CVGpilot
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RJ Winglets

Fri Feb 27, 2004 10:48 am



Hey I was wondering do winglets on RJ's really do anything as far as fuel, speed, control? If so how do the decide the angles, EX: USairways CRJ are 90* and ERJ's are more normal looking like at 70*or so. If they are all that great how come not all RJ's airlines have them on there aircraft EX: CO-ERJ145 and what's the story behind the spit Airbust winglets? Tho all winglets do look badass. Thanks
 
ssides
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RE: RJ Winglets

Fri Feb 27, 2004 10:52 am

I know CoEx flies the "XRJ" on its longest RJ routes, like IAH-BFL. Apparently it gives them a little extra range for the longer trips.
"Lose" is not spelled with two o's!!!!
 
planemaker
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RE: RJ Winglets

Fri Feb 27, 2004 10:58 am

If you go to http://www.aviationpartnersboeing.com you will find lots of info on the 737 and BBJ blended winglets.


Nationalism is an infantile disease. It is the measles of mankind. - A. Einstein
 
erj
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RE: RJ Winglets

Fri Feb 27, 2004 5:06 pm

Winglets provide better efficiency. If I remember correctly from my Aerodynamics classes (several years and many beers ago) winglets create a theoretical infinite wing, eliminating drag from vortices created by the traditional finite wing shape. I would conjecture that the pointed wing shape of the DO328 and B767 accomplishes this without winglets. Though, they aren't nearly as cool looking as the 8 foot blended winglets on the 737NG's  Smile

Hopefully there is an engineer out there that can explain these concepts better than I can.
 
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Starlionblue
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RE: RJ Winglets

Fri Feb 27, 2004 10:14 pm

Not an engineer, but I know this:

Even though the drag-creating vortices from the wingtips may be eliminated, the winglets themselves create their own wing(let)tip vortices. These are smaller of course, or there wouldn't be much point.

While it is clear that you always have to factor in weight penalties when adding the winglets, it is also important to weigh in the added manufacturing cost. Savings derived from the winglets have to be greater (normalized to current $/€/£) than the extra cost of the aircraft + maintenance over the calculation period.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Skibo777
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RE: RJ Winglets

Fri Feb 27, 2004 10:37 pm

I know that if you were to remove the tip tanks off the old Gulfstream 2, (each contain 250 gallons of fuel) and install the Aviation Partners Blended winglets, the A/C's range actually increases, along with the payload. So the winglets obviously are effective at increasing the range, speed, and altitude, and possibly worth the $600,000 price tag.
 
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Starlionblue
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RE: RJ Winglets

Fri Feb 27, 2004 10:46 pm

727 winglet retrofits increase climb rate, and thus allow the 727 to comply with noise regulations at many airports.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Olympus69
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RE: RJ Winglets

Fri Feb 27, 2004 11:39 pm

CVGpilot,

7 Replies, including mine, and none of them has really answered your questions. Try the Tech/Ops Forum.
 
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Starlionblue
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RE: RJ Winglets

Sat Feb 28, 2004 12:01 am

One answer is that there are many ways to aerodynamically skin a cat, just as there are many ways to build a wing or design an engine.

Maybe a certain company has expertise with a certain winglet look, and it costs that company less to continue along that route, research and manufacturing wise.

If you are Boeing or Airbus, you might be able to afford trying out 20 wingtip permutations every time and go for close to the optimum in each case (747, 767-400/777NG, 737, A318-321, A330-340, A300-600B, A380) while if you are Canadair you go with the tried and true. So if you lose a couple of tenth of a percent. It costs you less in the end maybe.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
QantasA332
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RE: RJ Winglets

Sat Feb 28, 2004 6:25 am

Winglets provide better efficiency. If I remember correctly from my Aerodynamics classes (several years and many beers ago) winglets create a theoretical infinite wing, eliminating drag from vortices created by the traditional finite wing shape.

Oh boy, not again...winglets do not create a theoretical infinite wing, and they do not completely eliminate Di ("induced drag", or drag from wingtip vorticies). I always refer to this link, but really do check out http://www.airliners.net/discussions/tech_ops/read.main/77356/4/, particularly my reply (#6). In it I explain exactly how winglets work.

Even though the drag-creating vortices from the wingtips may be eliminated, the winglets themselves create their own wing(let)tip vortices. These are smaller of course, or there wouldn't be much point.

A common misconception. Winglets DO NOT eliminate wingtip vorticies. Rather, they utilise them to produce forward lift (thrust). You are, however, completely correct that, because winglets are just little wings, they have vorticies and induced drag themselves.


Sorry I'm late replying to this,
QantasA332
 
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Starlionblue
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RE: RJ Winglets

Sat Feb 28, 2004 7:39 am

Thx for the info QantasA332. As I said, I'm not an engineer. I can figure out the economic factors, nothing much else. And from that standpoint, I can say that if winglets were the be all and end all of wing efficiency, they would be on every plane designed since their conception.

The fact that they are not on every new design indicates that there are many ways to increase efficiency, and even that in some cases there are economic arguments against them, such as in short-range operations.

On a tangent, will winglets/raked wingtips/fences produce greater wake turbulence?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
QantasA332
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RE: RJ Winglets

Sat Feb 28, 2004 8:30 am

On a tangent, will winglets/raked wingtips/fences produce greater wake turbulence?

Well yes, they all will, but that's to be expected. Any body on an aircraft will create a greater total wake and thus pressure drag, due to the nature of pressure drag itself. For anything, airflow will seperate while travelling around it, leaving a retarding ("dragging") high-pressure wake area of jumbled air. All things produce pressure drag.

Hope that helps,
QantasA332
 
CVGpilot
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RE: RJ Winglets

Sat Feb 28, 2004 9:04 am

Thanks Quantus and all.......
 
AirframeAS
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RE: RJ Winglets

Sat Feb 28, 2004 1:33 pm

I think the winglets are just decorations. The things that winglets say they can do, in my opinion, are myths. They dont do squat. Just for looks.
A Safe Flight Begins With Quality Maintenance On The Ground.
 
Guest

RE: RJ Winglets

Sat Feb 28, 2004 4:33 pm

Is that why the addition of winglets to the 737's provides a 7-10% improvement in fuel economy? The "displacement" of drag improves the overall performance of the aircraft thus reducing "work". This saves fuel and has multiple other benefits including the extension of engine service life, less wear and tear on the aircraft wing structure etc...

[Edited 2004-02-28 08:44:27]
 
MITaero
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RE: RJ Winglets

Sat Feb 28, 2004 5:07 pm

>The things that winglets say they can do, in my opinion, are myths. They dont do squat. Just for looks.

Aerodynamics isn't a matter of opinion.
 
QantasA332
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RE: RJ Winglets

Sat Feb 28, 2004 5:09 pm

Well said, MITaero! Amen to that!

Cheers,
QantasA332

 
FredT
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RE: RJ Winglets

Sat Feb 28, 2004 9:26 pm

As the winglets reduce the strength of the vortices, they should theoretically make wake turbulence less of an issue as the main culprit is the vortices, not the turbulent air left behind.

Cheers,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
QantasA332
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RE: RJ Winglets

Sun Feb 29, 2004 4:38 am

As the winglets reduce the strength of the vortices, they should theoretically make wake turbulence less of an issue as the main culprit is the vortices, not the turbulent air left behind.

Hmm, really? Pressure drag operates by the higher pressure of wake turbulence acting on the backs of bodies on the aircraft, as you must know, and in the vortice's case, all that's there to act against is the small profile of the winglet. Pressure drag shouldn't be reduced that much...but I could be wrong.

Cheers,
QantasA332
 
FredT
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RE: RJ Winglets

Sun Feb 29, 2004 10:20 pm

Yes, there is a turbulent wake behind most objects on an airframe. However, as I said, this is not the same as wake turbulence. The wake turbulence you need to watch out for is the lingering vortices - which are reduced by the winglets.

Cheers,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
pilotpip
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RE: RJ Winglets

Sun Feb 29, 2004 11:02 pm

AirframeAS,

I think the fact that Southwest is spending millions to retrofit their existing fleet because of the fuel cost savings it will realize as a result of the addition of winglets proves that they don't just look good.

I think that when you consider that Boeing, Airbus, Embraer, and Bombardier have spend millions on the design of winglets and nearly every new model or varient that has come from these manufacturers recently has incorporated some sort of wingtip enhancement such as a winglet or raked tip. Proves that they don't just look good.

While I also agree with the smart engineer types here, and all these other very intelligent postings here I also know this. Airlines are businesses, they wouldn't spend loads of cash on something that didn't improve the bottom line.
DMI
 
airplay
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RE: RJ Winglets

Sun Feb 29, 2004 11:56 pm

The choice to use winglets and their shapes and configuration are highly dependant on the design of the wing. Even though they may look similar, aircraft wings can be quite different.

Furthermore, winglets can be optimized for the operating requirments for the aircraft. The same winglet design may not be appropriate for the CRJ if its flight duration was increased or decreased for that matter.

Its my personal belief that the CRJ wouldn't have winglets if it wasn't a derivitive of the longer range Challenger. Aircraft with 1 or 2 hour flight durations don't typically get to enjoy the benifits of the winglets.

[Edited 2004-02-29 15:56:56]
 
Guest

RE: RJ Winglets

Mon Mar 01, 2004 12:29 am

The devil is in the details. It's not enough to simply slap a winglet on the end of a wing and call it good. The angles, length, etc. are critical. Even after the winglet is designed, it still has to be flown and tweaked. A good design will help, but get the angles of by a few fractions of a degree and your efficiencies go out the door. Like I said in an earlier post - it's almost a black art to get it right. Computers help, but they're not enough. If they were, there'd be no need for test pilots.
 
QantasA332
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RE: RJ Winglets

Mon Mar 01, 2004 8:42 am

Yes, there is a turbulent wake behind most objects on an airframe. However, as I said, this is not the same as wake turbulence. The wake turbulence you need to watch out for is the lingering vortices - which are reduced by the winglets.

Right. Of course. Upon doing a double take I realized we were talking about two different things.  Laugh out loud Silly me.

Cheers,
QantasA332
 
XFSUgimpLB41X
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RE: RJ Winglets

Mon Mar 01, 2004 11:15 am

The CRJ winglets also happen to be right at head level for me. The wing decided it would high five my head this morning. ouch!
Chicks dig winglets.

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