Errors while obtaining aero coefficients with control suface deflection on OpenVSP 3.45.4

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Anuj Kumar

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Sep 29, 2025, 8:36:32 AM (yesterday) Sep 29
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 Hi team,
I am trying to run a vlm/panel type analysis on openvsp.The model runs without any issue but once you put a control surface in the wing/tail.The analyses does not work and gives out the following error
Could not find start of control surface C:/Users/User/Desktop/plane.csf data in csf for control surface: 

Brandon Litherland

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Sep 29, 2025, 10:08:00 AM (yesterday) Sep 29
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As with any troubleshooting, it is best to include an example vsp3 file attached to your post.  In almost all cases, we won't be able to diagnose the problem without one.

Anuj Kumar

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Sep 29, 2025, 4:46:57 PM (23 hours ago) Sep 29
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Hi Brandon,
Thank you for the response. I was able to resolve this issue on my end.
I’m not sure if this is a legitimate issue, but I had to rename my lifting surfaces.It worked
main_wing → wing
horizontal tail → tail

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Brandon Litherland

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6:26 AM (9 hours ago) 6:26 AM
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Ohhhh.  Okay, I see what happened.
There is a bug in 3.45 that particularly affects control surfaces but can cause issues with other VSPAERO runs as well.  The parser that writes the names to file is missing the spaces in paths, filenames, and components. If there is a space in your path anywhere, you'll notice that the string written to the VSPAERO console or to file stops at the space.  As a workaround, remove all spaces from your path (folders to get to your model), your model name, and all component names and control surface names.  I'm not sure if the string has a character limit or not but that's also something to watch out for.

So changing the component from "horizontal tail" to "tail" got rid of the space and it worked.
We've discussed this bug in recent weeks and it should be fixed in a new release.

Thanks for bringing this up.

Neal Pfeiffer

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9:42 AM (6 hours ago) 9:42 AM
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Would using an underscore symbol ( _ ) allow it to work?


Anuj Kumar

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9:45 AM (6 hours ago) 9:45 AM
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yes,i also had to fix the .vsp3 file name to a single non space string.


Brandon Litherland

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1:02 PM (3 hours ago) 1:02 PM
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You would have to give it a try, Neal, but from what I've see so far it works.
I haven't had the time to really bash on the new solver and find all the bugs.  This was one of them, though.

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