Category: Chapter 1: OpenVSP Fundamentals

Repeating Stack Sections

Introduction

One of the more interesting features of the Stack component is the ability to repeat sections quickly. This enables the user to create interesting or useful patterns of geometry. In this example, we take a wedge section wrapped about a rod and repeat that section to create an auger. In a similar fashion, the user could easily create spirals, coils, springs, chains, etc. Creating an OpenVSP geometry with these features would be extremely difficult (and sometimes impossible) with any other component type.

Stack Design Policy

Introduction

Stack components have a Free design policy by default. However, if you want to enforce a Loop policy simply change the XSec Order under the Design tab from Free to Loop. Notice that Stack Loops are different from Fuselage Loops in that the last cross-section is enforced to coincide with the first section rather than the other way around. This means that the first and last cross-sections are dependent on the translation and rotation set under the XForm tab.

Stack Cap Treatment

Introduction

Cap treatment may be added to Stack components by changing the Nose or Tail Cap Type under the Design tab. Similar to Fuselages, a cap is a different type of closure than manually setting a point or line cross-section. Caps may ensure that the geometry is watertight on each end but may cause point overlap issues in solvers such as VSPAERO.

Changing Stack Cross-Section Type

Introduction

Changing Stack cross-section types is fairly straightforward as usual. Just like with Fuselages, simply choose the Type dropdown under the XSec tab and select the desired option. Note that for some section families, such as airfoils, the Chord and T/C parameters or others may be used to set width and height. Also remember that the cross-section normal direction points toward the end of the Stack which means that the leading edge of airfoils or left-side of custom curves will be associated with the left side of the Stack.   Additional information about each section type is found in the Cross-Section Details subject.