Boeing Split Scimitar Winglet

[Mike Kelly]

After learning OpenVSP over the past few months, I can't look at an airplane now without asking myself how can I model it in OpenVSP. I was at the airport last week and came across several 737-MAXs with the split scimitar winglet. This isn't a feature request, but I was curious if it was possible to model that in OpenVSP and how one would go about doing it. Thanks for any opinions.

[Rob McDonald]

I would model the main wing and 'up' winglet with a blended wing component.

The inboard part of the wing with the straight trailing edge would be the first wing section.

The main wing portion would be the second wing section.

The blend transition would be the third.

The main winglet would be the fourth.

I might add a fifth section to model the scimitar blended tip -- but OpenVSP might struggle with this a bit.

The 'down' winglet would be a second wing -- possibly attached in U,V coordinates -- but with a slight negative delta to 'bury' the root section.  It would get the same tip treatment as the main winglet.

Depending on the analysis you want to perform, the winglet junction may not work very well.  For example, you don't want a gap for VLM analysis.

Something like this...

Of course this wing is un-twisted and uses NACA 0010 airfoils.  It is just meant as a demonstration.  To properly design a wing, you need to select appropriate foils and then twist the wing to achieve the desired lift distribution.  Adding winglets does not guarantee a drag reduction -- the winglets must also be properly twisted and designed to have a beneficial effect.  It would not surprise me if this naive wing performed worse with the winglets than without.

Rob

On Thu, Jun 23, 2022 at 8:08 PM Mike Kelly <miked...@gmail.com> wrote:

After learning OpenVSP over the past few months, I can't look at an airplane now without asking myself how can I model it in OpenVSP. I was at the airport last week and came across several 737-MAXs with the split scimitar winglet. This isn't a feature request, but I was curious if it was possible to model that in OpenVSP and how one would go about doing it. Thanks for any opinions.

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[Mike Kelly]

Rob - thanks so much for taking the time on your detailed explanation and for providing the VSP file that I can examine and learn from.

Mike