Path: utzoo!attcan!uunet!husc6!bloom-beacon!bu-cs!purdue!decwrl!labrea!agate!eos!eugene
From: eugene@eos.UUCP (Eugene Miya)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle computer reprogramming
Message-ID: <1700@eos.UUCP>
Date: 12 Oct 88 07:13:19 GMT
References: <6689@nsc.nsc.com> <47200001@uicsrd.csrd.uiuc.edu>
Reply-To: eugene@eos.UUCP (Eugene Miya)
Organization: NASA Ames Research Center, Calif.
Lines: 28

You see understanding the problem is very simple (based on the one
thing I help launch). Solving it is tough.

You have this vehicle which has to traverse the thickness of the atmosphere,
but it's not that simple, the stuff moves in different directions at
different altitudes.  Slight differences may mean big expendatures of
fuel later down the flight path.  It's like the difference real and
apparent velocity in a plane.  Don't forget it's all transparent up
there.  I ask you the wind direction and velocity at 30K feet can you
tell me just by looking?  I doubt it (p.s. I want [u,v,w] not 95 deg.
true/39 knots).

The Shuttle has a unique problem: it's got wings.  These get in the way,
cylinders have few forces working on them (I had an Atlas).  The wings
are trying to "lift" (not a good word since it's upside down).  The
nunber of vectors to describe the forces acting on a flight path in
thick atmosphere gets complex.  The Shuttle can't sense wind very well
in flight, so weather ballons are sent up before hand.  It's just a mess.
Just deal with things in orbit and let the aerodynamics people deal with
these problems ;-).

Another gross generalization from

--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
  resident cynic at the Rock of Ages Home for Retired Hackers:
  "Mailers?! HA!", "If my mail does not reach you, please accept my apology."
  {uunet,hplabs,ncar,decwrl,allegra,tektronix}!ames!aurora!eugene
  "Send mail, avoid follow-ups.  If enough, I'll summarize."