nan error in the *.fem output

[Tad Chichester]

In the *.fem file output for version 3.25 and on, the sectional moments (last 3 columns) for each wing seem to be in error:

    Cx        Cy        Cz       Cmx       Cmy       Cmz
 -0.01845   0.01064   0.33157 -nan(ind)       nan -nan(ind)
 -0.02579   0.01500   0.37702 -nan(ind)       nan -nan(ind)
 -0.03165   0.01863   0.42074 -nan(ind)       nan -nan(ind)
 -0.03728   0.02240   0.45823 -nan(ind)       nan -nan(ind)
 -0.04079   0.02427   0.48187 -nan(ind)       nan -nan(ind) 

In version 3.24 and at least some versions prior, there is useful data. I have developed a FAR 23 flight loads program that uses the *.fem and *.lod file contents to develop distributed airloads, but cannot upgrade beyond 3.24 until this is resolved.

Is there a plan to fix? I am using OpenVSP/VSP Aero on Windows 10 64 bit system.

Thanks

Tad

 

[Rob McDonald]

This is the first anyone has brought this to our attention.

Have you tried 3.29.1?  It was released last week or so.

VSPAERO was updated in 3.25 -- and then finally got another big update in 3.29.0.  So, I would expect the same results for all versions in-between.

If this bug didn't get fixed in 3.29, then I'll work to make sure the VSPAERO developer knows about it.

Best,

Rob

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[Tad Chichester]

Yes - the little sample in my post was from 3.29.1 using just the default wing created when you first add a wing to a new model. It does the same for all of my "real" models. I am anxious to use some of the other new capability in 3.29.1 in my work, but can't until some kind of fix gets made. Maybe I'm the only person using the *fem aero data? There's a lot of good stuff there for doing practical work.

Thanks

TC

[Rob McDonald]

I'll be honest, I haven't looked in the *.fem file in a while.

Will it do this for a very simple case (say a default wing) -- or does it take something more complex.

Do you have a simple example you can share -- that I can pass to the VSPAERO developer?

Rob

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[Tad Chichester]

Sure. Here is the default wing model along with the the fem and lod output files from 3.29.1. Note that there are sectional moments output in the lod file, albeit with different reference points, so I'm assuming the data is in there somewhere!

TC

[Rob McDonald]

I've had some back and forth with Dave.

He sees and understands the problem.  He'll probably be able to put together a fix next week that will go into the next release.

I'll be at the Workshop all next week.  I'm not sure when the next release will come.

Rob

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[Tad Chichester]

Thanks Rob. I’ll look for the new release. 

TC