Ellipsoid

Contents

The Ellipsoid is a closed body with three radii, one along each axis. With all three equal it is a sphere; with two equal, a spheroid such as a radome, a tank end or a blister. It has one tab of its own, Design. The Gen, XForm, Mass and Sub tabs are described on their own pages.

Quick Start

1. Add an Ellipsoid. A new one is a sphere of radius 1.
2. Place it with the XForm tab.
3. Set A Radius, B Radius and C Radius.

Design

The surface is

$$\left(\frac{x - a}{a}\right)^2 + \left(\frac{y}{b}\right)^2 + \left(\frac{z}{c}\right)^2 = 1$$

so the Ellipsoid's nose, not its center, is at its origin, and it runs from $X = 0$ to $X = 2a$. Changing A Radius keeps the nose in place and moves the center. Rot Origin(X) on the XForm tab is a fraction of the length $2a$, so 0.5 turns the Ellipsoid about its center.

The surface follows this equation closely but not exactly: every point lies within 0.04 percent of the radius in its direction from the true ellipsoid. A radius may be zero, which flattens the Ellipsoid into an elliptical disk.