Re: ARIANE-5 Failure

[Dale Stanbrough <dale@goanna.cs.rmit.EDU.AU>]

Robert Dewar writes:
"Sounds bogus, ultimately the code is maintained by humans, we do not yet
 have robots that can write and maintain code. Sure the code may be in
 some other language than Ada and then generate Ada (if the Ada is not
 maintained, but is just used as an intermediate language, it is 
 essentially irrelevant that it is Ada). So the question is: what
 language WAS the software written in? And what is the argument that
 this code is easier to maintain than properly written Ada?"


I'm not sure this really answers Robert's questions. Nonetheless, here
they are...a few postings from previous years. 

I think I may have displaced David Weller as the ultimate posting hoarder! :-).

Dale
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From: berman@umbc.edu (Mike Berman)
Newsgroups: comp.lang.ada
Subject: DC-X use of Ada
Date: 15 Sep 1993 17:45:40 -0400
Organization: University of Maryland, Baltimore County Campus


In its September 13 "Filter Center", Aviation Week and Space Technology
mentions that McDonnell Douglas developed software for guidance and
control of the DC-X Single-Stage-to_Orbit (SSTO) launch vehicle using
the MATRIXx toolset from Integrated Systems, Inc. Use of the tool saved
an estimated 50% of normal development costs and "produced very reliable
code". The article mentions that there are more than 30,000 lines of Ada
code, but does not say how much was hand crafted vs. tool generated.

A recent posting summarized the successful first flight of the DC-X test
vehicle. An Ada success story? Could be...

-- 
Mike Berman
University of Maryland, Baltimore County     Fastrak Training, Inc.
berman@umbc.edu                              (301)924-0050
       The views represented in the above post are my own.
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Also posted... (and note info on the "explosion" later on).

Dale
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Newsgroups: comp.lang.ada
Subject: DC-X Test Flight
Date: 8 Sep 1993 13:10:45 -0500
Organization: Washington University in Saint Louis, MO
Summary: DC-X, whose software is in Ada, flew successfully in late August


Several months ago, Jerry Pournelle started his User's Column in Byte
with a description of the DC-X and its software.  Jerry
added that he spoke with the lead of the software development team and
found that, for the first time in the team's experience, software came
in on time and schedule.  The software for DC-X (Douglas Clipper -
Experimental) was written in Ada using MatrixX.

More information on DC-X can be found in the August 30 issue of Time,
page 47.

Thought this group might be interested.

-- Rick Conn

The following is from the posting to sci.space.news on 8/28/93. 

|> DC-X Post-Flight Condition
|> 
|> The worst thing that happened to DC-X during this first flight was that one
|> side of the fiberglass nose cone was scorched.  It will have to be replaced,
|> no big deal as there are several spares.  This probably happened right after
|> engine start, when the cloud of vented hydrogen around the vehicle ignited.
|> 
|> This looked scary, but is a routine part of operating DC-X, albeit one
|> that turned out to be a bit more spectacular than planned.  Liquid hydrogen
|> is run through the engines to precool them before startup, then vented to
the
|> air, producing the vapor clouds visible before engine start in the flight
test
|> video footage.  When the engines start, unless there's a strong breeze the
|> hydrogen concentration neaby is high enough to ignite, producing a
half-second
|> fireball around the bottom of the vehicle.
|> 
|> This is how DC-X lost its McDonnell-Douglas and SDIO decals and had its
white
|> factory paint job turned to mottled gray during the test stand engine
|> firings back in May and June.  Everything below the nose cone is designed to
|> stand the heat, and of course in any spaceworthy descendant of DC-X the nose
|> cone would not be made from fiberglass, since it would have to stand up to
|> far worse heat during reentry.  
|> 
|> Outside of that, DC-X's base suffered some minor dings from bits of concrete
|> sent flying around by the rocket blast during landing.  Nothing unexpected;
|> the base was designed to stand a fair amount of this.  

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