Introduction

By default, OpenVSP sets all airfoil sections to be vertical regardless of dihedral. This assumption works very well for relatively small dihedral angles and maintains surfaces as “watertight” for export to solvers or other tools. However, there are cases where it is preferred to have very large dihedral angles, such as with winglets, when vertical airfoils would collapse the wing section to a plate. By rotating the airfoils to match the dihedral angles, OpenVSP attempts to set the airfoils to be perpendicular to the wing rather than the horizontal and allow features such as winglets to have thickness corresponding to their design. Note that the entire wing will rotate airfoils with this setting and if there is a non-zero dihedral at the wing root, the surfaces will not be watertight. To avoid this, place a small wing section (span of ~0.05 ft to 0.1 ft) at the root with zero dihedral and then correct for this addition by changing the span, etc. of the next section. This enforces vertical airfoil sections at the root and will maintain a watertight surface in your model.

Introduction

You can change the how the ends or “caps” of your components are closed by altering the cap treatment. Options include Flat (default), Round, Edge, and Sharp. Note that OpenVSP will automatically blend between caps of different types at junctions such as the wingtip of the trailing edge.

Introduction

This tutorial will show the difference between using Relative (Rel) and Absolute (Abs) reference flags in setting Twist and Dihedral for a Wing. When using Absolute reference for these angles, the values entered are referenced to the component frame. When using Relative reference, the value is read as a shift or delta in the previous section’s Twist or Dihedral.

Introduction

This tutorial will cover the Sweep, Twist, and Dihedral parameters under the Section (Sect) tab of the Wing component. The Sweep can be defined as an angle through any percent chord location in a section. The Sweep and its control station do not have to be the same between sections. The Twist and Dihedral behave similar to sweep. Note that the Dihedral angle is set by the line through the chord of the inboard station at the Twist control point and the corresponding location in the outboard station.

Introduction

The component symmetry behavior depends on how you attach your component and what reference you are using for your Axial or Planar symmetry.