but the design, certification, and installation would end up costing more money than the winglets would save. Sorry, I can't make it any simpler than that for you.

Quoting EssentialPowr (Reply 31):
no airline bought them at $55 - $75/bbl oil. At $100/bbl oil, everyone bought them....

I think you'll find that winglets were selling when oil was priced that low. Prove me wrong.

Since you cannot, this:

Quoting EssentialPowr (Reply 31):
That, friend, is a marketing decision.

Is inaccurate. And you have yet to provide any definitive evidence that the marketing benefits of winglets outweigh the performance benefits. But hey, go ahead and try. It will be fun to watch.  yes 

Quoting EssentialPowr (Reply 33):
Why was that comment deleted?????????????

How should I know? I'm not a moderator. I explained this to you previously, too.

Quoting EssentialPowr (Reply 32):

Lot of "experts" on this topic; the bottom line is that wing span is always a better substitute, from a pure aerodynamic design standpoint, than winglets. Winglets increase bending moments, and are less efficient through varying alpha than a non winglet design.

Nobody is arguing that winglets DON'T increase bending moments. Everyone agrees with you on that.

I'm arguing that the performance benefits of winglets outweigh the marketing benefits. I base this on the myriad performance data and testimony from engineers, aerodynamicists, and operators.

I have seen no hard data supporting your point that the marketing benefits of winglets outweigh the performance benefits. And I don't think you can produce any meaningful data or independent studies to support your theory.

2H4
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EssentialPowr
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RE: Why Winglets On Regional Jets?

Mon Jan 12, 2009 3:03 am

The point is this. Winglets, blended or not, are not an automatic 3% DOC reduction.

A 3% reduction in drag at cruise alt is a figure I agree with for contemporary designs, but that is countered by increases in wing shear loads, bending moments, empty operating weights, high alpha drag ...even taxi clearance and ramp space... CFD, wing design and winglet design all progress at the EXACT same rate, which means that only retrofit packages for winglets are the focus here, since any wing desing is optimized from the outset (including or excluding winglets). Got a restrictive wing footprint requirement for a heavy design? I'll bet it'll have a winglet, as linear distance starts to override other constraints...

Cruise flight is really the only spectrum in which retro fit winglets have demonstrated merit, and of course it is only logical that as fuel prices escalate, winglet retrofits become more attractive. That is exactly what we've seen in the case of the 737, 752 and now, 753...

Why not for the ERJs, A320 series and 747-400D? That is the essense of the post, and key to grasping these concepts..

Cheers.

[Edited 2009-01-11 19:19:16]
 
tinpusher007
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RE: Why Winglets On Regional Jets?

Sun Mar 15, 2009 5:14 pm

My question about winglets relates to the blended winglets for the 767-300ER. Why did Boeing go with winglets instead of raked wingtips like they did on the 764ER? The winglets are huge and look terrible in my opinion. I know looks have nothing to do with it, but im just curious why they went with two different designs for what is essentially the same airframe?
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lowrider
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RE: Why Winglets On Regional Jets?

Sun Mar 15, 2009 5:39 pm



Quoting EssentialPowr (Reply 35):
747-400D?

Can't speak to the first two you mentioned but as to the 400D, I would bet the reason is because there are so few of them. How much money is it worth sinking into a 20 year old airframe with high cycles, when lower cycle ones with the winglets included are already available? There are simply not enough airframes to make it a worthwhile project.
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tinpusher007
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RE: Why Winglets On Regional Jets?

Sun Mar 15, 2009 5:41 pm



Quoting Lowrider (Reply 37):
Can't speak to the first two you mentioned but as to the 400D, I would bet the reason is because there are so few of them. How much money is it worth sinking into a 20 year old airframe with high cycles, when lower cycle ones with the winglets included are already available? There are simply not enough airframes to make it a worthwhile project.

Has more to do with the fact that these were designed for short hauls with lots and lots of pax, not long hauls like the standard 400.
"Flying isn't inherently dangerous...but very unforgiving of carelessness, incapacity or neglect."
 
lowrider
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RE: Why Winglets On Regional Jets?

Sun Mar 15, 2009 7:56 pm



Quoting Tinpusher007 (Reply 38):

Right, but I was refering to the reason there has not been a retrofit introduced for the 400D
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Viscount724
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RE: Why Winglets On Regional Jets?

Mon Mar 16, 2009 2:07 am



Quoting Lowrider (Reply 37):
Quoting EssentialPowr (Reply 35):
747-400D?

Can't speak to the first two you mentioned but as to the 400D, I would bet the reason is because there are so few of them. How much money is it worth sinking into a 20 year old airframe with high cycles, when lower cycle ones with the winglets included are already available? There are simply not enough airframes to make it a worthwhile project.

The -400D was designed so that the extended wingtips and winglets (the -400D lacks both and thus has the same wingspan as all other 747s) could be added later if an operator wated to use the aircraft in longhaul service. If I recall correctly, Boeing thought that either JL or NH may switch the -400Ds to longhaul routes once they had built up a lot of shorhaul domestic cycles in order to extend their lifespan.
 
norcal
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RE: Why Winglets On Regional Jets?

Mon Mar 16, 2009 5:09 pm



Quoting Saab2000 (Reply 21):
It also has high approach and landing speeds as well as high take-off speeds because of this. All the controllers think that because it's a small airplane it flies slow and uses short runways. But our approach speed at MLW is 146KIAS.

haha no kidding, the only thing that catches us on approach is a 747. The 2.5 degree nose down approach on the -200 scares a lot of jumpseaters too. You can feel them tense up when we fly that all the way down to the runway and then just flare for touchdown. The -200 is more like a GA aircraft in that sense, all because of the lack of slats.

That's why we nickname it the lawn dart (there are other unrelated nicknames like shortbus too)
 
tinpusher007
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RE: Why Winglets On Regional Jets?

Mon Mar 16, 2009 5:46 pm



Quoting NorCal (Reply 41):
haha no kidding, the only thing that catches us on approach is a 747. The 2.5 degree nose down approach on the -200 scares a lot of jumpseaters too. You can feel them tense up when we fly that all the way down to the runway and then just flare for touchdown. The -200 is more like a GA aircraft in that sense, all because of the lack of slats.

That's why we nickname it the lawn dart (there are other unrelated nicknames like shortbus too)

The 700/900 even with slats still fly slightly nose down all the way into the flare as well which I don't quite understand. It varies from level pitch to slightly nose low 1 degree or so, but its not really nose up like bigger aircraft with slats. The E13/45 also fly more nose up than even the 700/900 on final and they have no slats either...go figure
"Flying isn't inherently dangerous...but very unforgiving of carelessness, incapacity or neglect."

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