New Boeing 737 wingtip design

[EEJaime]

Hello all,

I noticed that the new Boeing 737-Max 8 and other models sport a new wingtip design. We've all seen the currently fashionable winglet design where the outboard 10% of the wing is swept upwards, I assume to take the drag vortices off the main plane, but this new design has a similar winglet, but it is bifurcated with the aft portion swept downward. It is counter-intuitive to think this cleans up the drag model. I am hoping someone on this forum that knows aerodynamics can provide an insight as to the concept.

Just curious because it is such a different look. Hope to hear from someone. Have a great day.

Regards,
EEJaime
California, USA

 

[KENAT]

bifurcated wing tip is not new as such, I think some A320 family aircraft have/had them.

Difference being the 320 are small & go stright up & down while 737 are angled though arguably the straight up down is more a fence than a winglet as such.

Some aircraft have long used downswept tips "Hoerner tips" and were some of the earlier wing tip devices.

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(probably not aimed specifically at you)
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[rb1957]

this goes back to the original (British, Cranfield?) work, Spillman I think, who modelled eagle wing tip feathers. Conventional wingtips (only upwards) are better than nothing at breaking up the tip vortex, both are probably better. I always smile when I see an A320 (tiny) wingtip; they made a big show at the time that these were the optimum design. I smile more at their newer (more conventional) "shark-tip" ... I guess optimum changes with time ?

another day in paradise, or is paradise one day closer ?

 

[KENAT]

Yeah, I mean the flight conditions of airliners (speed & altitude) haven't changed much in the last 30+ years so something else must explain the changes.

My guess is some combination of advances in CFD, FEA & materials but I could be wrong.

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[rb1957]

my money is on Airbus wanting to make a statement (posturing ?) back in the day (90s), and if you're going to introduce a different shape wingtip device, then you're better to say "this shape is best ...". Now, of course, they can say "the new 'shark-tip' is even better !" ... which can be read (by those of us with long memories and bitter dispositions) as saying "the old design wasn't the best, as advertised back in the day". Sure, CFD is better, then why would you replace a unique shape with one that looks quite similar to everyone else's from back in the day. Sure, I think the aero-design of wing tips has improved, so that now they are a curved extension of the wing, rather than an after-market, stuck-on, piece.

another day in paradise, or is paradise one day closer ?

 

[KENAT]

Or the old version was a last minute 'fix' for an otherwise already designed wing.

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[IRstuff]

From Google images, it looks like both Boeing and Airbus have both styles of winglets, particularly on 737. The 737Max appears to have one style of split, while retrofitted 737s have a different style. Airbus appears to have the sharkfin version, but there's a few versions of that

TTFN
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[Sparweb]

IRStuff,
Are you able to edit pictures and make them a tad smaller? My screen's scrolling to the right by about 3000 pix.

STF

 

[KENAT]

One way of looking at these wind devices is that it approximates a longer wing (higher aspect ratio) without actually increasing the wing span (significantly). Higher aspect ratio wings are generally better L/D.

There are a number of reasons for not just making the wings longer - for example 'structural', i.e. minimizing loading on the wings, as well as things as simple as fitting in the parking spots/on the taxiway at airports or fitting in existing hangers....

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[IRstuff]

Not until I get home. My workplace router blocks the upload site for ET, and these pictures are linked from their original URLs

Alternately, you might want to try Chrome, which seems to do its own scaling to keep things on the same screen

TTFN
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[tbuelna]

Why does the 737 Max with a new wing structure use a much different tip design than the 787?

 

[IRstuff]

787 was probably designed from the get-go to have its winglets, while the 737 Max is a retrofit, rather than a complete redesign

TTFN
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[IRstuff]

nice article about some of the differences in winglet design:

http://theflyingengineer.com/flightdeck/winglets-and-sharklets/

TTFN
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