Preset parameters may be altered under the Adjust tab in the Variable Presets window. Once any parameter is changed, you’ll notice that the “Save Changes” button becomes active under the Edit header. The Preset will keep the original values stored until you save the new settings. Note also that the Edit header corresponds to the Setting under the Select Preset header. This means that even if you have the variables from one setting displayed under the Create or Adjust tabs, the Setting chosen at the top of the window is the one that Save or Delete will operate on. Take care that you don’t accidentally delete the wrong Preset! When you want to choose a Preset to alter, make sure to choose the setting then click “Apply” to set all of the parameters to the Setting values before changing others. This way, you won’t accidentally overwrite the parameters that you didn’t want to change with those from another Setting.
This tutorial demonstrates how to create Groups and Settings in variable presets and how to add variables to the settings. To create a Preset, enter a name into the Group field and click Add. Now you can enter a name in the Setting field and click Add to activate the Preset. The Group and Setting should be displayed under the Select Preset header. Now you can add parameters to the variable list either by the drag-and-drop method or by selecting individual parameters from the dropdown menus.
Variable Presets are an incredibly versatile and powerful function within OpenVSP that enable multiple, preconfigured parameter settings to be swapped with the click of a button. In this tutorial, we will introduce Variable Presets and demonstrate how a wing’s surface resolution can be quickly changed by selecting and applying a preset.
You can inadvertently cause a conflict between design variables by choosing inactive or “dead” parameters that don’t have any control over your model or by adding multiple interconnected parameters to the same design variable list. For example, under the Wing Sect tab, if Span, Taper, and Root C are active, all other section planform parameters are deactivated. So just like trying to adjust the Area slider in this scenario, nothing will happen from the design variable window or files. However, if you were to add the Planform Total Area, Total Chord, and Total Span to the list, you’ll find that the values will be based on whichever parameter was changed last. Furthermore, if you try and alter the *.des text file and load values that are in conflict, your model will only update the values of some of the parameters.
One handy way of identifying potential conflicts among parameters is to see which values are updating automatically when you change a given parameter. In the above example with Span, Chord, and Area, you’ll find that adjusting the Area slider will update both Span and Chord automatically to new values. If you see this behavior, avoid adding one of these.
The Design Variable explorer is a handy way of finding the Container, Group, and Parm values for parameters that aren’t readily available by click-and-drag in the GUI. For example, the Translate options under the XForm tab don’t have a Parm popup that tells you this information. However, if you search for a component in the Container and the Attach Group, you’ll find a parm called “Trans_Attach_Flag” which controls this setting. You can change the value of this parameter under the Adjust tab and watch the checked box change in the GUI as the model updates to the new value. Not only is this useful for finding “hidden” parameters that you want to add to a Design file but the process may also be used to identify the Container, Group, and Parm values needed to interact with a model via scripts and the OpenVSP API in an automated way.
