The Scale XSec group under the Curve tab in the Curve Editor is where users will find the scaling parameters for the cross-section such as height, width, and area. Recall that the parameterized curve defined by the control points is in one coordinate space which is then scaled along the horizontal and vertical axes by width and height, respectively to achieve the final shape. Because the Edit Curve is an integrable function in all three curve types, the area bound by the curve may be computed. Alternatively, if the area is fixed then OpenVSP may iteratively solve for the remaining parameters. This is particularly useful for supersonic or flow-through sections.
Under normal circumstances, the range of the X and Y coordinates of the Edit Curve are from -0.5 to 0.5 or having unit distance. This ensures that the scaled height and width correspond to a representative physical dimension in the model. However, the curve is under no such constraint to prevent the range from being larger or smaller than the +/- 0.5 values. For example, a cross-section with height = 2.0, having Y coordinates from -1.0 to 1.0 (distance of 2.0), would have a measured physical height of 4.0. Again, users must take great care when setting control points in the display or in the Control Points fields to ensure that their design intent is being maintained.