Control Surface subsurfaces are unique to the OpenVSP Wing component and are used to define regions where ailerons, flaps, slats, etc. are placed in your model. The VSPAERO solver GUI and the API can also detect these types of subsurfaces and leverage them in vortex-lattice analyses. The region defined by a Control Surface may be tagged inside/outside as with any closed subsurface type and may also be defined on either the upper, lower, or both surfaces. Additionally, Control Surfaces may be tagged to attach at the leading edge rather than the trailing edge, if you wish.
Rather than define the subsurface with length and width in UW, Control Surfaces are defined in the chordwise direction as either a length or fraction of chord and in the spanwise direction by start/end U location. Note that by default, the Control Surface end angles will be automatically set to be aligned with the component X-axis.
The positive direction of control surface rotation will be about the +U axis along the wing. For a +U right-side wing, this means that trailing edge (TE) control surfaces will rotate TE down and leading edge (LE) control surfaces will rotate LE up on the RIGHT side and opposite this convention on the LEFT. It’s worth briefly noting here that the deflection setting in VSPAERO will therefore rotate the control surface in opposite directions like an aileron unless the gain for one surface is set to be negative e.g., VSPAERO > Control Grouping tab > Deflection Gain per Surface. Setting one of the gains to be negative will cause a negative rotation about the axis when a deflection is applied in VSPAERO.
Subsurfaces are lines, rectangles, or ellipses defined in the UW coordinates on an OpenVSP model surface. These features are honored by the CompGeom, CFD Mesh, and DegenGeom functions and may be used to model inlet/outlet boundary conditions, control surfaces, material properties, surface roughness, etc. This video provides an overview of the Subsurface panel in the OpenVSP GUI and demonstrates some basic use.
Linear parameter linking in OpenVSP is establishing a linear relationship between any two parameters according to a scale and offset by B = A*Scale + Offset where B is the dependent variable and A is the independent or driving variable. Setting up a linear link is relatively simple. Users may choose parameters from the dropdown menus or drag-and-drop a parameter onto the Parm A or Parm B variable selections and then click the Add Link button. All linear links will be displayed under the Parm Link List header. Note that you should use Links when specific linear relationships, including equality, are needed in your model but should avoid linking every parameter by default. As with many features in OpenVSP, less is often more.
Creating a linear link is very straightforward. Open the Model > Link menu and choose your A and B parameters to be linked. Recall that Parm B is the driven or dependent variable in the relationship. You may choose to set a Scale and/or Offset at the creation of the Link as well as any constraints on Parm B. Click Add Link to create the link and update the model.
To modify a Link, click on the Link in the Parm Link List and then alter the relationship using the activation buttons or entry fields.
Parametric clones are essentially when components are made to be identical to a parent component by linking all of the Design group parameters. This can be done quite easily by choosing Groups for two matching components and clicking Link All. However, in order for this process to work, each component must have the same number and type of Group so that the links relate directly to the parameters of the parent. This tutorial demonstrates creating clones with a Pod; a very simple example in which only the Design group parameters need to be linked to create a clone. A wing, on the other hand, requires that each component has the same number of sections, the same cross-section types, etc.
In some cases, users may wish to only link all of a certain group of parameters and allow others to remain free. In such a case, you may either pick and choose individual parameters one at a time or Link All for the chosen Group.
