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## How Wolfe's tether spreadsheet works

16 Dec 2015, 18:36 UTC (200 words excerpt, click title or image to see full post)

I want to do a series of blogs looking at different elevator and tether scenarios. They will be based on Chris Wolfe's spreadsheet for modeling tethers. I'll try to explain how it works.Tensile strengthDensity and tensile strength are important quantities for tether material. Tensile strength is measured in pascals.A pascal is a newton per square meter, newton/(meter2). A newton is a unit of force, mass times acceleration.Zylon has a tensile strength of 580 megapascals or 580 meganewtons per square meter. On earth's surface with it's 9.8 meter/sec2 acceleration, it would take a 591,836,735 kilogram mass to exert that much force. It would take a zylon cord with a cross section of one square meter to support this force. But that's more than half a million tonnes!10 tonnes is more plausible payload for space cargo. A much thinner cord could support this. Cross section of a Zylon cord need only be 1.72e-9 square meters. If a circular cross section, cord would be about 47 micrometers thick. Strands of hair can be anywhere from 17 to 181 micrometers thick.So number of newtons determines tether cross sectional area.How many newtons?How to figure number of newtons at the tether foot? First we set maximum ...