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Path: utzoo!linus!philabs!cmcl2!seismo!ut-sally!mordor!@S1-A.ARPA,@MIT-MC:JOSH@RUTGERS.ARPA
From: @S1-A.ARPA,@MIT-MC:JOSH@RUTGERS.ARPA
Newsgroups: net.space
Subject: Swimming in air, etc
Message-ID: <1783@mordor.UUCP>
Date: Tue, 14-May-85 00:08:09 EDT
Article-I.D.: mordor.1783
Posted: Tue May 14 00:08:09 1985
Date-Received: Thu, 16-May-85 05:14:13 EDT
Sender: daemon@mordor.UUCP
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From: JoSH <JoSH@RUTGERS.ARPA>

"Swimming" in air is no different from swimming underwater, except that
air is 800 or so times less dense than water, so you obtain 800 times
less impetus from a given stroke.  Of course the stroke is easier to
make, but not 800 times so.
 I have found (by experiment) that one can obtain 5 or so pounds of
thrust in air using a large (12") model airplane propellor and an 
electric motor small enough to hold in one hand (from a weed trimmer,
if you're interested).  An average person could get 1 f/s^2 out of
this, so only a few seconds of use would be needed for any one movement.
Thus I would expect that a unit with fold-up prop, rare-earth motor,
and nicads could be built to last a normal day's use without recharging
and be a conveniently clip-on-belt sized item.

--JoSH
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