VSPAero

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Elizabeth Feeley

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Aug 12, 2020, 6:44:25 PM8/12/20
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Hello,

I've been working on a model and I'm not getting reasonable results - am I doing something wrong in how I've set up the geometry? See VSPAero results attached.

Also, I noticed a pressure differential on one side of the aircraft but not on the other (see pressure map attachment). I must have set something up incorrectly since the Beta value for that pressure map is zero. 

Please advise, thank you!

Liz
Pitching Moment.PNG
Pressure Dist.PNG
BV_ht_vt.vsp3
CLvAOA.PNG

Rob McDonald

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Aug 12, 2020, 7:26:06 PM8/12/20
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One of your tails is at Y=5.0 -- which creates a crossing of panels between your horizontal and vertical tails.  Moving it to 5.1 to match the other tail and booms helped a lot.  Also, adding some panels to the wing is a reasonable thing to do.

One of your wake lines is going unstable and causing the asymmetry and blowing up the solution.

My modified model (shifting tail, adding some wing resolution) held together to about 7 deg alpha.  It blew up from there -- in this case, if you look closely, you can see a wing tip wake line going through one of the tail surfaces.

In this case, going to a Panel method actually helped quite a bit.  I threw some more resolution at the pod in the middle this time -- and only ran half as many points to speed things up, but it held together rather well.

Rob
VLM.png
VLMCM.png
VLMCL.png
PanelCM.png
PanelCL.png
Panel.png


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BV_ht_vt.vsp3
BV_ht_vt_pan.vsp3
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