Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!igor!eclipse!wab
From: wab@eclipse.Rational.COM (Bill Baker)
Newsgroups: sci.space.shuttle
Subject: Re: MANY QUESTIONS (Shuttle cabin survival)
Message-ID: <940@igor.Rational.COM>
Date: 21 Mar 91 02:52:57 GMT
References: <1991Mar13.045435.3817@zoo.toronto.edu> <923@igor.Rational.COM> <8097@crash.cts.com>
Sender: news@Rational.COM
Organization: Joan Vollmer Womens Academy
Lines: 111

In article <8097@crash.cts.com> adamsd@crash.cts.com (Adams Douglas) writes:
>If you're going to start mounting pyro-sep devices all over the orbiter,
>then the logical place to do it would be on the ET mounts. The reason there
>is no escape protocol when the SRBs are still attached is because all
>simulations show that a "normal" ET sep triggered at such a time would
>cause the orbiter to hang up on the aft attach points, flip over and break up.
>Remember, the ET explosion did _not_ cause Challenger to break up, it was
>being flopped around in a Mach 5 airflow that accomplished that.

This is exactly the point I was making.  Excluding pad failures, the
most likely periods for catastrophic failures are low ascent and
reentry.  Now, there may be a zillion things that could go wrong, but
the most likely result of any of them is breakup of the orbiter due to
aerodynamic effects.  Given this and including the fact that
(according to everything I read at the time of the Challenger crash)
the crew cabin is built much stronger than the rest of the orbiter,
the Challenger scenario (breakup, cabin surviving intact) is more
likely the model for future failures than the exception.  All
scenarios involving orbiter separation from the stack have a low
applicability because, most probably, there won't be an orbiter or a
stack left.

It seems like NASA came to the same conclusion that the orbiter is
very unlikely to survive intact from most failures, but their reply is
to assume that orbiter breakup equals immediate crew death.  So they
say, essentially, "If the orbiter does survive in one piece, here's a
big pole to slide out of it on."  Is there any other modern aircraft
whose entire crew survival system depends on a fire pole?

As I said, it seems to me that if we continue to lose a shuttle every
few years (1 in 78 chance of major failure with at least ten launches
a year equals an expensive fireworks demo at least once a decade) we
are going to see a lot of crew cabins surviving like the Challenger's.
Spinning extremely fast and on a ballistic road to hell, sure, but
still surviving the initial breakup mostly intact.  Next time we may
know for sure if a crew can survive this kind of failure, and if the
American public is treated to three minutes of screams as they plunge
to their doom NASA engineers will go down as the worst fools in
history.

>I, personally, would rather try to ditch or land with a reasonaly intact
>orbiter than a front cabin.

This seems to be the sentiment of most pilots, and in my opinion the
shuttle was built as a plane instead of as reentry capsule with lift
properties.  Tom Wolfe covers the philosphical differences between the
pilot/engineer camps in "The Right Stuff" but it boils down to this: A
plane has a pilot and a capsule has a test subject.  Pilots are in
control and they expect their machines to be built for them to make
heroic recoveries instead of punching out.  Pilots hate to punch out.
I'm sure that on the first shuttle launch Truly was thinking to
himself, "The hell with the ejection seats.  If the shit hits the fan,
I'm shutting down the computers and putting this baby down by the seat
of my pants."  So instead of thinking of the crew cabin as a
separatable capsule (which it wasn't designed to be, I know), they
think in terms of saving the "plane" or at least wrestling it into a
glide so they can slide down the pole and parachute, even though 
it's highly unlikely for a scenario allowing these heroics to occur.

In fact, I think the pole system (if you can call it a system) was
designed to create a scenario for heroics.  Unless the
computer-controlled flight software has an emergency stall profile
included, the orbiter must be manually controlled to get it
into a flight path from which it would be safe to bail out.  You 
certainly couldn't bail at supersonic speeds, and I imagine you'd
pretty much have to be low subsonic and in a reasonably flat attitude
to jump with a chance of surviving.  This means that someone's got to
fly the plane while everyone else jumps.

     Shuttle Commander:  I'll get this hummer flat and slow if it's
     the last thing I do.  You'll only have a few seconds so when you
     hear my signal jump and don't look back.

     Crew Member (preferably some sweet-faced Christa McAuliffe type):
     But what about you?  You'll never make it to the hatch before the
     orbiter dives out of control.

     SC:  'Tis a far, far better thing I do....

So, as has been said in this group before, the pole system is more a
political showpiece than a viable survival system.  I think you could
say the same about the flying basket and armored personal carrier
system for escaping from the shuttle on the pad.  Any pad failure so
serious that the crew has to escape quickly is most likely going to
result in an instantaneous fireball.  Planning for the slim chance
that there would be time to escape isn't worth the time and money, but
NASA built the basket anyway.  Why?  Not because they want to cover
every risk and damn the money.  No, because they've already thought of
the implications of the following scenario with no escape system:

     Mission Control:  T minus 7, engine start...T minus 4, turbopump
     failure!  Uncontrolled propellant venting!
     SC:  Oh Jesus....
     MC:  Fire on the pad!  Abort launch!  Main engine shutdown!
     Crew members:  Fire?  There's a fire in the engines!  Oh my God!
     MC:  ET valves are shut but we are still losing pressure in the
     hydrogen tank.
     SC:  Damn turbopump's holed the tank.  Mission Control, can we go
     down the elevator?
     MC:  Negative, the pad base is totally involved with flame.
     [This goes on for what seems like forever (but is probably less
     than a minute) with lots of screams and prayers.  Then the fire
     reaches the ET and boom!]
     MC:  Obviously a major malfunction....

Following which a grim Congressional committee plays the transcripts
for the current flunky in charge of NASA and NASA safety engineers spend
the rest of their lives hawking pencils.

I'm still waiting for one of those exhaustive Henry Spencer
rebuttals to my original posting.