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Re: Problems
- To: KellySt@aol.com, kgstar@most.magec.com, stevev@efn.org, jim@bogie2.bio.purdue.edu, zkulpa@zmit1.ippt.gov.pl, hous0042@maroon.tc.umn.edu, rddesign@wolfenet.com, David@InterWorld.com, lparker@destin.gulfnet.com, bmansur@oc.edu
- Subject: Re: Problems
- From: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)
- Date: Fri, 08 Mar 1996 18:47:53 +0100
To Brian
> Now that I have a concept of how to get a sail driven starship to TC in
>less than 50 years, I'm trying to get some questions answered on the ship's
>dry weight requirements and whether or not they can be met.
>My Argosy design, as of last night, requires:
>
>1000km wide sail.
>A crew of 400
>An exploration module (ion drive plus habitat) weight of 350,000 tons minus
>reaction mass
>A maximum cruise velocity of .75c.
>A minimum power requirement of 1E18W.
>
>1. Can a 1000 km wide sail made mostly of chicken wire or flimsy silver
>foil be rigged to support a 350,000 ton ship without being ripped to shreds?
The pressure on every part of the sail would be 10 bar (1E6 Pa). You could
easely bend chickenwire with such a force. Besides this, there have to be
connections to the ship, at these connections the pressures would be much
higher, since they collect all the force to a small area.
So if you aren't going to make connection wires every metre, I don't think
the thing will hold.
>2. Will the guy wires/cables snap under their own weight given a 10m/s^2
>acceleration?
That depends on the amount of cables (see above).
>3. How heavy would the cables need to be to prevent snapping. Tim gave me
>some equations a while back when I wanted to tether a solar collector array
>to Mercury. I haven't had time to try to make sense of them but he said the
>cables would probably snap under their own weight.
Yes, but that assumed very long cables, these cables are about 2 kilometres
at max.
Tim