SpelSim Description

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Contents

SpelSim is a Space Elevator calculator (eventually a simulator). You can select values for all of the key parameters of the system, and the program will calculate and display the key values of the space elevator cable under those conditions.

Units

All numbers are expressed in the MKS system, using meters (m), kilograms (kg), and seconds (s). Units for a field are shown to the right of the value. Fields which display no units to the right of the value are unitless. The notation (m^2) means meters squared; m/(s^2) means meters per second squared.

Interface Basics

The interface panel is divided into three columns, one each for

Each column is indicated by the corresponding keyword in bold.

To the right of the bold label in each column is a preselected set of known items from which you can choose. If you wish to set your own values for that column, select the "custom" entry. Editable fields in that column will turn white. Output-only fields will stay gray, and have italic labels. These fields contain values which are calculated based on your inputs.

To change a value, select the "custom" entry for that column, edit the value in the desired field, or delete it and type in a new value, and press Enter. When you press Enter, all of the output-only values will be recalculated and displayed. If the values you select do not give a sensible answer, you may see question marks in some fields. For example, if you select a weak material on a planet with strong gravity and slow rotation, the required values may exceed what can be represented in a double variable (about 10^300), so you will get question marks for the cable values.

The Planet

You can select values for the following planet parameters:

The following values for the planet are calculated and displayed:

For comments about the values used for the known planets, download the kit, unpack the source, and look in the file src/net/jimmc/spelsim/Planet.java.

The Material

You can select values for the following material parameters:

There are no additional values calculated and displayed for a material.

The Cable

You can select values for the following cable parameters:

Most of the below values for the cable are calculated numerically rather than functionally. The cable length is divided into a large number of separate elements which are treated as point masses connected by a massless cable. Today's computers are fast enough to do this calculation quickly even when using many thousands of elements to model the cable.

The following values for the cable are calculated and displayed:

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March 17, 2003