Boeing Deception: 777X Wing Actually Elongated 787 Wing

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Rabbi O'Genius
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Re: Boeing Deception: 777X Wing Actually Elongated 787 Wing

Postby Rabbi O'Genius » Wed Sep 12, 2018 3:21 pm

OK, I buy the argument that increasing the aspect ratio can decrease the induced drag.
But what about the tip vortices? If a wing is simply stretched but has the same form and lifting profile at the tip, it’s going to generate much the same vortices at the tip

The claim that winglet orientation is immaterial and that a horizontal winglet prevents air bleeding from bottom to top as effectively as a vertical one needs a bit of justification. From the (admittedly simplistic) “damming air from getting round the corner” point of view, it would seem so much easier for the flow to make the single +180 deg rotation from bottom to top around the tip (and initiate a vortex) instead of the +90, +180, -90 path needed to get round a vertical winglet (or the -90, +180, +180, -90 for a wingtip fence).

Furthermore, if you do have a vertical winglet, why would you give it a “lifting” profile?

If you do, the winglet itself will generate its own tip vortices, and the pressure differential created would assist the main vortex generation by helping move the air round the wingtip from bottom to top. Surely a winglet ought to have a neutral profile and AOA, so that it would generate no pressure differential, less drag, and no tip vortices of its own, and would constitute a buffer zone of “dead air” hindering the flow of air from bottom to top of the main wing.
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3WE
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Re: Boeing Deception: 777X Wing Actually Elongated 787 Wing

Postby 3WE » Wed Sep 12, 2018 3:54 pm

OK, I buy the argument that increasing the aspect ratio can decrease the induced drag.
But what about the tip vortices? If a wing is simply stretched but has the same form and lifting profile at the tip, it’s going to generate much the same vortices at the tip.
I think I am beginning to understand some stuff- it's all about trade offs.

Let's pretend our new tall 737 winglets are very malleable.

If we bend them down, maybe we do lose the vortex killing...but we get MORE lift...a deal that if you are going to put the metal and weight and drag out there, you get a BETTER deal making more lift than you do killing vortexes.

To the snip of your comment- maybe the vortex is the same as it was before...but RELATIVELY it's more wing VERSUS the vortex- thus a net gain (even though you still have the same vortex).

Or this restatement...you have a 90-degree vortex killer, but there's still a big vortex that works around it....so bend it flat and you are still sort of killing the same vortex, but getting some lift while you are at it???

Is that the whole deal with gliders?....really really really long wing with a vortex on the end- which only 'wastes' the outer 3 feet of the wing...vs. a short stubby wing where when you 'waste' the outer 3 feet in a vortex, it's more of the wing being wasted on a percentage basis???

...and you have to beware ammonia volatilization, or you can lose a lot of the N-value of manure.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.

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Gabriel
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Re: Boeing Deception: 777X Wing Actually Elongated 787 Wing

Postby Gabriel » Wed Sep 12, 2018 5:26 pm

OK, I buy the argument that increasing the aspect ratio can decrease the induced drag.
But what about the tip vortices? If a wing is simply stretched but has the same form and lifting profile at the tip, it’s going to generate much the same vortices at the tip

The claim that winglet orientation is immaterial and that a horizontal winglet prevents air bleeding from bottom to top as effectively as a vertical one needs a bit of justification. From the (admittedly simplistic) “damming air from getting round the corner” point of view, it would seem so much easier for the flow to make the single +180 deg rotation from bottom to top around the tip (and initiate a vortex) instead of the +90, +180, -90 path needed to get round a vertical winglet (or the -90, +180, +180, -90 for a wingtip fence).

Furthermore, if you do have a vertical winglet, why would you give it a “lifting” profile?

If you do, the winglet itself will generate its own tip vortices, and the pressure differential created would assist the main vortex generation by helping move the air round the wingtip from bottom to top. Surely a winglet ought to have a neutral profile and AOA, so that it would generate no pressure differential, less drag, and no tip vortices of its own, and would constitute a buffer zone of “dead air” hindering the flow of air from bottom to top of the main wing.
I will explain more later, but winglets need to generate lift to work. By now suffice to say that another proposed name for this device was "wingtip sail".

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3WE
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Re: Boeing Deception: 777X Wing Actually Elongated 787 Wing

Postby 3WE » Wed Sep 12, 2018 8:30 pm

By now suffice to say that another proposed name for this device was "wingtip sail".
Why not right-angle-spill-over-blocking-dam-device or RASOBDD?
I will explain more later...
Oh crap... :o :shock: :? :roll: ;) :mrgreen:
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.


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