Pod

Contents

The Pod is the simplest component: a streamlined body of revolution set by two numbers, a length and a fineness ratio. Its profile is fixed: a full, rounded nose, its greatest diameter at mid-length, and a tail that tapers to a point. It is the quickest way to put a store, a tank, a fairing or a placeholder body into a model. A body of any other shape is a Fuselage or Stack, or a Body of Revolution.

The Pod has one tab of its own, Design. The Gen, XForm, Mass and Sub tabs are described on their own pages.

Quick Start

1. Add a Pod. A new one is 10 long, with its nose at its origin and its axis along $X$.
2. Place it with the XForm tab.
3. Set Length.
4. Set Fine Ratio to twice the length-to-diameter ratio wanted (see below).

Design

Fine Ratio is the length over the greatest radius, not the usual fineness ratio of length over diameter, and it keeps that definition so that existing models keep their shape. The length-to-diameter ratio is half of it: the default Pod, Fine Ratio 15, has a diameter of $2L/15$, $L/D = 7.5$. For a pod of length-to-diameter ratio $L/D$, set Fine Ratio to $2\,L/D$.

The radius is greatest, $R = L / \mathrm{FineRatio}$, at mid-length, and the profile is the same at every size (Figure 1). It reaches half of $R$ at $0.05L$ and 90 percent of it at $0.19L$; aft of mid-length it stays above 90 percent to $0.6L$, falls to half at $0.82L$, and closes to a point at the tail. Changing either value keeps the nose at the origin; Rot Origin(X) on the XForm tab is a fraction of the length.

Figure 1. The radius of a Pod along its length, as fractions of its greatest radius R and its length L.