Parasite drag zero wetted areas

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Chris Eggert

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Jul 18, 2024, 1:50:42 PM (3 days ago) Jul 18

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Hi Rob,

I've seen some odd behavior in the parasite drag tool. I posted an issue on the github page https://github.com/OpenVSP/OpenVSP/issues/291 with more details and some supporting files. Essentially if I run Comp Geom repeatedly with the subsurfaces flag turned off, it will cause subsequent runs of the Parasite Drag tool to receive zeros for component wetted areas. It looks like the Comp Geom call within the Parasite Drag tool isn’t including all of the components that it should.

I'll just put one image here showing how repeated runs of the parasite drag tool (with no other operations in between) can still produce different SWet values under these conditions.

I have seen this issue in versions 3.31.1 and 3.36.0 with identical behavior, and the GUI appears to behave in the same way. Any info you have on this would be very helpful.

Rob McDonald

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Jul 19, 2024, 2:05:48 AM (2 days ago) Jul 19

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Chris,

I'm sorry this question keeps dropping out the bottom of my inbox.

I am not surprised there are bugs in Parasite Drag. It is a complex bit of code that was written by someone who was relatively inexperienced at the time. It really needs a thorough scrubbing. Unfortunately, I haven't been able to find the time to give it a line-by-line audit.