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Posting-Version: version B 2.10.2 9/5/84; site mnetor.UUCP
Path: utzoo!utcs!mnetor!fred
From: fred@mnetor.UUCP (Fred Williams)
Newsgroups: net.space
Subject: Re: reentry of paper airplanes?
Message-ID: <829@mnetor.UUCP>
Date: Fri, 17-May-85 15:26:03 EDT
Article-I.D.: mnetor.829
Posted: Fri May 17 15:26:03 1985
Date-Received: Fri, 17-May-85 16:19:51 EDT
References: <1631@mordor.UUCP> <3000006@pbear.UUCP>
Reply-To: fred@mnetor.UUCP (Fred Williams)
Organization: Computer X (CANADA) Ltd., Toronto, Ontario, Canada
Lines: 57
Summary: 

In article <3000006@pbear.UUCP> peterb@pbear.UUCP writes:
>If you want to observe it, make it out of steel and use ground radar.
>

	Well I did think we were talking about a "paper airplane". If you
want to make one out of steel, why not put tiles on it too and call
	I had understood that the question was: "Would the paper burn
before the aerodynamic pressures slowed the plane sufficiently to
allow a non-desrtructive re-entry?"  If we use steel, what would be
the point?  I would only be interested in finding out whether or not
the low cross-sectional density of a paper plane would allow it to
be slowed up sufficiently before heating.  A steel plane would surely
burn unless protected in some way, or unless possibly it were decelerated
to zero velocity with respect to the ground and dropped straight down
only under its own weight.  Then I imagine it would depend on the
initial height.
it a "space shuttle" or something like that.

>As for needing thousands of MPH difference to inject it into reentry,
>look at skylab. It came down on drag alone. I am not implying a shuttle
>rentry orbit, just a reentry. A meter per second against the orbit would
>cause the airplane to drop into a lower orbit. If you applied about 10G
>using a slingshot, I think you could easily acheive reentry insertion,
>but the reentry would take quite a number of orbits  until drag from the
>atmosphere would pull it in for good.
>
	Please understand, I don't dispute that an object in orbit would
eventually fall to earth.  But from a practical standpoint I would
hate to have to wait around for a relatively stable orbit to decay.
	Also, I would not recommend a shuttle "eva" activity in an
orbit that was so close to a re-entry that an astronaut could throw
an object into re-entry.  No, the fact that the reactionary force
would "throw" the astronaut into a higher orbit does not alter my
opinion!

>Anybody out there have the equations handy (I don't have my physics book
>at work) I would like to run up a simulation of this. Mail it and comments
>to me
>
>Peter Barada
>{ihnp4!inmet | harvard!ima}!pbear!peterb

	Now, this idea of simulation seems to have merit!  I was about
to suggest that a computer simulation could give you all the answers
and allow you to vary the conditions and run repeated cases to your
heart's content at a very small fraction of the cost.
	Sorry, I used to work on aero-dynamic simulations of 
artillery shells, but that was years ago, and I don't have any
materials from that job.  It is quite a complicated procedure.

	To people in general;
			I promise to *try* not to post anything further on
this topic.  I know some of you must be getting tired of it by
now.  Thanks for your patience and the absence of flames!

Cheers,		Fred Williams