Re: Interresting thread in comp.lang.eiffel

["Robert I. Eachus" <rieachus@earthlink.net>]

Ken Garlington wrote:
  
> Are we sure that there was no contractual arrangement between Arianespace
> and Sextant with respect to the use of the SRI on Ariane 5? The inquiry
> doesn't explicitly say either way, but having nothing at all would certainly
> be an unusual practice in my experience. My vague recollection of the
> Aviation Week & Space Technology articles from July-August 1996 was that
> there was some relationship, but I'll have to go by the library today to see
> for sure.

   As I remember it, there was planned to be a relationship as part of
the full-up
simulation of the flight control system.  When the decision was made not
to use the
SRIs in the simulation, that part of the contract was cut back or
cancelled.  I think
they still had the SRI hardware supplier on contract, but not the
software developers.

   I argee however, that the real lesson that should be drawn from this
is that there
has to be a project library--possibly on-line--that is accessable to all
subcontractors,
and that has at least all the interface specifications and the
operational concept. As
near as I can figure out, the management disconnect occured because
there was an original
test plan which covered all the bases, but changes to that plan were not
communicated to
everyone who needed to know about them.  As a result the lower level
test plans still
allocated test objectives to tests that were not conducted.  (The high
level objectives
were redistributed, but there were lower-level and derived requirements
that were never
reallocated.)

   Incidently, I was just looking at your YF-22 crash data.  The cause
may be called Pilot Induced Oscillation, but the real culprit was lack
of feedback to the pilot.  There was no
direct relationship between the position of the stick and the position
of the stabilators
in the later part of the event due to the rate-limited nature of the
stabilator controls.
I hope that this is fixed in the production F-22.  (The nasty effect of
the change in flight
control mode when the gear went up seems to have been key.  The pilot
was trying to cancel
out the change, but had no direct feedback.)