This release is either a big-little-release or a little-big-release, I’m not quite sure. It doesn’t have a lot of things in it (it is little). However, some of those things are quite consequential (it is big). I’ll leave it up to you to decide.

The most consequential change is a change to how twist and dihedral interact when lofting a wing. The order you apply transformation matrices matters, and back in 2022 (3.27.0) I made a change on behalf of a particular use case. As it turns out, it made other use cases worse — namely, people trying to model toe-in of winglets. This has been a popular GitHub issue (#292, 304, 328) and topic on the Google Group.

You can now get the behavior I think most people will want — and through some combination of options, you can also still get the special use case behavior. The default values for a new wing will reflect best practices, but you might need to play with existing models to get the behavior you want.

In addition, the airfoil thickness correction for dihedral rotation had a bug that has been fixed.

The Stack component now has quick buttons to turn ‘off’ skinning for a section or the whole stack. This will reduce all the skinning settings to a linear loft ‘ground state’ from which you can then build back up exactly the settings you want.

There is also now an ability to set a Stack to certain presets. These include the default stack, a cylinder (two ways), and a bunch of different ways of modeling engines. All these were possible before, but it was a bit of a hassle to get everything set up right. Now, you can select from 14 different ways of representing a nacelle from the click of a button. This should make the integrated flowpath modeling capabilities of OpenVSP much easier to use.

There is also now some documentation added to the Stack to hopefully make this stuff more clear.

Further, the integrated flowpath modeling gained three new flowpath representations — flowthrough, inlet to face, and nozzle to face negative only. These are useful for tasks like calculating the fuel volume available in a fuselage with an embedded flowpath.

Also, when modeling the inlet/exhaust as an extended flowpath, the extension can now be done in the global X direction.

For some reason, when the Pick capability was implemented, it was set up to only work with bodies in Wireframe mode. I don’t remember a reason for this, so I went ahead and made it work with Hidden, Shaded, and Texture views of Geoms. Let me know if this breaks anything.

If you don’t know about Pick — either press ‘p’ or click the ‘Pick’ button on the Geom Browser. Now move the mouse over the 3D window. Different geoms will be highlighted in red. Click on one and it will become the active geom. Press P or turn off the button to exit Pick mode.

There was a nasty bug when using composite laminates in the structures modeling stuff. It would cause the GUI to act bizarrely and eventually crash. As it turns out, it was an infinite loop in the GUI. Who knew?

There was also a bug where a co-planarity test for structures was performed with a tolerance in FEA scale on a geometry in VSP scale. If these were substantially different (say m vs mm), then FEA parts could be dropped from the model and other similar problems. Thanks Bryan S. for reporting these two structures bugs.

Sometimes the VSPAERO viewer would fail to load because it would complain about not being able to write or read a font file. That has been fixed.

The VSPAERO console output would default to an unreadable font when Windows was set to a Japanese locale. We’ve changed to a different font that will hopefully make things better and not worse. Let me know if you can’t read what VSPAERO is telling you.

The Python API for Ubuntu had a problem where it was built against the wrong version of NumPy. That should be fixed.

We’ve had to update the Intel MacOS build to MacOS-15. Hopefully this doesn’t cause any problems. We’re coming to the end of days for Intel MacOS. When it is deprecated by Apple, I expect GitHub Actions to stop supporting it and I will no longer be able to support the platform. Do yourself a favor and update now. The M1 processors are really fast. You’ll thank me.

Features:

• Buttons to turn off skinning for Stacks
• Shape presets for Stacks — makes engine flowpaths easy
• Negative only engine representations
• Extend flowpath in global X direction

Build System:

• x85 MacOS build now using MacOS 15

Fixes:

• Fix twist / dihedral interaction, add options for XZ only twist
• Fix correct thickness for dihedral
• Pick now works with hidden, shaded, and texture views
• FEA GUI Bug with laminates
• FEA Part dissappearing bug
• VSPAERO Viewer font fail to load
• VSPAERO console font on Windows Japanese locale unreadable
• Ubuntu Python NumPy version mixup