The Cross-Section Viewer window enables visualization of a normalized representation of the cross-section profile you have selected. In some cases, this is useful for verifying that the model representation on the screen is true to the underlying curve. This feature is also very useful for matching known cross-section profiles to your designed curves. Note that you can change the color of the cross-section line and also insert images into the XSec View background to closely match known sections or photos.
OpenVSP maintains uniqueness for all parameters in all components of every model. You can quickly view the details of every accessible parameter in your model by clicking on the Name of that parameter in the GUI box. For example, to view the Span parameter of a Wing component, click “Span” in the Sect tab. You can use the information shown to identify the Name, Group, Max/Min, etc. as well as Links and Advanced Links for that parameter. OpenVSP also allows you to quickly populate variable selection areas by dragging-and-dropping the variables. You only need to click and drag the variable name (button) to the variable selection or add region and then drop. VSP will either automatically select or add the parameter depending on where you drop. This feature is exceptionally useful for variable selection operations within Design Variables, Variable Presets, and Linking.
The free Fuselage design policy is similar to the loop policy except that any cross-section may be placed anywhere along the design length of the Fuselage component. This includes the first and last cross-sections which means that depending on the location of these sections, the actual physical length of the part modeled may be nowhere near the same length specified in design. As long as the user ensures that at least one section is placed at the 0.0 and 1.0 length positions, the design length and physical length will be similar. Exceptions are when Skinning forces the surface to loft forward of the 0.0 X position or aft of the 1.0 X position. Uses for this design policy include shaping engine nacelles with flat inlet and exits to be defined as boundary conditions for flow solvers. Freeform geometries are another application. This tutorial demonstrates how to use the free design policy and an example case.
By changing the Fuselage design policy from monotonic to loop, the first cross-section is enforced to be at the same location as the final section at 1.0x design length. The final section is also forced to exactly match the design of the first section. This ensures that the component surface follows a user-defined loop and closes. Typical uses of this feature are to design “hollow” nacelles, rocket nozzles, tubes/pipes, or turbojet/fan engine station internals. This tutorial demonstrates how to apply the loop design policy to a Fuselage component and some of the important aspects of modeling this way.