Help needed with Issues with holes forming in mesh

[Carter Johnston]

Hello,

I've been trying for about an hour to fix this hole that is appearing in my fuselage mesh when I try to simulate my model in VSPAero. I'm sure this might be a trivial fix, but I am still learning the program and I'm just not sure where I'm going wrong here. 

Also, as a side note, I've been trying to think of ways to model the fuselage as a hollow box with a certain wall thickness. So far my ideas have been to either put in a slightly downscaled version of the fuselage inside, set the mass to zero and set the priority so that it overrides the larger fuselage. The other thought was to just calculate the density per area by multiplying the density of my material by the wall thickness and using the thin shell method. Not sure if either of those would work though. Just throwing out some ideas.

Any suggestions would be appreciated.

[Rob McDonald]

That looks like a bug.  I'll have to dig into it.

What are you trying to achieve when you say 'model the fuselage as a hollow box with a wall thickness'?  Are you just trying to calculate the mass properties?  Are you trying to construct an offset interior volume?  What is the purpose?

OpenVSP calculates mass properties using three contributions for each component.

The volumetric mass

A wetted area mass

A point mass

You can use any or all of them.  If you just want to know the mass properties of a fuselage that is a thin shell, set the volumetric density to 0, the point mass to 0, and the area based density to the mass/area for the material (i.e. the volumetric density times the thickness).

If you want to construct an offset surface, then you want to look into Conformal components.

Rob

[Carter Johnston]

I see. Is there any way I could try to fix it on my end? Should I try to rebuild the geometry? 

I apologize for not being clear on the fuselage point. I am trying calculate the mass properties. I'm designing a UAV so I want to do CG analysis with the electrical components inside of the fuselage and treat the fuselage as a hollow box with a certain wall thickness say 3/32". What would be the best approach for that situation?

[Rob McDonald]

That is a perfect application for using the area based density for the fuselage skin and then using one of the other approaches for the internal components.

Note, the skin density is only applied to the OML of whatever Set you have in the analysis.  So, if you have components (say batteries) entirely contained within the fuselage, their area density will never make a contribution (though their volumetric and point mass contributions will still come through).

You will also want to learn about how Priority is applied to overlapping components.  There are posts in this group and also videos on the Ground School -- and probably a Workshop video too.

Rob