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From: swift@reed.UUCP (Theodore Swift)
Newsgroups: net.space
Subject: Re: swimming in space
Message-ID: <1539@reed.UUCP>
Date: Thu, 16-May-85 22:07:04 EDT
Article-I.D.: reed.1539
Posted: Thu May 16 22:07:04 1985
Date-Received: Sat, 18-May-85 02:05:13 EDT
References: <1709@mordor.UUCP>
Reply-To: swift@reed.UUCP (ted swift)
Organization: Reed College, Portland, Oregon
Lines: 28
Keywords: butterflies...
Summary: there are bulk/surface area problems 

>   I belive that the rocket-propulsion schemes (throwing a ball,
>blowing a balloon) are all much much less efficient than something
>that involves taking advantage of pushing off of the air itself.
>(i.e., heavier than air flight with wings and propellors can be done
>with a lot less power than a plain reaction rocket-engine)
> The suggestion of swim fins seems like about the best idea. 

In considering "efficiency" you might consider that swim fins push
against water, and your proposed "air fins" work against air (at a 
reduced pressure of something like 10 psi to boot, if what I've heard
is correct).  I believe air is something like 1/20 as dense as air (at
14.7psi), so to get the "same effect" you'd need fins 20 times bigger,
i.e., big mongo butterfly wings!  This might be OK in Heinlein's big
flying chamber on the moon (see, I believe, _The Moon is a Harsh Mistress_)
but it's downright lethal in a space station.  If you brush the wrong
switch with your multicolored wings (made by Hobie, no doubt :-)) you're
liable to do something irreversibly bad. (see Niven's stories about 
Belters- people who live in small ships in the Asteroid belt.)
   The idea of a balloon is good, as long as you take care where and how
you inhale.  I'd suggest inhaling through both sides of your mouth, then
exhaling into the balloon.  Better yet, don't get into the situation of
being stuck out there in the first place.  It would be hard to do, anyway
since you'd have to leave your last wall with SOME velocity.
  If the ship fired it's rockets while one was floating in "midair", of
course the ship would accelerate "at you" at whatever rate the engines were
giving it.  This could hurt.  A lot.
  Most of these questions can be answered by taking a good squint at
Sir Isaac's three laws.