From: Vincent Cate (vince@offshore.ai)
Subject: Re: Lunar Sample Return via Tether 
Newsgroups: sci.space.tech
Date: 2004-01-12 10:35:51 PST 
 

vince@offshore.ai (Vincent Cate) wrote:
> In order to avoid spinning too fast when you are winching a sample 
> in on one tether, you let the other tether out on the other side 
> at the same time.  This stores up the angular momentum and gets 
> the other tether ready to pickup a sample.

Sample #92 in my simulator now does this (winching one tether in 
while another is winching out).  

In order to get rid of waves in the tether I gave the winch 
a new option.  You can specify that a winch should only pull
in when the tension is less than some percentage of the recent 
average tension seen at the winch (you specify the time 
period).  Also when letting out you can specify that the 
minimum tension for letting out is a percentage of the recent 
average.  Values near 100% (so limit is recent average) work 
well at minimizing waves even though the speed and tension 
are changing as we come in or out.

Also, much of the power for winching in can come from the
winch/generator on the tether that is going out. They 
won't be going the same speed most of the time since 
the tension is higher for whichever is longer at the time.
You can specify a winch/generator power limit too.

Simulator is at:
   http://spacetethers.com/spacetethers.html

  - Vince

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Vincent Cate                           Space Tether Enthusiast 
 vince@offshore.ai                      http://spacetethers.com/
 Anguilla, East Caribbean               http://offshore.ai/vince
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You have to take life as it happens, but you should try to make it
happen the way you want to take it.    - German Proverb